Prevalence and predictors of metabolic syndrome in schizophrenia patients from Assam.

BACKGROUND: Metabolic abnormalities contribute enormously to morbidity and mortality in schizophrenia.
OBJECTIVES: Our objectives were to determine the (i) prevalence of metabolic syndrome (MS); and (ii) predictors for MS in schizophrenia patients from Assam.
MATERIALS AND METHODS: Seventy-five schizophrenia patients were evaluated for MS. Risk factors were assessed by odds ratios (ORs) with 95% confidence intervals (CIs).
RESULTS: Fifty-nine patients (78.7%) had a metabolic abnormality. Twenty-two patients (29.3%, 95% CI: 19.9%-40.8%) fulfilled the criteria for MS. Female gender (adjusted OR = 7.8, 95% CI: 1.7-36.4), smoking (adjusted OR = 7.9, 95% CI: 1.7-35.8), family history of chronic lifestyle disease (adjusted OR = 4.4, 95% CI: 1.3-15.2), and atypical antipsychotic use (adjusted OR = 4.3, 95% CI: 1.1-16.9) significantly predicted MS.
CONCLUSION: Metabolic abnormalities exist widely in schizophrenics from Assam. Females, smokers, and those with family history of chronic diseases and using atypical antipsychotics are at greater risk.

INTRODUCTION

Schizophrenia is a debilitating mental disorder. Despite the advances in mental health services, patients with schizophrenia have a poor quality of life and low life expectancy than the general population.[1] The excess mortality and morbidity in schizophrenia is largely attributed to comorbidities such as diabetes mellitus (DM), cardiovascular diseases (CVD), hypertension (HTN), obesity, and dyslipidemia.[123]

Metabolic syndrome (MS) refers to a constellation of interrelated risk factors that predispose to CVD, DM, and atherogenic dyslipidemia. In this context, MS in schizophrenia in the Indian scenario deserves attention. Often dubbed as the “heart disease capital” and “diabetic capital” of the world, India is a major hotspot for cardiometabolic abnormalities. Although there are some reports on the prevalence of MS in schizophrenia from certain parts of India,[456] data from Northeast are lacking. Assam is the most populated state in Northeast India and has a sizeable burden of schizophrenia.[7] Northeast India is geographically, culturally, and genetically unique. It is often regarded as an ethnological transition zone between the Indian sub-continent in the West and the East/Southeast Asia region in the East.[8] Thus, data on the prevalence and risk factors for MS in schizophrenia from this population are of special interest.

With this background, we conducted this study with the primary aim of estimating the prevalence of MS in a sample of schizophrenia patients from Assam. In addition, we determined the predictors of MS in those patients.

MATERIALS AND METHODS

Study design

We conducted an analytical cross-sectional study in Gauhati Medical College and Hospital, Assam, after obtaining the Institutional Ethical Committee approval. The patients were enrolled after they voluntarily agreed to be interviewed and gave their consent.

Sample size

The prevalence of MS in schizophrenia patients from India varies from 12% to 36%.[456] Assuming the prevalence in Assam to be 25%, we calculated the required sample size with a 95% confidence interval (CI) and 10% margin of error. On this basis, it was found that at least 73 patients would be needed.

Subjects

We recruited 75 schizophrenia patients diagnosed by experienced psychiatrists as per the International Classification of Disease-10 guidelines. Pregnant women were excluded from the study. We collected data on sociodemographic factors, lifestyle habits, family history, and antipsychotic usage in interview schedules, which were validated and pilot-tested in ten patients before initiating the actual study.

Waist circumference (WC) and blood pressure (BP) were measured using standard protocol. Fasting venous samples were collected for quantifying fasting blood glucose (FBG), high-density lipoprotein cholesterol (HDL-C), and triglyceride (TGL) in VITRO S 5600 Autoanalyzer (Ortho Clinical Diagnostics, USA) photometrically. The results were validated using third party control materials (Bio-Rad, USA and Christian Medical College, Vellore, India).

We used guidelines recommended jointly[9] by the International Diabetic Federation, National Heart Lung and Blood Institute, World Health Federation, American Heart Association, International Atherosclerosis Society, and International Association for the Study of Obesity to identify MS. Accordingly, the presence of three or more of the following five components defined MS: Increased WC (≥90 cm for men, ≥80 cm for women); elevated TGLs (≥150 mg/dL) or drug treatment for elevated TGL; reduced HDL-C (<40 mg/dL in males, <50 mg/dL in females) or drug treatment for reduced HDL-C; elevated BP (systolic ≥130 mmHg and/or diastolic ≥85 mmHg) or antihypertensive treatment in a patient with HTN; and elevated FBG (≥100 mg/dL) or drug treatment for hyperglycemia.

Statistics

Continuous data were expressed as means with standard deviation. The proportion of MS and its individual components were summarized as count and percentage, with 95% CI. Potential risk factors between the patients with and without MS were compared, using Fischer's exact test or Chi-square test, as applicable. The association of the risk factors with MS was estimated using odds ratios (ORs) with 95% CIs in OpenEpi version 3.0.1 (http://www.OpenEpi.com). Further, these were verified using adjusted ORs through multiple logistic regressions in SPSS version 17.0 suite (SPSS, Chicago, IL, USA). A two-tailed P < 0.05 was considered statistically significant.

RESULTS

The patient characteristics are summarized in Supplementary Table 1. The criteria for MS (≥ 3 components) were met by 22 patients (29.3%, 95% CI: 19.9%–40.8%) [Supplementary Table 2]. Overall, 59 patients (78.8%, 95% CI: 72.5%–82.2%) had at least one MS component. Reduced HDL-C was the most common abnormality (49.3%), followed by raised BP (45.3%), elevated TGL (36%), increased WC (22.7%), and elevated FBG (12%).

Sociodemographic profile, clinical variables, and background information

Click here for additional data file.

Distribution of metabolic abnormalities in the study subjects (n=75)

Click here for additional data file.

Univariate analyses revealed female gender (OR = 3.1, 95% CI: 1.1–9.4), smoking (OR = 3.2, 95% CI: 1.1–9.8), and having a family history for lifestyle diseases (OR = 3.7, 95% CI: 1.3–11.5) as significant (P < 0.05) risk factors for MS [Table 1]. Newly diagnosed and antipsychotic naive patients apparently had 50% lesser risk for MS although not significantly (OR = 0.5, 95% CI: 0.1–1.9). However, patients using atypical antipsychotics were at significantly enhanced risk (OR = 3.8, 95% CI: 1.2–11.8) for MS than patients who were drug-naïve or on typical antipsychotics.

Table 1

Schizophrenia patients with and without metabolic syndrome

In multivariate analysis, the female gender (adjusted OR = 7.8, 95% CI: 1.7–36.4), smoking (adjusted OR = 7.9, 95% CI: 1.7–35.8), a family history of chronic lifestyle disease (adjusted OR = 4.4, 95% CI: 1.3–15.2), and use of atypical antipsychotics (adjusted OR = 4.3, 95% CI: 1.1–16.9) persisted to be independent determinants for MS [Table 1]. Collectively, these four predictors accounted for 40% (Nagelkerke R2 = 0.40) of the variance, with a correct prediction rate of 78.7%.

DISCUSSION

The prevalence of MS in schizophrenia varies across different ethnic groups.[61011121314] The criteria for MS were satisfied by 29.3% of our patients. This was similar to the findings of Bajaj et al.[6] but higher than in South India[4] and lower than in North India.[5] The Indian population is heterogeneous. Differences in lifestyle and sociodemographic profile may be a reason for dissimilar prevalence of MS across different regions. Further, although MS is recognized worldwide as a distinct entity, the guidelines for identifying MS by different organizations vary. Using different guidelines in the same sample may yield considerably different estimates for MS prevalence.[14] Hence, to avoid such ambiguities, we used the guidelines issued jointly by different international bodies to unify and harmonize the criteria for MS.[9] Among the neighboring East/Southeast Asian nations, the proportion of MS in our patients was comparable to that in Japanese,[10] higher than in Indonesians,[11] and remarkably lower than in Thai,[12] and Koreans.[13] Despite Indians having a predisposition to develop MS in general, schizophrenia patients from India have comparatively lower MS prevalence. This might be due to the lower rates of prescribing atypical antipsychotics (which is considered a major risk factor for MS) in India.[15] In the current study also, only 42 patients (56%) used atypical antipsychotics.

More than three-fourths of the patients had at least one metabolic abnormality. Reduced HDL-C and HTN are widely prevalent in Assam.[1617] Their increased prevalence in our subjects may be a reflection of the existing predisposition to these conditions in the general population. However, the frequency of increased WC and elevated FBG in our sample was substantially higher than in the general population. As opposed to nearly 7% and 1% of the general population of Assam who are overweight and diabetic;[18] 22.7% and 12% of our schizophrenic patients had increased WC and elevated FBG, respectively.

In the risk factor assessment, female patients exhibited greater risk of developing MS. This is in agreement with the previous studies.[1119] Besides, a positive history for chronic noncommunicable diseases in the family resulted in nearly 4.5 times greater odds of developing MS. Among the modifiable risk factors, smoking, which is a known risk factor for cardiometabolic derangements, greatly enhanced the risk for MS in our patients. Moreover, use of atypical antipsychotics produced about four times greater likelihood for developing MS. This is of concern because atypical antipsychotics are the first-choice medications for schizophrenia. Previously, schizophrenics on atypical antipsychotics were found to be more susceptible for MS than those who were drug-naïve or on typical antipsychotics.[619] These risk factors for MS notwithstanding, it is believed that schizophrenia itself can independently predispose to MS, possibly by altering insulin sensitivity and glucose homeostasis.[3]

Our study had limitations such as cross-sectional nature (that precluded identifying temporal relationship between schizophrenia and the metabolic abnormalities) and lack of reliable information on duration of antipsychotic use in patients using medication.

CONCLUSION

We described MS and its components in schizophrenia patients from Assam for the first time. We also identified the important risk factors for MS in these patients. Schizophrenia patients often receive inadequate medical care and low rates of treatment for co-morbidities like HTN, DM, dyslipidemia and obesity.[20] Health-care providers should be trained and sensitized for monitoring schizophrenic patients for metabolic derangements. Methods to tackle MS and the responsible risk factors should be incorporated as part of the detailed workup and management protocol for schizophrenia.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.