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08/31/2011 - pallor in anemia

posted Sep 28, 2011, 5:33 PM by Chief Resident   [ updated Sep 28, 2011, 5:34 PM by Purnema Madahar ]
Time to clean out our 'parking lot', which only has one item left: what's the value of pallor in the detection of anemia?

It's not easy to find a good study that's applicable to our clinical setting: lots of studies in resource-poor settings (with higher prevalence of anemia) or in children. One of the better studies is the attached paper from India, that also does a good job of walking the reader through the necessary methodology.

The study prospectively looked at consecutive medicine inpatient and those outpatient that were referred to a lab for a CBC. Pallor was assessed as absent, mild, moderate or severe at the conjunctiva, tongue, palm and nailbed. The reference standard was hemoglobin, which was used to classify anemia as mild < 12, moderate < 9 and severe < 7.

The mean Hb level was 11.1 (SD 2.6). Severe tongue pallor performed best for ruling in moderate or severe anemia with LR 7.6 and 9.87 respectively. The absence of pallor at any of the sites had LRs from 0.25 to 0.60. Interestingly, the interobserver agreement was poor with kappa of 0.07 (conjunctival) to 0.19 (tongue) for the different sites.

The authors conclude:
1. Presence of pallor can modestly raise the probability of severe anaemia while its absence can rule out severe anaemia.
2. Neither presence nor absence of pallor, regardless of its severity, can accurately rule in or rule out moderate anaemia.