ABSTRACT:

Introduction:

Inappropriate use and increase of health care spending reinforce the need to extend our knowledge about the quality of medication use.

Objectives:

To describe and evaluate the profile of medication use in a representative sample of adult users of primary care services in the Unified Health System (SUS) of Minas Gerais.

Method:

Cross-sectional study, with 1,159 interviewees in 104 municipalities and 253 health care services. Data on sociodemographic characteristics, health conditions and use of medicines were collected, and these variables were stratified by age group. Univariate and multivariate analyses, using logistic regression, were conducted to identify predictors of self-medication. We set a significance level of 5% for all tests.

Results:

The prevalence of medication use was 81.8%, with an average of 2.67 medicines per user, which increased with age. The most used drugs were losartan, hydrochlorothiazide and simvastatin, which differed between age groups. Significant self-medication was observed not only in young adults but also in the elderly. The predictors of self-medication were: being a young adult, having a higher level of education, not having chronic diseases, having worse self-perception of health and not adhering to prescription drugs. Young and elderly adults showed characteristics that made them more vulnerable in relation to the rational use of medicines.

Conclusion:

This study can contribute to improving primary care, where it identified problems related to the extent of medication use, especially among young adults and the elderly in Minas Gerais.

Keywords:
Use of medicines; Self-medication; Pharmacoepidemiology; Primary health care; Public health

INTRODUCTION

Medicines are essential to health and play a significant role in improving quality of life and life expectancy¹1. Arrais PSD, Brito LL, Barreto ML, Coelho HLL. Prevalência e fatores determinantes do consumo de medicamentos no Município de Fortaleza, Ceará, Brasil. Cad Saúde Pública 2005; 21(6): 1737-46. http://doi.org/10.1590/S0102-311X2005000600021
https://doi.org/http://doi.org/10.1590/S... , but its improper use can have consequences for the individual, society and health care systems²2. Pereira VOM, Acurcio FA, Guerra Júnior AA, Silva GD, Cherchiglia ML. Perfil de utilização de medicamentos por indivíduos com hipertensão arterial e diabetes mellitus em municípios da Rede Farmácia de Minas. Cad Saúde Pública 2012; 28(8): 1546-58. http://doi.org/10.1590/S0102-311X2012000800013
https://doi.org/http://doi.org/10.1590/S... , which is a global problem³3. Holloway KA, Ivanovsha V, Wagner AK, Vialle-Valentin C, Ross-Degnan D. Have we improved use of medicines in developing and transitional countries and do we know how to? Two decades of evidence. Trop Med Int Health 2013; 18(6): 656-64. http://doi.org/10.1111/tmi.12123
https://doi.org/http://doi.org/10.1111/t... and of interest to public health. This reinforces the need for research on the use and quality of use of medicines.

In most countries, medicines have been the fastest growing health cost component. This is partly due to the continued launch of expensive new drugs, stricter clinical goals and demographic changes⁴4. Wettermark B, Elseviers M, Almarsdóttir AB, Andersen M, Benko R, Bennie M, et al. Introduction to drug utilization research. In: Elseviers M, Wettermark B, Almarsdóttir AB, Andersen M, Benko R, Bennie M, et al., editors. Drug utilization research: methods and applications. Nova York: Wiley Blackwell; 2016. p. 3-12..

Since it is a social process, the use of medicines is influenced by several factors¹1. Arrais PSD, Brito LL, Barreto ML, Coelho HLL. Prevalência e fatores determinantes do consumo de medicamentos no Município de Fortaleza, Ceará, Brasil. Cad Saúde Pública 2005; 21(6): 1737-46. http://doi.org/10.1590/S0102-311X2005000600021
https://doi.org/http://doi.org/10.1590/S... ^,55. Castro CGSO. Estudos de utilização de medicamentos: noções básicas. Rio de Janeiro: FIOCRUZ; 2000.^,66. Bertoldi AD, Barros AJD, Hallal PC, Lima RC. Utilização de medicamentos em adultos: prevalência e determinantes individuais. Rev Saúde Pública 2004; 38(2): 228-38. http://doi.org/10.1590/S0034-89102004000200012
https://doi.org/http://doi.org/10.1590/S... , such as demographic structure, morbidity profile and socioeconomic, behavioral and cultural characteristics of the pharmaceutical market and government policies directed at the sector⁷7. Costa KS, Barros MBA, Francisco PMSB, César CLG, Goldbaum M, Carandina L. Utilização de medicamentos e fatores associados: um estudo de base populacional no município de Campinas, São Paulo, Brasil. Cad Saúde Pública 2011; 27(4): 649-58. http://doi.org/10.1590/S0102-311X2011000400004
https://doi.org/http://doi.org/10.1590/S... , aspects that are constantly changing.

Thus, periodic assessment of a population’s way of using medicines helps identify possible changes in use and provides up-to-date information on medication use and the related factors. This information can assist in the planning of health services and future research⁸8. Galvão TF, Silva MT, Gross R, Pereira MG. Medication use in adults living in Brasilia, Brazil: a cross sectional, population based study. Pharmacoepidemiol Drug Saf 2014; 23(5): 507-14. http://doi.org/10.1002/pds.3583
https://doi.org/http://doi.org/10.1002/p... , in addition to help decide on priorities in public health policies⁹9. Leite SN, Vieira M, Veber AP. Estudos de utilização de medicamentos: uma síntese de artigos publicados no Brasil e América Latina. Ciên Saúde Colet 2008; 13(Supl. 0): 793-802. http://doi.org/10.1590/S1413-81232008000700029
https://doi.org/http://doi.org/10.1590/S... relevant to the needs of society.

More specifically, the assessment of drug use among age groups provides an epidemiological view of the disease landscape, current treatment standards and pharmacotherapeutic approaches in each age group. In addition, changes associated with age, body function and body composition, justify a more rigorous monitoring of the therapeutic regimen, to ensure the effective and safe use of medicines among older individuals¹⁰10. Eriksson I, Bergman I, Vlahovic-Palcevski V, Euler MV. Comparative studies of patient and prescriber characteristics. In: Elseviers M, Wettermark B, Almarsdóttir AB, Andersen M, Benko R, Bennie M, et al., editors. Drug utilization research: methods and applications. Nova York: Wiley Blackwell ; 2016. p. 184-93..

The evaluation of medication use by the population cared for in primary health care (PHC) of the Unified Health System (SUS) analyzes health care itself¹¹11. Fleith VD, Figueiredo MA, Figueiredo KFLRO, Moura EC. Perfil de utilização de medicamentos em usuários da rede básica de saúde de Lorena, SP. Ciên Saúde Colet 2008; 13(Supl. 0): 755-62. http://doi.org/10.1590/S1413-81232008000700026
https://doi.org/http://doi.org/10.1590/S... , bearing in mind that PHC plays an essential role in comprehensive care, organizing and coordinating the health care process, including pharmaceutical care.

The state of Minas Gerais is very extensive and has a diverse population composition. Also, the state has a well-defined and organized SUS-PHC system, and pharmaceutical care is connected with the Pharmacy Network of Minas. Accordingly, the aim of the present study was to determine the profile of medication use in a representative sample of users of SUS-PHCs in Minas Gerais, aged 18 years or older, seeking to identify trends in medicine use according to age group. In addition, the factors associated with the practice of self-medication among PHC users were identified. Studies like this are scarce, and the information thus obtained allows filling gaps in our knowledge of the frequency and quality of medication use at this level of care, especially with regard to its inappropriate use and the risks arising from this practice.

METHOD

We conducted a cross-sectional study with state coverage, between September 2014 and May 2015. The units of analysis were the individuals cared for by the services of SUS-PHCs, aged 18 or older using medications, and the medications themselves. The information was obtained in person, in the health units, using a semi-structured questionnaire that was previously validated. The present study used the same methodological course and instruments as the Services component of the National Survey on Access, Use and Promotion of Rational Use of Medicines (PNAUM)¹²12. Álvares J, Alves MCGP, Escuder MML, Almeida AM, Izidoro JB, Guerra Júnior AA, et al. Pesquisa Nacional sobre Acesso, Utilização e Promoção do Uso Racional de Medicamentos: métodos. Rev Saúde Pública2017; 51(Supl. 2): 1-9. https://doi.org/10.11606/S1518-8787.2017051007027
https://doi.org/https://doi.org/10.11606... .

The sample size, representative of users aged 18 years or older, was estimated using the following steps: first, the representative sample size of the municipalities in Minas Gerais was calculated, and then the representative sample of the APS-SUS health services in the state of Minas Gerais, based on the selected municipalities; finally, the representative sample of users was selected, given the previously chosen health services. Details of the procedure for calculating the sample size of municipalities (104) and health services (253) are described elsewhere¹³13. Barbosa MM, Garcia MM, Nascimento RCRM, Reis EA, Guerra Júnior AA, Acurcio FA, et al. Avaliação da infraestrutura da assistência farmacêutica no sistema único de saúde em Minas Gerais. Ciên Saúde Colet 2017; 22(8): 2475-86. http://doi.org/10.1590/1413-81232017228.10952017
https://doi.org/http://doi.org/10.1590/1... .

In each primary care health service, the number of users was proportional to the population of the municipality: municipalities with less than 30 thousand inhabitants, two to five users interviewed; municipalities with 30 to 80 thousand inhabitants, three to six users; and municipalities with 80 thousand inhabitants or more, four to seven users. The estimated sample size was 1,254 users, but with losses, 1,159 interviews were conducted.

SUS-PHC users were randomly selected according to a predefined order, when they were at a clinic visit on the days of the field research. The criteria stipulated for this selection occurred in such a way that interviewers were not allowed to choose users when composing the sample, to get a close as possible random draw¹²12. Álvares J, Alves MCGP, Escuder MML, Almeida AM, Izidoro JB, Guerra Júnior AA, et al. Pesquisa Nacional sobre Acesso, Utilização e Promoção do Uso Racional de Medicamentos: métodos. Rev Saúde Pública2017; 51(Supl. 2): 1-9. https://doi.org/10.11606/S1518-8787.2017051007027
https://doi.org/https://doi.org/10.11606... . The interview was conducted before the clinic visit, and the information regarding the use of medicines was collected through the following question: In the past 30 days, did you use any medicines? The self-report of this response was checked, when possible, with the user’s possession of the prescription of the drugs.

Medicines were classified according to the third and fifth levels of the Anatomical Therapeutic Chemical Classification System (ATC)¹⁴14. WHO Collaborating Centre for Drugs Statistics Methodology. Anatomical Therapeutic Chemical Classification - ATC Code [Internet]. Oslo; 2018 [acessado em 8 jan. 2018]. Disponível em: Disponível em: http://www.whocc.no/atc_ddd_index/
http://www.whocc.no/atc_ddd_index/... , corresponding respectively to pharmacological subgroup and chemical substance.

The exploratory variables analyzed were as follows. Sociodemographic variables were: sex, age group (18 to 44, 45 to 64 and ≥65 years), education (incomplete primary and complete primary or more), economic class and having private health insurance. The economic class was according to the Brazil Economic Classification Criterion of 2014, of the Brazilian Association of Research Companies.

The characteristics of medication use evaluated were polypharmacy (use of five or more medicines simultaneously, by the same individual), self-medication and adherence to the prescribed medication, the last two being determined through the following questions, respectively: Considering all the times using medicines, do you generally use any medicine without a prescription?; Do you ever stop using any medicine prescribed by the doctor? With positive answers, the individual was asked in which situations.

Regarding the variables associated with health status indicators, the following were analyzed: self-perceived health, number of self-reported chronic diseases (none, one or two or more, i.e., multimorbidity) and main self-reported chronic diseases, and hospitalization and emergency room care in the last year. These exploratory variables were described by simple absolute and relative frequencies, and Pearson’s χ² test or Fisher’s exact test were used to assess the differences between age groups. For the mean and median number of drugs, analysis of variance (ANOVA) and the Jonckheere-Terpstra test were applied. A significance level of 5% was used in all tests.

Finally, to assess the association of self-medication with the explanatory variables, univariate and multivariate analyses were performed using logistic regression, calculating the odds ratio (OR), with a 95% confidence interval (95%CI). In the univariate analysis, variables that were associated with the outcome with p ≤ 0.20 were included in the multivariate analysis. The backward method was chosen to arrive at the final model, ending with variables showing p ≤ 0.05. The quality of the adjustment was verified by the Hosmer-Lemeshow test, and statistical analyses were performed using the Statistical Package for the Social Sciences (SPSS) program, version 22.

The ethical guidelines for conducting research were met (with approval by the National Research Ethics Commission, process No. 398.131/2013). All participants signed an informed consent form.

RESULTS

Among the 1,159 APS-PHC users interviewed, 949 (81.8%) reported having used medicines in the last 30 days. Sociodemographic characteristics related to health and medication use are presented in Table 1, showing significant differences between age groups. The majority of medication users (80.1%) were women, but the proportion of men increased with age, reaching 34.7% in the age group of 65 years or older. Almost half (47.0%) of these users had incomplete primary education, and the elderly (≥65 years) had the lowest levels of education. Regarding the economic class, most users belonged to class C (62.2%), followed by class D or E (20%). Among the elderly, largest proportion of individuals were in economic class D or E (32.6%), and the great majority (78.5%) reported multimorbidity (data not shown in table). Approximately half of medication users reported having multimorbidity (49.5%), with a significant difference between age groups (p < 0.001).

Regarding the characteristics of medication use, self-medication was found in almost half of the users (48.2%), with a higher proportion among the younger users (57.7%) and a substantial proportion among the elderly (31.9%). Among the reasons for self-medication (data not shown in table), the most reported were “having the medicine at home” (89.1%) and “previous use of the medicine” (86.7%). The latter reason showed significant differences (p = 0.003) between the age groups.

When investigating the non-adherence to prescribed medications, a greater proportion was also found in those aged 18-44 years (28.5%). The main reasons for this non-use (data not shown in table) were previous negative experience with the use the medicine (71.4%) and belief that the medicine was very strong or weak (60.5%). The latter reason showed significant differences (p = 0.017) between age groups, with a greater proportion among users aged 45-64 years (65.6%).

Considering the total number of users, the mean number of drugs used was 2.67 ± 1.89 (SD). This mean varied significantly (p < 0.001) for each age group: (1.94 ± 1.28) for the age group between 18 and 44 years; (3.04±2.04) for those aged 45 to 64; and (3.72 ± 2.10) for those ≥65 years. The median number of drugs used was 2.00 (interquartile range, (1.00 - 4.00) and also varied significantly (p < 0.001) between age groups (data not shown in table).

Among the 2,536 drugs self-reported by users, 2,372 active ingredients were identified according to the fifth level of the ATC. The most used were losartan (7.0%), hydrochlorothiazide (6.6%), simvastatin (5.4%), omeprazole (4.8%) and metformin (4.2%) (Table 2), which was observed in higher proportions in the age group of 65 years or older. Unlike most medications, which had a higher proportion of use among the elderly, clonazepam and fluoxetine showed a higher proportion of use in the younger adults (18-44 years). In this age group, the most used drugs were: ferrous sulfate (5.6%), hydrochlorothiazide (4.6%), folic acid (4.3%), omeprazole (4.3%) and clonazepam (4.0%).

In general, the profile of the most used drugs matched the most prevalent diseases in the population studied: hypertension (50.3%), dyslipidemia (31.2%), depression (28.0%), arthritis/arthrosis or rheumatism (20.4%) and diabetes mellitus (16.5%). The medicines most often used by the elderly were clonazepam, diazepam, fluoxetine and ibuprofen, which are considered potentially inappropriate for use in this age group¹⁵15. American Geriatrics Society. 2019 Updated Beers Criteria for Potentially Inappropriate Medication Use in Older Adults: the American Geriatrics Society 2019 Beers Criteria Update Expert Panel. J Am Geriatr Soc 2019; 67(4): 674-94. http://doi.org/10.1111/jgs.15767
https://doi.org/http://doi.org/10.1111/j... .

The most used pharmacological subgroups (Table 3), considering the third level of ATC, were “angiotensin II antagonists” (7.1%), “low potency diuretics/thiazides” (6.7%) and “lipid-modifying agents” (6.1%). The proportion of consumption of the pharmacological subgroups was, in general, higher in the age group ≥65 years. The subgroup “other analgesics and antipyretics” showed a higher proportion in those 18-44 years old. In addition, the second and third groups of medicines most used in this age group were hormonal contraceptives (7.8%) and antidepressants (7.2%), respectively. We found that the pharmacological subgroups most used, in relation to the general sample, were for the cardiovascular and nervous system, particularly antihypertensive and psychotropic drugs, respectively.

Table 4 presents the results of the univariate and multivariate logistic models for the predictors of self-medication, which was associated with age group. Young adults (18 -44 years old) were 1.83 times more likely to practice self-medication compared to the elderly (≥65 years old). In addition, an association was observed between self-medication and individuals with higher education (OR = 1.58; 95% CI 1.17 - 2.14), without chronic diseases (OR = 1.67; 95%CI 1.19 - 2.37), with worse self-perceived health (OR = 1.70; 95%CI 1.26 - 2.28), and also those not adhering to prescription drugs (OR = 1.98; 95%CI 1.43 - 2.73).

DISCUSSION

The results of this survey showed a high prevalence of medication use, which increased with age group. The most used drugs were losartan, hydrochlorothiazide, simvastatin, omeprazole and metformin. Frequent self-medication was observed among young adults and the elderly. Predictors of self-medication were: being a young adult, having a higher level of education, not having chronic diseases, having worse self-perceived health and not adhering to prescription drugs. In addition, the elderly were more vulnerable because of the poorer quality of medication use.

The overall prevalence of medication use observed in this study (81.8%) was higher than that of other studies carried out in PHCs in Brazil¹¹11. Fleith VD, Figueiredo MA, Figueiredo KFLRO, Moura EC. Perfil de utilização de medicamentos em usuários da rede básica de saúde de Lorena, SP. Ciên Saúde Colet 2008; 13(Supl. 0): 755-62. http://doi.org/10.1590/S1413-81232008000700026
https://doi.org/http://doi.org/10.1590/S... ^,1616. Costa CMFN, Silveira MR, Acurcio FA, Guerra Júnior AA, Guibu IA, Costa KS, et al. Utilização de medicamentos pelos usuários da atenção primária do sistema único de saúde. Rev Saúde Pública 2017; 51(Supl. 2): 1-11. https://doi.org/10.11606/S1518-8787.2017051007144
https://doi.org/https://doi.org/10.11606... ^,1717. Bertoldi AD, Barros AJD, Wagner A, Ross-Degnan D, Hallal PC. Medicine access and utilization in a population covered by primary health care in Brazil. Health Policy 2009; 89(3): 295-302. http://doi.org/10.1016/j.healthpol.2008.07.001
https://doi.org/http://doi.org/10.1016/j... ^,1818. Vosgerau MZS, Soares DA, Souza RKT, Matsuo T, Carvalho GS. Consumo de medicamentos entre adultos na área de abrangência de uma Unidade de Saúde da Família. Ciên Saúde Colet 2011; 16(Supl. 1): 1629-38. http://doi.org/10.1590/S1413-81232011000700099
https://doi.org/http://doi.org/10.1590/S... and those with a national¹1. Arrais PSD, Brito LL, Barreto ML, Coelho HLL. Prevalência e fatores determinantes do consumo de medicamentos no Município de Fortaleza, Ceará, Brasil. Cad Saúde Pública 2005; 21(6): 1737-46. http://doi.org/10.1590/S0102-311X2005000600021
https://doi.org/http://doi.org/10.1590/S... ^,66. Bertoldi AD, Barros AJD, Hallal PC, Lima RC. Utilização de medicamentos em adultos: prevalência e determinantes individuais. Rev Saúde Pública 2004; 38(2): 228-38. http://doi.org/10.1590/S0034-89102004000200012
https://doi.org/http://doi.org/10.1590/S... ^,77. Costa KS, Barros MBA, Francisco PMSB, César CLG, Goldbaum M, Carandina L. Utilização de medicamentos e fatores associados: um estudo de base populacional no município de Campinas, São Paulo, Brasil. Cad Saúde Pública 2011; 27(4): 649-58. http://doi.org/10.1590/S0102-311X2011000400004
https://doi.org/http://doi.org/10.1590/S... ^,88. Galvão TF, Silva MT, Gross R, Pereira MG. Medication use in adults living in Brasilia, Brazil: a cross sectional, population based study. Pharmacoepidemiol Drug Saf 2014; 23(5): 507-14. http://doi.org/10.1002/pds.3583
https://doi.org/http://doi.org/10.1002/p... ^,1919. Silva AL, Ribeiro AQ, Klein CH, Acurcio FA. Utilização de medicamentos por idosos brasileiros, de acordo com a faixa etária: um inquérito postal. Cad Saúde Pública 2012; 28(6): 1033-45. http://doi.org/10.1590/S0102-311X2012000600003
https://doi.org/http://doi.org/10.1590/S... ^,2020. Bertoldi AD, Pizzol TSD, Ramos LR, Mengue SS, Luiza VL, Tavares NUL, et al. Perfil sociodemográfico dos usuários de medicamentos no Brasil: resultados da PNAUM 2014. Rev Saúde Pública 2016; 50(Supl. 2): 1-11. http://doi.org/10.1590/s1518-8787.2016050006119
https://doi.org/http://doi.org/10.1590/s... and international²¹21. Milián AJG, Carbonell LA, Puig PL, Alós IY, Salvador AKR, Hernández NB. Consumo de medicamentos referidos por la población adulta de Cuba, año 2007. Rev Cuba Med Gen Integr 2009; 25(4): 5-16.^,2323. Kantor ED, Rehm CD, Haas JS, Chan AT, Giovannucci EL. Trends in prescription drug use among adults in the United States from 1999-2012. JAMA 2015; 314(17): 1818-31. http://doi.org/10.1001/jama.2015.13766
https://doi.org/http://doi.org/10.1001/j... population base. Specifically, the prevalence of medication use in the age group of 65 years or older (90%) was similar to that of national studies in PHCs¹⁶16. Costa CMFN, Silveira MR, Acurcio FA, Guerra Júnior AA, Guibu IA, Costa KS, et al. Utilização de medicamentos pelos usuários da atenção primária do sistema único de saúde. Rev Saúde Pública 2017; 51(Supl. 2): 1-11. https://doi.org/10.11606/S1518-8787.2017051007144
https://doi.org/https://doi.org/10.11606... and population-based studies²⁰20. Bertoldi AD, Pizzol TSD, Ramos LR, Mengue SS, Luiza VL, Tavares NUL, et al. Perfil sociodemográfico dos usuários de medicamentos no Brasil: resultados da PNAUM 2014. Rev Saúde Pública 2016; 50(Supl. 2): 1-11. http://doi.org/10.1590/s1518-8787.2016050006119
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https://doi.org/https://doi.org/10.1590/... , but higher than that found in studies conducted exclusively with the elderly both in PHCs²⁵25. Goulart LS, Carvalho AC, Lima JC, Pedrosa JM, Lemos PL, Oliveira RB. Consumo de medicamentos por idosos de uma Unidade Básica de Saúde de Rondonópolis/MT. Estud Interdiscipl Envelhec 2014; 19(1): 79-94.^,2626. Marin MJS, Cecílio LCO, Perez AEWUF, Santella F, Silva CBA, Gonçalves Filho JR, et al. Caracterização do uso de medicamentos entre idosos de uma unidade do Programa Saúde da Família. Cad Saúde Pública 2008; 24(7): 1545-55. http://doi.org/10.1590/S0102-311X2008000700009
https://doi.org/http://doi.org/10.1590/S... and in population-based setting¹⁹19. Silva AL, Ribeiro AQ, Klein CH, Acurcio FA. Utilização de medicamentos por idosos brasileiros, de acordo com a faixa etária: um inquérito postal. Cad Saúde Pública 2012; 28(6): 1033-45. http://doi.org/10.1590/S0102-311X2012000600003
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https://doi.org/http://doi.org/10.1590/S... . The mean number of drugs consumed per individual (2.67) was similar to that of studies carried out in PHCs in Brazil¹⁶16. Costa CMFN, Silveira MR, Acurcio FA, Guerra Júnior AA, Guibu IA, Costa KS, et al. Utilização de medicamentos pelos usuários da atenção primária do sistema único de saúde. Rev Saúde Pública 2017; 51(Supl. 2): 1-11. https://doi.org/10.11606/S1518-8787.2017051007144
https://doi.org/https://doi.org/10.11606... and in other countries²⁹29. Ofori-Asenso R, Brhlikova P, Pollock AM. Prescribing indicators at primary health care centers within the WHO African region: a systematic analysis (1995-2015). BMC Public Health 2016; 16: 1-14. http://doi.org/10.1186/s12889-016-3428-8
https://doi.org/http://doi.org/10.1186/s... , but higher than that of other studies⁷7. Costa KS, Barros MBA, Francisco PMSB, César CLG, Goldbaum M, Carandina L. Utilização de medicamentos e fatores associados: um estudo de base populacional no município de Campinas, São Paulo, Brasil. Cad Saúde Pública 2011; 27(4): 649-58. http://doi.org/10.1590/S0102-311X2011000400004
https://doi.org/http://doi.org/10.1590/S... ^,88. Galvão TF, Silva MT, Gross R, Pereira MG. Medication use in adults living in Brasilia, Brazil: a cross sectional, population based study. Pharmacoepidemiol Drug Saf 2014; 23(5): 507-14. http://doi.org/10.1002/pds.3583
https://doi.org/http://doi.org/10.1002/p... ^,1717. Bertoldi AD, Barros AJD, Wagner A, Ross-Degnan D, Hallal PC. Medicine access and utilization in a population covered by primary health care in Brazil. Health Policy 2009; 89(3): 295-302. http://doi.org/10.1016/j.healthpol.2008.07.001
https://doi.org/http://doi.org/10.1016/j... ^,2222. Carrera-Lasfuentes P, Aguilar-Palacio I, Roldán EC, Fumanal SM, Hernandez MJR. Consumo de medicamentos en población adulta: influencia del autoconsumo. Aten Primária 2013; 45(10): 528-35. http://doi.org/10.1016/j.aprim.2013.05.006
https://doi.org/http://doi.org/10.1016/j... ^,3030. Francisco PMSB, Bastos TF, Costa KS, Prado MAMB, Barros MBA. The use of medication and associated factors among adults living in Campinas, São Paulo, Brazil: differences between men and women. Ciên Saúde Colet 2014; 19(12): 4909-21. http://doi.org/10.1590/1413-812320141912.18702013
https://doi.org/http://doi.org/10.1590/1... , whose averages ranged between 1.5 and 2.2. These higher prevalences and means observed may be related to the nature of the sample and to the advances in the provision of health services that SUS and the Family Health Strategy have provided to the country³¹31. Arantes LJ, Shimizu HE, Merchán-Hamann E. Contribuições e desafios da Estratégia Saúde da Família na Atenção Primária à Saúde no Brasil: revisão da literatura. Ciên Saúde Colet 2016; 21(5): 1499-509. http://doi.org/10.1590/1413-81232015215.19602015
https://doi.org/http://doi.org/10.1590/1... and Minas Gerais.

The tendency of increasing number of medications with age group is in accordance with the literature⁷7. Costa KS, Barros MBA, Francisco PMSB, César CLG, Goldbaum M, Carandina L. Utilização de medicamentos e fatores associados: um estudo de base populacional no município de Campinas, São Paulo, Brasil. Cad Saúde Pública 2011; 27(4): 649-58. http://doi.org/10.1590/S0102-311X2011000400004
https://doi.org/http://doi.org/10.1590/S... ^,1616. Costa CMFN, Silveira MR, Acurcio FA, Guerra Júnior AA, Guibu IA, Costa KS, et al. Utilização de medicamentos pelos usuários da atenção primária do sistema único de saúde. Rev Saúde Pública 2017; 51(Supl. 2): 1-11. https://doi.org/10.11606/S1518-8787.2017051007144
https://doi.org/https://doi.org/10.11606... ^,2020. Bertoldi AD, Pizzol TSD, Ramos LR, Mengue SS, Luiza VL, Tavares NUL, et al. Perfil sociodemográfico dos usuários de medicamentos no Brasil: resultados da PNAUM 2014. Rev Saúde Pública 2016; 50(Supl. 2): 1-11. http://doi.org/10.1590/s1518-8787.2016050006119
https://doi.org/http://doi.org/10.1590/s... , and the use of multiple medicines is common in older adults, due to the greater number of morbidities. However, this requires greater attention, since it is an important risk factor for prescription and adherence problems, adverse drug events and other adverse health effects³²32. Steinman MA, Hanlon JT. Managing medications in clinically complex elders: “There’s got to be a happy medium”. JAMA 2010; 304(14): 1592-601. http://doi.org/10.1001/jama.2010.1482
https://doi.org/http://doi.org/10.1001/j... .

Psychopharmaceuticals were among the pharmacological groups most used in this survey, as shown in another survey conducted in the SUS-PHC¹⁶16. Costa CMFN, Silveira MR, Acurcio FA, Guerra Júnior AA, Guibu IA, Costa KS, et al. Utilização de medicamentos pelos usuários da atenção primária do sistema único de saúde. Rev Saúde Pública 2017; 51(Supl. 2): 1-11. https://doi.org/10.11606/S1518-8787.2017051007144
https://doi.org/https://doi.org/10.11606... . This may reflect the increase in the use of these drugs in recent decades³³33. Rocha BS, Werlang MC. Psicofármacos na estratégia da saúde da família: perfil de utilização, acesso e estratégias para a promoção do uso racional. Ciên Saúde Colet 2013; 18(11): 3291-300. http://doi.org/10.1590/S1413-81232013001100019
https://doi.org/http://doi.org/10.1590/S... . In addition, the most prevalent class of antidepressants is in line with the trend towards increasing the prescription of antidepressants seen in primary care³⁴34. Lockhart P, Guthrie B. Trends in primary care antidepressant prescribing 1995-2007: a longitudinal population database analysis. Br J Gen Pract 2011; 61(590): e565-572. http://doi.org/10.3399/bjgp11X593848
https://doi.org/http://doi.org/10.3399/b... . Therefore, it is necessary to develop strategies in the PHC to better understand this high use of psychotropic drugs, especially among young adults, and to intervene to reduce their use.

Low schooling was observed in a greater proportion among the elderly (65 years old or older), as well as multimorbidity and belonging to the lower economic classes (D/E). These characteristics make the elderly more vulnerable with regard to the use of medications and may represent problems in decision making regarding prescribed antihypertensive medications³⁵35. Sociedade Brasileira de Cardiologia, Sociedade Brasileira de Hipertensão, Sociedade Brasileira de Nefrologia. VI Diretrizes Brasileiras de Hipertensão. Arq Bras Cardiol 2010; 95(1 Supl. 1): 1-51.. The elderly have peculiar physiological and clinical conditions associated with more complex treatment regimens, such as polypharmacy²⁸28. Neves SJF, Marques APO, Leal MCC, Diniz AS, Medeiros TS, Arruda IKG. Epidemiologia do uso de medicamentos entre idosos em área urbana do Nordeste do Brasil. Rev Saúde Pública 2013; 47(4): 759-68. http://doi.org/10.1590/S0034-8910.2013047003768
https://doi.org/http://doi.org/10.1590/S... , and together with the aforementioned characteristics, they become weaker in understanding, adhering to and following the prescribed therapeutic regimen.

Among the drugs most used by individuals 65 and over, there were some potentially inappropriate medicines (PIM) for the elderly¹⁵15. American Geriatrics Society. 2019 Updated Beers Criteria for Potentially Inappropriate Medication Use in Older Adults: the American Geriatrics Society 2019 Beers Criteria Update Expert Panel. J Am Geriatr Soc 2019; 67(4): 674-94. http://doi.org/10.1111/jgs.15767
https://doi.org/http://doi.org/10.1111/j... , a reality observed in other national studies²⁴24. Lutz BH, Miranda VIA, Bertoldi AD. Inadequação do uso de medicamentos entre idosos em Pelotas, RS. Rev Saúde Pública 2017; 51: 1-12. https://doi.org/10.1590/S1518-8787.2017051006556
https://doi.org/https://doi.org/10.1590/... ^,3636. Oliveira MG, Amorim WW, Jesus SR, Rodrigues VA, Passos LC. Factors associated with potentially inapropriate medication use by the elderly in the Brazilian primary care setting. Int J Clin Pharm 2012; 34: 626-32. http://doi.org/10.1007/s11096-012-9656-9
https://doi.org/http://doi.org/10.1007/s... ^,3737. Cassoni TCJ, Corona LP, Romano-Lieber NS, Secoli SR, Duarte YAO, Lebrão ML. Uso de medicamentos potencialmente inapropriados por idosos do Município de São Paulo, Brasil: Estudo SABE. Cad Saúde Pública 2014; 30(8): 1708-20. http://doi.org/10.1590/0102-311X00055613
https://doi.org/http://doi.org/10.1590/0... . The higher proportion of medication use and the occurrence of a cascade of inappropriate prescription of drugs in this age group³⁸38. DeRhodes, KH. The dangers of ignoring the Beers criteria- The prescribing cascade. JAMA Intern Med 2019; 179(7): 863-4. http://doi.org/10.1001/jamainternmed.2019.1288
https://doi.org/http://doi.org/10.1001/j... characterize a relevant public health problem, given its association with morbidity and mortality, and also with the costs to health care services due to adverse reactions³⁸38. DeRhodes, KH. The dangers of ignoring the Beers criteria- The prescribing cascade. JAMA Intern Med 2019; 179(7): 863-4. http://doi.org/10.1001/jamainternmed.2019.1288
https://doi.org/http://doi.org/10.1001/j... ^,3939. Guaraldo L, Cano FG, Damasceno GS, Rozenfeld S. Inappropriate medication use among the elderly: a systematic review of administrative databases. BMC Geriatr 2011; 11: 1-10. http://doi.org/10.1186/1471-2318-11-79
https://doi.org/http://doi.org/10.1186/1... . Thus, multidisciplinary health teams are recommended to identify and possibly mitigate the inappropriate use of medications to ensure patient safety and improve the quality of care provided.

Regarding self-medication, about half of the interviewees answered that they had used some medicines without a prescription. This prevalence was higher than that reported by other national¹⁶16. Costa CMFN, Silveira MR, Acurcio FA, Guerra Júnior AA, Guibu IA, Costa KS, et al. Utilização de medicamentos pelos usuários da atenção primária do sistema único de saúde. Rev Saúde Pública 2017; 51(Supl. 2): 1-11. https://doi.org/10.11606/S1518-8787.2017051007144
https://doi.org/https://doi.org/10.11606... ^,4040. Arrais PSD, Fernandes MEP, Pizzol TSD, Ramos LR, Mengue SS, Luiza VL, et al. Prevalência da automedicação no Brasil e fatores associados. Rev Saúde Pública 2016; 50(Supl. 2): 1-11. http://doi.org/10.1590/s1518-8787.2016050006117
https://doi.org/http://doi.org/10.1590/s... ^,4141. Alves FHC. A automedicação em usuários da atenção primária do sistema único de saúde [dissertação]. Belo Horizonte: Universidade Federal de Minas Gerais; 2017.^,4242. Domingues PHF, Galvão TF, Andrade KRC, Sá PTT, Silva MT, Pereira MG. Prevalência da automedicação na população adulta do Brasil: revisão sistemática. Rev Saúde Pública 2015; 49: 1-8. http://doi.org/10.1590/S0034-8910.2015049005709
https://doi.org/http://doi.org/10.1590/S... and international²²22. Carrera-Lasfuentes P, Aguilar-Palacio I, Roldán EC, Fumanal SM, Hernandez MJR. Consumo de medicamentos en población adulta: influencia del autoconsumo. Aten Primária 2013; 45(10): 528-35. http://doi.org/10.1016/j.aprim.2013.05.006
https://doi.org/http://doi.org/10.1016/j... ^,4343. Selvaraj K, Kumar SG, Ramalingam A. Prevalence of self-medication practices and its associated factors in Urban Puducherry, India. Perspect Clin Res 2014; 5(1): 32-6. http://doi.org/10.4103/2229-3485.124569
https://doi.org/http://doi.org/10.4103/2... studies. Young adults (18-44 years old) showed greater use of self-medication, a common feature among studies in the literature¹⁶16. Costa CMFN, Silveira MR, Acurcio FA, Guerra Júnior AA, Guibu IA, Costa KS, et al. Utilização de medicamentos pelos usuários da atenção primária do sistema único de saúde. Rev Saúde Pública 2017; 51(Supl. 2): 1-11. https://doi.org/10.11606/S1518-8787.2017051007144
https://doi.org/https://doi.org/10.11606... ^,2222. Carrera-Lasfuentes P, Aguilar-Palacio I, Roldán EC, Fumanal SM, Hernandez MJR. Consumo de medicamentos en población adulta: influencia del autoconsumo. Aten Primária 2013; 45(10): 528-35. http://doi.org/10.1016/j.aprim.2013.05.006
https://doi.org/http://doi.org/10.1016/j... ^,4040. Arrais PSD, Fernandes MEP, Pizzol TSD, Ramos LR, Mengue SS, Luiza VL, et al. Prevalência da automedicação no Brasil e fatores associados. Rev Saúde Pública 2016; 50(Supl. 2): 1-11. http://doi.org/10.1590/s1518-8787.2016050006117
https://doi.org/http://doi.org/10.1590/s... . This age group was 1.8 times more likely to self-medicate than individuals aged 65 or older. However, among the elderly, there was a significant portion of self-medication, and this requires greater attention, since it is a practice little explored in the literature⁴⁴44. Secoli SR, Marquesini EA, Fabretti SC, Corona LP, Romano-Lieber NS. Tendência da prática de automedicação entre idosos brasileiros entre 2006 e 2010: Estudo SABE. Rev Bras Epidemiol 2018; 21(Supl. 2): e180007. http://doi.org/10.1590/1980-549720180007.supl.2
https://doi.org/http://doi.org/10.1590/1... .

It was also observed that the higher level of education and the absence of chronic diseases were predictors for self-medication among the participants. Greater access to information can contribute to the practice among the more educated⁴⁵45. Vilarino JF, Soares IC, Silveira CM, Rödel APP, Bortoli R, Lemos RR. Perfil da automedicação em município do Sul do Brasil. Rev Saúde Pública 1998; 32(1): 43-9. http://doi.org/10.1590/S0034-89101998000100006
https://doi.org/http://doi.org/10.1590/S... . With regard to chronic diseases, both a reduction⁴⁵45. Vilarino JF, Soares IC, Silveira CM, Rödel APP, Bortoli R, Lemos RR. Perfil da automedicação em município do Sul do Brasil. Rev Saúde Pública 1998; 32(1): 43-9. http://doi.org/10.1590/S0034-89101998000100006
https://doi.org/http://doi.org/10.1590/S... ^,4646. Domingues PHF, Galvão TF, Andrade KRC, Araújo PC, Silva MT, Pereira MG. Prevalência e fatores associados à automedicação em adultos no Distrito Federal: estudo transversal de base populacional. Epidemiol Serv Saúde 2017; 26(2): 319-30. http://dx.doi.org/10.5123/s1679-49742017000200009
https://doi.org/http://dx.doi.org/10.512... and increase ⁴⁰40. Arrais PSD, Fernandes MEP, Pizzol TSD, Ramos LR, Mengue SS, Luiza VL, et al. Prevalência da automedicação no Brasil e fatores associados. Rev Saúde Pública 2016; 50(Supl. 2): 1-11. http://doi.org/10.1590/s1518-8787.2016050006117
https://doi.org/http://doi.org/10.1590/s... in self-medication has been noted among patients. On the other hand, users with worse self-perceived health, more often in those with multimorbidity, showed a greater chance of self-medication⁴⁷47. Coelho MTAD, Santos VP, Carmo MBB, Souza AC, França CPX. Relação entre a autopercepção do estado de saúde e a automedicação entre estudantes universitários. Rev Psicol Diversid Saúde 2017; 6(1): 1141. http://dx.doi.org/10.17267/2317-3394rpds.v6i1.1141
https://doi.org/http://dx.doi.org/10.172... .

Thus, such results are worrisome, because when self-medication is not responsible, there is the possibility of worsening health problems and spread of communicable diseases⁴⁸48. Naves JOS, Castro LLC, Carvalho CMS, Merchán-Hamann E. Automedicação: uma abordagem qualitativa de suas motivações. Ciên Saúde Colet 2010; 15(Supl. 1): 1751-62. http://doi.org/10.1590/S1413-81232010000700087
https://doi.org/http://doi.org/10.1590/S... . Self-medication is a common phenomenon, but it requires attention mainly among the elderly, who are more susceptible to adverse events. This reaffirms the importance of better monitoring and guidance to PHC users on the use of medicines, to reduce inappropriate self-medication and its consequences.

Compliance with the prescribed therapeutic regimen is one of the steps proposed by the World Health Organization for the rational use of medicines, and it is important to investigate the non-adherence of medicines prescribed by the doctor. In the present study, the highest proportions of this practice were found in the 18-44 age group, as observed in another national study in PHCs¹⁶16. Costa CMFN, Silveira MR, Acurcio FA, Guerra Júnior AA, Guibu IA, Costa KS, et al. Utilização de medicamentos pelos usuários da atenção primária do sistema único de saúde. Rev Saúde Pública 2017; 51(Supl. 2): 1-11. https://doi.org/10.11606/S1518-8787.2017051007144
https://doi.org/https://doi.org/10.11606... . The main reason for non-adherence was previous negative experience with the use of a medication. It is noteworthy that non-adherent individuals were almost twice as likely to self-medicate when compared to those who were adherent. A possible explanation is that this was due to the failure of effective communication between users and prescribers or to the lack of trained drug dispensers, such as pharmacists, as well as to inadequate pharmacotherapeutic monitoring by health services. The interaction of the pharmacist with the users of health services, during the dispensing of medicine, constitutes a decisive and opportune moment for guidance and support regarding the occurrence of problems related to their use and which can result in non-adherence to therapy or its recurrence.

The primary strength of the study can be highlighted by the collection of primary data and the state representation of users aged 18 years or older from SUS-PHCs, which allowed us to outline an overview of the global use of medicines in Minas Gerais. Furthermore, the stratification by age groups made it possible to characterize differences between groups and trends in the population studied, useful information in view of the demographic transition going on in the country.

However, it is important to consider some research limitations, such as the self-reporting of the information and the 30-day recall period, subject to memory bias. In addition, the results obtained in this study reflect the population aged 18 years or older using public health services, and not the general population.

CONCLUSION

The characteristics observed and analyzed demonstrated the presence of vulnerable groups in relation to the rational use of medicines, such as young adults, with low adherence to the prescribed therapeutic regimen and the practice of self-medication, and the elderly, who had a lower level of education and economic class, greater use of medicines, some of which were MPI for the age group, in addition to considerable self-medication and more multimorbidities.

This information can be of help in public health decisions, and the findings of high consumption and inappropriate use of medicines serve as a warning to multiprofessional teams and managers of public health systems. PHC teams are advised to always pay attention to the identification and development of measures to confront low adherence to the prescribed regimen and the common practice of self-medication among young adults, as well as the use of PIM and self-medication among the elderly. In this sense, it is advisable to reinforce the presence of pharmacists at the PHC level, since when fulfilling their role, essential in pharmaceutical assistance and dispensing medications, they contribute to the appropriate confrontation of problems related to drug use.

It is important to note that, as a whole, the results corroborate the complexity of the social process that involves the use of medicines, which may become more pronounced over the years, given the demographic and epidemiological transition underway in the country. Thus, the findings identify relevant issues regarding the use of medicines in the state of Minas Gerais, in different age groups. From the perspective of public health, they constitute guidelines for the development of actions and programs in favor of improving the quality of the use of medicines in the scope of primary care.

ACKNOWLEDGMENTS

We are grateful for the financial support from Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG), Conselho Nacional de Desenvolvimento Científico (CNPq) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).

References

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