. 2014 Dec 13;4(12):e006859. doi: 10.1136/bmjopen-2014-006859

Table 4.

Newcastle-Ottawa Quality Assessment Scale—Observational Study Star Template

Study	Selection	Comparability	Outcome/exposure
Appiah et al⁵⁶	*/**	/*	/*
Huebner et al⁵⁵	*/**	/*	/*
Liang et al⁵⁴	*/**	/*	/*
Shrestha et al²⁹	*/**	/*	/*
White et al⁵³	**/**	/*	/*

Selection—maximum of 4 stars (representativeness of exposed cohort; selection of non-exposed cohort; and exposure).

Comparability—maximum of 2 stars (comparability between cohorts).

Outcome/ Exposure—maximum of 3 stars (adequacy of outcome, follow-up duration).