Response and Relapse in Patients With Schizophrenia Treated With Olanzapine, Risperidone, Quetiapine, or Haloperidol: 12-Month Follow-Up of the Intercontinental Schizophrenia Outpatient Health Outcomes (IC-SOHO) Study

Martin Dossenbach, M.D.; Cesar Arango-Dávila, M.D., M.Sc.; Hernan Silva Ibarra, M.D.; Eric Landa, M.D.; Jaime Aguilar, M.D.; Osvaldo Caro, M.D.; Joanna Leadbetter, Ph.D.; and Sheila Assunção, M.D., Ph.D.

Objective: The primary aim of this study was to compare the effectiveness of 12 months' treatment with olanzapine, risperidone, quetiapine, or haloperidol in preventing relapse of schizophrenia. The study also examined other measures of clinical effectiveness and tolerability.

Method: Outpatients with schizophrenia (ICD-10 or DSM-IV), who initiated or changed antipsychotic treatment, entered this 3-year, naturalistic, prospective, observational study between November 2000 and December 2001. At baseline, subsets of patients were prescribed monotherapy with olanzapine (N = 3222), risperidone (N = 1116), quetiapine (N = 189), or haloperidol (N = 256). Patients remaining on monotherapy were assessed using the Clinical Global Impression-Schizophrenia scale. Relapse rate was determined from the responder subset. Treatment patterns, patient perception of treatment compliance, substance and alcohol intake patterns, and treatment tolerability were recorded. Results are based on 12-month treatment data.

Results: Compared to haloperidol-treated patients, olanzapine- and risperidone-treated patients had approximately 3 to 4 times higher odds of response at 12 months (p <= .001) and 6 times lower odds of relapse (p <= .001 for olanzapine-treated patients).Among patients treated with atypical antipsychotics, olanzapine- and risperidone-treated patients had lower odds of relapse (although the difference was not significant at p <= .001) and significantly higher odds of response (p <= .001) compared to quetiapine-treated patients. The tolerability profile generally favored the atypical antipsychotics over haloperidol.

Conclusion: These interim results support the findings of randomized controlled trials and verify that in this naturalistic study, patients treated with olanzapine or risperidone monotherapy were less likely to experience relapse than patients who received haloperidol. The clinical effectiveness and tolerability profile varied significantly between the atypical antipsychotics.

(J Clin Psychiatry 2005;66:1021-1030)

Received Sept. 7, 2004; accepted March 24, 2005. From Eli Lilly and Company, Ges.m.b.H, Vienna, Austria (Dr. Dossenbach); the Sebastián de Belalcazar Clinic, Cali, Colombia (Dr. Arango-Dávila); University Psychiatric Clinic, University of Chile, Santiago, Chile (Dr. Silva Ibarra); Sanatorium of San Juan de Dios, Zapopan, Jalisco, Mexico (Dr. Landa); Angeles de las Lomas Hospital and San Rafael Clinic, Huixquilucan, Edo de México, Mexico (Dr. Aguilar); First Hospital Panamericano, Cidra, Puerto Rico (Dr. Caro); Clinical Outcomes and Research Institute, Eli Lilly Australia Pty Limited, Macquarie Park, New South Wales, Australia (Dr. Leadbetter); and Eli Lilly of Brazil, São Paulo, Brazil (Dr. Assunção).

This study was supported by a research grant from Eli Lilly and Company, Indianapolis, Ind. The authors acknowledge the independent medical writing assistance provided by ProScribe Medical Communications, funded in part from an unrestricted financial grant from Eli Lilly Australia Pty Limited, Macquarie Park, New South Wales, Australia.

Drs. Dossenbach, Leadbetter, and Assunção are employees of Eli Lilly and Company. Dr. Arango-Dávila has received grant/research support from Eli Lilly Australia. Dr. Landa had been on the speakers board for Eli Lilly. Dr. Aguilar has received grant/research support from and has been on the speakers or advisory board for Eli Lilly. Dr. Caro has been a consultant for, has received grant/research support from, and has been on the speakers or advisory board for Eli Lilly. Dr. Silva Ibarra reports no other financial or other relationship relevant to the subject of this article.

Dr. Dossenbach presented a summary of the IC-SOHO study at the 157th annual meeting of the American Psychiatric Association, May 5, 2004, in New York, N.Y.

Corresponding author and reprints: Martin Dossenbach, M.D., Eli Lilly and Company, Ges.m.b.H., Koelblgasse 8-10, Postfach 114, A-1030, Wien, Austria (e-mail: d.m@lilly.com).