Table 1 Study design and country.
Study design | n = number of studies | ||||
Total N = 74 | 2006–2010 | 2011–2015 | 2016–2020 | ||
Clinical studies | 65 | 5 | 29 | 31 | |
Interventional | |||||
Randomised controlled trial (RCT) | 15 | 0 | 5 | 10 | |
Clinical trial – single arm | 5 | 1 | 1 | 3 | |
Clinical trial – cross over | 1 | 0 | 1 | 0 | |
Observational | |||||
Cross-sectional | 26 | 4 | 10 | 12 | |
Longitudinal/cohort | 18 | 0 | 12 | 6 | |
Instrument validation studies | 9 | 1 | 5 | 3 | |
Countrya | Total N = 74 | n = number of interventional studies | n = number of observational studies | ||
International (>2 countries) | 19 | 11 | 8 | ||
USA | 7 | 2 | 5 | ||
UK | 7 | 4 | 3 | ||
Netherlands | 6 | 1 | 5 | ||
Italy | 4 | 0 | 4 | ||
Denmark | 3 | 2 | 1 | ||
Germany | 3 | 0 | 3 | ||
Korea | 3 | 0 | 3 | ||
Spain | 2 | 1 | 1 | ||
Mexico | 2 | 0 | 2 | ||
France | 2 | 0 | 2 | ||
Belgium | 1 | 0 | 1 | ||
