Reliability of the erythrocyte sedimentation rate in general practice

Because of the need for an accurate determination of the erythrocyte sedimentation rate (ESR), and because of the fact that many general practitioners frequently determine ESR in their own surgery, we investigated the reliability of the blood test in this setting. For this purpose, blood samples, obtained from the local hospital laboratory, were distributed, and the participating general practice centres were requested to determine ESR in each sample. A clinically important intra- and interpractice variability was found in the ESR values measured. The experiment was then repeated one year later under more standardized conditions, which resulted in a significant decrease in the intra- and interpractice variability (p = 0.04 and 0.003, respectively). Vibrations within the hospital building could not account for the systematically higher ESR values measured in the hospital laboratory. We conclude that a considerable increase in the quality of ESR performance in general practice can be achieved by means of relatively simple interventions.