Olanzapine in Chinese patients with schizophrenia or bipolar disorder: a systematic literature review

Abstract

Background: Despite the burden of schizophrenia and bipolar disorder in the Chinese population, country-specific data to guide practitioners regarding antipsychotic therapy are lacking. The primary aim of this systematic review was to examine evidence of the efficacy, effectiveness, and safety of olanzapine in Chinese populations.

Methods: A systematic literature search was conducted using databases covering international and Chinese core journals using search terms related to schizophrenia and bipolar disorder, specified countries (People's Republic of China, Hong Kong, Taiwan), and olanzapine treatment. Following initial screening, inclusion and exclusion criteria were applied to the search results to identify relevant studies from which data were extracted.

Results: A total of 489 publications were retrieved and 61 studies were identified for inclusion. Most studies were related to schizophrenia (n=54), with six studies related to bipolar disorder and one study related to both conditions. The quality of study methods and reporting in international journals was noticeably better than in Chinese language journals. Most studies included relatively small patient populations and were of short duration. The efficacy of olanzapine in Chinese populations was confirmed by multiple comparative and noncomparative studies that found statistically significant reductions in symptom measures in studies conducted for ≥6 weeks (schizophrenia) or ≥3 weeks (bipolar disorder). Findings related to effectiveness (treatment discontinuation, quality of life, and neurocognitive improvements) were generally consistent with those observed in non-Chinese populations. No new safety signals specific for Chinese populations were raised for olanzapine.

Conclusion: Chinese and non-Chinese populations with schizophrenia or bipolar disorder treated with olanzapine display broadly similar responses. Differences between these populations, especially in relation to the relative efficacy of olanzapine versus other antipsychotics, may warrant further investigation via studies incorporating both populations. Use of local data to provide evidence for practice guidelines should be encouraged, and may promote ongoing improvements in the quality of research and study reporting.

Keywords: Chinese; bipolar disorder; olanzapine; outcomes; schizophrenia.

Figure 1

Publication flow diagram.

Figure 2

Discontinuation rates in long-term (12-month) maintenance studies. Notes: Dark bar represents data from Fang et al and gray bar represents data from Guo et al.

Figure 3

Mean change in Short Form-36 domain scores from baseline after 12 months of treatment with olanzapine in patients with schizophrenia reported in two quality of life studies. Notes: Long dashed lines represent data from Guo et al; short dashed lines represent data from Fang et al.