Observer bias and error in the integumentary clinical diagnosis of chronic anaemia.

In 74 patients believed to have chronic anaemia, 1 541 individual clinical assessments of haemoglobin levels were made from various sites. By comparison with laboratory values, there were statistically significant differences in the majority. In most instances these were not clinically important. The conjunctivae, the oral mucosa and the tongue were the integumentary sites that seemed to give the most accurate clinical assessment, while the appearance of nail-bed, palmar creases and facies did not correlate with laboratory findings. Bias appeared to be a factor in clinical estimates. There was no evidence that experience made clinicians more accurate.