Table 1.
Summary of study characteristics for the 130 included papers
| Characteristic | n (%) |
|---|---|
| Publication year | |
| 2019 | 47 (36%) |
| 2020 | 45 (35%) |
| 2021 | 38 (29%) |
| Journala | |
| American Journal of Epidemiology | 50 (38%) |
| Epidemiology | 24 (18%) |
| European Journal of Epidemiology | 21 (16%) |
| International Journal of Epidemiology | 34 (26%) |
| Journal of Clinical Epidemiology | 1 (1%) |
| Study design | |
| Prospective longitudinal study | 85 (65%) |
| Retrospective analysis of routinely collected data | 15 (12%) |
| Pooled cohort analysis | 9 (7%) |
| Case-control study | 7 (5%) |
| Cross-sectional study | 5 (4%) |
| Case-cohort study | 2 (2%) |
| Otherb | 7 (5%) |
| Type of outcome used for analysis | |
| Binary | 45 (35%) |
| Categorical (excluding binary) | 3 (2%) |
| Continuous | 33 (25%) |
| Time to event | 49 (38%) |
| Causal question inclusion criteriac | |
| Explicitly stated interest in a causal effect | 33 (25%) |
| Estimate was given a causal interpretation | 130 (100%) |
| Typical signals of a causal analysisc | |
| A directed acyclic graph was used to depict causal assumptions | 40 (31%) |
| A set of variables were identified to control for confounding | 106 (82%) |
| Effect was estimated using a regression model with adjustment for a set of covariatesd | 129 (99%) |
aNumber of papers published between January 2019 and December 2021 based using a Pub Med search for (("2019/01/01"[Date - Publication] : "2021/12/31"[Date - Publication])) AND ("Journal name"[Journal]): American Journal of Epidemiology, 876; Epidemiology, 496; European Journal of Epidemiology, 370; International Journal of Epidemiology, 814; Journal of Clinical Epidemiology, 996
bSecondary analysis of trial data (n = 2); prospective follow-up of cohort recruited for trial (n = 2); pooled analysis of data from case-control and cohort studies (n = 1); pooled analysis of data from case-control studies (n = 1); transportability study using data from 4 clinical trials and 1 observational cohort (n = 1)
cCategories are not mutually exclusive
dOne study used structural equation modelling seemingly without adjustment for covariates, although a causal conclusion was made