Diagnostic accuracy of "pallor" for detecting mild and severe anaemia in hospitalized patients.

Objective: To determine the accuracy of pallor of conjunctiva, nailbed, and palm in detecting mild and severe anaemia.

Methods: Three hundred and five consecutive patients admitted in the medical and surgical wards of Mayo Hospital, Lahore were enrolled in the study. Conjunctiva, nailbed, and palm of patients were assessed. Mild anaemia was defined as Hb < 11.5 g/dl for females and Hb <13 g/dl for males. Severe anaemia was defined as Hb <7 g/dl. Likelihood ratios (LR) and their 95% confidence intervals (CI) for both presence and absence of pallor at each site were calculated. To compare the accuracy of different pallor sites in diagnosing severe anaemia, their areas under receiver operating characteristics curves (AUC) were compared.

Results: Mild anaemia was present in 64.3% patients while severe anaemia was present in 7% patients. Presence of nailbed pallor had moderate accuracy for diagnosing mild anaemia (LR 5.6, 95% CI 4.7-6.7) while absence of pallor at nailbed, conjunctiva, and palm (LR 0.6 for all) did not rule out mild anaemia. All sites had modest accuracy for detecting severe anaemia (LR 2.5-3.0). Absence of pallor at conjunctiva (LR 0.1, 95% CI 0.03-0.5) and palm (LR 0.1, 95% CI 0.03-0.5) convincingly ruled out severe anaemia. Comparison of the AUC for different pallor sites showed that all sites were equally useful for detecting severe anaemia.

Conclusion: Pallor is not an accurate sign for mild anaemia. Pallor of conjunctiva, palm, and nailbed has modest accuracy in detecting severe anaemia. Absence of pallor at conjunctiva and palm convincingly rules out severe anaemia.