Prevalence of outcomes and risk factor analyses
The prevalence of an outcome, expressed as percentage, will be calculated by dividing the number of cases by the total number of participants (for that specific study) multiplied by 100. The 95% confidence intervals (95% CI) will be calculated by the Wilson method. When there is more than one subgroup of survivors or when a control group is included, the proportion of the cases in the separate groups will be compared with a Chi squared test. Subsequently, the respective contributions of risk factors, and their single and, where feasible, joint effects on the prevalence of respective outcomes will be estimated using multivariable regression analyses. Per health outcome, the possible determinants will be selected based on clinical knowledge and previous literature. For each covariate a direct analytical graph will be made to assess whether it is a (proxy) confounder, mediator, collider or competing exposure. To prevent overcorrection, cancer treatment and type of cancer will not be evaluated in the same model as they are strongly correlated.