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Predictors of excellent response to lithium: results from a nationwide register-based study

Kessing, Lars Vedela; Hellmund, Gunnarb; Andersen, Per Kraghb

International Clinical Psychopharmacology: November 2011 - Volume 26 - Issue 6 - p 323–328
doi: 10.1097/YIC.0b013e32834a5cd0
Original Articles

The aim of this study was to identify sociodemographic and clinical predictors of excellent response, that is, ‘cure’ of future affective episodes, to lithium in monotherapy. We used nationwide registers to identify all patients with a diagnosis of bipolar disorder in psychiatric hospital settings who were prescribed lithium from 1995 to 2006 in Denmark (N=3762). Excellent lithium responders were defined as patients who after a stabilization lithium start-up period of 6 months, continued lithium in monotherapy without getting hospitalized. The rate of excellent response to lithium in monotherapy was 8.9% [95% confidence interval (CI): 7.9–9.9] at 5-year follow-up and 5.4% (95% CI: 4.4–6.3) at 10-year follow-up. The rate of nonresponse to lithium monotherapy was significantly increased for female patients [hazards ratio (HR)=1.12, 95% CI: 1.04–1.21) and for patients with a depressive index episode compared with patients in remission or with a diagnosis of other or unspecified bipolar disorder before first lithium purchase (HR=1.13, 95% CI: 1.03–1.25). The rate of nonresponse increased by 3% (95% CI: 2–5%) for every psychiatric hospitalization before first purchase of lithium. Patients with somatic comorbidity had increased rates of non-response to lithium compared with patients without somatic comorbidity (HR=1.23, 95% CI: 1.00–1.52).

It is concluded that the prevalence of excellent response to lithium monotherapy is low and such patients are characterized by few earlier psychiatric hospitalizations, a manic index episode before lithium and reduced somatic comorbidity.

aPsychiatric Center Copenhagen, University Hospital of Copenhagen, Rigshospitalet

bDepartment of Biostatistics, University of Copenhagen, Copenhagen, Denmark

Correspondence to Professor Lars Vedel Kessing, DMSc, Psychiatric Center Copenhagen, University Hospital of Copenhagen, Rigshospitalet, Blegdamsvej 9, Copenhagen 2100, Denmark Tel: +45 3545 6237; fax: +45 3545 6218; e-mail: lars.vedel.kessing@regionh.dk

Received June 15, 2011

Accepted June 28, 2011

© 2011 Lippincott Williams & Wilkins, Inc.