Elsevier

Journal of Affective Disorders

Volume 174, 15 March 2015, Pages 303-309
Journal of Affective Disorders

Research report
Gender differences in the treatment of patients with bipolar disorder: A study of 7354 patients

https://doi.org/10.1016/j.jad.2014.11.058Get rights and content

Abstract

Background

Gender differences in treatment that are not supported by empirical evidence have been reported in several areas of medicine. Here, the aim was to evaluate potential gender differences in the treatment for bipolar disorder.

Methods

Data was collected from the Swedish National Quality Assurance Register for bipolar disorder (BipoläR). Baseline registrations from the period 2004–2011 of 7354 patients were analyzed. Multiple logistic regression analysis was used to study the impact of gender on interventions.

Results

Women were more often treated with antidepressants, lamotrigine, electroconvulsive therapy, benzodiazepines, and psychotherapy. Men were more often treated with lithium. There were no gender differences in treatment with mood stabilizers as a group, neuroleptics, or valproate. Subgroup analyses revealed that ECT was more common in women only in the bipolar I subgroup. Contrariwise, lamotrigine was more common in women only in the bipolar II subgroup.

Limitations

As BipoläR contains data on outpatient treatment of persons with bipolar disorder in Sweden, it is unclear if these findings translate to inpatient care and to outpatient treatment in other countries.

Conclusions

Men and women with bipolar disorder receive different treatments in routine clinical settings in Sweden. Gender differences in level of functioning, bipolar subtype, or severity of bipolar disorder could not explain the higher prevalence of pharmacological treatment, electroconvulsive therapy, and psychotherapy in women. Our results suggest that clinicians׳ treatment decisions are to some extent unduly influenced by patients׳ gender.

Introduction

Bipolar disorder is a serious psychiatric disease with an estimated lifetime prevalence of 0.6% for bipolar disorder type I (BP I), 0.4% for bipolar disorder type II (BP II), and 2.4% for bipolar spectrum disorders (BPS) according to a recent study conducted by the World Health Organization (Merikangas et al., 2011). Although the lifetime prevalence of bipolar disorder appears to be roughly equal in both genders (Angst, 1998, Bebbington and Ramana, 1995, Gold, 1998, Grant et al., 2005), a number of reports suggest gender differences in the symptomatic picture among bipolar patients. Many, but not all, studies report that women with bipolar disorder are more likely to suffer from subsyndromal depressed mood and dysphoria (Altshuler et al., 2010, Diflorio and Jones, 2010, Morgan et al., 2005, Rasgon et al., 2005a), even though the number of depressives episodes and the time spent in syndromal depression do not differ between men and women (Baldassano et al., 2005, Diflorio and Jones, 2010, Grant et al., 2005, Hendrick et al., 2000, Kawa et al., 2005, Kessing, 2004, Suominen et al., 2009). A majority of studies shows that women are more likely than men to be diagnosed with the BP II subtype, and to experience hypomanic episodes (Angst, 1998, Baldassano et al., 2005, Cassano et al., 1992, Diflorio and Jones, 2010, Merikangas et al., 2011, Schneck et al., 2008). Finally, a number of studies point out that women are more likely than men to suffer from mixed episodes (Benazzi, 2003, Diflorio and Jones, 2010, Grant et al., 2005, Kessing, 2004, Kessing, 2008, Suppes et al., 2005).

There is a range of treatment options for bipolar disorder, including mood stabilizers such as lithium, neuroleptics (both first and second generation neuroleptics), electroconvulsive treatment (ECT), psychotherapy, and psychoeducation. By and large, there is no clear-cut evidence suggesting that treatment response to these modalities differs between men and women, and hence no justification for adjusting the bipolar disorder treatment according to gender. Data are inconclusive with respect to the response to mood stabilizers; some studies find possible gender differences (Hendrick et al., 2000, Kawa et al., 2005, Leibenluft, 1996, Viguera et al., 2000) while others do not (Arnold et al., 2000, Dilsaver et al., 1993, Freeman et al., 1992, Post et al., 1987, Secunda et al., 1985, Swann et al., 1997, Viguera et al., 2001). There is no evidence to suggest that bipolar men and women respond differently to ECT or psychotherapy. High teratogenic risk in some mood stabilizers, such as valproate and carbamazepine (Yonkers et al., 2004), as well as risk for menstrual abnormalities and polycystic ovary syndrome (PCOS) (O’Donovan et al., 2002, Rasgon et al., 2005b), should, however, be taken into account when treating women. Reproductive considerations for women of a fertile age could therefore lead to gender differences in prescribing patterns of these specific medications. Kriegshauser et al. (2010) found that women have more fear than men of gaining weight as an adverse effect of medication, which could affect the choice of medication in women.

The importance of gender to treatment choice for bipolar disorder has not previously been systematically studied. Hence, it is not known whether men and women are offered different treatments in clinical practice. In the STEP-BD study (Systematic Treatment Program for Bipolar Disorder), there was no gender difference in the use of antidepressants in bipolar patients (Baldassano et al., 2005), but we lack data on potential gender differences with respect to the use of lithium, mood stabilizers, ECT, and psychotherapy in bipolar patients in routine clinical practice. We know from studies of other medical disorders, such as coronary artery disease, that there have been unjustified differences in treatment between men and women, and attention to this has led to adjustments in clinical practice (Heer et al., 2002, Tsuyuki et al., 1994).

The aim of this study was to survey whether men and women with bipolar disorder in psychiatric outpatient care receive different treatments. The null hypothesis was that we would find no gender difference in the treatment of bipolar disorder.

Section snippets

Sources of data and study population

Data were derived from the Swedish national quality assurance register for bipolar disorders (BipoläR). BipoläR contains individualized data concerning case-mix, medical interventions, and treatment outcomes. It was established in 2004 with the aim of improving the quality of care for bipolar patients in Sweden. The register captures basic clinical epidemiological data along with longitudinal data on the natural history and clinical course of the disease. Data is collected by the treating

Results

Demographic and clinical characteristics of the analyzed group are summarized in Table 1. There was an overrepresentation of women (61%) in our study population with a mean (SD) age of 47.9 (23.3) years for women and 50.1 (15.5) years for men. With respect to diagnostic subgroups, 46% of the patients were diagnosed with BP I, 37% with BP II, 14% with NOS, and 3% with SAD (percentages not shown in table). Women were more likely than men to be diagnosed with BP II and BP NOS, while men were more

Discussion

We analyzed individual data from more than 7000 bipolar patients to elucidate potential gender differences with respect to clinical interventions for bipolar disorder. The data were collected from and reflect routine clinical practice in Sweden. The study demonstrated distinct gender differences. Women with bipolar disorder were more likely to receive treatment with antidepressants, benzodiazepines, ECT, lamotrigine, and psychotherapy. Particularly in bipolar type I, women were more likely than

Conclusion

Our study demonstrates significant gender differences in the routine clinical treatment of bipolar disorders in Sweden. Women are more likely to be treated with antidepressants, ECT, lamotrigine, benzodiazepines, and psychotherapy, while men are more likely to be treated with lithium. The higher prevalence of medical interventions in women could not be explained by differences in global assessment of functioning, bipolar subtype, previous suicide attempts, number of depressive, mixed and manic

Role of funding source

This research was supported by grants from the Regional Research and Development Unit Västra Götaland FoU (VGFOUREG-158591), the Swedisfrh Medical Research Council (K2011-61X-14647-09-3, K2010-61X-21569-01-1, and K2010-61P-21568-01-4), the Swedish foundation for Strategic Research, the Swedish Brain foundation, and the Swedish Federal Government under the LUA/ALF agreement (ALFGBG-142041).

The funding source had no involvement in study design, data collection, data analysis, data interpretation,

Conflict of interest

Alina Karanti, M.D.

AK declares that, over the past three years, she has received compensation for lectures from Eli Lilly Sweden. No other equity ownership, profit-sharing agreements, royalties, or patent.

- ConsultantNone
- Grant/ResearchNone
- Speakers BureauNone
- Major stockholderNone
- Other financial or Material supportNone

As of 11/06/14

Bo Runeson, M.D., Ph.D.

BR declares that he has received compensation for lectures from AstraZeneca, Eli Lilly Sweden and Lundbeck pharmaceuticals. No other

Acknowledgments

The quality register BipoläR is acknowledged for providing data for this study. This research was supported by Grants from the Regional Research and Development Unit Västra Götaland FoU (VGFOUREG-158591), the Swedish Medical Research Council (K2011-61X-14647-09-3, K2010-61X-21569-01-1, and K2010-61P-21568-01-4), the Swedish Foundation for Strategic Research (KF10-0039), the Swedish Brain Foundation (FO2014-0125), and the Swedish Federal Government under the LUA/ALF agreement (ALFGBG-142041).

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