Key features of the included pooled analyses/meta-analyses and systematic reviews (PMASRs)
| Included PMASRs | N (%) | Range | |
| Minimum | Maximum | ||
| Included PMASRs, n | 42 (100) | – | – |
| Included meta-analysis, n | 31 (74) | – | – |
| Included systematic review and meta-analysis, n | 11 (26) | – | – |
| Systematic review and meta-analysis that only included prospective cohorts, n | 1 (2) | – | – |
| PMASRs that only included prospective cohorts, n | 7 (17) | – | – |
| Publication year | – | 1991 | 2017 |
| Funding (industry-funded PMASRs) | 2 (5) | – | – |
| Funding (non-industry-funded PMASRs) | 26 (62) | – | – |
| Funding (no funding/not reported) | 14 (33) | – | – |
| Age (years) | – | 8 | 107 |
| PMASRs that used random-effects model, n | 25 (60) | – | – |
| PMASRs that used fixed-effects model, n | 3 (7) | – | – |
| PMASRs that used random-effects and fixed-effects models, n | 8 (19) | – | – |
| PMASRs that reported subgroup analysis, n | 26 (62) | – | – |
| PMASRs that reported publication bias, n | 23 (55) | – | – |
| PMASRs that reported meta-regression, n | 14 (33) | – | – |
| PMASRs that reported Grading of Recommendations Assessment, Development and Evaluation (GRADE), n | 0 (0) | – | – |
| PMASRs that reported risk of cancer as outcome, n | 40 (95) | – | – |
| PMASRs that reported all-cause mortality as outcome, n | 1 (2) | – | – |
| PMASRs that reported cancer-specific mortality as outcome, n | 3 (7) | – | – |
| AMSTAR scores of PMASRs (out of 11) | – | 1 | 8 |
| AMSTAR, Assessing the Methodological Quality of Systematic Reviews. | |||