The quality of medical evidence in hematology-oncology

PURPOSE: The purpose of this study was to evaluate the quality of the medic al evidence available to the clinician in the practice of hematology/oncolo gy. METHODS: We selected 14 neoplastic hematologic disorders and identified 154 clinically important patient management decision/interventions, ranging fr om initial treatment decisions to those made for the treatment of recurrent or refractory disease. We also performed a search of the scientific litera ture for the years 1966 through 1996 to identify all randomized controlled trials in hematology/oncology. RESULTS: We identified 783 randomized controlled trials (level 1 evidence) pertaining to 37 (24%) of the decision/intervenlions. An additional 32 (21% ) of the decision/interventions were supported by evidence from single arm prospective studies (level 2 evidence). However, only retrospective or anec dotal evidence (level 3 evidence) was available to support 55% of the ident ified decision/interventions. In a retrospective review of the decision/int erventions made in the management of 255 consecutive patients, 78% of the i nitial decision/interventions in the management of newly diagnosed hematolo gic/oncologic disorders could have been based on level 1 evidence. However, more than half (52%) of all the decision/interventions made in the managem ent of these 255 patients were supported only by level 2 or 3 evidence. CONCLUSIONS: We conclude that level 1 evidence to support the development o f practice guidelines is available primarily for initial decision/intervent ions of newly diagnosed diseases. Level 1 evidence to develop guidelines fo r the management of relapsed or refractory malignant diseases is currently lacking. Am J Med. 1999;106:198-205. (C) 1999 by Excerpta Medica, Inc.