Topiramate's effectiveness on weight reduction in overweight/obese persons with schizophrenia: study protocol for a randomized controlled trial

Abstract

BACKGROUND: Schizophrenia is a psychiatric disorder with a higher mortality than that of the general population. Most of the deaths are due to cardiovascular causes and are related to metabolic risks. This risk is due not only to antipsychotics but also to inherent factors of the disorder. Studies in the West have shown topiramate to be effective in schizophrenia to reduce weight gain and for symptomatic control. Whether this is effective for South Asians is not known. It is important because South Asians have a higher risk of metabolic syndrome. We aim to conduct a double-blind, randomized controlled trial comparing topiramate add-on therapy with treatment as usual with antipsychotics in patients with schizophrenia in an outpatient setting in Sri Lanka. METHODS/DESIGN: Ninety patients with schizophrenia presenting to the Colombo North Teaching Hospital will be randomized to intervention and control groups equally using permuted block randomization. Patients with comorbid metabolic disorders and taking prescribed weight-controlling medications will be excluded. The intervention group will be prescribed topiramate in addition to their antipsychotics in a predefined dosing regimen targeting a dose of 100 mg per day. The control subjects are to receive a placebo. As the primary outcome, anthropometric measurements including weight, waist circumference, skinfold thickness, and body mass index will be recorded at baseline and monthly during the study period of 3 months. The secondary outcome is the change in symptoms according to the clinician-administered Brief Psychiatric Rating Scale. Assessment of capacity will be performed and informed consent obtained from all subjects. Ethics approval has been obtained from the ethical review committee of the Faculty of Medicine, University of Kelaniya, and the trial has been registered in the Sri Lanka Clinical Trials Registry. DISCUSSION: In this double-blind, randomized controlled trial, we will attempt to assess the effectiveness of topiramate as an add-on therapy compared with treatment as usual for weight control in patients with schizophrenia. To our knowledge, this is the first such study in South Asia, where metabolic risks are found to be higher than in the West and could have unique ethnic factors related to weight gain in schizophrenia.