Iosief Abraha1, Francesco Cozzolino2, Massimiliano Orso2, Mauro Marchesi3, Antonella Germani3, Guido Lombardo4, Paolo Eusebi2, Rita De Florio5, Maria Laura Luchetta6, Alfonso Iorio7, Alessandro Montedori2. 1. Health Planning Service, Regional Health Authority of Umbria, Via Mario Angeloni, 61, 06124 Perugia, Italy. Electronic address: iosief_a@yahoo.it. 2. Health Planning Service, Regional Health Authority of Umbria, Via Mario Angeloni, 61, 06124 Perugia, Italy. 3. Transfusion Medicine Service, Azienda Ospedaliera di Perugia, Piazzale Menghini, 1, Perugia 06129, Italy. 4. Surgical and Biomedical Sciences, University of Perugia, Piazzale Gambuli, 1, Perugia 06129, Italy. 5. General Medicine, Azienda USL Umbria 1, Via Guerriero Guerra, 21, Perugia 06127, Italy. 6. General Medicine, Azienda USL Umbria 2, Viale Donato Bramante, 37, Terni 05100, Italy. 7. Department of Clinical Epidemiology and Biostatistics, McMaster University, CRL 140, 1280 Main Street West, Hamilton, Ontario, Canada.
Abstract
OBJECTIVES: To describe the characteristics, and estimate the incidence, of trials included in systematic reviews deviating from the intention-to-treat (ITT) principle. STUDY DESIGN AND SETTING: A 5% random sample of reviews were selected (Medline 2006-2010). Trials from reviews were classified based on the ITT: (1) ITT trials (trials reporting standard ITT analyses); (2) modified ITT (mITT) trials (modified ITT; trials deviating from standard ITT); or (3) no ITT trials. RESULTS: Of 222 reviews, 81 (36%) included at least one mITT trial. Reviews with mITT trials were more likely to contain trials that used placebo, that investigated drugs, and that reported favorable results. The incidence of reviews with mITT trial ranged from 29% (17/58) to 48% (23/48). Of the 2,349 trials, 597 (25.4%) were classified as ITT trials, 323 (13.8%) as mITT trials, and 1,429 (60.8%) as no ITT trials. The mITT trials were more likely to have reported exclusions compared to studies classified as ITT trials and to have received funding. CONCLUSION: The reporting of the type of ITT may differ according to the clinical area and the type of intervention. Deviation from ITT in randomized controlled trials is a widespread phenomenon that significantly affects systematic reviews.
OBJECTIVES: To describe the characteristics, and estimate the incidence, of trials included in systematic reviews deviating from the intention-to-treat (ITT) principle. STUDY DESIGN AND SETTING: A 5% random sample of reviews were selected (Medline 2006-2010). Trials from reviews were classified based on the ITT: (1) ITT trials (trials reporting standard ITT analyses); (2) modified ITT (mITT) trials (modified ITT; trials deviating from standard ITT); or (3) no ITT trials. RESULTS: Of 222 reviews, 81 (36%) included at least one mITT trial. Reviews with mITT trials were more likely to contain trials that used placebo, that investigated drugs, and that reported favorable results. The incidence of reviews with mITT trial ranged from 29% (17/58) to 48% (23/48). Of the 2,349 trials, 597 (25.4%) were classified as ITT trials, 323 (13.8%) as mITT trials, and 1,429 (60.8%) as no ITT trials. The mITT trials were more likely to have reported exclusions compared to studies classified as ITT trials and to have received funding. CONCLUSION: The reporting of the type of ITT may differ according to the clinical area and the type of intervention. Deviation from ITT in randomized controlled trials is a widespread phenomenon that significantly affects systematic reviews.
Authors: Matheus Oliveira Almeida; Bruno T Saragiotto; Chris G Maher; Leonardo Oliveira Pena Costa Journal: BMJ Open Date: 2017-09-27 Impact factor: 2.692