Statistical analysis

Baseline characteristics of the pooled study cohorts are presented as absolute and relative frequencies for categorical variables and means (standard deviations) or medians (25th, 75th percentiles) for continuous variables. Cumulative incidences and incidence rates per 1000 person‐years were calculated for AF, HF, and death as competing risks. Cumulative incidence curves were calculated using the Aalen–Johansen method.

The association of reduced renal function with AF, HF, and with death modelled as a competing risk was assessed using separate Cox proportional hazards regression models for each endpoint. Time since baseline was used as the time scale and eGFR category at baseline as the exposure (≥90, 60 to <90, and <60 mL/min/1.73 m²). The models were adjusted for age, sex, and cohort (Model 1) along with cardiovascular risk factors at baseline (body mass index, smoking status, diabetes, and systolic blood pressure) in Model 2. In a further analysis, an incremental adjustment for log‐transformed biomarker concentrations (hs‐CRP, hs‐cTnI, and NT‐proBNP) was performed based on Model 2. Non‐detectable biomarker measurements were set to half of the lower limit of detection of the assay. Subjects were censored at the end of follow‐up, upon death, or at the time of their cardiovascular event in the respective analyses. Scaled Schoenfeld residuals against follow‐up time were plotted for each covariate to verify the proportional hazards assumption.

Finally, in subjects with CKD, restricted cubic spline regression curves were used to visualize the association between eGFR and AF/HF and the association between log‐transformed biomarker concentrations and AF/HF. Statistical analysis was performed with SAS version 9.4 (SAS Institute, Cary, NC, USA) and R version 4.0.2 (R Foundation for Statistical Computing, Vienna, Austria).