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Aug 26, 2020 · Objective To assess the risk of bias associated with missing outcome data in systematic reviews. Design Imputation study. Setting Systematic reviews. Population 100 systematic reviews that included a group level meta-analysis with a statistically significant effect on a patient important dichotomous efficacy outcome. Main outcome measures Median percentage change in the relative effect ...
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Conclusion Even when applying plausible assumptions to the...
- Peer Review
Conclusion Even when applying plausible assumptions to the...
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- Definitions
- Categories of Participants with Potential MPD
- Eligibility Criteria
- Search Strategy
- Random Sampling of Citations
- Selection Process
- Data Abstraction
- Sample Size
- Data Analysis
MPD refers to outcome data for trial participants that are not available to the systematic reviewer authors (from the published trial reports or personal contact with trial authors) for inclusion in their meta-analyses. MPD do not relate to any of the following: 1. Missing studies (e.g., unpublished studies); 2. Entire unreported outcomes (e.g., ou...
We will use the following mutually exclusive categories of participants that could be potentially counted as having MPD, at the trial level: “mistakenly randomized and inappropriately excluded,” “did not receive any treatment,” “withdrew consent,” “outcome not assessable,” “dead,” “experienced adverse events,” “non-compliant,” “discontinued prematu...
The inclusion criteria for a systematic review: 1. 1. Meets the following minimum criteria we set for a systematic review of trials: 1.1. a. Described as “systematic review” and/or “meta-analysis” of trials; 1.2. b. Compares a clinical intervention to another (or to no intervention); 1.3. c. Reports a search strategy of at least one database; 2. 2....
We will search for Cochrane systematic reviews in the Cochrane Library. We will use the Ovid MEDLINE interface to search for non-Cochrane systematic reviews in the Core Clinical Journals (119 English language clinical journals indexed under Abridged Index Medicus by the National Library of Medicine (available at http://www.nlm.nih.gov/bsd/aim.html)...
We will retrieve two random samples of Cochrane and non-Cochrane systematic reviews from the pool of citations identified by our search. We will screen these two samples for eligibility using the above criteria. We will repeat the random sampling process as needed until reaching the final sample size, which will include the same number of Cochrane ...
We will conduct title and abstract screening, full-text screening, and data abstraction in teams of two reviewers working independently and in duplicate. At the title and abstract screening stage, we will obtain the full text for any citation included by at least one reviewer. At the full-text screening and data abstraction stages, the reviewers wi...
We will conduct data abstraction using web-based systematic review software (DistillerSR™). In a first phase, we will collect data from the eligible systematic reviews and the eligible meta-analyses. In the second phase, we will collect data from trials included in the eligible meta-analyses. Phase 1: we will abstract the following data from each e...
The sample size will be based on the goal of achieving enough precision (CI width of 0.1) around the proportion of systematic reviews (both Cochrane and non-Cochrane) for which the pooled effect estimate crosses the boundary of conventional statistical significance (further details below under “Impact of different methods of dealing with MPD on poo...
Agreement
We will assess agreement between reviewers for inclusion of systematic reviews at the full-text screening stage for their first judgment (i.e., before the step of reaching agreement by consensus) using chance-corrected agreement (kappa statistic). If fewer than 15% or more than 85% of citations are included in this study, we will measure agreement using chance-independent agreement (phi statistic). We will interpret the agreement statistics using the guidelines proposed by Landis and Koch...
Characteristics of the included systematic reviews
We will conduct a descriptive analysis of the characteristics of included systematic reviews and the comparisons of interest. For all descriptive analyses, we will use percentages for dichotomous variables. To describe the distribution of continuous variables, we will use the mean and standard deviation when distribution is near normal and median and interquartile range (IQR) when the distribution is substantially skewed. We will use the Shapiro-Wilk test to evaluate whether the distributions...
Categories of trial participants reviewers considered as having MPD
For each category of participants that could be potentially counted as having MPD (refer to section above on “Categories of participants with potential MPD”), we will calculate: 1. The percentage of systematic reviews documenting that category; 2. The percentage of trials documenting that category; 3. The distribution across trials of the proportion of participants belonging to that category. We will compare (1) data from the trial regarding the number of participants in the different categor...
- Elie A Akl, Elie A Akl, Lara A Kahale, Arnav Agarwal, Nada Al-Matari, Shanil Ebrahim, Shanil Ebrahim...
- 2014
The potential impact of missing dichotomous outcomes depends on the frequency (or risk) of the outcome. For example, if 10% of participants have missing outcomes, then their potential impact on the results is much greater if the risk of the event is 10% than if it is 50%. The following table illustrates the potential impact of observed risks.
Aug 26, 2020 · Potential impact of missing outcome data on treatment e ects in systematic review s: imputation study Lara A Kahale, 1,2 Assem M Khami s, 3 Batoul Diab, 1 Y aping Chang, 4 Luciane C ruz Lopes, 5
Jul 23, 2015 · Background When potentially associated with the likelihood of outcome, missing participant data represents a serious potential source of bias in randomized trials. Authors of systematic reviews frequently face this problem when conducting meta-analyses. The objective of this study is to conduct a systematic survey of the relevant literature to identify proposed approaches for how systematic ...
- Elie A. Akl, Elie A. Akl, Lara A. Kahale, Thomas Agoritsas, Romina Brignardello-Petersen, Romina Bri...
- 2015
Nov 14, 2024 · Background Missing outcome data can pose a serious threat to the validity of randomised clinical trial results. We aimed to study the extent of missing outcome data in randomised clinical trials of psychological interventions. Methods We performed a retrospective study of randomised clinical trial reports of psychological interventions published in World Psychiatry, JAMA Psychiatry, Lancet ...
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A typical simple imputation technique for dichotomous outcomes includes the best-case and worst-case scenarios.14 The best-case scenario assumes that all missing participants have a favourable outcome in the experimental group and poor outcome in the control group; the converse is assumed for the worst-case scenario. These two extremes are typically used as a sensitivity analysis and may ...
