Diagnostic accuracy of routine postoperative body temperature measurements

BACKGROUND: On surgical wards, body temperature is routinely measured, but there is no proof that this is useful for detecting postoperative infection. The aim of this study was to compare temperature measurements (the test) with the confirmed absence or presence of a postoperative infection (the reference standard). METHODS: A prospective triple-blinded diagnostic study involving 308 consecutive patients was performed. A positive test result was defined as a postoperative temperature > or = 38.0 degrees C. The reference standard was considered to indicate a postoperative infection if results of a bacterial culture were positive or if an infection was suspected on clinical grounds. RESULTS: Data for 284 of 308 patients were analyzed (2282 temperature measurements). The prevalence of infection was 7% (19 of 284 patients). The temperature curves of patients were used as units of analysis and revealed that a temperature > or = 38.0 degrees C had a sensitivity of 37% (95% confidence interval [CI], 0.16%-0.62%) and a specificity of 80% (95% CI, 0.75%-0.85%). The likelihood ratio for a positive test result was 1.8 (95% CI, 0.7-4.0) and for a negative test result was 0.8 (95% CI, 0.4-1.4). When all 2282 measurements were considered as independent test results, the positive predictive value was only 8% (95% CI, 5%-13%). Six of 8 patients with a severe infection had temperatures < 38 degrees C. CONCLUSION: Routine measurement of body temperature is of limited value in the detection of infection after elective surgery for noninfectious conditions. Serious postoperative infections can even occur without an accompanying increase in temperature