Table 6. Newcastle-Ottawa quality assessment scale for randomized controlled trials.

† Okun et al. [27] was labeled as an observational study.

Scoring explanation for each category (a maximum of one star can awarded for each category with the exception of two stars in the comparability category):

- Is the case definition adequate? A* - yes, with independent validation, B - yes, with record linkage or based on self-reports

- Representativeness of the cases: A* - consecutive or obvious representative series of cases

- Selection of controls: A* - community controls

- Definition of controls: N/A - not applicable

- Comparability: * study controls for one important factor, ** study controls for two important factors

- Ascertainment of exposure: A* - secure record

- Same method of ascertainment for cases and controls - A*

- Non-response rate: A* - same rate for both groups

Randomized controlled trials	Selection				Comparability	Exposure			Quality score
	Is the case definition adequate?	Representativeness of the cases	Selection of controls	Definition of controls	Comparability of cases and controls based on the design or analysis	Ascertainment of exposure	Same method of ascertainment for cases and controls	Non-response rate
Celiker et al. 2019 [24]	A*	A*	A*	N/A	*	A*	A*	A*	7
Follett et al. 2010 [25]	A*	A*	A*	N/A	*	A*	A*	A*	7
Odekerken et al. 2013 [28]	A*	A*	A*	N/A	**	A*	A*	A*	8
Okun et al. 2009 [26]	A*	A*	A*	N/A	**	A*	A*	A*	8
Okun et al. 2014 [27] †	B	A*	A*	N/A	*	A*	A*	A*	6
Rothlind et al. 2007 [29]	A*	A*	A*	N/A	**	A*	A*	A*	8
Weaver et al. 2012 [13]	A*	A*	A*	N/A	**	A*	A*	A*	8