. 2023 Jul 13;96(7):931–963. doi: 10.1007/s00420-023-01981-w

Table 4.

Assessment of the methodological quality using the “Newcastle–Ottawa Quality Assessment Scale” for cohort studies and evaluation of the validity of the questionnaire used

Authors, year	Selection				Comparability	Outcome			Total score (out of 9)	Validity of outcome measurement instruments
	Representativeness of the exposed cohort Maximum: *	Selection of non-exposed cohort Maximum: *	Ascertain-ment of exposure Maximum: *	Presence of outcome of interest at start of study Maximum: *	Comparability of cohorts Maximum: **	Assessment of outcome Maximum: *	Follow-up time Maximum: *	Adequacy of follow-up Maximum: *
Brendler-Lindqvist et al. (2022)	*	*	*		**	*	*	*	********^a	International classification system
Espinoza-Castro et al. (2021)		*					*	*	***	Validated in Spanish^b
Holten et al. (2018)		*	*		**		*	*	******	Validated in original language^b
Hultin et al. (2016)	*	*			**		*	*	******	Validated in Swedish^c

^aInterpretation: 0–3 stars: low methodological quality, 4–6 stars: moderate methodological quality, 7–9: high methodological quality

^bValidated version was used

^cNot known if validated version was used