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Letters to the Editor

Reply to Metabolic Syndrome in Inpatients Treated With Clozapine

See the original letter

Dr Bai and Colleagues Reply

To the Editor: First, we would like to thank Dr Suzuki for his comment on our recent publication.1 We agree that the generalizability of the results to outpatients is limited because our study was performed among an inpatient sample. However, contrary to Dr Suzuki’s assumption, long-term hospitalization of these patients did not mean that all of them had shown poor response to clozapine.

The study was performed in Yu-Li Veterans Hospital, which is the largest mental hospital in Taiwan to offer long-term care for refractory schizophrenia patients who have poor support systems. Our study subjects were patients who began receiving clozapine treatment after they were transferred to this hospital, and our previous reports showed that around one-third of these patients had significant clinical response,2 but because of having a poor support system, they could not be discharged from the hospital.

The patients with good clinical response would have had more freedom in that they could have supportive employment in the town of Yu-Li and go to the grocery for between-meal snacks. However, they still had to go back to the wards at night, and their medication use was monitored by ward staff; therefore, the drug adherence, anthropometric, and biochemical assessments were reliable. The rate of response to clozapine in our patients was similar to those in other reports from Western countries.3-5 Therefore, our study subject composition is not a biased sample.

Dr Suzuki also pointed out that the weight gain in our sample seemed to be less than in other reports.6,7 But those reports were short-term studies from Western countries. The ethnic difference in the prevalence of metabolic syndrome has been discussed in our articles.1,2,8-11 Furthermore, most of these Western reports were outpatient studies that might have included more patients with good clinical response. Our previous study showed that good clinical response was related to more weight gain.2

Finally, the aim of this 8-year cohort study was to investigate the association of weight gain and metabolic syndrome. From the scientific point of view, the inpatient setting can better control for possible confounding factors, such as drug adherence, metabolic parameter assessment, diet content, exercise level, and environmental factors. We still hope, though, that an outpatient cohort study can be conducted to validate our results, although it will be difficult to control these factors in an outpatient setting.

References

1. Bai YM, Lin CC, Chen JY, et al. Association of weight gain and metabolic syndrome in patients taking clozapine: an 8-year cohort study [published online ahead of print November 20, 2010]. J Clin Psychiatry. 2010. PubMed doi:10.4088/JCP.09m05402yel

2. Bai YM, Lin CC, Chen JY, et al. Association of initial antipsychotic response to clozapine and long-term weight gain. Am J Psychiatry. 2006;163(7):1276-1279. PubMed doi:10.1176/appi.ajp.163.7.1276

3. Szymanski S, Masiar S, Mayerhoff D, et al. Clozapine response in treatment-refractory first-episode schizophrenia. Biol Psychiatry. 1994;35(4):278-280. PubMed doi:10.1016/0006-3223(94)91259-9

4. Pickar D, Owen RR, Litman RE, et al. Clinical and biologic response to clozapine in patients with schizophrenia. Crossover comparison with fluphenazine. Arch Gen Psychiatry. 1992;49(5):345-353. PubMed

5. Kane JM. Clinical efficacy of clozapine in treatment-refractory schizophrenia: an overview. Br J Psychiatry suppl. 1992;(17):41-45. PubMed

6. Frankenburg FR, Zanarini MC, Kando J, et al. Clozapine and body mass change. Biol Psychiatry. 1998;43(7):520-524. PubMed doi:10.1016/S0006-3223(97)00488-5

7. Allison DB, Mentore JL, Heo M, et al. Antipsychotic-induced weight gain: a comprehensive research synthesis. Am J Psychiatry. 1999;156(11):1686-1696. PubMed

8. Bai YM, Chen JY, Chen TT, et al. Weight gain with clozapine: 8-year cohort naturalistic study among hospitalized Chinese schizophrenia patients. Schizophr Res. 2009;108(1-3):122-126. PubMed doi:10.1016/j.schres.2008.10.023

9. Bai YM, Chen TT, Yang WS, et al. Association of adiponectin and metabolic syndrome among patients taking atypical antipsychotics for schizophrenia: a cohort study. Schizophr Res. 2009;111(1-3):1-8. PubMed doi:10.1016/j.schres.2009.03.014

10. Bai YM, Chen JY, Yang WS, et al. Adiponectin as a potential biomarker for the metabolic syndrome in Chinese patients taking clozapine for schizophrenia. J Clin Psychiatry. 2007;68(12):1834-1839. PubMed doi:10.4088/JCP.v68n1202

11. Bai YM, Lin CC, Chen JY, et al. Weight gain among patients on clozapine. Psychiatr Serv. 1999;50(5):704-705. PubMed

Ya Mei Bai, MD, PhD

ymbi@mail2000.com.tw

Chao-Cheng Lin, MD

Tzu Ting Chen, MD

Tung-Pine Su, MD

Author affiliations: Department of Psychiatry, Taipei Veterans General Hospital, and Department of Psychiatry, College of Medicine, National Yang-Ming University (Drs Bai and Su); Department of Psychiatry, National Taiwan University Hospital, and Graduate Institute of Medical Informatics, Taipei Medical University (Dr Lin), Taipei; and Department of Psychiatry, Yu-Li Veterans Hospital, Yu-Li (Dr Chen), Taiwan. Potential conflicts of interest: None reported. Funding/support: The study discussed in this letter was supported by grants from National Science Council, Taiwan (NSC 96-2314-B-075-009, 97-2314-B-075-003-MY2).

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