title: The quality of medical evidence in hematology-oncology.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the quality of the medical evidence available to the clinician in the practice of hematology/oncology.
  
  
  METHODS
  We selected 14 neoplastic hematologic disorders and identified 154 clinically important patient management decision/interventions, ranging from initial treatment decisions to those made for the treatment of recurrent or refractory disease. We also performed a search of the scientific literature 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/interventions. An additional 32 (21%) of the decision/interventions were supported by evidence from single arm prospective studies (level 2 evidence). However, only retrospective or anecdotal evidence (level 3 evidence) was available to support 55% of the identified decision/interventions. In a retrospective review of the decision/interventions made in the management of 255 consecutive patients, 78% of the initial decision/interventions in the management of newly diagnosed hematologic/oncologic disorders could have been based on level 1 evidence. However, more than half (52%) of all the decision/interventions made in the management of these 255 patients were supported only by level 2 or 3 evidence.
  
  
  CONCLUSIONS
  We conclude that level 1 evidence to support the development of practice guidelines is available primarily for initial decision/interventions of newly diagnosed diseases. Level 1 evidence to develop guidelines for the management of relapsed or refractory malignant diseases is currently lacking.
authors.affiliation: Department of Medicine, James Graham Brown Cancer Center, University of Louisville, Kentucky, USA.
authors.forename: B
authors.initials: B
authors.lastname: Djulbegovic
authors.forename: T P
authors.initials: TP
authors.lastname: Loughran
authors.forename: C A
authors.initials: CA
authors.lastname: Hornung
authors.forename: G
authors.initials: G
authors.lastname: Kloecker
authors.forename: E N
authors.initials: EN
authors.lastname: Efthimiadis
authors.forename: T J
authors.initials: TJ
authors.lastname: Hadley
authors.forename: J
authors.initials: J
authors.lastname: Englert
authors.forename: M
authors.initials: M
authors.lastname: Hoskins
authors.forename: G H
authors.initials: GH
authors.lastname: Goldsmith
mesh_terms: D019317:Evidence-Based Medicine; D019337:Hematologic Neoplasms / Q000628:therapy*; D006801:Humans; D016032:Randomized Controlled Trials as Topic; D016019:Survival Analysis; D016896:Treatment Outcome