Abstract:

In Brazil, the frailty index has not been evaluated previously for its capacity to predict mortality in community-dwelling elderly. The objective of the current study was to evaluate the association between frailty index and mortality in the elderly. This was a prospective study consisting of data from the FIBRA Network-2008-2009 in Campinas, São Paulo State, with information on community-dwelling older adults from the urban area and through the Mortality Information System. Comparisons and statistical associations were performed with the following tests: Mann-Whitney, Kruskal-Wallis, chi-square, and Cox regression with 95% confidence intervals. A total of 689 older adults participated 72.1 ± 5.3 years), of whom 68.8% were women. The prevalence rate for frailty was 38.8%, compared to 51.6% for pre-frailty and 9.6% for fit elders; overall mean frailty index was higher in women. There was no association between frailty index and chronological age. Cox regression showed that the variables age HR: 1.10; 95%CI: 1.05-1.15) and gender HR: 0.57; 95%CI: 0.33-0.99) were significantly associated with mortality. No association was found between frailty index and mortality HR: 3.02; 95%CI: 0.24-37.64). Frailty index was not capable of predicting mortality in community-dwelling elderly Brazilians.

Keywords:
Aged; Frail Elderly; Health of the Elderly; Mortality

Introduction

Frailty is defined as a clinical syndrome with increased vulnerability to various types of internal and external stressors. The syndrome reflects a decline in energy reserves, inherent to physiological aging, which can be aggravated by current and life-course biological and environmental variables ¹1. Mitnitski AB, Mogilner AJ, Rockwood K. Accumulation of deficits as a proxy measure of aging. ScientificWorldJournal 2001; 1:323-36.^,22. Kulminski A, Yashin A, Ukraintseva S, Akushevich I, Arbeev K, Land K, et al. Accumulation of health disorders as a systemic measure of aging: findings from the NLTCS data. Mech Ageing Dev 2006; 127:840-8.^,33. Fried LP, Tangen C, Walston J, Newman AB, Hirsch C, Gottdiener J, et al. Frailty in older adults: evidence for a phenotype. J Gerontol A Biol Sci Med Sci 2001; 56:M146-56.^,44. Walston J, Hadley EV, Ferrucci L, Guralnik JM, Newman AB, Studenski SA, et al. Research agenda for frailty in older adults: toward a better understanding of physiology and etiology: summary from the American Geriatrics Society/National Institute on Aging Research Conference on Frailty in older adults. J Am Geriatr Soc 2006; 54:991-1001.. It involves a set of characteristics and genetic and environmental determinants that distinguish individuals in a cohort ⁴4. Walston J, Hadley EV, Ferrucci L, Guralnik JM, Newman AB, Studenski SA, et al. Research agenda for frailty in older adults: toward a better understanding of physiology and etiology: summary from the American Geriatrics Society/National Institute on Aging Research Conference on Frailty in older adults. J Am Geriatr Soc 2006; 54:991-1001.^,55. Karunananthan S, Wolfson C, Bergman H, Béland F, Hogan DB. A multidisciplinary systematic literature review on frailty: overview of the methodology used by the Canadian Initiative on Frailty and Aging. BMC Med Res Methodol 2009; 9:68.^,66. Sternberg SA, Schwartz AW, Karunananthan S, Bergman H, Clarfield AM. The identification of frailty: a systematic literature review. J Am Geriatr Soc 2011; 59:2129-38.. There is a consensus among researchers concerning the notion of increased vulnerability, heterogeneity, and multidimensionality associated with frailty ⁴4. Walston J, Hadley EV, Ferrucci L, Guralnik JM, Newman AB, Studenski SA, et al. Research agenda for frailty in older adults: toward a better understanding of physiology and etiology: summary from the American Geriatrics Society/National Institute on Aging Research Conference on Frailty in older adults. J Am Geriatr Soc 2006; 54:991-1001.^,77. Rockwood K, Mitnitski A. Frailty in relation to the accumulation of deficits. J Gerontol A Biol Sci Med Sci 2007; 62:722-7.^,88. Yang Y, Lee LC. Dynamics and heterogeneity in the process of human frailty and aging: evidence from the U.S. older adult population. J Gerontol B Psychol Sci Soc Sci 2010; 65:246-55.^,99. Rodríguez-Mañas L, Féart C, Mann G, Viña J, Chatterji S, Chdozko-Zajko W, et al. Searching for a operational definition of frailty: a Delphi method based consensus statement. The Frailty Operative Definition-Consensus Conference Project. J Gerontol A Biol Sci Med Sci 2013; 68:62-7.^,1010. Morley JE, Vellas B, van Kan GA, Anker SD, Bauer JM, Bernabei R, et al. Frailty consensus: a call for action. J Am Med Dir Assoc 2013; 14:392-7.. In clinical terms, it includes risks of adverse events such as falls, reduced mobility, loss of independence, hospitalization, disability, and death. Among these outcomes, mortality, functional disability, and institutionalization are the most common findings in the literature ⁶6. Sternberg SA, Schwartz AW, Karunananthan S, Bergman H, Clarfield AM. The identification of frailty: a systematic literature review. J Am Geriatr Soc 2011; 59:2129-38.^,1111. Bouillon K, Kivimaki M, Hamer M, Sabia S, Fransson EI, Singh-Manoux A, et al. Measures of frailty in population based studies: an overview. BMC Geriatr 2013; 13:64..

There are different ways of operationalizing the frailty phenomenon ³3. Fried LP, Tangen C, Walston J, Newman AB, Hirsch C, Gottdiener J, et al. Frailty in older adults: evidence for a phenotype. J Gerontol A Biol Sci Med Sci 2001; 56:M146-56.^,44. Walston J, Hadley EV, Ferrucci L, Guralnik JM, Newman AB, Studenski SA, et al. Research agenda for frailty in older adults: toward a better understanding of physiology and etiology: summary from the American Geriatrics Society/National Institute on Aging Research Conference on Frailty in older adults. J Am Geriatr Soc 2006; 54:991-1001.^,55. Karunananthan S, Wolfson C, Bergman H, Béland F, Hogan DB. A multidisciplinary systematic literature review on frailty: overview of the methodology used by the Canadian Initiative on Frailty and Aging. BMC Med Res Methodol 2009; 9:68.^,66. Sternberg SA, Schwartz AW, Karunananthan S, Bergman H, Clarfield AM. The identification of frailty: a systematic literature review. J Am Geriatr Soc 2011; 59:2129-38.^,99. Rodríguez-Mañas L, Féart C, Mann G, Viña J, Chatterji S, Chdozko-Zajko W, et al. Searching for a operational definition of frailty: a Delphi method based consensus statement. The Frailty Operative Definition-Consensus Conference Project. J Gerontol A Biol Sci Med Sci 2013; 68:62-7.. According to a literature review by Boiullon et al. ¹¹11. Bouillon K, Kivimaki M, Hamer M, Sabia S, Fransson EI, Singh-Manoux A, et al. Measures of frailty in population based studies: an overview. BMC Geriatr 2013; 13:64., the most widely adopted model is the frailty phenotype proposed by Fried et al. ³3. Fried LP, Tangen C, Walston J, Newman AB, Hirsch C, Gottdiener J, et al. Frailty in older adults: evidence for a phenotype. J Gerontol A Biol Sci Med Sci 2001; 56:M146-56., followed by the frailty index FI) described by Mitnitski et al. ¹1. Mitnitski AB, Mogilner AJ, Rockwood K. Accumulation of deficits as a proxy measure of aging. ScientificWorldJournal 2001; 1:323-36. and Rockwood & Mitnitski ⁷7. Rockwood K, Mitnitski A. Frailty in relation to the accumulation of deficits. J Gerontol A Biol Sci Med Sci 2007; 62:722-7..

FI is a mathematical model derived from data from the longitudinal Canadian Study of Health and Aging CSHA) ¹1. Mitnitski AB, Mogilner AJ, Rockwood K. Accumulation of deficits as a proxy measure of aging. ScientificWorldJournal 2001; 1:323-36.^,1212. Searle SD, Mitnitski AB, Gahbauer EA, Gill TM, Rockwood K. A standard procedure for creating a frailty index. BMC Geriatr 2008; 8:24.. It does not provide for a specific set of clinical markers present in old age, as in the model by Fried et al. ³3. Fried LP, Tangen C, Walston J, Newman AB, Hirsch C, Gottdiener J, et al. Frailty in older adults: evidence for a phenotype. J Gerontol A Biol Sci Med Sci 2001; 56:M146-56., but rather a sum of observed deficits in different systems at the time of measurement signs, symptoms, functional disability, diseases, laboratory results) ¹1. Mitnitski AB, Mogilner AJ, Rockwood K. Accumulation of deficits as a proxy measure of aging. ScientificWorldJournal 2001; 1:323-36.^,22. Kulminski A, Yashin A, Ukraintseva S, Akushevich I, Arbeev K, Land K, et al. Accumulation of health disorders as a systemic measure of aging: findings from the NLTCS data. Mech Ageing Dev 2006; 127:840-8.^,77. Rockwood K, Mitnitski A. Frailty in relation to the accumulation of deficits. J Gerontol A Biol Sci Med Sci 2007; 62:722-7., based on the notion that age-related changes have a cumulative effect on health. It is based on the quantification of observed changes in a variety of physiological, psychological, and functional conditions and the search for relations between them and adverse outcomes in the elderly ¹²12. Searle SD, Mitnitski AB, Gahbauer EA, Gill TM, Rockwood K. A standard procedure for creating a frailty index. BMC Geriatr 2008; 8:24.^,1313. Drubbel I, Numans ME, Kranenburg G, Bleijenberg N, de Wit NJ, Schuurmans MJ. Screening for frailty in primary care: a systematic review of the psychometric properties of the frailty index in community-dwelling older people. BMC Geriatr 2014; 14:27.. According to the Rockwood & Mitnitski ⁷7. Rockwood K, Mitnitski A. Frailty in relation to the accumulation of deficits. J Gerontol A Biol Sci Med Sci 2007; 62:722-7., frailty results from an accumulation of deficits and expresses a continuous scale ranging from 0 to 1, which reflects the relationship between the number of deficits the individual presents and the total number of possible deficits from a model corresponding to the study sample for example, an individual with 4 deficits in 38 study variables has a frailty index of 0.10) ⁷7. Rockwood K, Mitnitski A. Frailty in relation to the accumulation of deficits. J Gerontol A Biol Sci Med Sci 2007; 62:722-7.^,1212. Searle SD, Mitnitski AB, Gahbauer EA, Gill TM, Rockwood K. A standard procedure for creating a frailty index. BMC Geriatr 2008; 8:24..

The FI does not require the inclusion of a specific number of deficits. Previous studies have used 30 to 70 variables ¹1. Mitnitski AB, Mogilner AJ, Rockwood K. Accumulation of deficits as a proxy measure of aging. ScientificWorldJournal 2001; 1:323-36.^,22. Kulminski A, Yashin A, Ukraintseva S, Akushevich I, Arbeev K, Land K, et al. Accumulation of health disorders as a systemic measure of aging: findings from the NLTCS data. Mech Ageing Dev 2006; 127:840-8.^,77. Rockwood K, Mitnitski A. Frailty in relation to the accumulation of deficits. J Gerontol A Biol Sci Med Sci 2007; 62:722-7.^,1414. Song X, Mitnitski A, Rockwood K. Prevalence and 10-year outcomes of frailty in older adults in relation to deficit accumulation. J Am Geriatr Soc 2010; 58:681-7.^,1515. Fang X, Shi J, Song X, Mitnitski A, Tang Z, Wang C, et al. Frailty in relation to the risk of falls, fractures, and mortality in older Chinese adults: results from the Beijing Longitudinal Study of Aging. J Nutr Health Aging 2012; 16:903-7.. However, to be part of the index, the variable must meet the following criteria: associated with age and negative health outcomes; present in at least 1% of the population; includes various organ systems; does not contain more than 5% missing data; and is not saturated, i.e., present in at least 80% of individuals below 90 years of age ¹²12. Searle SD, Mitnitski AB, Gahbauer EA, Gill TM, Rockwood K. A standard procedure for creating a frailty index. BMC Geriatr 2008; 8:24.^,1616. Rockwood K, Mitnitski A. Frailty defined by deficit accumulation and geriatric medicine defined by frailty. Clin Geriatr Med 2011; 27:17-26.^,1717. Howlett SE, Rocwood K. New horizons in frailty: ageing and the deficits-scaling problems. Age Ageing 2013; 42:416-23.. In community-dwelling elderly, the prevalence of frailty measured by the FI model is around 24% ¹⁴14. Song X, Mitnitski A, Rockwood K. Prevalence and 10-year outcomes of frailty in older adults in relation to deficit accumulation. J Am Geriatr Soc 2010; 58:681-7.^,1818. Collard RM, Boter H, Schoevers RA, Voshaar RCO. Prevalence of frailty in community-dwelling older persons: a systematic review. J Am Geriatr Soc 2012; 60:1487-92.^,1919. Shamlyian T, Talley KMC, Ramakrishnan R, Kane R. Association of frailty with survival: a systematic literature review. Ageing Res Rev 2013; 12:719-36.. It is higher in women than in men and increases with age ¹³13. Drubbel I, Numans ME, Kranenburg G, Bleijenberg N, de Wit NJ, Schuurmans MJ. Screening for frailty in primary care: a systematic review of the psychometric properties of the frailty index in community-dwelling older people. BMC Geriatr 2014; 14:27.^,1414. Song X, Mitnitski A, Rockwood K. Prevalence and 10-year outcomes of frailty in older adults in relation to deficit accumulation. J Am Geriatr Soc 2010; 58:681-7.^,1515. Fang X, Shi J, Song X, Mitnitski A, Tang Z, Wang C, et al. Frailty in relation to the risk of falls, fractures, and mortality in older Chinese adults: results from the Beijing Longitudinal Study of Aging. J Nutr Health Aging 2012; 16:903-7.^,1919. Shamlyian T, Talley KMC, Ramakrishnan R, Kane R. Association of frailty with survival: a systematic literature review. Ageing Res Rev 2013; 12:719-36.^,2020. Kulminski AM, Ukraintseva SV, Kulminskaya IV, Arbeev KG, Land K, Yashin AI. Cumulative deficits better characterize susceptibility to death in elderly people than phenotypic frailty: lessons from the Cardiovascular Health Study. J Am Geriatr Soc 2008; 56:898-903..

In Song et al. ¹⁴, FI consisted of 36 deficits that included health conditions, signs and symptoms, and functional disability. Frail individuals were defined as those that scored > 0.25. The results showed that mean FI was higher in elderly individuals that died during follow-up compared to those that survived. Having more deficits was associated with greater risk of adverse events. Frail elderly showed 15% greater risk of death than non-frail elders, independently of gender ¹⁹19. Shamlyian T, Talley KMC, Ramakrishnan R, Kane R. Association of frailty with survival: a systematic literature review. Ageing Res Rev 2013; 12:719-36.. FI is a more robust predictor of mortality than chronological age ²2. Kulminski A, Yashin A, Ukraintseva S, Akushevich I, Arbeev K, Land K, et al. Accumulation of health disorders as a systemic measure of aging: findings from the NLTCS data. Mech Ageing Dev 2006; 127:840-8.^,77. Rockwood K, Mitnitski A. Frailty in relation to the accumulation of deficits. J Gerontol A Biol Sci Med Sci 2007; 62:722-7.^,1414. Song X, Mitnitski A, Rockwood K. Prevalence and 10-year outcomes of frailty in older adults in relation to deficit accumulation. J Am Geriatr Soc 2010; 58:681-7..

In Kulminski et al. ²⁰20. Kulminski AM, Ukraintseva SV, Kulminskaya IV, Arbeev KG, Land K, Yashin AI. Cumulative deficits better characterize susceptibility to death in elderly people than phenotypic frailty: lessons from the Cardiovascular Health Study. J Am Geriatr Soc 2008; 56:898-903., FI showed greater accuracy than frailty phenotype in discriminating elderly with moderate to severe frailty ³3. Fried LP, Tangen C, Walston J, Newman AB, Hirsch C, Gottdiener J, et al. Frailty in older adults: evidence for a phenotype. J Gerontol A Biol Sci Med Sci 2001; 56:M146-56., since it assesses frailty as the product of the cumulative effect of deficits in multiple physiological systems on a continuous scale rather than by specific indicators present in old age ¹¹11. Bouillon K, Kivimaki M, Hamer M, Sabia S, Fransson EI, Singh-Manoux A, et al. Measures of frailty in population based studies: an overview. BMC Geriatr 2013; 13:64.^,1414. Song X, Mitnitski A, Rockwood K. Prevalence and 10-year outcomes of frailty in older adults in relation to deficit accumulation. J Am Geriatr Soc 2010; 58:681-7.^,1919. Shamlyian T, Talley KMC, Ramakrishnan R, Kane R. Association of frailty with survival: a systematic literature review. Ageing Res Rev 2013; 12:719-36.^,2020. Kulminski AM, Ukraintseva SV, Kulminskaya IV, Arbeev KG, Land K, Yashin AI. Cumulative deficits better characterize susceptibility to death in elderly people than phenotypic frailty: lessons from the Cardiovascular Health Study. J Am Geriatr Soc 2008; 56:898-903.^,2121. Blodgett J, Theou O, Kirkland S, Andreou P, Rockwood K. Frailty in NHANES: comparing the frailty index and phenotype. Arch Gerontol Geriatr 2015; 60:464-70.. Based on the concept of biological heterogeneity, a higher FI score is associated with greater risk of death, independently of chronological age ¹1. Mitnitski AB, Mogilner AJ, Rockwood K. Accumulation of deficits as a proxy measure of aging. ScientificWorldJournal 2001; 1:323-36.. In this context, the current study’s hypothesis was that the frailty index is capable of predicting mortality, independently of chronological age. There are no Brazilian studies on frailty and mortality in the elderly using the cumulative deficits model. The study aimed to investigate the prevalence of frailty based on the frailty index and the association between this measure of frailty and death in community-dwelling elderly.

Material and methods

This study was based on two databases. One was the electronic database from the FIBRA Study the Portuguese acronym for Frailty in Elderly Brazilians), conducted in Campinas, São Paulo State, Brazil, in the context of a multicenter, population-based cross-sectional study aimed at investigating frailty and its relations with socio-demographic, psychosocial, clinical, cognitive, anthropometric, functional capacity, and physical and mental health variables in community-dwelling elderly. The second database was from the Mortality Information System SIM) of the city of Campinas for the years 2009, 2010, 2011, 2012, and 2013, accessed every six months.

The FIBRA Study project was submitted to the Ethics Committee for Research in Human Subjects, School of Medicine, State University in Campinas, and approved under case review n. 208/2007. The current study was submitted as an addendum to the main project and was approved under case review n. 736.943∕2010. The ethical principles of the Declaration of Helsinki were followed, and all the participants signed a free and informed consent form.

Participants

Participants in the FIBRA Study were recruited in family or individual households located in 90 randomly selected urban census tracts in Campinas, in which previously specified quotas of men and women were recruited, 65 to 69, 70 to 74, 75 to 79, and 80 years and older. The quotas were proportional to their presence in the elderly population in each census tract. The following eligibility criteria were adopted: age 65 years or older, permanent resident in the household and in the census tract, and absence of severe cognitive, communicative, or sensory impairment or severely impaired mobility. The exclusion criteria were: problems with memory, attention, orientation in time and space, and communication, suggestive of dementia; bedridden elderly; elderly with severe stroke sequelas, with loss of strength and/or aphasia; advanced or unstable Parkinson’s disease, with serious impairment of mobility, speech, or affect; seriously impaired hearing or vision, hindering communication; and terminal illness ²²22. Ferrucci L, Guralnik JM, Studenski S, Fried LP, Cutler Jr. GB, Walston JD, et al. Designing randomized, controlled trials aimed at preventing or delaying functional decline and disability in frail, older persons: a consensus report. J Am Geriatr Soc 2004; 52:625-34.. Of all the elderly recruited, 1,055 appeared at the data collection sites and 900 comprised the sample. The 155 exclusions were due to the following: age under 65 years, and non-resident in the census tract, and withdrawal.

The 900 selected elderly participated in the first phase of the data collection, consisting of a section on socio-demographic, anthropometric, clinical, and frailty measures ³3. Fried LP, Tangen C, Walston J, Newman AB, Hirsch C, Gottdiener J, et al. Frailty in older adults: evidence for a phenotype. J Gerontol A Biol Sci Med Sci 2001; 56:M146-56.. In this phase, the score obtained on the Mini Mental State Examination MMSE) was used as the criterion for participation in the second data collection phase, on self-rated physical and mental health, functional performance, and subjective well-being. The following cutoff scores were used for exclusion: 17 for illiterate individuals; 22 for elderly with 1 to 4 years of schooling; 24 for those with 5 to 8 years of schooling; and 26 for those with at least 9 years of schooling ²³23. Folstein MF, Folstein SE, McHugh PR. "Mini-mental state". A practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res 1975; 12:189-98.^,2424. Bertolucci PHF, Brucki SMD, Campacci S, Juliano Y. O Mini-Exame do Estado Mental em uma população geral: impacto da escolaridade. Arq Neuropsiquiatr 1994; 52:1-7.^,2525. Brucki SMD, Nitrini R, Caramelli P, Bertolucci PHF, Okamoto IH. Sugestões para o uso do Mini-Exame do Estado Mental no Brasil. Arq Neuropsiquiatr 2003; 61:777-81.. Six hundred and eighty-nine elderly without cognitive deficit suggestive of dementia selected according to this criterion constituted the current study’s sample. Mean age was 72.1 ± 5.3 years; 68.8% were women ²⁶26. Neri AL, Yassuda MS, Araújo LF, Eulálio MC, Cabral BE, Siqueira MEC, et al. Metodologia e perfil sociodemográfico, cognitivo e de fragilidade de idosos comunitários de sete cidades brasileiras: Estudo FIBRA. Cad Saúde Pública 2013; 29:778-92. Figure 1).

Variables and measures

The target variables were investigated according to the following conditions:

a) FI: composition of the index used 40 variables from different domains assessed by the FIBRA Study, according to the eligibility criteria in Searle et al. ¹²12. Searle SD, Mitnitski AB, Gahbauer EA, Gill TM, Rockwood K. A standard procedure for creating a frailty index. BMC Geriatr 2008; 8:24. and Song et al. ¹⁴14. Song X, Mitnitski A, Rockwood K. Prevalence and 10-year outcomes of frailty in older adults in relation to deficit accumulation. J Am Geriatr Soc 2010; 58:681-7.. Among the available anthropometric measures, the following were selected: body mass index BMI) and waist to hip ratio WHR) ²⁷27. Santos DM, Siquieri R. Índice de massa corporal e indicadores antropométricos de adiposidade em idosos. Rev Saúde Pública 2005; 39:163-8.. In self-rated health, the following were chosen: chronic diseases, signs and symptoms, difficulties in performing activities of daily living, falls, number of medication, smoking, alcohol consumption, self-perceived health, and leisure-time physical exercise and sports ³3. Fried LP, Tangen C, Walston J, Newman AB, Hirsch C, Gottdiener J, et al. Frailty in older adults: evidence for a phenotype. J Gerontol A Biol Sci Med Sci 2001; 56:M146-56.^,1212. Searle SD, Mitnitski AB, Gahbauer EA, Gill TM, Rockwood K. A standard procedure for creating a frailty index. BMC Geriatr 2008; 8:24.^,2828. Lawton M, Brody E. Assessment of older people: self-maintaining and instrumental activities of daily living. Gerontologist 1969; 9:179-86.^,2929. Strawbridge WJ, Wallhagen MI, Cohen RD. Successful aging and well-being: self-rated compared with Rowe and Kahn. Gerontologist 2002; 42:727-33.. Physical performance measures included: gait speed and grip strength ³3. Fried LP, Tangen C, Walston J, Newman AB, Hirsch C, Gottdiener J, et al. Frailty in older adults: evidence for a phenotype. J Gerontol A Biol Sci Med Sci 2001; 56:M146-56.. The selected psychosocial variables were: depressive symptoms and life satisfaction ³⁰30. Yesavage JA, Brink TL, Rose TL, Lum O, Huang V, Adey M, et al. Development and validation of a geriatric depression screening scale: a preliminary report. J Psychiatr Res 1983; 17:37-49.^,3131. Almeida OP, Almeida SA. Short versions of the Geriatric Depression Scale: a study of their validity for the diagnosis of major depressive episode according to ICD-10 and DSM-IV. Int J Geriatr Psychiatry 1999; 14:858-65..

Frailty indices were calculated for all the participants, based on the selected variables. When the variables were dichotomous e.g. hypertension - yes vs. no), the attribute’s presence was scored as 1 and its absence as 0. For continuous variables, intermediate points were created e.g., self-rated health as very good = 0; good = 0.25; fair = 0.5; bad = 0.75; and very bad = 1.0). For cognitive status, the points corresponded to the quintiles obtained by the sample in the cognitive screening test 1st quintile = 1; 2nd quintile = 0.75; 3rd quintile = 0.5; 4th quintile = 0.25; and 5th quintile = 0). The study followed the rules recommended in the literature for assessing parameters, such as waist to hip ratio men > 1 = 1.0; women > 0.85 = 1,0; men < 0.99 = 0; and women < 0.84 = 0) ²⁷27. Santos DM, Siquieri R. Índice de massa corporal e indicadores antropométricos de adiposidade em idosos. Rev Saúde Pública 2005; 39:163-8., low grip strength the lowest 20% of values in the distribution of the means on three attempts, adjusted by gender and BMI = 1.0) ³3. Fried LP, Tangen C, Walston J, Newman AB, Hirsch C, Gottdiener J, et al. Frailty in older adults: evidence for a phenotype. J Gerontol A Biol Sci Med Sci 2001; 56:M146-56., low gait speed values above the 80th percentile in the distribution of the mean times in seconds that the individual took to walk 4.6 meters three times) ³3. Fried LP, Tangen C, Walston J, Newman AB, Hirsch C, Gottdiener J, et al. Frailty in older adults: evidence for a phenotype. J Gerontol A Biol Sci Med Sci 2001; 56:M146-56. and low level of physical activity the lowest 20% of values in the distribution of the sum of kcal spent in physical exercise, adjusted by gender = 1.0) ³3. Fried LP, Tangen C, Walston J, Newman AB, Hirsch C, Gottdiener J, et al. Frailty in older adults: evidence for a phenotype. J Gerontol A Biol Sci Med Sci 2001; 56:M146-56.. For each elderly individual, FI was calculated, based on the sum of the scores for frailty divided by 40, which was the total number of selected items in the protocol. Unanswered items were excluded from the participant’s score. The lowest denominator considered was 29 deficits. Based on Rockwood et al. ³²32. Rockwood K, Andrew M, Mitnitski A. Comparison of two approaches to measuring frailty in elderly people. J Gerontol A Biol Sci Med Sci 2007; 62:738-43., on a scale from 0 to 1, individuals were classified as fit when they scored ≤ 0.11, as pre-frail when they scored from 0.12 to 0.24, and as frail when they scored ≥ 0.25 Table 1) ¹⁴14. Song X, Mitnitski A, Rockwood K. Prevalence and 10-year outcomes of frailty in older adults in relation to deficit accumulation. J Am Geriatr Soc 2010; 58:681-7..

b) Gender and age: two self-report items, male vs. female; years of age; date of birth).

c) Mortality: in the database of the SIM for Campinas, we identified and counted the surviving and non-surviving elderly from 2009 to 2013 at each moment when the database was consulted. The database was obtained by probabilistic record linkage using the blocking strategy in multiple linked steps: first name, last name, year of birth, and home address. It was measured as the proportion of deaths in elderly in Campinas, and the variable was categorized as “yes” or “no”.

Statistical analysis

The FIBRA Study forms were consecutively checked by two supervisors before keying-in. The electronic database was checked by two trained evaluators, with 100% agreement required. Frequency measures were performed for the scores obtained by the elderly in each of the health and psychosocial variables comprising the FI and in the score ranges corresponding to the three levels of frailty. Statistical comparisons between the frailty indices for the groups formed by men and women were performed using the Mann-Whitney test and between the age groups according to the Kruskal-Wallis test. The Dunn test was used for post hoc comparison of the results from the Kruskal-Wallis test. The rates of surviving and non-surviving elderly by gender, age, and frailty levels were compared with the chi-square test. Associations between the independent variables gender, age, and frailty and mortality were studied by Cox regression. The analyses used SAS, version 9.2 SAS Inst., Cary, USA). Statistical significance was set at 5%, or p < 0.05.

Results

Of the 689 elderly whose data were analyzed according to the FI protocol, 86.6% 588) answered 40 items; 9.75% answered 39; 2.81% answered 38; 0.15% answered 37; 0.30% answered 31; and 0.15% answered 29. Twelve elderly were excluded who failed to respond to more than 30% of the study items. Table 1 showed the absolute frequencies and percentages of the variables that comprised the FI according to the score adopted. The observed frailty indices were generally low or intermediate: the lowest observed index was 0.03 and the highest 0.62, with low dispersion around the mean 0.23 ± 0.10) and a median of 0.22. Prevalence of frail elderly was 38.8%, pre-frail elderly 51.6%, and fit elderly 9.6%.

Women showed significantly higher mean values for subcomponents of the frailty index compared to men in BMI, WHR, fatigue, hypertension, arthritis, osteoporosis, urinary incontinence, falls, sleep problems, and need for help using transportation and shopping. The mean indices in men exceeded those in women for the variables cancer, smoking, alcohol consumption, and need for help preparing meals. Overall mean FI was higher in women 0.25 ± 0.10) than in men 0.20 ± 0.10) Table 2).

As for mean values for each FI component and age bracket, the variables with significant differences were: cognitive status, WHR, level of physical activity, fatigue, grip strength, slow gait, falls, sleep problems, and need for help using transportation, shopping, and doing household chores. Differences between age brackets were verified with the multiple comparisons test and are represented by letters in Table 3. Overall mean FI did not differ statistically by age bracket p = 0.063).

In the five years of follow-up, 8.2% of the elderly died. There was no significant difference between mortality and the variables gender and FI Table 4). There was a significantly higher percentage of mortality in elderly 75 years and older Table 4).

Cox multiple regression analysis adjusted by age, gender, and frailty index showed that the variables age and gender were significantly associated with mortality. Increased risk of death in the elderly was associated with older age each additional year of age was associated with an increase of 10.2% in mortality) and male gender 73% greater risk of death than in women). No association was observed between FI and mortality in the overall sample Table 5).

Discussion

Prevalence of frail elderly was 38.8%, higher than the mean prevalence in a review of 24 population-based studies in elderly 65 years and older, showing FI prevalence of 24% range: 18-44%) ¹⁹19. Shamlyian T, Talley KMC, Ramakrishnan R, Kane R. Association of frailty with survival: a systematic literature review. Ageing Res Rev 2013; 12:719-36.. A survey by Collard et al. ¹⁸18. Collard RM, Boter H, Schoevers RA, Voshaar RCO. Prevalence of frailty in community-dwelling older persons: a systematic review. J Am Geriatr Soc 2012; 60:1487-92., involving 21 studies of community-dwelling elderly 61,500 participants), found prevalence rates ranging from 4 to 59%. The total FIBRA Campinas sample n = 900), which used the model by Fried et al. ³3. Fried LP, Tangen C, Walston J, Newman AB, Hirsch C, Gottdiener J, et al. Frailty in older adults: evidence for a phenotype. J Gerontol A Biol Sci Med Sci 2001; 56:M146-56., showed 7.7% frail, 52.3% pre-frail, and 40% fit or non-frail elderly. Elderly women and elders 80 years or older scored on more frailty criteria, when compared to elderly men and elders under 80 years of age ²⁶26. Neri AL, Yassuda MS, Araújo LF, Eulálio MC, Cabral BE, Siqueira MEC, et al. Metodologia e perfil sociodemográfico, cognitivo e de fragilidade de idosos comunitários de sete cidades brasileiras: Estudo FIBRA. Cad Saúde Pública 2013; 29:778-92.^,3333. Borim FSA, Costa TB, Moraes ZV, Pinto JM, Guariento ME, Neri AL. Indicadores de fragilidade. In: Neri AL, Guariento ME, organizadoras. Fragilidade, saúde e bem-estar em idosos. Dados do Estudo FIBRA Campinas. Campinas: Alínea Editora; 2011. p. 205-24..

This wide variation may be explained by the difference in the instrument for assessing the syndrome and differences in the sample’s composition, especially relating to ethnicity and nationality. Despite the universal decline in the mechanisms for adaptation and biological regulation associated with aging, different trajectories can distinguish individuals from different cohorts and different contexts ⁸8. Yang Y, Lee LC. Dynamics and heterogeneity in the process of human frailty and aging: evidence from the U.S. older adult population. J Gerontol B Psychol Sci Soc Sci 2010; 65:246-55.^,2020. Kulminski AM, Ukraintseva SV, Kulminskaya IV, Arbeev KG, Land K, Yashin AI. Cumulative deficits better characterize susceptibility to death in elderly people than phenotypic frailty: lessons from the Cardiovascular Health Study. J Am Geriatr Soc 2008; 56:898-903.^,3434. Arbeev KG, Ukraintseva SV, Akushevich I, Kulminski AM, Arbeeva LS, Akushevich L, et al. Age trajectories of physiological indices in relation to healthy life course. Mech Ageing Dev 2011; 132:93-102.^,3535. Mitnitski A, Song X, Rockwood K. Trajectories of changes of twelve years in the health status of Canadians from late middle age. Exp Gerontol 2012; 47:893-9.^,3636. Wang C, Song X, Mitnitski A, Fang X, Tang Z, Yu P, et al. Effect of health deficit accumulation and mortality risk in older adults in the Beijing Longitudinal Study of Aging. J Am Geriatr Soc 2014; 62:821-8.^,3737. Harttgen K, Kowal P, Strulik H, Chatterji S, Vollmer S. Patterns of frailty in older adults: comparing results from higher and lower income countries using the Survey of Health, Ageing and Retirement in Europe SHARE) and the Study on global AGEing and adult health SAGE). PLoS One 2013; 8:e75847..

Women showed higher frailty indices than men, corroborating findings in the literature, for example the National Population and Health Survey NPHS) ¹⁴14. Song X, Mitnitski A, Rockwood K. Prevalence and 10-year outcomes of frailty in older adults in relation to deficit accumulation. J Am Geriatr Soc 2010; 58:681-7., Survey of Health, Ageing, and Retirement in Europe SHARE) ³⁸38. Romero-Ortuno R, Kenny RA. The frailty index in Europeans: association with age and mortality. Age Ageing 2012; 41:684-9., and Beijing Longitudinal Study of Aging¹⁵15. Fang X, Shi J, Song X, Mitnitski A, Tang Z, Wang C, et al. Frailty in relation to the risk of falls, fractures, and mortality in older Chinese adults: results from the Beijing Longitudinal Study of Aging. J Nutr Health Aging 2012; 16:903-7.. Unlike these studies, which also found higher frailty indices and higher frailty prevalence rates in the older elderly, the current study did not show differences between these variables frailty index and age bracket). Individuals in the same age bracket may present different health profiles. However, the current sample did not show differences in relation to age groups as the frailty index proposes.

In this study, risk of death in men was 1.73 times higher than in women. In a study of elderly Chinese, women showed higher mean FI than men, while the incidence of death was higher for men than for women ³⁹39. Shi J, Yang Z, Song X, Yu P, Fang X, Tang Z, et al. Sex differences in the limit to deficit accumulation in late middle-aged and older Chinese people: results from the Beijing Longitudinal Study of Aging. J Gerontol A Biol Sci Med Sci 2014; 69:702-9.. In a sample of elderly Brazilians, males were 2.7 times more likely to die than females ⁴⁰40. Maia FOM, Duarte YAO, Lebrão ML, Santos JLF. Fatores de risco para mortalidade em idosos. Rev Saúde Pública 2006; 40:1049-56.. According to the literature, men generally die more from acute illnesses, while women live longer and with more disabilities and more comorbidities ⁴¹41. Theou O, Rockwood MRH, Mitnitski A, Rockwood K. Disability and comorbidity in relation to frailty: how much do they overlap? Arch Gerontol Geriatr 2012; 55:e1-e8.^,4242. Banks J, Muriel A, Smith JP. Disease prevalence, disease incidence, and mortality in the United States and in England. Demography 2010; 47:S211-31.. Kulminski et al. ²⁰20. Kulminski AM, Ukraintseva SV, Kulminskaya IV, Arbeev KG, Land K, Yashin AI. Cumulative deficits better characterize susceptibility to death in elderly people than phenotypic frailty: lessons from the Cardiovascular Health Study. J Am Geriatr Soc 2008; 56:898-903. assessed the prevalence of morbidity in men and women in relation to mortality, using the cumulative deficits model. They found that morbidity and risk of mortality according to gender may vary as a result of the set of deficits used, the cohort, and environmental factors. These results show the paradox of morbidity and mortality: despite worse health conditions, women present higher survival rates than men.

The association between chronological age and mortality has been widely reported in the literature ⁴⁰40. Maia FOM, Duarte YAO, Lebrão ML, Santos JLF. Fatores de risco para mortalidade em idosos. Rev Saúde Pública 2006; 40:1049-56.^,4141. Theou O, Rockwood MRH, Mitnitski A, Rockwood K. Disability and comorbidity in relation to frailty: how much do they overlap? Arch Gerontol Geriatr 2012; 55:e1-e8.^,4242. Banks J, Muriel A, Smith JP. Disease prevalence, disease incidence, and mortality in the United States and in England. Demography 2010; 47:S211-31.. Physiological changes associated with aging and lower functional reserve are important factors influencing the relationship between age and mortality, especially in advanced old age ³⁶36. Wang C, Song X, Mitnitski A, Fang X, Tang Z, Yu P, et al. Effect of health deficit accumulation and mortality risk in older adults in the Beijing Longitudinal Study of Aging. J Am Geriatr Soc 2014; 62:821-8.^,4141. Theou O, Rockwood MRH, Mitnitski A, Rockwood K. Disability and comorbidity in relation to frailty: how much do they overlap? Arch Gerontol Geriatr 2012; 55:e1-e8.^,4242. Banks J, Muriel A, Smith JP. Disease prevalence, disease incidence, and mortality in the United States and in England. Demography 2010; 47:S211-31..

According to the theoretical formulation of the frailty index model, the index represents a measure of the individual’s biological age, and FI should thus be a more robust predictor of mortality than chronological age itself ¹1. Mitnitski AB, Mogilner AJ, Rockwood K. Accumulation of deficits as a proxy measure of aging. ScientificWorldJournal 2001; 1:323-36.^,77. Rockwood K, Mitnitski A. Frailty in relation to the accumulation of deficits. J Gerontol A Biol Sci Med Sci 2007; 62:722-7.. Unlike findings from international studies, the current study found no association between FI and mortality ¹⁴14. Song X, Mitnitski A, Rockwood K. Prevalence and 10-year outcomes of frailty in older adults in relation to deficit accumulation. J Am Geriatr Soc 2010; 58:681-7.^,3636. Wang C, Song X, Mitnitski A, Fang X, Tang Z, Yu P, et al. Effect of health deficit accumulation and mortality risk in older adults in the Beijing Longitudinal Study of Aging. J Am Geriatr Soc 2014; 62:821-8.^,3838. Romero-Ortuno R, Kenny RA. The frailty index in Europeans: association with age and mortality. Age Ageing 2012; 41:684-9.. As far as we know, this is the first study in which FI does not predict mortality in community-dwelling elderly. The main objective of the frailty index as a measure is to assess biological heterogeneity in order to identify the individuals most vulnerable to adverse health events ¹1. Mitnitski AB, Mogilner AJ, Rockwood K. Accumulation of deficits as a proxy measure of aging. ScientificWorldJournal 2001; 1:323-36.^,77. Rockwood K, Mitnitski A. Frailty in relation to the accumulation of deficits. J Gerontol A Biol Sci Med Sci 2007; 62:722-7.. However, this result was not observed in this sample. This may be related to the limitation of the index in terms of the variability in health in old age and its different influences on the occurrence of negative events ³⁷37. Harttgen K, Kowal P, Strulik H, Chatterji S, Vollmer S. Patterns of frailty in older adults: comparing results from higher and lower income countries using the Survey of Health, Ageing and Retirement in Europe SHARE) and the Study on global AGEing and adult health SAGE). PLoS One 2013; 8:e75847.^,4343. Mitnitski A, Song X, Skoog I, Broe GA, Cox JL, Grunfeld E, et al. Relative fitness and frailty of elderly men and women in developed countries and their relationship with mortality. J Am Geriatr Soc 2005; 53:2184-9.. That is, some deficits have a greater effect than others on mortality rates ⁴⁰40. Maia FOM, Duarte YAO, Lebrão ML, Santos JLF. Fatores de risco para mortalidade em idosos. Rev Saúde Pública 2006; 40:1049-56.. For example, elderly individuals with heart disease, diabetes, and hypertension score lower on the index when compared to elderly with osteoporosis and arthritis, which require help using transportation and performing household chores. Still, the former conditions are more lethal than the latter. Besides, there is no consensus at present on the cutoff point as the classificatory criterion for FI or for characterizing frail elderly in different contexts ³⁴34. Arbeev KG, Ukraintseva SV, Akushevich I, Kulminski AM, Arbeeva LS, Akushevich L, et al. Age trajectories of physiological indices in relation to healthy life course. Mech Ageing Dev 2011; 132:93-102.^,3535. Mitnitski A, Song X, Rockwood K. Trajectories of changes of twelve years in the health status of Canadians from late middle age. Exp Gerontol 2012; 47:893-9.^,3636. Wang C, Song X, Mitnitski A, Fang X, Tang Z, Yu P, et al. Effect of health deficit accumulation and mortality risk in older adults in the Beijing Longitudinal Study of Aging. J Am Geriatr Soc 2014; 62:821-8.^,3737. Harttgen K, Kowal P, Strulik H, Chatterji S, Vollmer S. Patterns of frailty in older adults: comparing results from higher and lower income countries using the Survey of Health, Ageing and Retirement in Europe SHARE) and the Study on global AGEing and adult health SAGE). PLoS One 2013; 8:e75847.^,4242. Banks J, Muriel A, Smith JP. Disease prevalence, disease incidence, and mortality in the United States and in England. Demography 2010; 47:S211-31.^,4343. Mitnitski A, Song X, Skoog I, Broe GA, Cox JL, Grunfeld E, et al. Relative fitness and frailty of elderly men and women in developed countries and their relationship with mortality. J Am Geriatr Soc 2005; 53:2184-9.. Despite this lack of consensus in the literature, the cutoff points used in the current study followed the recommendations made by the developers of the FI ¹²12. Searle SD, Mitnitski AB, Gahbauer EA, Gill TM, Rockwood K. A standard procedure for creating a frailty index. BMC Geriatr 2008; 8:24.^,1414. Song X, Mitnitski A, Rockwood K. Prevalence and 10-year outcomes of frailty in older adults in relation to deficit accumulation. J Am Geriatr Soc 2010; 58:681-7.^,3232. Rockwood K, Andrew M, Mitnitski A. Comparison of two approaches to measuring frailty in elderly people. J Gerontol A Biol Sci Med Sci 2007; 62:738-43.. According to Martin et al. ⁴⁴44. Martin FC, Brighton P. Frailty: diferente tools for diferente purposes? Age Ageing 2008; 37:129-31. and Walston & Bandeen-Roche ⁴⁵45. Walston JD, Bandeen-Roche K. Frailty: a tale of two concepts. BMC Med 2015; 13:185., although the developers of the frailty index suggest that the items comprising the measure are correlated, there is still no evidence on the internal validity of the set of items in the FI, since the number and nature of the variables differ in the studies that used the operational model. The original FI study used 70 variables to compose the measure, including diseases, signs and symptoms, functional disabilities in basic and instrumental activities of daily living, cognitive decline, and psychological disorders ³²32. Rockwood K, Andrew M, Mitnitski A. Comparison of two approaches to measuring frailty in elderly people. J Gerontol A Biol Sci Med Sci 2007; 62:738-43.. The FIBRA study used 40 variables to comprise the FI. According to the authors ⁷7. Rockwood K, Mitnitski A. Frailty in relation to the accumulation of deficits. J Gerontol A Biol Sci Med Sci 2007; 62:722-7.^,1212. Searle SD, Mitnitski AB, Gahbauer EA, Gill TM, Rockwood K. A standard procedure for creating a frailty index. BMC Geriatr 2008; 8:24., a composite index with at least 30 variables is capable of predicting adverse health outcomes. It is also necessary to understand the underlying mechanisms in the interaction of deficits in the pathophysiology of frailty ⁴⁵45. Walston JD, Bandeen-Roche K. Frailty: a tale of two concepts. BMC Med 2015; 13:185..

For convenience purposes, the data in the FIBRA Study were collected in a social setting in the community that is well-known and easy for participants to access. This decision may have partly selected elderly individuals in better physical condition. Likewise, when selecting the elderly for the second phase of data collection using the MMSE, FIBRA clearly opted for elderly with more intact cognition. Song et al. ¹⁴14. Song X, Mitnitski A, Rockwood K. Prevalence and 10-year outcomes of frailty in older adults in relation to deficit accumulation. J Am Geriatr Soc 2010; 58:681-7. did not use a cognitive screening test in their sample selection. In the Beijing Longitudinal Study of Aging, the MMSE score was not used as an exclusion criterion for participants ¹⁵15. Fang X, Shi J, Song X, Mitnitski A, Tang Z, Wang C, et al. Frailty in relation to the risk of falls, fractures, and mortality in older Chinese adults: results from the Beijing Longitudinal Study of Aging. J Nutr Health Aging 2012; 16:903-7.^,3939. Shi J, Yang Z, Song X, Yu P, Fang X, Tang Z, et al. Sex differences in the limit to deficit accumulation in late middle-aged and older Chinese people: results from the Beijing Longitudinal Study of Aging. J Gerontol A Biol Sci Med Sci 2014; 69:702-9.. Ours is the first Brazilian study on the prevalence of FI and its association with socio-demographic variables and mortality as the outcome. The data showed that women presented higher FI than men. For the study population, the frailty index did not serve as a good measure of frailty, since it was not associated with either mortality or chronological age. Future studies may assess and compare different measures of frailty with unfavorable outcomes, besides identifying factors that protect against negative events related to the frailty syndrome.

Acknowledgments

The research project was funded by the Brazilian National Research Council CNPq) and the Brazilian Graduate Studies Coordinating Board Capes) grant n. 5550822006-7). Capes provided a post-doctoral scholarship for F. S. A. Borim.

References

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