Table 1.

Grade assessment of certainty of estimate of effect size and summary of findings

GRADE assessment of certainty
									Absolute risk
Outcome	Risk of bias	Inconsistency	Indirectness	Imprecision	Publication bias	No of studies	No of participants	Relative difference (95% CI)	Medium risk	Exposed risk (95% CI)	Certainty (reasons for downgrading)
All-cause mortality	Serious limitations (uncontrolled confounding)	Serious inconsistency (heterogeneity)	No serious indirectness	No serious imprecision	Undetected	3	391 429	OR=1.00 (0.94 to 1.06)	323.5 age-standardised mortality rate per 100 000 person-years5	323.5 (304.1 to 342.8) age-standardised mortality rate per 100 000 person-years	Very low (risk of bias; inconsistency)
Self-rated health	Serious limitations (incomplete follow-up)	Serious inconsistency (heterogeneity)	No serious indirectness (borderline)	No serious imprecision	Undetected	5	45 904	OR=1.26 (1.01 to 1.57)	25.0%*	29.6% (25.2% to 34.4%)	Very low (risk of bias; inconsistency)
Mental health symptoms	Serious limitations (uncontrolled confounding and incomplete follow-up)	No serious inconsistency (borderline)	No serious indirectness	No serious imprecision	Undetected	11	55 121	OR=1.44 (1.23 to 1.70)	18.5†	24.6% (21.8% to 27.8%)	Very low (risk of bias)

*http://healthsurvey.hscic.gov.uk/data-visualisation/data-visualisation/explore-the-trends/general-health.aspx.

†http://healthsurvey.hscic.gov.uk/support-guidance/public-health/health-survey-for-england-2016/well-being-and-mental-health.aspx.

GRADE, Grades of Recommendations, Assessment, Development and Evaluation.