Table 3.

Quality assessment of the enrolled studies

Study	Selection				Comparability	Outcome		Results
	Representativeness of the sample	Sample size	Non-respondents	Ascertainment of the exposure (risk factor):	Comparability of subjects in different outcome groups on the basis of design or analysis	Assessment of outcome	Statistical test
Garvin and Sledge [6]	*	*		*		*	*	5/10
Pennington et al. [7]	*	*	*	*		*	*	6/10
Garbin et al. [5]	*	*		*	**	**	*	8/10
Steadman et al. [13]	*	*		*	**	**	*	8/10
Azodo et al. [1]	*	*		*		*	*	5/10
Premadasa et al. [14]	*	*	*	*	**	**	*	9/10
McCombs et al. [15]	*	*		*		**	*	6/10
Ullah et al. [16]	*	*		*	**	**	*	8/10

Scale of studies (points): Very Good: 9–10, Good: 7–8, Satisfactory: 5–6, and Unsatisfactory: 0 to 4