Table 1 Pros and cons of different approaches for incorporating adverse effect data in a systematic review*
Method | Look in the trials/studies included in the systematic review of benefit. | Look in all retrieved trials/studies of that intervention, even in those excluded from the analysis of benefit | Look for studies that specifically evaluate adverse effects of the intervention |
|---|---|---|---|
Protocol | Should usually be the minimum recommendation | Studies rejected from analysis of benefit (e.g. because beneficial outcomes are measured in a different way, which cannot be combined with other studies), may be included to allow adverse effect data collection. Two sets of inclusion criteria will be needed – for benefit, and for adverse effects | Design separate strategy to identify studies that report adverse effects, including those that do not look at beneficial effects. |
Might amount to a separate review nested within a traditional Cochrane review | |||
Pros | Less demanding on time and resources | More comprehensive than just looking at included trials | Most comprehensive |
Does not require new literature search strategy | Can potentially cover a more representative group of patients | May be able to evaluate rare, or long-term, or previously unrecognized adverse effects | |
Cons | Data may be very limited and biased towards common, short-term harms | Relatively time consuming as full-text articles of all potentially relevant studies need checking Data may be limited to well-recognized and commonly seen adverse effects. | Time and resource intensive |
Benefit and harm cannot be compared directly as the data come from different sources | Special techniques required in synthesizing data from a diverse range of sources | ||
Increased quantity of data but greater risk of biased and poor quality data | |||
Benefit and harm cannot be compared directly as the data come from different sources. |