Study Type/s
New user active comparator cohort studies are classified as ‘complex’ analyses.
Study Design
New user cohorts.
Participant/s
At least two cohorts, including a cohort of new users of at least one drug/medicinal product under investigation (target cohort) and a cohort of new users of at least one drug/medicinal product as an active comparator (comparator cohort). Typically, new user cohorts exclude previous users of either cohort in the previous year as well as people with <1 year of data visibility before inclusion.
Follow-up
Participants in each cohort will be followed from therapy initiation date (index date). Two possibilities of analyses will be offered:
- In a ‘fixed’ follow-up analysis, follow-up will continue until death, loss to follow-up or a pre-specified time period (e.g., 3 years) regardless of treatment duration
- In an ‘on treatment’ analysis, follow-up will continue until treatment cessation, death, or loss of follow-up
Outcome/s
One or more study outcomes will be pre-specified, based on previous DARWIN EU algorithms or newly developed and validated ones.
In addition, a long list of negative control outcomes will be assessed, which are not known to have a causal association with the drug/s or medicinal product/s under study.
Analyses
Details will be discussed during programming of pipelines, but new users cohort analyses will include:
- Large-scale characterisation of participants in the target and comparator cohorts, including all features available in the data before or on index date
- Large-scale propensity scores (LSPS) will be estimated as the probability of exposure (target cohort) conditional on all available covariates available in the data with a prevalence >1%. LSPS will be estimated using Lasso regression
- Incidence rate/s of each of the outcomes of interest in the target and comparator cohorts after LSPS matching, stratification, or inverse probability weighting
- Diagnostic/s:
- Covariate balance
- Equipoise: plots of the distribution of the propensity score stratified by target vs comparator cohort
- Analyses will not be conducted where there is insufficient data, based on a pre-specified minimum detectable rate ratio (e.g., MDRR>5)
- Optional: In addition to the two above, residual confounding/systematic error will be available for estimation, as based on the number of negative control outcomes significantly associated with the exposure of interest
- Rate Ratios or Hazard Ratio/s and 95% confidence intervals will be estimated using Poisson or Cox models respectively, comparing the target vs comparator (reference) cohorts after LSPS matching, stratification, or inverse probability weighting
- Optionally, calibrated RR or HR will be estimated after empirical calibration using negative control outcomes