Biochemical risk factors for development of obesity in first-episode schizophrenia

Obesity is a serious health issue for many patients with schizophrenia. There is a lack of predictors for and understanding of the development of obesity in the early phase of the illness. Therefore we investigated a set of routine biochemistry variables in blood as predictors of the development of obesity and weight gain over 5 years in an observational cohort study of patients with first-episode schizophrenia (n=59). Twelve percent of the patients were obese at baseline and 37% were obese at the 5-year follow-up. The mean body mass index (BMI) change over 5 years was a 4.1 kg/m(2) increase (4.5 SD). Obesity was predicted by baseline hemoglobin levels (odds ratio per standard deviation [OR/SD] 3.3, 95% confidence interval [CI] 1.4 to 7.5), red blood cell count (OR/SD 2.6, 95% CI 1.2 to 5.5), hematocrit (OR/SD 2.8, 95% CI 1.3 to 5.9), gamma-glutamyltransferase (OR/SD 2.8, 95% CI 1.2-6.3) and creatinine (OR/SD 3.1, 95% CI 1.2 to 8.0). After adjustment for baseline BMI, the associations were attenuated for gamma-glutamyltransferase and creatinine. Low baseline BMI was associated with a greater BMI increase. The major conclusion is that easily available routine biochemistry markers can be useful in predicting the development of obesity in first-episode schizophrenia. The mechanisms underlying the observed associations are unknown, but the predictors identified in this study could signify dehydration or insulin resistance. These observations open a new window to future research on the mechanisms underlying the development of obesity in schizophrenia.