Safety and efficacy of noninvasive ventilation in patients with blunt chest trauma: a systematic review

Table 3 Quality assessment of observational studies

		Selection		Comparability		Outcome/exposure
Study	Representation of the exposed cohort	Selection of non exposed cohort	Ascertainment of exposure	Outcome not present at start	Comparability of cohorts based on design or analysis	Assessment of outcomes	Time for follow-up	Adequacy of follow-up	Overall score
Linton et al. (1982)	*	*	*	*	-	*	-	-	Moderate
Vidhani et al. (2001)	*	-	*	*	*	_	_	-	Low

^aAsterisks in each category signify identification of an appropriate methodological process in the study. Studies were considered to be of high quality if less than two components of the Newcastle-Ottawa Scale were missing, fair quality if two or three components were missing and low quality if more than three components were missing.

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