title: Stability of lithium treatment in bipolar disorder - long-term follow-up of 346 patients.
abstract: BACKGROUND
  The purpose of this study was to investigate the effectiveness and stability of long-term lithium treatment in a prospective, international, multicenter cohort of bipolar patients in a naturalistic setting.
  
  
  METHODS
  Patients were selected according to DSM IV criteria for bipolar disorder and required long-term treatment. They were prospectively followed and documented in five centers belonging to the International Group for the Study of Lithium-Treated Patients. This was a prospective cohort study without a comparison group. Lithium treatment was administered in a naturalistic and specialized outpatient setting. All patients underwent a comprehensive psychiatric examination, which included the use of standard rating scales, as well as an evaluation of clinical course based on the morbidity index (MI). Wald tests were used to assess the significance of fixed effects and covariates when analyzing the relationship between depressive, manic, and total morbidity index and several characteristics of illness course.
  
  
  CONCLUSIONS
  A total of 346 patients with bipolar disorder I or II were followed for a mean period of 10.0 years (standard deviation (SD) 6.2, range 1 to 20). The morbidity index remained stable over time: the mean MI was 0.125 (SD 0.299) in year 1 and 0.110 (SD 0.267) in year 20. The MI was not associated with the duration of lithium treatment, the number or frequency of episodes prior to treatment, or latency from the onset of bipolar disorder to the start of lithium treatment. The drop-out rate was high over the study period. Our findings suggest that long-term response to lithium maintenance treatment remains stable over time.
authors.affiliation: Institute for Social Medicine, Epidemiology and Health Economics, Charité University Medical Center, Berlin, 10098 Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Berghöfer
authors.affiliation: Department of Psychiatry, Dalhousie University, Halifax, Nova Scotia B3H 4R2 Canada.
authors.forename: Martin
authors.initials: M
authors.lastname: Alda
authors.affiliation: Department of Psychiatry and Psychotherapy, Charité University Medical Center, Berlin, 10098 Germany.
authors.forename: Mazda
authors.initials: M
authors.lastname: Adli
authors.affiliation: Department of Psychiatry and Psychotherapy, University of Cologne Medical School, Cologne, 50923 Germany.
authors.forename: Christopher
authors.initials: C
authors.lastname: Baethge
authors.affiliation: Department of Psychiatry and Psychotherapy, Universitätsklinikum Carl Gustav Carus Dresden, Technische Universität Dresden, Dresden, 01307 Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Bauer
authors.affiliation: Department of Psychiatry, Schlosspark Clinic, Berlin, 14059 Germany.
authors.forename: Tom
authors.initials: T
authors.lastname: Bschor
authors.affiliation: Mood Disorders Center of Ottawa and Department of Psychiatry, University of Toronto, Toronto, M5S 2E4 Canada.
authors.forename: Paul
authors.initials: P
authors.lastname: Grof
authors.affiliation: Drug Commission of the German Medical Association, Berlin, 10623 Germany.
authors.forename: Bruno
authors.initials: B
authors.lastname: Müller-Oerlinghausen
authors.affiliation: Department of Adult Psychiatry, Poznan University of Medical Sciences, Poznan, 61-701 Poland.
authors.forename: Janusz K
authors.initials: JK
authors.lastname: Rybakowski
authors.affiliation: Department of Adult Psychiatry, Poznan University of Medical Sciences, Poznan, 61-701 Poland.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Suwalska
authors.affiliation: Department of Psychiatry and Psychotherapy, Universitätsklinikum Carl Gustav Carus Dresden, Technische Universität Dresden, Dresden, 01307 Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Pfennig
keywords: Bipolar disorder; Lithium; Long-term treatment; Morbidity index; Stability