To the Editor: We thank Drs. Alamiri and Balf for their comments. In response to Dr. Alamiri, olanzapine remained at a fixed dose in our study in order to attenuate the effect of different doses of the drug on body weight. Furthermore, in China it is standard practice to treat patients with acute episode psychosis with olanzapine in doses of 10–20 mg per day.
Regarding the reporting of adverse events, we would like to note that because there were such few events, we only reported emergent adverse events.
We would also like to clarify that the mean duration of illness should have been 6.8 months for the metformin group and 7.6 months for the placebo group, and we are glad to have the opportunity to make this correction.
Although we recognize that completer analysis and intent-to-treat analysis are methods that may contain some biases, we did not find a good approach to avoid these biases.
It is possible for metformin to reduce caloric intake. In our study, the total caloric intake range was 7,980–9,250 kilojoule per day, and we did not evaluate changes in caloric intake or control food intake because we examined these issues in a previous analysis (1).
Metformin treatment can induce some severe adverse events, such as lactic acidosis, which remains a potential issue concerning its use. In future studies, it is necessary to conduct a risk-benefit assessment of metformin treatment, monitor for adverse events, and examine antipsychotic-metformin pharmacokinetic interactions.
1.Wu RR, Zhao JP, Jin H, Shao P, Fang MS, Guo XF, He YQ, Liu YJ, Chen JD, Li LH: Lifestyle intervention and metformin for treatment of antipsychotic-induced weight gain: a randomized controlled trial. JAMA 2008; 299:185–193
The author’s disclosures accompany the original article.
This letter (doi: 10.1176/appi.ajp.2008.08030432r) was accepted for publication in May 2008.