Women with bipolar disorder spend more days in psychiatric inpatient units per hospitalization than their male counterparts, according to results from a register-based study published in the Journal of Affective Disorders.
Investigators derived psychiatric hospitalization data from the Swedish National Patient Register for the years 2005 to 2014. Adults (≥18 years) with bipolar disorder were retrospectively followed from their index inpatient admission to all subsequent psychiatric hospitalizations. Variables captured at index hospitalization included gender, bipolar disorder subtype, comorbid substance/alcohol use disorders, and comorbid personality disorders. Psychotropic medication use was assessed through the Prescribed Drug Register. Mixed-effects models were used to evaluate the influence of patient variables on length of hospital stay.
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The eligible study population comprised 16,271 individuals (60.0% women) with 39,653 admissions between October 2005 and December 2014. The mean (standard deviation [SD]) number of admissions per patient-year was 0.66 (SD, 0.75) for men and 0.69 (SD, 0.77) for women (P =.039). Women were significantly more likely than men to be diagnosed with the depressive subtype (odds ratio [OR], 1.30; 95% CI, 1.18-1.42; P <.001) and the grand other subtype (OR, 1.08; 95% CI, 1.00–1.17; P =.043). Women were also more likely to have a diagnosis of comorbid cluster B personality disorders (OR, 3.57; 95% CI, 1.66-7.67; P =.001) and to be readmitted (OR, 1.18; 95% CI, 1.10-1.23; P <.001) after initial discharge. However, women were less likely than men to present with mania (OR, 0.61; 95% CI, 0.047-0.79; P<.001), comorbid current (OR, 0.47; 95% CI, 0.32-0.67; P <.001) or former (OR, 0.62; 95% CI, 0.40-0.95; P=.027) alcohol use disorders, and current comorbid substance use disorders (OR, 0.66; 95% CI, 0.46-0.94; P =.022). No gender differences were observed in likelihood of receiving any psychotropic drug class.
Women spent an average of 21.6 (SD, 27.4) days in hospital per admission compared with just 20.1 (SD, 26.5) days observed among men (P <.001). In the unadjusted model, this amounted to 7.5% (95% CI, 4.2%-11.0%; P <.001) extra days in hospital per admission for women. When adjusted for bipolar subtype, comorbidities, and psychotropics use, however, this association decreased to 3.7% (95% CI, 0.1%-6.9%; P=.028) additional days per admission.
The use of only register data may limit the accuracy of certain patient measures; medication compliance, for example, could not be ascertained from prescription records alone. Even so, these data suggest that gender may influence psychiatric hospitalization stay length. Gender-sensitive practices are thus important in clinical management of bipolar disorder.
Ragazan DC, Eberhard J, Ösby U, Berge J. Gender influence on the bipolar disorder inpatient length of stay in Sweden, 2005–2014: a register-based study [published online May 28, 2019]. J Affect Disord. doi: 10.1016/j.jad.2019.05.052