A retrospective analysis of risk and protective factors for natural death in bipolar disorder

Objective: Many of the prior mortality studies on bipolar disorder have emerged primarily from the larger health service groups, with a tendency to focus on suicide alone. This study examines personal and clinical characteristics of bipolar patients in Taiwan in order to identify the factors associated with early natural death. Method: Bipolar patients admitted to a psychiatric hospital in Taiwan between 1987 and 2002 were retrospectively followed through record linkage for cause of death. One living bipolar individual was matched to each deceased patient as a control subject for age, gender, and date of index admission. Clinical data and the results of laboratory examinations during the last period of hospitalization were obtained through a review of medical records. Results: In a total of 60 natural deaths, the principal cause was circulatory disease (33.3%). Conditional logistic regressions revealed that the variables most strongly associated with natural deaths were years of antipsychotic treatment prior to the last visit (95% CI for odds ratio [OR] = 0.77 to 0.98), serum alanine aminotransferase levels (95% CI for OR = 1.02 to 1.25), and leukocyte counts (95% CI for OR = 1.01 to 2.50). Years of lithium treatment (95% CI for OR = 0.74 to 0.97) may be substituted for antipsychotic treatment as a protective factor. Conclusions: Systemic inflammation and nonhepatic tissue damage during the acute phase of bipolar disorder may be risk factors for early natural death. Psychiatric treatment, including medication with antipsychotics or lithium, could be a factor in protecting against early natural death.