The account for provider and center effects in multicenter interventional and surgical randomized controlled trials is in need of improvement:: a review

Objective: To systematically review the account of center and provider effects in large surgical and interventional randomized controlled trials. Study Design: A systematic review of multicenter interventional randomized trials of 200+ patients. The search included Medline from 1 January 2000 through 11 October 2005 and a hand search of the bibliographies of retrieved articles. One author abstracted all data using standardized abstraction forms; a second reviewer assessed a random sample of reports as quality-assurance procedure. Results: Sixty-eight reports met inclusion criteria. The trials predominantly reported on cardiology (n = 23, 34%). The number of participating providers was reported in I I trials (16%). Both the performed control and performed interventional procedures were described in 43 trials (63%). The use of stratified random allocation on center was reported in 26 trials (38%) and on provider in 6 trials (9%). The analysis was adjusted for center in four trials (6%) and for provider in three trials (4%). Conclusions: Only few trials account for center or provider effect in the design and analysis. Authors and journal editors could play an important role in improving the reporting of trials. (c) 2008 Elsevier Inc. All rights reserved.