Evaluating non-randomised intervention studies

Abstract

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Interpretation of the evidence for the efficacy and safety of statin therapy

“…using the wrong statistical model). 6,7,93,[106][107][108] Consequently, relying on evidence from observational studies about the effects of treatment on common outcomes -rather than considering it to be "hypothesisgenerating" -may well have adverse consequences for patients and public health.…”

“…106 It has been concluded that these reviews identified many examples where the results of the same intervention were on average the same, but also many examples where the results differed. For example, there have been many claims about the benefits of various vitamin supplements based on observational studies 128,129 that have been reliably refuted by large-scale randomized trials.…”

“…These findings are consistent with empirical studies in which biases in observational studies were shown to be large enough to conclude falsely that treatment produced benefit or harm, with none of a range of statistical strategies (such as regression analysis or propensity matching) capable of adjusting adequately or predictably for bias. 93,[106][107][108] Biases due to differences in the ascertainment of health outcomes Observational studies of treatment effects are often based on health outcome data that have been recorded without consistent coding or validation. [92][93][94][95] Moreover, by contrast with the situation in randomized controlled trials with blinded treatment assignment (i.e.…”

Comparative clinical effectiveness of management strategies for sciatica: systematic review and network meta-analyses

“…The RCT is widely regarded as the design of choice when assessing the effectiveness of health care interventions 168 and we acknowledge the controversy over the inclusion of non-randomised evidence. Non-randomised studies were included in the search because some treatment approaches may not have been evaluated by RCTs, and also to increase the precision of the findings for interventions evaluated by a limited number of studies.…”

Pain perception in Parkinson’s disease: A systematic review and meta-analysis of experimental studies

“…[14] (see Table 1). Overall scores were not computed due to concerns over their interpretability [14], but the impact of poorly endorsed validity criteria was examined in moderator analysis.…”