Schizophrenic patients treated with olanzapine(Drug information on olanzapine) (Zyprexa) required less health care services and incurred less overall health care costs over a 28-week period than patients treated with risperidone(Drug information on risperidone) (Risperdal). This was the result of a study presented by Eli Lilly and Company researchers at the European College of Neuropsychopharmacology meeting held in Paris from Oct. 31, 1998 to Nov. 4, 1998.
Investigators at Eli Lilly and Company have previously found that schizophrenic patients treated with olanzapine have lower overall health care utilization and costs than those treated with the neuroleptic haloperidol(Drug information on haloperidol) (Haldol) (see Mental Health Economics, Dec. 1998, p 8). These investigators now sought to distinguish olanzapine from risperidone in their effects on overall health care costs and on the quality of patients' lives.
David Grainger and colleagues at Eli Lilly and Company's Global Health Outcomes section analyzed data from an international study conducted by Pierre Tran, M.D., and colleagues at Lilly Research Laboratories (Tran et al., 1997). This study evaluated the efficacy and safety of these agents in 339 patients with schizophrenia and schizoaffective disorder. In addition to ascertaining that patients treated with olanzapine required fewer medical resources with commensurately less overall treatment costs than patients receiving risperidone, the investigators found a trend, albeit not statistically significant, of greater improvement in quality of life with olanzapine treatment.
The 28-week prospective comparative study had randomized patients to receive either olanzapine 10 mg/day to 20 mg/day or risperidone 4 mg/day to 12 mg/day. Patients were dosed at physicians' discretion within these ranges to optimize therapeutic benefit and minimize adverse effects. By completion of the 28-week treatment period, a statistically significant advantage with olanzapine was evident in change on the Positive and Negative Symptom Scale (PANSS) among patients achieving at least a 30% improvement in total score.
Relapse in this study was defined as 20% or greater worsening in PANSS total score, along with a Clinical Global Impression-Severity of Illness score equal to or greater than 3. Fewer patients receiving olanzapine experienced relapse (4% at three months and 9% at six months) than did those treated with risperidone (9% at three months and 29% at six months).
In correlating costs with the different levels of medical resource utilization by these groups, Grainger and colleagues factored hospitalizations; emergency room services; day hospital treatments; home visits by health professionals; and outpatient visits to psychiatrists, other physicians and to other mental health care providers. The per-patient cost of 28 weeks of treatment averaged $5,630 for patients receiving olanzapine and $6,123 for those treated with risperidone. The investigators calculated that the olanzapine-treated patients realized an average monthly cost-savings of $493 relative to the risperidone-treated patients.
The Heinrichs-Carpenter Quality of Life Scale (QLS) was administered to gauge such factors as interpersonal relations and productivity in occupational roles. While the mean change to endpoint on QLS total score, and on three of four subscales, revealed no statistically significant differences between treatment, there was a trend favoring olanzapine. The researchers reported, "The olanzapine group demonstrated significantly (p=0.012) greater improvement in interpersonal relations, and the differences favoring olanzapine in total score neared significance (p=0.074)."
The researchers acknowledged several factors that could limit the validity of their findings. First, the findings were based only on study completers (48 on olanzapine and 43 on risperidone) and no data were available after patients withdrew from the study. They also note that there is not yet clear clinical relevance for statistical differences in quality of life measures. Their descriptive analysis of medical resource utilization was restricted to patients in the United States who completed the trial, and so it did not address differences in utilization patterns across countries.