Table 1.

Characteristics of included studies.

Characteristic	Number (%) of studies
Year of publication
Before 1990	4 (9%)
1990–2000	12 (27%)
After 2000	29 (64%)
Geographic location
USA	29 (64%)
UK	5 (11%)
other in Europe	3 (7%)
Canada	3 (7%)
Asia	3 (7%)
Australia	1 (2%)
Israel	1 (2%)
Study design
Pre-/post-intervention	16 (36%)
Descriptive	13 (29%)
Retrospective	9 (20%)
Interrupted time series	2 (4%)
Cohort studies	2 (4%)
Trend analysis	1 (2%)
User interviews	1 (2%)
Randomized controlled trial	1 (2%)
Age of studied population
Not reported	30 (67%)
Adults	12 (27%)
Children	3 (7%)