Objectives: To estimate the proportion of routine clinical interventions in internal medicine that are supported by the results of randomized controlled trials or consensus amongst experienced internists.
Design: Retrospective review of case records allowed one or more major diagnosis-intervention combination(s) to be identified for each patient. The scientific literature was searched for metaanalyses and randomized controlled trials in electronic databases that supported the specific intervention used. When support from randomized trials was lacking, possible consensus on management was sought by asking national expert panels of experienced clinicians.
Setting: Department of Medicine at a Swedish teaching hospital.
Subjects: At total of 197 consecutively admitted medical inpatients.
Results: Fifty per cent of the diagnosis-intervention combinations (186/369) were supported by results from randomized controlled trial evidence and 34% (125/369) were supported by consensus amongst experienced clinicians. The proportion of interventions based on randomised controlled trials was highest in patients with cardiac (64%) and other circulatory diagnoses (73%). There were no important differences between sexes or between age groups.
Conclusions: Half of the interventions used in routine clinical practice amongst medical inpatients are supported by results from randomized controlled trials. These results refute popular claims that only a small proportion of medical interventions are supported by scientific evidence.