Objectives: This study was conducted (1) to assess the prophylactic efficacy of lithium and carbamazepine in the maintenance treatment of schizoaffective disorder (SAD) with long-term follow-up, (2) to find predictors of the success or failure of prophylaxis, and (3) to search for differences in outcome between schizoaffective patients diagnosed according to either ICD-10 or DSM-IV.
Methods: Participating patients met the ICD-10 and/or DSM-IV criteria for schizoaffective disorder. Outcome was assessed using the Morbidity Index and time elapsed until the first recurrence during prophylaxis. Predictor variables were age at onset of illness, gender, and family history, as well as the following parameters prior to prophylaxis: time between onset of illness and start of prophylactic treatment (latency), severity of illness (hospitalization rate), number of hospital admissions and polarity of schizoaffective disorder (schizobipolar vs. schizounipolar). The time spent in the hospital per year was used to compare the course of illness before maintenance therapy to the time during maintenance therapy. Co-medication was taken into account. The clinical data during prophylaxis were ascertained prospectively.
Results: Forty-nine patients met the ICD-10 criteria for schizoaffective disorder, 34 of whom also met the DSM-IV criteria. All 49 patients underwent prophylactic therapy with either lithium (n=41) or carbamazepine (n=8) for an average of 6.8 years. After initiating prophylaxis, the number of days spent in the hospital declined dramatically from an average of 71 days to 11 days per year. No independent variable proved to be a consistent predictor of the course of treatment. In regard to the subgroup of patients diagnosed according to DSM-IV, no significant differences were observed when this subgroup was compared to the whole sample.
Limitations: As this is a naturalistic study it does not allow for exact quantitative measures of effectiveness.
Conclusions: This study is the first of its kind to investigate the efficacy of maintenance therapy in SAD over such an extended period of time. The results of the study show that lithium and carbamazepine appear to be highly effective in treating patients with schizoaffective disorder. However, it remains unclear how many schizoaffective patients will respond to mood stabilizer treatment and whether predictors of clinical relevance exist. In our sample, differences in the ICD-10 and DSM-IV diagnostic criteria for schizoaffective disorder were not related to significant differences in clinical outcome.