Table 4.

GRADE assessment of the certainty of evidence.

Factors	No. of included studies	Study design	Initial certainty	Risk of bias	Inconsistency	Indirectness	Imprecision	Publication bias	Upgrading factors	Final certainty of evidence
Educational level	4	Cross-sectional	Low	Downgraded 1 level	Not downgraded	Not downgraded	Not downgraded	Unable to assess	None identified	Very low
Night shift frequency	2	Cross-sectional	Low	Downgraded 1 level	Not downgraded	Not downgraded	Not downgraded	Unable to assess	None identified	Very lowi
Employment type	3	Cross-sectional	Low	Downgraded 1 level	Not downgraded	Not downgraded	Downgraded 1 level	Unable to assess	None identified	Very low
Self-efficacy	3	Cross-sectional	Low	Downgraded 1 level	Downgraded 1 level	Not downgraded	Downgraded 1 level	Unable to assess	None identified	Very low
Professional identity	3	Cross-sectional	Low	Downgraded 1 level	Downgraded 1 level	Not downgraded	Not downgraded	Unable to assess	None identified	Very low
Perceived organizational support	3	Cross-sectional	Low	Downgraded 1 level	Downgraded 1 level	Not downgraded	Downgraded 1 level	Unable to assess	None identified	Very low
Empowering leadership	2	Cross-sectional	Low	Downgraded 1 level	Downgraded 1 level	Not downgraded	Not downgraded	Unable to assess	None identified	Very low