Associations between diabetic retinopathy, mortality, disease, and mental health: an umbrella review of observational meta-analyses

Table 1 Credibility assessment criteria and grading

Grading of evidence	Criteria
Grade I^*	- Statistical significance of p < 1*10^–6, including more than 1,000 cases (or more than 20, 000 participants for continuous outcomes) - Have the largest component study reporting a significant result (p < 0.05), have a 95% prediction interval that excluded the null - Did not have large heterogeneity (I² < 50%) - Showed no evidence of small study effects (p > 0.10) and excess significance bias (p > 0.10)
Grade II^*	- Significance of p < 0.001, including more than 1,000 cases (or more than 20,000 participants for continuous outcomes) - Have the largest component study reporting a statistically significant result (p < 0.05)
Grade III^*	- Significance of p < 0.01 with more than 1,000 cases (or more than 20,000 participants for continuous outcomes)
Grade IV	- Remaining significant associations with p < 0.05

^*Note that an AMSTAR grade of ‘low’ or ‘critically low’ downgraded the classification by one grade

ISSN: 1472-6823