Making the diagnosis of osteomyelitis. The role of prevalence

Clinicians may have poor sensitivity in determining whether a given diabetic patient with a foot ulcer has osteomyelitis. Thus many turn to diagnostic tests. The literature was reviewed and data on the sensitivity and specificity of five commonly used diagnostic tests were compiled. Using Bayes' theorem, the authors' analysis suggests that pretest probability may be more important in the decision-making process than individual test characteristics. Also, a positive probe-to-bone test is as predictive of osteomyelitis as the other four tests. A negative magnetic resonance imaging test most likely rules out osteomyelitis. Interpretation of any test result is greatly influenced by the pretest probability of disease. Future work needs to focus on aiding the clinician in determining the patient's probability of disease prior to testing in order to optimize patient care.