Association of proteinuria with incident atrial fibrillation in the general Japanese population

Background: Although proteinuria has been associated with incident atrial fibrillation (AF) in Western countries, the association has not been investigated in the general Japanese population. Methods: Participants aged ≥40 years who underwent the Japanese specific health check-up in Kanazawa City in 2013 and who completed a urine dipstick test were included in this study. Exposure was considered as presence or absence of proteinuria (≥1+). The outcome was incident AF confirmed by 12-lead electrocardiography. The Cox proportional hazard model was used to compute hazard ratio (HR) of proteinuria (≥1+) for incident AF after adjustment for traditional risk factors. We also completed stratified analyses by baseline characteristics. Results: A total of 37,910 participants aged ≥40 years were included (mean age: 72.3 years, male sex: 37%). Proteinuria ≥1+ was observed in 2.765 (7.3%) participants. During a median follow-up period of 5 years, 708 incident AF cases were observed. Proteinuria ≥1+ was associated with incident AF (HR, 1.47: 95% confidence interval, 1.18–1.84) after covariate adjustment. Stratified analysis demonstrated that the association of proteinuria with AF was stronger in participants <75 years [HR 1.89 (95% CI 1.32–2.70)] compared with those ≥75 years [HR 1.27 (95% CI 0.95–1.69)] (interaction p-value = 0.02). Conclusions: Proteinuria was significantly associated with incident AF in the general Japanese population. The evaluation of proteinuria using urine dipstick test may be useful in the evaluation of incident AF, especially in younger general population.