Accuracy and Reliability of Pallor for Detecting Anaemia: A Hospital-Based Diagnostic Accuracy Study
Open Access
- 1 January 2010
- journal article
- research article
- Published by Public Library of Science (PLoS) in PLOS ONE
- Vol. 5 (1), e8545
- https://doi.org/10.1371/journal.pone.0008545
Abstract
Anaemia is a common disorder. Most health providers in resource poor settings rely on physical signs to diagnose anaemia. We aimed to determine the diagnostic accuracy of pallor for anaemia by using haemoglobin as the reference standard. In May 2007, we enrolled consecutive patients over 12 years of age, able to consent and willing to participate and who had a haemoglobin measurement taken within a day of assessment of clinical pallor from outpatient and medicine inpatient department of a teaching hospital. We did a blind and independent comparison of physical signs (examination of conjunctivae, tongue, palms and nailbed for pallor) and the reference standard (haemoglobin estimation by an electronic cell counter). Diagnostic accuracy was measured by calculating likelihood ratio values and 95% confidence intervals (CI) at different haemoglobin thresholds and area under the receiver operating characteristic curve. Two observers examined a subset of patients (n = 128) to determine the inter-observer agreement, calculated by kappa statistics. We studied 390 patients (mean age 40.1 [SD 17.08] years); of whom 48% were women. The haemoglobin was <7 g/dL in 8% (95% confidence interval, 5, 10) patients; <9 g/dL in 21% (17, 26) patients and <12 g/dL in 64% (60, 70) patients. Among patients with haemoglobin <7 g/dL, presence of severe tongue pallor yielded a LR of 9.87 (2.81, 34.6) and its absence yielded a LR of 0. The tongue pallor outperformed other pallor sites and was also the best discriminator of anaemia at haemoglobin thresholds of 7 g/dL and 9 g/dL (area under the receiver operating characteristic curves (ROC area = 0.84 [0.77, 0.90] and 0.71[0.64, 0.76]) respectively. The agreement between the two observers for detection of anaemia was poor (kappa values = 0.07 for conjunctival pallor and 0.20 for tongue pallor). Clinical assessment of pallor can rule out and modestly rule in severe anaemia.This publication has 23 references indexed in Scilit:
- Algorithm for the diagnosis of anaemia without laboratory facilities among small children in a malaria endemic area of rural TanzaniaActa Tropica, 2006
- Pallor as a sign of anaemia in small Tanzanian children at different health care levelsActa Tropica, 2006
- Evaluation of the WHO Haemoglobin Colour Scale for diagnosis of anaemia in children and pregnant women as used by primary health care nurses and community health workers in western KenyaTropical Medicine & International Health, 2006
- Refining clinical diagnosis with likelihood ratiosThe Lancet, 2005
- Test Research versus Diagnostic ResearchClinical Chemistry, 2004
- Valeur diagnostique de la pâleur des téguments dans l'anémie chez les femmes enceintes au BéninSanté Publique, 2004
- Recognition of pallor associated with severe anaemia by primary caregivers in western KenyaTropical Medicine & International Health, 2002
- Simplifying likelihood ratiosJournal of General Internal Medicine, 2002
- The Relation of Conjunctival Pallor to the Presence of AnemiaJournal of General Internal Medicine, 1997
- The Relation of Conjunctival Pallor to the Presence of AnemiaJournal of General Internal Medicine, 1997