Methodological quality assessment
Each article meeting the inclusion criteria was independent-
ly assessed by two raters for reporting quality using two
scales. The first scale, by Tooth et al. [7], is a validated and
reliable list of criteria for evaluating threats to internal and
external validity in observational studies. This scale has 33
questions covering the areas of recruitment, data collection,
biases, data analysis, study population and generalisability.
The maximum possible score is 33, a higher score indicat-
ing greater reporting quality. The second scale by
Stalenhoef et al. [8] has 10 criteria and was developed for
evaluating falls research in older adults. The higher the
score the more complete the reporting of details.