Evaluating non-randomised intervention studies - NIHR Health ...

© Queen’s Printer and Controller of HMSO 2003. All rights reserved.Review Method of incorporating Results of quality investigationquality into synthesisCole, 1993 327 Qualitative Quality was not discussed in terms of the results of each study, but the authors do acknowledge that seriouslimitations in trial design and measures were presentCole, 1996 185 Quantitative Quality score did not appear to be associated with the RDAbsolute risk reductions for each individualstudy were plotted against quality score ona forest plotColeridge Smith, Qualitative Results of quality assessment were used to include/exclude studies. Only those with internal validity graded as1999 97 strong or moderate were included in the review of treatments. Recommendations appear to be largely based onthe strength of the evdienceCollingsworth, Qualitative Authors concluded that “despite their methodological shortcomings the conclusions from all 12 studies were1997 260 broadly in agreement and substantiated the findings from the non-empirical work”Cooper, 1994 313 Quantitative Clinical improvement was lower in higher quality studies, but the difference was not significant. In studies ofCompared high and low quality ‘very good’ quality a 75% clinical improvement was observed, compared with 86% for ‘good’ studies and 83%for ‘borderline’ studies (p = 0.17)Cowley, 1995 109 Qualitative Studies classified as A/B/C for each study design but only the results of ‘A’ category studies were discussed. OneRCT, four NRS and 32 uncontrolled studies were given an A rating: key results were discussed. No conclusiveevidence was identifiedCox, 1989 242 Qualitative Studies grouped by quality score (high/medium/low) and results discussed in terms of quality. Three high-qualitystudies were equivocal regarding treatments reviewedCuijpers, 1998 243 Quantitative Small non-significant difference in overall ES was observed between studies with and without a control groupUse of control group investigated in (1.14 and 1.06)subgroup analysisCuratolo, 1998 248 Not consideredde Craen, 1996 244 Quantitative Including the quality score as an additional weighting factor in the analysis did not change the results (data notQuality weightingpresented)de Kruif, 1996 245 Qualitative Results of QA were discussed with reviewers’ conclusions. High-quality studies appeared to show positive effectand low-quality were equivalent. Identified trend of effectiveness of myofeedback not conclusive owing tomethodological limitationsde Oliveira, 1996 246 Quantitative All studies bar one scored >0.6. When the lower-quality study was excluded from the meta-analysis the resultsExcluded lower quality studiesdid not change (no data presented)Detsky, 1987 309 Quantitative Quality scores were negatively correlated with the differences in complication (correlation coefficient –0.56,Correlation analysisp = 0.13) and fatality rates (coefficient –0.51, p = 0.031) between groups, i.e. studies with better-quality scoresshowed a smaller trend in favour of intervention groupcontinuedHealth Technology Assessment 2003; Vol. 7: No. 27155