A bipolar II cohort (ABC): The association of functional disability with gender and rapid cycling

- The study population comprised rigorously defined cases of bipolar II disorder.
- Comorbidity rates in this clinical population did not differ by gender.
- Only 5% of all cases were rated as having a high level current and past year functioning.
- Females had higher levels of functional impairment than males.
- Rapid cycling is very common in bipolar II disorder and accounts for a significant proportion of the variance in functioning.

BackgroundBipolar II disorder (BP II) is a chronic, frequently co-morbid, and complex disorder with similar rates of attempted suicide to BP I. However, case identification for BP II studies that is based on clinician diagnosis alone is prone to error. This paper reports on differences between clinical and research diagnoses and then describes the clinical characteristics of a carefully defined BP II cohort.MethodsA cohort of rigorously defined BP II cases were recruited from a range of primary and secondary health services in the North of England to participate in a programme of cross-sectional and prospective studies. Case identification, and rapid cycling, comorbidities and functioning were examined.ResultsOf 355 probable clinical cases of BP II disorder, 176 (∼50%) met rigorous diagnostic criteria. The sample mean age was ∼44 years, with a mean duration of mood disorder of ∼18 years. Two thirds of the cohort were female (n=116), but only 40% were in paid employment. Current and past year functioning was more impaired in females and those with rapid cycling.LimitationsThis paper describes only the preliminary assessments of the cohort, so it was not possible to examine additional factors that may contribute to the explained variance in functioning.ConclusionsThis carefully ascertained cohort of BP II cases show few gender differences, except for levels of functional impairment. Interestingly, the most common problem identified with using case note diagnoses of BP II arose because of failure to record prior episodes of mania, not failure to identify hypomania.