Key item | No of articles providing recommendation | Topic of recommendation | N articles addressing area (%)a |
---|---|---|---|
Protocol development | 16 | Need for protocol to be written in advance | 12 (75%) |
 |  | Items to be included in protocol | 11 (69%) |
Research question | 20 | Scope of research question | 20 (100%) |
Search strategy | 33 | General methods for conducting searches in context of observational studies | 22 (67%) |
 |  | Specific challenges in searching for observational studies | 12 (36%) |
Study eligibility | 22 | Specifying eligibility criteria | 22 (100%) |
 |  | Assessment of eligibility | 6 (27%) |
Data extraction | 9 | Methods for data extraction | 9 (100%) |
Dealing with different study designs | 25 | Inclusion of different study designs in a single review | 10 (40%) |
 |  | Combining results from different study designs in a single meta-analysis | 15 (60%) |
Risk of bias assessment | 39 | Methods to assess the risk of bias in individual studies | 39 (100%) |
Publication bias | 20 | Inclusion of unpublished studies | 5 (25%) |
 |  | Methods to assess publication bias | 7 (35%) |
Heterogeneity | 39 | Measurement of heterogeneity | 39 (100%) |
 |  | Exploring potential causes of heterogeneity | 16 (41%) |
Statistical analysis | 52 | Deciding to combine results in a single effect estimate | 20 (38%) |
 |  | Choosing fixed or random effects meta-analysis | 16 (31%) |