Study characteristics.

Major components	Danielsson 2008	Pejtersen 2011	Danielsson 2014 & 2016	Platts 2020	Nielsen 2020
1. Was the sample frame appropriate to address the target population?	yes	yes	yes	yes	yes
2. Were study participants sampled in an appropriate way?	yes	yes	yes	yes	yes
3. Was the sample size adequate?	yes	yes	yes	yes	yes
4. Were the study subjects and the setting described in detail?	no	yes	no	yes	yes
5. Was the data analysis conducted with sufficient coverage of the identified sample?	yes	yes	yes	yes	yes
6. Were valid methods used for the identification of the condition?	yes	yes	yes	yes	yes
7. Was the condition measured in a standard, reliable way for all participants?	yes	yes	yes	yes	yes
8. Was there appropriate statistical analysis?	yes	no	yes	no	yes
9. Was the response rate adequate, and if not, was the low response rate managed appropriately?	yes	yes	yes	yes	no
Result (0–9)	8	8	8	8	8