Prevalence and predictors of metabolic syndrome in patients with schizophrenia and healthy controls: A study in rural South Indian population

Abstract

Introduction

Metabolic syndrome (MetS) has been extensively studied as a co-morbidity in patients with schizophrenia. A disparity is noted between hospital and community based estimates in India. We aimed to examine the prevalence and predictors of MetS in schizophrenia patients and general population controls in a rural population in South India.

Methods

Patients (n = 157) and general population controls (n = 263) were recruited from a rural area in South India. Diagnosis of MetS was established using International Diabetes Federation (IDF) criteria. Patients were also assessed on clinical parameters, treatment details, dietary and physical activity patterns. Predictors of MetS were estimated based on subgrouping of patients with and without MetS.

Results

50 (31.8%) of the patients and 76 (28.9%) of the controls were diagnosed to have MetS. Female gender and ongoing antipsychotic exposure were noted to be significant predictors of MetS with odds ratio (95% confidence interval) of 2.87 (1.2–6.86) and 4.42 (1.37–14.25) respectively. Three empirically defined treatment groups ‘never treated’, ‘ever treated’ and ‘continuous treatment’ groups had odds ratios (95% CI) of 0.53 (1.68–6.58), 0.92 (0.5–1.69) and 3.33 (1.68–6.58) when compared to the control group.

Conclusions

Patients who were naïve to antipsychotics had a significantly lower prevalence of MetS compared to general population. This finding doesn't support the antipsychotic independent risk for MetS in patients with schizophrenia. Female gender and regular antipsychotic exposure predicted MetS.

Introduction

The turn of twenty-first century has seen a major transition in public health indicators of mortality and disability from communicable to non-communicable disorders, and, this is particularly so for low and middle income countries (LAMICs) (Murray et al., 2012). According to Global Burden of Disease report, mental health disorders and other non-communicable disorders account for > 40% of years of life lost (YLL) and 70% of years lived with disability (YLD) (University of Washington, Institute for Health Metrics and Evaluation, 2013). Schizophrenia being one of the severe mental disorders, results in an average reduction of longevity of fifteen years in men and twelve years in women compared to those who do not suffer this illness (Crump et al., 2013). While suicide and homicide account for only 15% of this reduction, more than one third of reduced longevity is attributable to cardiovascular diseases (Crump et al., 2013, Lawrence et al., 2013).

Metabolic syndrome (MetS) comprises of core components of central obesity, insulin resistance, dyslipidemia and hypertension across all the expert panel consensus statements viz., World Health Organization (WHO), National Cholesterol Education Program – Adult Treatment Panel III (NCEP ATP III) and International Diabetic Federation (IDF). (WHO, 1999, Grundy et al., 2005, Alberti et al., 2005). Each of the individual components of metabolic syndrome and their combination significantly contribute mortality due to cardiovascular events (Pouliot et al., 1994, Robins et al., 2003, Hu et al., 2004). Patients with schizophrenia have been noted to be at higher risk of developing metabolic syndrome (Mitchell et al., 2013a, Mitchell et al., 2013b) and its individual components like insulin resistance (Holt et al., 2005), central obesity (Coodin, 2001) and hypertension (De Hert et al., 2011), explaining the high proportion of increased risk for cardiovascular mortality. Though the second-generation anti-psychotics significantly increase the prevalence of this co-morbidity (Mitchell et al., 2013a, Mitchell et al., 2013b, Saddichha et al., 2007) even un-medicated patients and their first-degree relatives are noted to be at higher risk in individual studies (Ryan et al., 2003). These findings have resulted in speculations for shared etiological pathways for the two disorders independent of antipsychotic exposure (Venkatasubramanian et al., 2007).

The prevalence of MetS varies widely among studies from different populations and countries. Though this could be partly attributed to variability in the definitions used across studies the variation remains even among studies which have used uniform definitions with race and ethnicity specific diagnostic criteria (Cameron et al., 2004, O'Neill and O'Driscoll, 2015). A recent systematic review and meta-analysis on the subject which included studies from twelve countries reported a varying pooled prevalence ranging from 25.4% in Brazil to 50.2% in Australia (Vancampfort et al., 2015). The same study also included 16 studies from India of which 14 included patients with schizophrenia and one study each in Bipolar Disorder and Majar Depressive Disorder. The pooled prevalence of MetS from Indian studies was 26.3% which was lower than the rates noted from high income countries. Of these fourteen studies twelve were from studies conducted in urban hospital settings and two were based on community samples.

Studies on MetS in patients with schizophrenia from India conducted in hospitals report a prevalence rate ranging from 11% to 45% (Grover et al., 2014, Meena and Gautam, 2011). A systematic review examined the urban and rural prevalence of MetS in schizophrenia in India found a pooled prevalence of 33.05% among the studies conducted in hospital setting while a significantly lower pooled prevalence of 10.81% in community based studies. (Ganesh et al., 2016). This highlights an evident disparity in the prevalence of MetS between and hospital and community studies but the data from the community is limited to only two studies. (Ganesh et al., 2016).

In this study, we examined the prevalence of MetS in a mixed group of treated and untreated patients with schizophrenia and controls in a rural community. Secondarily, we examined the determinants of metabolic syndrome accounting for dietary and lifestyle factors.