CHADS2 Score and Risk of New-onset Peripheral Arterial Occlusive Disease in Patients without Atrial Fibrillation: A Nationwide Cohort Study in Taiwan

Aim: Although our recent cross-sectional study demonstrated that the CHADS(2) score is associated with an ankle-brachial index of < 0.9 in patients without atrial fibrillation (AF), the true cause-effect relationship between these parameters remains to be evaluated. Hence, the aim of this study was to investigate whether the CHADS(2) score is a useful predictor of new-onset PAOD in non-AF patients. Methods: From January 1, 2000 to December 31, 2001, a total of 723,750 patients older than 18 years of age with no past history of PAOD, rheumatic heart disease or AF were surveyed from the "National Health Insurance Research Database." The CHADS2 score was calculated for each patient. Finally, 581,997 (score 0), 84,971 (score 1), 31,473 (score 2), 14,432 (score 3), 8,156 (score 4), 2,430 (score 5) and 291 (score 6) patients were studied and followed for the onset of PAOD. We further divided the study patients into four groups: group 1 (score 0), group 2 (score 1-2), group 3 (score 3-4) and group 4 (score 5-6). Results: During the follow-up period of 9.83 +/- 0.01 years, 24,775 (3.4%) patients experienced new-onset PAOD. The overall incidence of PAOD was 0.6 per 1,000 patient-years. The rate of PAOD increased from 1.8% (group 1) to 18.7% (group 4) (p< 0.001). According to a multivariate analysis, groups 2-4 were significantly associated with new-onset PAOD (all p< 0.001). In addition, the hazard ratio of each two-point increment in the CHADS(2) score for predicting PAOD was 2.51 (p< 0.001). Conclusions: The CHADS(2) score is a useful predictor of new-onset PAOD in non-AF patients.