Transformation of excess mortality in people with schizophrenia and bipolar disorder in Taiwan

Given the concerns regarding the adverse health outcomes associated with weight gain and metabolic syndrome in relation to use of second-generation antipsychotics (SGAs), we aimed in this study to explore whether the increase in the use of SGAs would have any impacts on the trend of excess mortality in people with schizophrenia and bipolar disorder (BPD).

Two nationwide samples of individuals with schizophrenia and BPD were identified in Taiwan's National Health Insurance Research Database in 2003 and in 2008, respectively. Age- and gender-standardized mortality ratios (SMRs) were calculated for each of the 3-year observation periods. The SMRs were compared between the calendar year cohorts, by disease group, and by causes of death.

The mortality gap for people with schizophrenia decreased slightly, revealing an SMR of 3.40 (95% CI 3.30-3.50) for the 2003 cohort and 3.14 (3.06-3.23) for the 2008 cohort. The mortality gap for BPD individuals remained relatively stable with only those aged 15-44 years having an SMR rising significantly from 7.04 (6.38-7.76) to 9.10 (8.44-9.79). Additionally, in this group of BPD patients aged 15-44 years, the natural-cause-SMR increased from 5.65 (4.93-6.44) to 7.16 (6.46-7.91).

Compared with the general population, the gap in the excess mortality for people with schizophrenia reduced slightly. However, the over 200% difference between the cohorts in the excess mortality for BPD individuals aged 15-44 years could be a warning sign. Future research to further examine the related factors underlying those changes is warranted.