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

152Review Method of incorporating Results of quality investigationquality into synthesisACCP/AACVPR, Qualitative Studies were classified according to level of evidence and recommendations were graded accordingly.1997 393 Methodological issues were discussed narrativelyAnders, 1996 81 Quantitative The t-test of quality score differences was non-significant (p = 0.25). The authors conclude that they cannotSubgroup analysis according to size of effect; reject the null hypothesis; no difference in the quality score between studies existedbetween group differences in mean qualityscores investigatedAronson, 1996 249 Quantitative Pooling all studies indicated a strongly positive effect (RR 2.09, 95% CI: 1.31 to 3.32, p = 0.002). Eliminating oneSensitivity analysis sequentially removing NRS with no control group and then one RCT with a treated control group lowered the relative response togroups of studies with sharedtreatment (RR 1.93, 95% CI: 1.13 to 3.29, p = 0.02). Further elimination of an RCT with possibly contaminatedmethodological deficienciesrandomisation increased the relative response to treatment (RR 2.70, 95% CI: 1.89 to 3.86, p = 0.006), andeliminated the statistical heterogeneity of the results. The three NRS which remained in the analysis were HCTsand therefore likely to have biased resultsAudet, 1993 176 Qualitative Study results were discussed in terms of methodological quality. Only two studies were of sufficiently high qualityto demonstrate a positive effect from teachingBaker, 1994 82 Quantitative Two higher quality studies indicated statistically significant reductions in mortality; of the five others, three hadForest plot used to present study results statistically significant reductions and two were non-significantranked by qualityBass, 1993 88 Qualitative Studies grouped by design, and quality score and overall rank presented: some NRS ranked more highly thanRCTs. Found reasonably high-quality evidence to support the interventionBauman, 1997 208 Qualitative A statement was made regarding the overall quality of included studies. Quality stated to be poor, limiting theinterpretation of resultsBerard, 1997 209 Quantitative The correlation between effect size and quality score (r = –0.07, p = 0.19) or sample size (r = 0.04, p = 0.63)Correlation analysis to investigate ES and were not found to be significantquality scoreBeyer, 1998 210 Quantitative When all studies were pooled, a small, positive, but non-significant effect from influenza vaccine was producedSubgroup analysis according to(RD –0.6, 95% CI: –3 to 1.9). The two poor-quality studies (both of the NRS) showed a much more stronglyquality (high/medium/low)protective effect from the vaccine (RD –9.4, no CIs given), and the medium- and high-quality studies (all RCTs)indicated a much more conservative effect (RD –0.3 and 1.1, respectively, no CIs given)Boers, 1991 212 Qualitative Methodological characteristics were discussed in detail and studies were categorised and discussed according tostrength of evidence. Insufficient evidence was found to make any recommendations regarding drugcombinationsBours, 1998 73 Quantitative Three studies with only positive results had lower quality scores; those with only negative results had similarVisual plot used to map relationship between scores to those with mixed (+ve/–ve) outcomes. Studies with highest scores demonstrated no effect. Five NRSstudy outcome and methodological score scored more highly than any RCTAppendix 7continued