Table 1.

Percentage of studies meeting quality indicators.

Quality indicator
Ethics
1	Approval of ethics committee.	71.4%
	Reporting
2	Description of participants' characteristics: inclusion and exclusion criteria for all participants (including control group, if applicable).	75%
3	Report of the period of time in which the sample was recruited.	78.6%
4	Report of estimates of the random variability in the data for the main outcome(s).	85.7%
5	Report of effect size(s) of main outcome(s).	96.4%
6∗	Report of exact p-value(s) for the main result(s), except when the probability value is less than 0.001.	79.2%
	External validity
7	Use of random sampling methods to recruit participants.	10.7%
8∗	Report of the proportion of participants that agreed to participate.	48.1%
9	Inclusion of a priori power analyses.	7.14%
	Internal validity
10	Use of previously validated instruments to measure main outcomes.	89.3%
11	Report of the internal reliability of measurement instruments within the study.	39.3%
12∗	Inclusion of specific analyses to control for potential confounders (e.g., sex, age, health status, etc.).	58.3%
	Open science
13	Pre-registration of the study design, primary outcomes and analysis plan.	0%
14	Open access to databases (i.e., databases available in public repositories).	3.57%

Note: Quality indicators marked with an asterisk were not applicable in some cases. Thus, there were 27 studies that met the eighth indicator, while for the sixth and twelfth indicators there were 24 studies.