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Kapoor, et al.(1), for estimation of hemoglobin, have compared
the methods of Hemocue and Cyan-methemoglobin and suggested a correction
factor. The basis for this comparative study is finally to estimate the
anemia prevalence. Authors used overall pooled mean of the measurement
in two methods and suggested a correction factor for Hemocue method. The
use of suggested correction factor would under estimate the hemoglobin
as compared to standard method in <7-hemoglobin category. As observed by
the authors, this category produces low mean differences among three
categories of Hemoglobin levels (7, 7-10, >10) in both the samples
(capillary and venous). In this category, the misclassification of
individuals assessed by Hemocue method after applying the suggested
correction factor would be high. This is likely to result in
overestimation of anemia prevalence. Authors could also have reported
anemia frequency by two methods and examine the concordance in the
paired sample to achieve their objective. If at all any correction
factor is required, that should be after careful examination and
demonstration of various cutoff points so that the misclassification is
minimum. Further the determination of correction factor for hemoglobin
should have also taken into consideration of age and sex of 151 and 351
subjects reported by the authors.
L. Satyanarayana,
Assistant Director (Biostatistics),
Institute of Cytology and Preventive
Oncology (ICMR), MAMC Campus,
New Delhi 110 002,
India.
Reference
1. Kapoor S K, Kapil U, Dwivedi S N, Anand K, Pathak P, Singh P.
Comparison of HemoCue method with Cyanmethemoglobin method for
estimation of Hemoglobin. Indian Pediatr 2002; 39: 743-746.
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