Table A-2Quality assessment tool for studies reported adverse events24

CriterionExplanationScore
Quality criterion 1: Nonbiased selection1: study is a properly randomized controlled trial, or an observational study with a clear predefined inception cohort (that attempted to evaluate all patients in the inception cohort)
0: study does not meet above criteria (e.g., convenience samples)
Quality criterion 2: Adequate description of population1: study reports two or more demographic characteristics, presenting symptoms/syndrome and at least one important risk factor for complications
0: study does not meet above criteria
Quality criterion 3: Low loss to follow-up1: study reports number lost to follow-up, and the overall number lost to follow-up is low (threshold set at 5% for studies of carotid endarterectomy and 10% for studies of rofecoxib)
0: study does not meet above criteria
Quality criterion 4: Adverse events prespecified and defined1: study reports explicit definitions for major complications that allow for reproducible ascertainment (what adverse events were being investigated and what constituted an “event”)
0: study does not meet above criteria
Quality criterion 5: Ascertainment technique adequately described1: study reports methods used to ascertain complications, including who ascertained, timing, and methods used
0: study does not meet above criteria
Quality criterion 6: Nonbiased ascertainment of adverse events1: independent or masked assessment or complications (for studies of carotid endarterectomy, someone other than the surgeon who performed the procedure; for studies of rofecoxib, presence of an external endpoint committee blinded to treatment allocation)
0: study does not meet above criteria
Quality criterion 7: Adequate statistical analysis of potential confounders1: study examines one or more relevant confounders/risk factors (in addition to the comparison group in controlled studies), using acceptable statistical techniques such as stratification or adjustment
0: study does not meet above criteria
Quality criterion 8: Adequate duration of follow-up1: study reports duration of follow-up and duration of follow-up adequate to identify expected adverse events (threshold set at 30 days for studies of carotid endarterectomy and 6 months for studies of rofecoxib)
0: study does not meet above criteria
Total quality score = sum of scores (0–8)>6: Good
4–6: Fair
<4: Poor

Reprinted from Chou R, Fu R, Carson S, et al. Methodological shortcomings predicted lower harm estimates in one of two sets of studies of clinical interventions. J Clin Epidemiol 2007 Jan;60(1):18–28, with permission from Elsevier.

From: Assessing the Risk of Bias of Individual Studies in Systematic Reviews of Health Care Interventions

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