Imprecision – serious imprecision was assumed to occur when
the review collated ,300 total events (dichotomous outcomes)
or a total population size ,400 (continuous outcomes). Very
serious imprecision occurred when there were ,100 total
events or a population size of ,150 or where these were not
reported and could not be estimated. Where the events or
population were not reported, but the effect was statistically
significant the evidence were assessed as at serious risk of bias.
Where the number of events was not provided for dichotomous
outcomes then we assumed that imprecision was serious
(rather than very serious) if the review stated that there were at
least 1000 participants