Metabolic syndrome and cardiovascular risk among institutionalized patients with schizophrenia receiving long term tertiary care
Lee Seng Esmond Seow ⁎ , Siow Ann Chong, Peizhi Wang, Saleha Shafie, Hui Lin Ong, Mythily Subramaniam
Research Division, Institute of Mental Health, Singapore
Abstract
Background:Metabolic syndrome (MetS) and cardiovascular risk are highly prevalent among individuals with schizophrenia. This study aimed to determine the cardiometabolic profile and the associated risk factors in a group of institutionalized patients with schizophrenia or schizoaffective disorder receiving prolonged hospital care in the only tertiary psychiatric institution in Singapore.
Methods:Patients residing in long stay wards who were hospitalized for a minimum period of 1 year were recruited. Fasting blood sample was collected to obtain levels of blood glucose, total cholesterol, high-density lipoprotein (HDL) and triglycerides. Waist circumference, blood pressure, height and weight were also measured. The prevalence of MetS and the 10-year cardiovascular risk were determined.
Results:This inpatient group had a mean age of 56.1 years and an average length of hospitalization of 8.8 years. The prevalence of MetS in this group was 51.9% and 26.9% based on the AHA/NHLBI and modified NCEP ATP III criteria respectively. Those in the high risk BMI category and those who had pre-existing diabetes had higher odds of MetS. Their 10-year cardiovascular risk was estimated at 12.8%, indicating intermediate risk based on the Framingham risk function.
Conclusion:Despite the low smoking rate in this group of inpatients, their cardiovascular risk appeared to be relatively high possibly due to old age and age-related conditions such as hypertension and low HDL. While literature has found the use of atypical antipsychotic medications to increase the risk of MetS, we did not find any significant association. Additionally, the duration of hospitalization did not affect the rate of MetS in our sample.
© 2017 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/
licenses/by-nc-nd/4.0/).
1. Introduction
Metabolic syndrome (MetS) comprises a constellation of different medical conditions, including central obesity, glucose intolerance, dyslipidemia and hypertension, which are associated with an increased risk for cardiovascular diseases (CVD) [1]. The study of MetS in patients with
schizophrenia in particular has received significant attention in the literature [2,3]. Elevated medical morbidity and mortality rates have been observed in patients with schizophrenia, along with shortened life expectancy com- pared to the general population[4–6]. This has been largely due to CVD as well as from other causes such as suicide and accidents[4–7]. Koponen et al.[8]reported that individuals with schizophrenia were three times more likely than those from the general population to suffer from sudden cardiac death. Besides the presence of metabolic syndrome, other risk factors such as age, gender and cigarette smoking were also widely recognized for developing CVD[9]. Together, these factors may combine and interact multiplicatively to promote vascular risk and complicate treatment[10].
While the pathophysiology of MetS has not yet been fully understood, insulin resistance and central role of visceral adiposity remain as the two most important underlying causes [11,12]. The presence of Type 2 diabetes mellitus
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Comprehensive Psychiatry 74 (2017) 196–203
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Funding: This research is supported by the Singapore Ministry of Health's National Medical Research Council under the Centre Grant Programme (Grant No.: NMRC/CG/004/2013).
⁎Corresponding author at: Research Division, Institute of Mental Health, Buangkok Green Medical Park, 10 Buangkok View, Singapore 539747.
E-mail addresses:[email protected](L.S.E. Seow), [email protected](S.A. Chong),[email protected] (P. Wang),[email protected](S. Shafie),
[email protected](H.L. Ong),[email protected] (M. Subramaniam).
http://dx.doi.org/10.1016/j.comppsych.2017.01.017
0010-440X/© 2017 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/
licenses/by-nc-nd/4.0/).
(T2DM) was found to be higher among those with schizophrenia than matched controls, as well as those who were prescribed antipsychotics[13]. Hansen et al.[14]found the comorbidity of schizophrenia and T2DM to be associated with an at-risk allele located in the TCF7L2 gene, thus suggesting common genetic predisposition. In recent decades, the differential mortality gap between schizophre- nia individuals and the general community is believed to have worsened despite improvements in mental health services [6,15]. Some reports have suggested that the use of second-generation antipsychotic medications (i.e., atyp- ical antipsychotics) can potentially further influence mortal- ity rates among patients with schizophrenia [6,16]. It has been shown that atypical antipsychotics use was associated with higher risk of hyperglycemia and impaired glucose levels, hence leading to increased rates of metabolic syndrome [17]. The incidence of metabolic syndrome was estimated at 20% following a 1-year treatment with an atypical antipsychotic drug [18]. Other studies have also found increasing age-adjusted deaths and standardized mortality ratios for all causes of death including cardiovas- cular deaths to be possibly a result of deinstitutionalization [15,19]. For example, studies in Japan revealed MetS prevalence to be two-three folds higher in the outpatient compared to the inpatient population [20,21]. It has been suggested that less monitoring and more freedom for the patients accompanied by change in hospitalization environ- ment to shorter inpatient stay and outpatient care have led them to adopt an unhealthy lifestyle and become less inclined to seek health care[22,23]. These adverse lifestyle factors affecting vascular risk may include poor dietary habits, obesity, physical inactivity, and increased cigarette or alcohol intake. In particular, studies have shown that individuals with schizophrenia or psychosis engaged in less moderate and vigorous physical activity[24,25], higher levels of sedentary behavior during waking days[26], and poorer diet characterized by high saturated fat intake and low fiber consumption[27]compared to controls.
Physical health problems have been associated with increased burden among mental health patients which may in turn result in poorer outcomes for their psychiatric conditions, greater symptom severity [28], and eventually leading to decreased compliance with treatment. In this respect, it is therefore essential to identify comorbid medical conditions for psychiatric patients as this plays a significant role in aiding the improvement of subsequent outcomes, both medical and psychiatric.
The Institute of Mental Health (IMH) is the only tertiary psychiatric hospital in Singapore that offers a comprehensive range of psychiatric, rehabilitative and counseling services to those with mental illnesses. The Institute has about 2000 beds in its inpatient setting and approximately 60% of which are housed in long-stay wards for patients requiring long-term care. A large majority of those staying in the long-stay wards suffer from severe and chronic mental illness, and are not manageable at home, homeless or
abandoned by their family members[29]. These individuals tend to require highly structured nursing care and to a large extent, hospital care has replaced home care for them. The current study thus seeks to look into the cardiovascular health status and to examine the abovementioned factors associated with metabolic syndrome among this group of psychiatric inpatients receiving long term hospital care, particularly those with schizophrenia.
2. Methods 2.1. Recruitment
Data were collected in the period of July 2014 to April 2015 from fourteen long-stay wards that house inpatients who had resided in the hospital for more than one year.
Inclusion criteria included those aged 21 and above and those who have been diagnosed with schizophrenia or schizoaffective disorder by trained consulting psychiatrists based on Fourth Edition of the Diagnostic and Statistical Manual of Mental Disorders, or DSM-IV criteria. Only inpatients with a minimum hospitalization stay of one year were included and these were classified as “long-stay”
patients. Exclusion criteria included those with a history of intellectual disability or dementia, and those who are unable to provide consent. Neither outpatients nor acute ward patients who generally have shorter hospitalization stay were recruited. The study was administered in one of these three languages—English, Chinese and Malay, and thus only participants who spoke and understood these languages were recruited. The response rate for the study was 73.2% and the main reason for not providing consent despite approach was patients' unwillingness to subject themselves to venepunc- ture. Ethics approval was obtained from the Domain Specific Review Board of National Healthcare Group, Singapore.
Written informed consent was obtained from the patients.
2.2. Data collection
Sociodemographic and clinical information was obtained through a structured interview and further verified with the patients' medical records. Medical histories such as the duration of illness, length of hospitalization stay, current psychiatric and non-psychiatric medications use, and daily drug dosage were collected. Smoking histories were self-reported. Subjects were defined as having a history of smoking if they had smoked prior to the current admission or as current smokers if they continued to smoke during those times when they were out of the wards or on home leave.
All anthropometric measurements were standardized and collected by trained research assistants. Waist circumference was measured at the narrowest part of the body below the costal margins[30]. For resting blood pressure, the mean of two readings measured at a 1-min interval was taken using a digital sphygmomanometer (Omron HEM-7211) in a seated position on the left arm. Other measurements collected
included the height and weight; used for the calculation of body mass index (BMI). The suggested categories based on Asian populations are as follows: less than 18.5 kg/m2 underweight; 18.5–23 kg/m2increasing but acceptable risk;
23–27.5 kg/m2 increased risk; and 27.5 kg/m2 or more indicates high risk [31]. Participants were also asked to provide a sample of fasted venous blood to obtain data on their levels of fasting blood glucose, total cholesterol, high-density lipoprotein (HDL) and triglycerides.
2.3. Metabolic syndrome
The study used the modified National Cholesterol Education Program's Adult Treatment Panel III (NCEP ATP III) [32]
criteria for establishing MetS. Diagnosis of MetS is met if three or more of the five following criteria are present: (1) elevated waist circumference (abdominal obesity) of≥90 cm for men and≥80 cm for women; modified for Asian populations[31], (2) elevated triglycerides (≥150 mg/dL), (3) reduced HDL (≤40 mg/dL) in males and (≤50 mg/dL) in females, (4) elevated blood pressure (systolic≥130 mmHg and/or diastolic
≥85 mmHg), and (5) elevated fasting glucose (≥100 mg/dL).
In addition, we also established the prevalence of MetS using the American Heart Association and the National Heart, Lung and Blood Institute (AHA/NHLBI) criteria for comparison purpose [33]. The AHA/NHLBI differed slightly from the ATP III but retained the same cut-offs for all the parameters in the above five criteria: (1), (2) or on drug treatment for elevated triglycerides, (3) or on drug treatment for reduced HDL-C, (4) or on drug treatment for hypertension, and (5) or on drug treatment for elevated glucose.
2.4. Framingham risk and vascular age
The Framingham function was used to determine the overall cardiovascular risk profile, fatal or non-fatal cardio- vascular events (including any type of angina, myocardial infarction, other types of coronary ischemia, congestive heart failure, intermittent claudication or peripheral vascular diseases) of the patients [34]. Gender-specific Cox proportional-hazards regression was used to calculate the 10-year general CVD risk that incorporated age, total cholesterol and HDL-C levels, systolic blood pressure (SBP), treatment for hypertension, smoking and diabetes status. Vascular age (VA) or heart age was derived by transforming the CVD risk estimate of an individual to the age of a person of the same gender with the same risk but with all other risk factor levels in normal ranges (i.e., non-treated SBP of 125 mm Hg, total cholesterol of 180 mg/dL, HDL of 45 mg/dL, non-smoker and non-diabetic) [34]. Difference between VA and actual age of each patient, known as VAdiff, was also calculated for comparison purpose.
2.5. Statistical analyses
Statistical analyses were performed using IBM SPSS, version 23.0. Statistical significance was set atp b0.05 level using two-sided tests. Descriptive statistics were tabulated for
the overall sample. Mean and standard deviation were calculated for continuous variables, and frequencies and percentages for all other categorical variables. Fisher's exact test or chi-square test was performed to analyze categorical variables while Student'sttest or Mann–WhitneyUtest was performed to analyze continuous variables. A binary logistic regression was also performed with all sociodemographic and clinical variables entered as independent variables to estimate the adjusted odd ratio (OR) and confidence intervals (CI) of MetS in the schizophrenia inpatients.
3. Results 3.1. Prevalence
The prevalence of metabolic syndrome in the long-stay patients with schizophrenia was 26.9% (29/108) based on the modified NCEP ATP III criteria. The proportions of the sample meeting criteria for the various elevated cut points were as follows in decreasing order: 43.5% (n = 47) for waist circumference, 37.0% (n = 40) for blood pressure, 35.2%
(n= 38) for HDL, 34.3% (n= 37) for triglycerides, and 23.1%
(n= 25) for fasting glucose. Based on the AHA/NHLBI criteria, the prevalence of MetS was higher at 51.9% (56/108).
3.2. Sociodemographic and clinical factors
Table 1 presents the sociodemographic and clinical characteristics of our study subjects, and of those with or without metabolic syndrome. Overall, the patient group had a mean age of 56.1 years, illness duration of 26.6 years, and length of hospitalization of 8.8 years. The patient group also had a higher proportion of males, Chinese, those below 60 years of age, and those in the low risk group for BMI classification. In terms of medications, a higher proportion of them were prescribed with only typical anti-psychotics and was not on medications for any of the three conditions, i.e., dyslipidemia, hypertension or diabetes.
For comparison between those with and without MetS status, only BMI (both mean score and classification) and the use of anti-diabetic medications revealed significant differ- ences. Those with MetS had a significantly higher BMI compared to those without, with the mean BMI at 25.2 kg/m2 (SD = 2.9) and 22.9 kg/m2 (SD = 3.4) respectively (pb 0.001). There were also a significantly higher proportion (17.8% more) of patients on anti-diabetic medications among those with MetS compared to those without (p = 0.009).
3.3. Metabolic syndrome and cardiovascular risk factors Table 2presents the metabolic syndrome and cardiovascu- lar characteristics of our study subjects, and of those with or without metabolic syndrome. The means of all laboratory test and other important parameters, along with the Framingham 10-year CVD risk and vascular age were also computed.
Comparisons between those with and without MetS for all above variables were analyzed. For the parameters, the group of patients with MetS reported significantly higher waist
circumference, fasting glucose and triglycerides, and lower high-density lipoprotein (HDL) than those without.
For metabolic risk, statistically significant differences for all MetS components (except blood pressure) between the two groups were observed, with those having MetS consistently reporting higher proportion in the increased risk categories across all five components. For cardiovascular risk, only diabetes mellitus and reduced HDLC risk status showed significant differences with the MetS group reporting higher proportion of both than those in the non-MetS group.
The mean 10-year CVD risk and vascular age for the sample was 12.8% (SD = 9.2) and 58.9 years (SD = 15.7) respectively.
The mean 10-year CVD risk for those with MetS (M = 15.6%, SD = 10.0) was higher than those without MetS (M = 12.0%, SD = 8.7) but no significant difference was observed. For vascular age, there was also no significant difference reported despite the higher mean VA reported in the MetS group (M = 63.1 years, SD = 13.7) compared to the non-MetS group (M = 57.4 years, SD = 16.2). However, VAdiff was signifi- cantly higher in the MetS group (M = 8.8 years, SD = 8.1) than the non-MetS group (M = 0.65 years, SD = 10.3).
Table 1
Sociodemographic and clinical characteristics of subjects according to MetS status based on NCEP ATP III criteria.
Total (N= 108)
Metabolic Syndrome
p-Value
No (N= 79) Yes (N= 29)
Age in years, mean (SD) 56.1 (9.9) 56.7 (10.5) 54.3 (7.7) 0.272
Age group,n(%)
Below 60 years 65 (60.2) 44 (55.7) 21 (72.4) 0.116
60 years and above 43 (39.8) 35 (44.3) 8 (27.6)
Gender,n(%)
Male 94 (87.0) 68 (86.1) 26 (89.7) 0.755a
Female 14 (13.0) 11 (13.9) 3 (10.3)
Ethnicity,n(%)
Chinese 87 (80.6) 64 (81.0) 23 (79.3) 0.751a
Malay 16 (14.8) 12 (15.2) 4 (13.8)
Indian 5 (4.6) 3 (3.8) 2 (6.9)
Smoking history,n(%)
Yes 75 (69.4) 57 (72.2) 18 (62.1) 0.313
No 33 (30.6) 22 (27.8) 11 (37.9)
BMI in kg/m2, mean (SD) 22.9 (3.4) 22.1 (3.2) 25.2 (2.9) b0.001
BMI classification,n(%)
Underweight (b18.5)b 12 (11.1) 12 (15.2) 0 (0)
Low risk (18.5–23) 46 (42.6) 40 (50.6) 6 (20.7) 0.001
Moderate risk (23–27.5) 38 (35.2) 22 (27.8) 16 (55.2)
High risk (≥27.5) 12 (11.1) 5 (6.3) 7 (24.1)
Duration of illness in years, mean (SD) 26.6 (9.1) 27.1 (9.3) 25.1 (8.3) 0.232c
Duration of stay in years, mean (SD) 8.8 (7.1) 8.7 (7.5) 8.8 (6.1) 0.776c
CPZ equivalence dose in mg, mean (SD) 755.3 (736.4) 783.3 (783.5) 678.9 (594.9) 0.758c
CPZ equivalence dose,n(%)
No medicationb 3 (2.8) 3 (3.8) 0
Low (1–299 mg) 28 (25.9) 22 (27.8) 6 (20.7) 0.473
Middle (300–999 mg) 48 (44.4) 32 (40.5) 16 (55.2)
High (≥1000 mg) 29 (26.9) 22 (27.8) 7 (24.1)
Type of antipsychotics prescribed,n(%)
No medicationb 3 (2.8) 3 (3.8) 0 (0)
Atypical 19 (17.6) 15 (19.0) 4 (13.8) 0.808a
Typical 47 (43.5) 33 (41.8) 14 (48.3)
Both 39 (36.1) 28 (35.4) 11 (37.9)
Anti-diabetic medication,n(%)
Yes 12 (11.1) 5 (6.3) 7 (24.1) 0.009
No 96 (88.9) 74 (93.7) 22 (75.9)
Anti-lipidemic medication,n(%)
Yes 45 (41.7) 30 (38.0) 15 (51.7) 0.199
No 63 (58.3) 49 (62.0) 14 (48.3)
Anti-hypertensive medication,n(%)
Yes 33 (30.6) 24 (30.4) 9 (31.0) 0.948
No 75 (69.4) 55 (69.6) 20 (69.0)
a Fisher's exact test.
b Groups excluded from chi-square analysis for respective categories.
c Mann–WhitneyUtest.
3.4. Sociodemographic and clinical correlates of MetS Of the sociodemographic and clinical correlates, only BMI classification and use of anti-diabetic mediations were associated with metabolic syndrome (Table 3). Those who were in the low risk BMI group were less likely than those in the high risk to develop MetS. Those who were on anti-diabetic medications were also more likely to have MetS than those who were not. Other variables of interest such as the type of anti-psychotic used and duration of hospitalization stay did not reveal any significant findings.
4. Discussion
The current study aimed to look at the physical health of a group of institutionalized patients with schizophrenia who had received prolonged tertiary care in a psychiatric hospital in Singapore. In terms of the prevalence rates for metabolic syndrome, the percentage of the long-stay patients with MetS dropped by almost half from 51.9% to 26.9% when a different criterion was used to calculate MetS in the same sample. The former is based on the AHA/NHLBI criteria that include those with predisposing conditions such as hyper-
lipidemia, hypertension and diabetes and were being treated, as well as those who had current clinical and biochemical parameters in the undesirable range. The reduction of MetS proportion from the former to the latter which is purely based on current parameters may imply that a portion of these patients without current MetS status have had their pre-existing conditions controlled by medications. Nonethe- less, it is unknown whether the control could be attributed to the impact of institutionalization.
Studies examining MetS in only inpatient group with schizophrenia have been limited. Using the figures reported by a recent large study in Japan[20], the MetS prevalence rate of 26.9% in our group of institutionalized patients is higher compared to their inpatient group (13.0%) but lower compared to their outpatient group (34.2%) based on the NCEP ATP III criteria. Inpatients with schizophrenia in Japan typically have long hospital stays and the reported mean ages for both the inpatient and outpatient groups were 59.6 and 52.6 years respectively, somewhat comparable to the mean age of 56.1 years in our sample. Comparing the results with local data from a predominantly outpatient group recruited from the same hospital[35], the prevalence was found to be lower at 46.0% among schizophrenia patients compared to 51.9% in our sample using the AHA/NHLBI
Table 2
Metabolic syndrome and cardiovascular risk factors of subjects according to MetS status based on NCEP ATP III criteria.
Total (N= 108)
Metabolic syndrome
p-Value No (N= 79) Yes (N= 29)
Parameters, mean (SD)
Waist circumference in cm 87.7 (9.8) 85.0 (9.0) 95.3 (8.0) b0.001
SBP in mmHg 122.4 (17.5) 121.0 (17.5) 126.2 (16.9) 0.115a
DBP in mmHg 75.2 (10.4) 74.4 (10.6) 77.5 (9.9) 0.172
Fasting glucose in mmol/L 5.2 (1.0) 5.0 (1.0) 5.4 (0.9) 0.005a
HBA1C in % 5.5 (0.6) 5.5 (0.6) 5.6 (0.6) 0.330a
Total cholesterol in mmol/L 4.4 (0.8) 4.4 (0.8) 4.5 (0.8) 0.718a
HDL-C in mmol/L 1.2 (0.3) 1.3 (0.3) 1.0 (0.2) b0.001a
LDL-C in mmol/L 2.5 (0.6) 2.5 (0.6) 2.7 (0.6) 0.204
Triglycerides in mmol/L 1.5 (0.7) 1.3 (0.5) 2.0 (0.8) b0.001a
Metabolic risk,n(%)
Waist circumference (men≥90 cm; women≥80 cm) 47 (44.3) 23 (29.5) 24 (85.7) b0.001b
HDL cholesterol (men≤1.03 mmol/L; women≤1.29 mmol/L) 38 (35.2) 15 (19.0) 23 (79.3) b0.001
Triglyceride (≥1.69 mmol/L) 37 (34.3) 15 (19.0) 22 (75.9) b0.001
Blood pressure (SBP≥130 mmHg or DBP≥85 mmHg) 40 (37.0) 25 (31.6) 15 (51.7) 0.055
Fasting blood glucose, FBC (≥5.56 mmol/L) 25 (23.1) 12 (15.2) 13 (44.8) 0.001
Cardiovascular risk,n(%)
Age (men≥40 years; women≥45 years) 102 (94.4) 75 (94.9) 27 (93.1) 0.658b
Current cigarette use (y/n) 7 (6.5) 7 (8.9) 0 (0) –
Diabetes mellitus (fasting glucose≥7.00 mmol/L or known diagnosis) 16 (14.8) 8 (10.1) 8 (27.6) 0.024
TC (≥5.18 mmol/L) 16 (14.8) 12 (15.2) 4 (13.8) 1.000b
HDLC (menb1.17 mmol/L; womenb1.29 mmol/L) 56 (51.9) 31 (39.2) 25 (86.2) b0.001b
SBP (men≥140 mmHg women≥130 mmHg) 22 (20.4) 14 (17.7) 8 (27.6) 0.259
DBP (men≥90 mmHg, women≥80 mmHg) 14 (13.0) 9 (11.4) 5 (17.2) 0.423
Abnormal BP or known diagnosis of hypertension 49 (45.4) 35 (44.3) 14 (48.3) 0.713
Framingham 10-year CVD risk (%) ± SD 12.8 (9.2) 12.0 (8.7) 15.6 (10.0) 0.056a
Vascular age in years, mean ± SD 58.9 (15.7) 57.4 (16.2) 63.1 (13.7) 0.090
VAdiffin years, mean ± SD 2.8 (10.4) 0.65 (10.3) 8.8 (8.1) b0.001a
a Mann–WhitneyUtest.
b Fisher's exact test.
criteria. However, the mean age in the majority outpatient sample was much younger at 36.6 years, which make it difficult to draw any conclusive interpretation on the differences between inpatient and outpatient groups.
Given the controlled conditions of a ward setting, the inpatients in our current study underwent supervised diet and regular physical activities over a prolonged period of at least one year. The study therefore included the length of hospitalization stay as a variable of interest but we did not find a significant association between the duration of institutionalization and MetS status within our sample.
While other studies have found physical health problems leading to increased length of hospitalization stay among psychiatric patients [36,37], the literature on the impact of length of stay on their improved medical status and in this case metabolic syndrome is limited. Benefits including
increased weight loss and glycemic control following diet modification among a group of obese patients with type II diabetes were evident after just 12-weeks of treatment and the effects were maintained over the year-long treatment [38]. Another study also found long-term beneficial effects on weight loss, fasting glucose and lipid concentrations, as well as reduced diabetes risk following 3 years of lifestyle intervention [39]. These evidence suggest that perhaps beyond certain brief duration of institutionalization, extend- ed period of stay may not have any further significant positive implications on the overall physical health status of the inpatients.
Contrary to the literature, our study also did not find an effect of the type of anti-psychotic medication prescribed on MetS status. One possible explanation for the lack of significant finding may be due to our variable construct for the type of antipsychotics prescribed where three categories of atypical, typical, and both atypical and typical were used.
We did not consider the drug dosage or examine the influence of specific typical and atypical antipsychotic medication on the MetS status. In a clinical drug trial that comprised patients treated with haloperidol and other atypical agents such as risperidone, clozapine and sertindole, patients treated with clozapine and olanzapine were found to demonstrate the maximal weight gain, followed by risper- idone, haloperidol and finally, sertindole [40]. In other words, the extent of drug-induced contribution to MetS varies among atypical antipsychotics and not all atypical antipsychotics will result in a more adverse consequence than typical antipsychotics. Therefore, our variable construct may not be sensitive enough to detect the change in metabolic profile with respect to the type of antipsychotic used.
Our study lends support to the literature that proposes that insulin resistance and central role of visceral adiposity are the two main underlying causes for MetS. Firstly, both waist circumference and fasting blood glucose were found to be significant predictors for MetS status in our bivariate analyses. In addition, our study also found significant differences in MetS status by BMI classification and the use of anti-diabetic medications, and these two variables remained significant in multivariable analyses. Those who had higher BMI class, which is an indication for obesity, were found to be at higher odds for MetS. The use of anti-diabetic medications, which represents pre-diagnosed diabetes, was also found to be associated with the presence of MetS.
In terms of cardiovascular risk, our sample demonstrated a relatively high 10-year CVD risk of slightly above 10%.
This could be mainly contributed by the age factor (older age) and other age-related medical conditions such as hypertension (high prevalence) in our sample rather than current smoking which had a low prevalence as a result of the institutionalization. Our study did not find any significant differences in terms of 10-year cardiovascular risk, or vascular age between those with and without MetS.
Table 3
Sociodemographic and clinical correlates of MetS based on NCEP ATP III criteria.
Metabolic syndrome
OR 95% CI p-Value
Age group
Below 60 years 2.540 0.614 10.513 0.198
60 years and above Ref.
Gender
Male 3.880 0.445 33.861 0.220
Female Ref.
Ethnicity
Chinese 1.288 0.108 15.380 0.841
Malay 0.959 0.055 16.755 0.997
Indian Ref.
Smoking history
Yes 0.455 0.114 1.810 0.264
No Ref.
BMI classification
Underweight (b18.5) – – – –
Low risk (18.5–22.9) 0.033 0.005 0.246 0.001 Moderate risk (23.0–27.4) 0.252 0.037 1.702 0.157 High risk (≥27.5) Ref.
Duration of illness in years 0.989 0.911 1.073 0.782 Duration of stay in years 1.004 0.917 1.100 0.927 CPZ equivalence dose
No medication – – – –
Low (1–299 mg) 0.766 0.104 5.647 0.794
Middle (300–999 mg) 2.045 0.451 9.276 0.354 High (≥1000 mg) Ref.
Type of antipsychotics prescribed
No medication – – – –
Atypical Ref.
Typical 1.301 0.229 7.389 0.767
Both 0.604 0.098 3.740 0.588
Anti-diabetic medication
No 0.106 0.013 0.839 0.034
Yes Ref.
Anti-lipidemic medication
No 0.755 0.202 2.829 0.677
Yes Ref.
Anti-hypertensive medication
No 2.149 0.525 8.792 0.287
Yes Ref.
However, those with MetS were found to have much higher VAdiff than those without MetS (8.8 years versus 0.65 years), and this likely represents the higher cardiovas- cular risk associated with the patients' metabolic syndrome, after accounting for their mean actual age (56.7 years among those without MetS and 54.3 years among those with MetS).
Our study has several limitations. The study sample size is small and the results may not be highly conclusive. The current study was targeted on a group of long stay patients with schizophrenia where a large proportion of them were cognitively incapable of providing consent or exhibited non-compliance with study procedures leading to their exclusion. This contributes to the lack of generalizability of our findings to all institutionalized patients. We did not collect information on the patients' sedentary behavior or physical activity level, which have shown to have an influence on one's metabolic health. Nonetheless, the accuracy of all data collected is high with little reliance on self-reports (except smoking history), as all clinical and other important information were obtained from their medical records or established using laboratory testing.
5. Conclusion
The prevalence of MetS in a group of institutionalized patients who were receiving tertiary care for a minimum duration of 1 year in Singapore was estimated at 51.9% based on the AHA/NHLBI criteria. This dropped to 26.9% when we used the modified NCEP ATP III criteria which did not account for those who had pre-existing conditions such as hyperlipid- emia and hypertension but had their parameters controlled.
Despite the low smoking rate in this group of inpatients, their cardiovascular risk falls under intermediate risk based on the Framingham risk function. This could possibly be due to old age and presence of age-related conditions such as hypertension and low HDL in this group of inpatients.
Overall, our study supported evidence for central obesity and insulin resistance to be the main indications for MetS.
The length of hospitalization stay, however, did not seem to affect the rate of MetS in our sample perhaps beyond a short period of institutionalization. Although we did not find an effect of the type of antipsychotics on the MetS status, the prescription of atypical anti-psychotic medications for treatment in the long-stay wards continues to warrant close monitoring.
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