Socio-demographic and Clinical Factors
Seventy-five patients (66.4%) were diagnosed with BD-I at baseline, while 38 (33.4%) were diagnosed with BD-II. The mean age was 38 years (SD=12.6, range 17–73 years), 29% were married, and 57% were female. Seventy-four patients (66%) reported at least one suicide attempt lifetime. Suicide attempters in the sample had made an average of 2.6 attempts (SD=1.9, range 1–11), defined as self-injury with intent to die.
Bonferonni correction for 22 tests would set significance at p<0.002. Using this threshold, the FD group reported more years ill, more depressive episodes, and a greater total number of mood episodes (). There were no other between-group differences. Using a less conservative significance cutoff of α=0.01, the FD group was, on average, older at baseline assessment, less likely to be diagnosed Type I BD, less likely to have co-morbid alcohol use disorder, reported fewer reasons for living, and was more likely to report a history of psychotherapy (). The FD and FM groups did not differ in gender distribution, proportion married, co-morbid Cluster B or drug use disorder, lifetime aggression, impulsivity or hostility, number of manic episodes, or hospitalizations. The groups did not differ in age of first mood episode, first hospitalization, or first psychotropic medication ().
Relationship of First Episode Polarity to Clinical and Demographic Variables in 113 Patients with Bipolar Disorder
The FD group was more likely to have a lifetime history of suicide attempt. FD group attempters had made twice as many suicide attempts as FM group attempters. The groups did not differ in age of first attempt, medical severity of the most lethal past attempt, or reported suicidal intent preceding the most medically serious attempt ().
Relationship of First Episode Polarity to Suicidality in 113 Patients with Bipolar Disorder
Logistic regression analysis
We performed multiple logistic regression analysis of prior suicide attempt status to examine its relationship to first episode polarity. We tested exploratory models adjusting for variables associated with initial episode polarity in bivariate tests. Since suicidal behavior in BD has been associated with depressive symptoms, and since the more years someone is ill, the more time they have to make an attempt, our primary model included the following independent variables: polarity of initial episode, years ill, number of major depressive episodes (excluding the initial episode for the FD group), and the interaction between first episode polarity and number of major depressive episodes.
Results showed that FD group membership was associated with eightfold odds of a lifetime history of suicide attempt, adjusting for years ill and total number of lifetime major depressive episodes (Wald −2.10; OR 8.33; 95% CI 1.85 to 33.33; p=0.005). Years ill, number of lifetime major depressive episodes and its interaction with first episode polarity were not significant predictors.
To the above model, we sequentially added variables associated at p<0.05 in bivariate tests with initial episode polarity. The results did not change substantially after sequentially including the following additional covariates: BD-I vs. II/NOS subtype, age, impulsivity, history of alcohol use disorder, history of psychotherapy, number of lifetime psychotic episodes, number of lifetime manic episodes (excluding the first episode in the FM group), and the interaction between lifetime manic episodes and first episode polarity (data not shown).
When reasons for living was added to the model, it was inversely associated with suicide attempt history (Wald 6.28; OR 0.98; 95% CI 0.97 to 1.00; p=0.01). In this model, initial episode polarity was no longer significant (Wald 1.30; OR 3.02; 95% CI 0.45 to 20.22; p=0.25), and no other variable was associated with suicide attempt status (data not shown). However, this model included only 70 cases (out of 100 in the original model) due to missing data.
When we added hostility to the original model, first episode polarity was still significant with a slightly lower odds ratio (Wald 4.30; OR 7.07; 95% CI 1.11 to 44.94; p=0.04). Hostility was also associated with suicide attempt status (Wald 5.70; OR 1.06; 95% CI 1.01 to 1.11; p=0.02). A five-point increase in Buss-Durkee hostility score was associated with a 34% greater odds of a prior suicide attempt (data not shown).