Prevalence and incidence in relation to increasing age strata
Figure 1 shows the effect of age on AF prevalence in an AF cohort. In general, prevalence increased in a non-linear fashion from age <45 years to ≥ 85 years (table 2). There was a departure from linear effects of age to non-linearity for age groups> 55 years relative to those < 55 years. On average, the obtained prevalence ratios for different age groups relative to the age <45 year group were as follows: (a) 45-54 years:4.59 (95%CI 4.50-4.69); (b) 55-64 years: 9.22 (95%CI 9.04-9.40); (c) 65-75 years: 31.85 (95%CI 31.28-32.47); (d) 75-84 years: 49.46 (95%CI 48.55-50.38); and (e) > 85 years: 60.64 (95%CI 59.43-61.88).
The incidence rate for older females was much higher than older males. For age < 65 years, the incidence rate for females was less than males (Table 1). The incidence ratios for elderly females relative to younger females was 15.07 (95%CI 14.47-15.70), a value that is about 50% than for elderly males (10.57 (95%CI 10.24-10.92)). Incidence rates increased steadily with age, with the exception of the 65-74 and 75-84 having similar rates (Figure 2).
A detailed treatment of prevalence and incidence measures in terms of frequency estimates and 95% CI is provided suppl table S4 age group (ages < 45, 45-54, 55-64, 65-74, 75-84, >85 years) and gender.