Could our pretest probabilities become evidence based? A prospective survey of hospital practice

OBJECTIVE: We sought to measure the proportion of patients on our clinical service who presented with clinical problems for which research evidence was available to inform estimates of pretest probability. We also aimed to discern whether any of this evidence was of sufficient quality that we would want to use it for clinical decision making. DESIGN: Prospective, consecutive case series and literature survey. SETTING: Inpatient medical service of a university-affiliated Veterans' Affairs hospital in south Texas. PATIENTS: Patients admitted during the 3 study months for diagnostic evaluation. MEASUREMENTS: Patients' active clinical problems were identified prospectively and recorded at the time of discharge, transfer, or death. We electronically searched MEDLINE and hand-searched bibliographies to find citations that reported research evidence about the frequency of underlying diseases that cause these clinical problems. We critically appraised selected citations and ranked them on a hierarchy of evidence. RESULTS: We admitted 122 patients for diagnostic evaluation, in whom we identified 45 different principal clinical problems. For 35 of the 45 problems (78%; 95% confidence interval [95% CI], 66% to 90%), we found citations that qualified as disease probability evidence. Thus, 111 of our 122 patients (91%; 95% CI, 86% to 96%) had clinical problems for which evidence was available in the medical literature. CONCLUSIONS: During 3 months on our hospital medicine service, almost all of the patients admitted for diagnostic evaluation had clinical problems for which evidence is available to guide our estimates of pretest probability. If confirmed by others, these data suggest that clinicians' pretest probabilities could become evidence based.