Clinical use of the erythrocyte sedimentation rate in the evaluation of febrile intravenous drug users

Study objective: To investigate the use of the erythrocyte sedimentation rate in the evaluation of febrile IV drug users. Design: Prospective observational cohort study. Setting: Municipal hospital emergency department. Type of participants: One hundred six IV drug users aged 18 years or older, with rectal temperatures of 37.8 C or more. Interventions: Clinical and laboratory variables were obtained by trained research assistants, using a standardized data collection instrument. Results: The erythrocyte sedimentation rate was the only variable consistently associated with illness severity in both the univariate and multivariable analyses (P < .0001). At an erythrocyte sedimentation rate of 100 mm/hr or more, the test had a specificity of 96% (95% confidence interval, 81% to 100%). In contrast, the erythrocyte sedimentation rate displayed a relatively poor sensitivity at low values (88% [95% confidence interval, 77% to 95%] at an erythrocyte sedimentation rate less than 20). Conclusion: An erythrocyte sedimentation rate of 100 or more should be regarded as a marker for serious illness in IV drug users with fever, but a "normal" erythrocyte sedimentation rate of less than 20 does not reliably exclude the presence of serious disease in this patient population.