ORIGINAL ARTICLES

Reliability and validity of palmar and conjunctival pallor for anemia detection purposes

Mônica Glória N Spinelli^I; José Maria P Souza^II; Sônia B de Souza^III; Edna H Sesoko^I

^ISecretaria Municipal da Assistência Social da Prefeitura do Município de São Paulo. São Paulo, SP, Brazil
^IIDepartamento de Epidemiologia da Faculdade de Saúde Pública da Universidade de São Paulo. São Paulo, SP, Brazil
^IIIDepartamento de Nutrição da Faculdade de Saúde Pública da Universidade de São Paulo. São Paulo, SP, Brazil

Correspondence

ABSTRACT

OBJECTIVE: To evaluate the reliability and the validity of the use of simple clinical signs as a method of anemia detection.
METHODS: The study was carried out in a São Paulo, Brazil, day-care center, and included 135 children from ages 3 months-6 years. Hemoglobin level results and palmar and conjunctival pallor assessment were used. Children with Hb under 11g/dl were considered as anemic; subjective criteria were used for the assessment of palmar and conjunctival pallor. Kappa statistics were used in order to verify agreement, and, in order to evaluate the technique’s validity, sensitivity and specificity levels were calculated.
RESULTS: The results show low levels of agreement. There was a greater level of sensitivity to conjunctival pallor than to palmar pallor. Specificity results may be considered as good.
CONCLUSIONS: It is still early to recommend the routine use of this technique. However, it could promote substantial savings if perfected.

Keywords: Anemia, diagnosis. Pallor. Reproducibility of results. Anemia blood. Hemoglobins analysis.

INTRODUCTION

Iron-deficiency anemia is still an important public health problem in Brazil, despite the amount of knowledge available concerning forms of intervention.⁹ Whereas the prevalence of iron deficiency worldwide is estimated in 25%,¹² in Brazil no nationwide data are available. Results related to restricted populational groups, however, allow us to assume that prevalence is high.^10,11 Small children, female adolescents and pregnant women are the most vulnerable groups.^1,12

Anemia is defined as a pathological process during which the hemoglobin concentration (Hb) in red blood cells is abnormally low. It occurs as a result of an imbalance between the amount of iron biologically available, and organic needs.²

Iron deficiency accounts for most cases of anemia.⁹ It may present itself at several degrees of severity. Severe anemia increases the risk of demise; moderate anemia contributes towards an increase in the patient’s susceptibility to infections, as well as retarding growth and cognitive and psycho-motor development and causing behavioral problems.³

Anemia diagnosis in developing countries is a difficult task. Recommendations based on hemoglobin levels are valuable for controlling anemia, but only when they can be measured. Laboratory evaluations are not always viable for population-wide interventions.¹³ For the detection of moderate and severe anemia in children aged 2 months-5 years, WHO and UNICEF proposed examinations based on simple criteria and clinical signs, such as palmar and conjunctival pallor.³ Studies conducted in Africa^13,5 and in the United States⁷ suggest palms and nailbeds for easier pallor identification. Luby et al ⁵ investigated palms, tongue, conjunctiva and nailbeds. This type of screening allowed for the detection of anemia by healthcare professionals in basic healthcare units. Children thus identified were referred to hospitals in case of severe anemia and treated in situ in case anemia was diagnosed as moderate. According to this method, moderate anemia is diagnosed by the presence of moderate palmar pallor, and severe anemia by the presence of severe palmar pallor.³ Despite the initial studies for the development of this technique having been conducted in Africa, where the population has different characteristics from that of Brazil, we believe that further studies on this subject in Brazil would be of interest.

Considering the high number of children who attend public-network day-care centers, the difficulty and cost of periodical and systematical blood testing for all children, and the need for anemia detection, the present study was developed in order to test the reliability and validity of palmar and conjunctival pallor for anemia detection.

METHODS

The study was carried out in a São Paulo municipal day-care center. It included 135 children ages 3 months-6 years. Hemoglobin levels and clinical signs – palmar and conjunctival pallor – were collected.

Hemoglobin results for capillary blood drawn from the fingertip – after obtaining parental consent – were used for the assessment of anemia. Blood collection and result reading were performed by a trained professional, using a HemoCue meter. Anemia was defined as a hemoglobin level <11,0 g/dl.

Palmar and conjunctival pallor were evaluated by a nutritionist, trained by the healthcare team of the Municipal Social Assistance Secretariat – training included the observation and discussion of a number of children who presented such clinical signs and whose hemoglobin levels were known –, and by three members of the day-care center staff, who had a high level of involvement with the children, their families, and their habits. The auxiliary nurse was responsible for all healthcare-related actions taken at the center. Each child was classified as to whether it presented or not palmar pallor and conjunctival pallor, according to subjective criteria.

In order to evaluate conjunctival pallor, the examiner everted the child’s lower eyelid and observed its tonality. For palmar pallor, the examiner opened one of the child’s hands and examined the color of the palm.

Each observer registered her evaluation in a separate form, without knowing what had been observed by the other examiners, or the results of the Hb tests. All evaluations were done simultaneously.

The study conducted in Africa considered nailbed and tongue pallor as well. The present study, however, was restricted to the examinations suggested in the Agenda Mínima (Minimal Agenda) of the Secretariat of Social Assistance of the Municipal Government of São Paulo.⁵

Kappa statistics⁴ were used to verify the level of reliability (agreement) between techniques and among examiners. The Kappa statistic measures the ratio of agreement observed between examiners – not due to chance – by means of a categorical scale. Its formula is as follows:

where:
po = gross observed agreement
pe = expected agreement due to chance

Null or negative values indicate a lack of agreement; maximum value is 100%

A classification according to hemoglobin levels was adopted for technique sensitivity and specificity calculations, by examiner.^4,6 The study of validity was done based on the obtained sensitivity and specificity values. Calculations were done using Epidat 1.0,⁸ software. Point estimates and confidence intervals were presented.

RESULTS

Of the 135 children studied, 53.3% (72) were male and 46.7% (63) female. Ages ranged from 3 to 67 months. Mean age was 27.57 months and median age was 27 months.

Hb results were obtained for 79.3% of children (107). Thirty-five percent of these (38) had Hb levels >11 g/dl, being classified as anemic; 64.5% (69) had Hb levels ³11 g/dl, considered as normal.

Minimum value registered was 7.7 g/dl, maximum level, 14.5 g/dl, mean value, 11.46 g/dl, and median value, 11,6 g/dl.

Tables 1 and 2 present the results of palmar and conjunctival pallor classification, respectively, according to the various examiners.

Table 3 presents the agreement, for each examiner, between palmar and conjunctival pallor evaluation.

It should be noted that, despite gross agreement varying between 77,7% and 86.6%, the maximum level of adjusted agreement (Kappa) was 72,0% (Table 3).

Kappa for the four examiners simultaneously:

Palmar pallor: 35,8 %

Conjunctival pallor : 38,6%

Tables 4 and 5 show the validity of palmar and conjunctival pallor diagnoses, respectively.

Sensitivity values for palmar pallor – ranging from 15.8% to 50.0% – are presented in Table 4; sensitivity values for conjunctival pallor are slightly higher (Table 5).

DISCUSSION

The level of agreement, for each examiner, between palmar and conjunctival pallor assessment techniques was quite low, despite the two observations having been done simultaneously. The levels of agreement between the four examiners for both techniques were also low.

The levels of sensitivity to palmar and conjunctival pallor in relation to the Hb diagnosis standards were generally low. Specificity results may be considered as good.

In the present study, conjunctival pallor was more accurately perceived than palmar pallor, which suggests that the pigmentation present in the palm was a hindering factor for observation. The proposition of using more than one part of the body for evaluation purposes is due exactly to such difficulties in observing palmar tonality, as well as to the better results achieved in other studies in which a larger number of observations were combined.^{3, 5,13}

Kalter et al³ (1997) observed that the combined observation of palmar and conjunctival pallor was able to detect between 71% and 87% of all cases of moderate anemia, and 50% or more of all cases of mild anemia; roughly one-half of non-anemic children were incorrectly classified as being anemic. The authors also reported low to moderate levels of sensitivity and specificity concerning the diagnosis of mild or moderate anemia (Hb 5-10 g/dl) through palmar or conjunctival pallor.

Zucker et al¹³ (1997) found that 60% of cases of severe anemia in children (Hb<5 g/dl) could be detected through clinical signs alone, and that such an evaluation could be used for identifying children with moderate or severe anemia. Luby et al⁵ (1995) recognized the validity of this method for the detection of severe anemia (93% sensitivity) and were able to identify 66% of children with moderate anemia.

In Brazil, we believe it to be still early for the recommendation of such techniques as a routine procedure, since the children who attend day-care centers rarely present Hb levels as low as those found in African studies. The results could thus end up by excluding a number of children who should have been referred to medical treatment. In addition, given the level of subjectivity of this technique, its implementation would require intense, multiple-stage training – a burden to children, who would have do be examined repeatedly. On the other hand, it is a simple and easily applied technique (it does not require any investment beyond training, and may be done by any member of day-care staff, as long as he or she is trained), which could promote substantial savings once perfected.

ACKNOWLEDGEMENTS

We would like to thank nurse Vanja Lúcia F Luccas, of the Secretaria da Assistência Social da Prefeitura do Município de São Paulo (Secretariat of Social Assistance of the Municipal Government of São Paulo), for her collaboration duringthe data collection stage of the study.

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Correspondence to
Mônica Glória N. Spinelli
Rua Itacolomi, 293 apto 81
01239-020 São Paulo, SP, Brazil
E-mail: spinelli@usp.br

Received on 18/8/2002.
Reviewed on 10/3/2003.
Approved on 4/4/2003.