Accuracy and Use of WHO Hemoglobin Color Scale for Diagnosis of Anemia Among Pregnant Women by Health Care Providers in Peri-Urban Settings in Karachi, Pakistan

Presentation at the Global Maternal Newborn Health Conference, October 19, 2015

Background: Anemia is a major public health problem of developing countries. Approximately half of the pregnant women are anemic in Pakistan. Anemia in pregnancy can lead to adverse outcomes including maternal, fetal and perinatal death. Diagnosis of anemia is based on clinical examination at most of the rural and remote areas of population. WHO Hemoglobin Color Scale (HCS) is claimed as a simple and low cost technique to detect anemia at primary health care settings of low income countries. The objective of this study was to assess the diagnostic accuracy of HCS comparing clinical signs assessment technique (CSAT) of health care providers against the gold standard of laboratory hemoglobinometry.

Methodology: A cross sectional validation survey was conducted among 189 pregnant women, recruited from two maternal and child health centers located in two separate towns of peri-urban settings in Karachi city, Pakistan, from June 2012 to February 2013. Anemia was assessed by HCS and CSAT by health care providers and compared with laboratory hemoglobinometry. Validity indices for HCS and CSAT were calculated. Receiver-operating characteristic (ROC) analysis was undertaken and the area under the curve (AUC) was calculated for HCS and CSAT.

Results: About 73% of women were found anemic (Hb < 11 g/dL), by hemoglobinometry, at the study antenatal clinics. The sensitivity and specificity of HCS was 70.9% (95% CI: 62.7-78.3) and 49.1% (95% CI: 35.1-63.2), for CSAT it was 95.7% (95% CI: 91.0-98.4) and 5.7% (95% CI: 1.2-15.7), respectively. Positive predictive value (PPV) of HCS and CSAT was 78.7% (95% CI: 70.7-85.5) and 73.0% (95% CI: 66.0-79.2), while negative predictive value (NPV) of HCS and CSAT was 38.8% (95% CI: 27.1-51.5) and 33.3% (95% CI: 7.5-70.1), respectively. The AUC for HCS for diagnosis of anemia was 0.60 (95% CI: 0.52-0.66) compared to 0.50 (95% CI: 0.43-0.57) for CSAT (p=0.01).

Conclusion: The overall diagnostic accuracy of HCS is low. Nonetheless, the accuracy of HCS is better than CSAT method for assessing anemia by health care providers among pregnant women. HCS method may need to be piloted with other community based health care providers in Pakistan.