The treated prevalence and incidence of bipolar disorder among national health insurance enrollees in Taiwan, 1996–2003

We used the NHI database to estimate the treated prevalence and incidence of bipolar disorder. The national health research institute (NHRI) provided a population based data file of 200,432 random subjects, about 1% of the population, for the study. We obtain a random sample of 136,045 subjects as a fixed cohort from 1996 to 2003. We identified study subjects who had at least one service claim during these years for either ambulatory or inpatient care with a principal diagnosis of bipolar disorder. The cumulative treated prevalence increased from 0.60 per 1,000 to 4.51 per 1,000 from 1996 to 2003. The annual treated incidence was around 0.48 per 1,000 per year to 0.71 per 1,000 per year during 1997–2003. Higher treated incidence was detected in the 45–64 (hazard ratio [HR], 1.63; 95% CI, 1.26–2.12) and 65 years or older age groups (HR, 1.57; 95% CI, 1.14–2.15), female (HR, 1.23; 95% CI, 1.04–1.46), non-aborigine (HR, 3.12; 95% CI, 1.26–7.75), with a fixed premium (HR, 1.60; 95% CI, 1.18–2.17), and those who lived in the eastern region (HR, 3.26; 95% CI, 2.31–4.59). According to the trends from 1996 to 2003, more persons with bipolar disorder had sought treatment in the NHI program in Taiwan. However, the treated prevalence of bipolar disorder in NHI was still lower than those of community studies in Western countries. In the future, we will continue to use NHI data to perform outcome evaluation and follow-up studies of bipolar disorder.