Voruganti_SchizRes_2007v96p215
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Schizophrenia Research
Volume 96, Issues 1-3, November 2007, Pages 215-222
doi:10.1016/j.schres.2007.07.016
Copyright © 2007 Published by Elsevier B.V.
Dysglycemia in a community sample of people treated for schizophrenia: The Diabetes in Schizophrenia in Central-south Ontario (DiSCO) study
L.P. Vorugantia,,, Z. Punthakeeb, R.J. Van Lieshouta, D. MacCrimmona, G. Parkera, A.G. Awadd and H.C. Gersteinb,c
aDepartment of Psychiatry and Behavioural Neurosciences, 100 West 5th Street, Hamilton, Ontario Canada L8N 3K7
bDivision of Endocrinology and Metabolism, Canada
cPopulation Health Institute Aventis Chair in Diabetes Research, Professor, Department of Medicine and Director, Division of Endocrinology and Metabolism, McMaster University, Hamilton, Canada
dUniversity of Toronto, Canada
Received 10 April 2007; revised 15 July 2007; accepted 19 July 2007. Available online 30 August 2007.
Abstract
Objective
Despite increasing recognition of schizophrenia as a risk factor for diabetes, the prevalence and correlates of dysglycemia in people with schizophrenia have not been adequately studied. Discerning the modifiable risk factors is crucial for developing diabetes prevention strategies in schizophrenia.
Methods
Socio-demographic, clinical and recent laboratory data were compiled from the case records and supplemental sources of 1123 people treated for schizophrenia who were living across five different communities in the region.
Results
Screening rates for fasting plasma glucose (FPG) varied between 63–100% across the five communities, while other metabolic indices were monitored less frequently. 39 subjects (3.5%) in the sample had an existing diagnosis of type 2 diabetes. Among the others, 845 (78%) had FPG measured in the preceding 6months, with the following results: FPG ≤5.6mmol/l in 474 (56%), 5.6–6.9mmol/l in 268 (31%), and ≥7mmol/l in 103 (12.2%) subjects. Dysglycemia (FPG ≥5.6mmol/l) was significantly associated with older age (odds ratio [OR] 1.031), longer duration of schizophrenia (OR 1.062), self reported family history of diabetes (OR 8.87), body mass index (OR 1.081), excess weight (OR 1.014) and independent living status (OR 1.779), while European ethnicity (OR 0.706) and regular physical activity (OR 0.958) lowered the risk. No statistically significant correlations were noted with gender, level of education or functioning, or the type of antipsychotic drug prescribed.
Conclusions
There was a two-fold increase in the prevalence of dysglycemia, while there was a substantial under-recognition of and intervention for, diabetes and pre-diabetes in this sample of people treated for schizophrenia.
Keywords: Diabetes; Pre-diabetes; Schizophrenia; Antipsychotic drugs; Metabolic risk
Article Outline
1. Introduction
2. Methods
3. Data analysis
4. Results
4.1. Sample description
4.2. Screening practices
4.3. Prevalence of an elevated glucose level
4.4. Risk factors for dysglycemia in people with schizophrenia and no history of diabetes
4.5. Prevalence of diabetes and care profile
5. Discussion
6. Conclusions
Role of funding source
Contributors
Conflict of interest
Acknowledgements
References
1. Introduction
The schizophrenia–diabetes comorbidity continues to attract attention from clinicians and researchers alike. The growing prevalence of these chronic, comorbid disorders, and a lack of corresponding increase in awareness and treatment efforts have been aptly characterized as a case of “dual disorder and dual neglect” (Meyer and Nasrallah, 2003). The range of publications on the subject includes studies on the prevalence of diabetes in schizophrenia (Dixon et al., 2000), associated risk factors in general and the role antipsychotic drugs in particular ([Sernyak et al., 2002] and [Newcomer, 2005]), efforts to develop appropriate life style modification programs (McKibbin et al., 2006), and speculations about the origins and pathophysiology of the comorbidity ([Dinan, 2004] and [Ryan and Thakore, 2002]). Much of the literature to date has helped to highlight the extent and significance of the comorbidity, but has not considered the scope for preventive intervention. Identifying vulnerable subgroups of schizophrenic population and exploring the extent of pre-diabetes and its correlates will help to examine the scope for early intervention and develop appropriate preventive strategies.
The diabetes prevention program in schizophrenia [DPPS] was established as a collaborative clinical-research initiative at the McMaster University with a view to study various aspects of schizophrenia–diabetes comorbidity; and the following article describes the results of an audit of the psychiatric records of a representative sample of community-dwelling adults treated for schizophrenia, in order to identify the extent and quality of diabetes-focused monitoring being performed. The objectives of the study were to
a. document the contemporary practice of screening for blood glucose abnormalities and recording relevant risk factors by mental health professionals,
b. compile prevalence rates for diabetes, pre-diabetes and other risk factors for type 2 diabetes mellitus,
c. examine the relationships between impaired fasting glucose (IFG) and various generic and illness (schizophrenia)-specific risk factors, and
d. identify subgroups of patients with increased risk who might benefit from the initiation of preventive measures.
2. Methods
The Diabetes in Schizophrenia in Central-south Ontario (DiSCO) study was a cross-sectional survey of a sample of community-dwelling adults (aged 16 or above) of both sexes, diagnosed with, and treated for schizophrenia or schizoaffective disorder (DSM IV). Five communities across Central-south Ontario, with populations ranging from 16000 and 400000 were chosen to represent key socio-demographic characteristics including urban vs. rural, culturally homogeneous vs. multi-cultural, recently diagnosed vs. chronically mentally ill, and those living in catchment areas of a teaching institution vs. community hospitals. People with recurrent or persistent forms of schizophrenia in these communities are generally treated in an inpatient setting during an acute exacerbation of illness, and become affiliated with one of the community-based mental health programs for their psychiatric, rehabilitative, housing or other needs.
A list of potential subjects in each community was compiled through the “snowballing” technique (Morrison, 1988) of identifying the local community mental health facilities (case management, housing, vocational rehabilitation or clubhouse programs) involved in providing services for people with schizophrenia, and then obtaining the list of subjects affiliated with each of the identified facilities. Such a comprehensive search strategy was helpful in ensuring the inclusion of nearly all of the people in each region who have been affected by a persistent illness and were being treated or actively monitored. If a subject was affiliated with more than one facility or a professional, steps were taken to avoid duplication of listing. Since the study was primarily conducted from psychiatric services perspective, the audit was confined to the information compiled in various mental health facilities and no attempts were made to obtain and examine the records of other medical specialists, social services or criminal justice system. The study was approved as a health records review project by the research ethics board based at St. Joseph's Healthcare/McMaster University, Hamilton.
Case records of the identified subjects were screened to ascertain the diagnosis of schizophrenia, which was followed by systematic chart reviews and obtaining corroborating information from the subject's health care professionals (family physicians, psychiatrists and case managers). The audit was conducted between August and December 2005; and all the facilities were reliant on conventional paper records at the time. A structured data sheet was used to guide the chart review process, which was performed by clinician-investigators who removed personal identifiers prior to transfer to the database for analysis. Accuracy of data compilation was ensured through an independent review of a random sample 10% of the charts in each center by the principal investigator.
Information gathered included socio-demographic data (age, sex, education, occupation, living arrangement, ethnicity and marital status), information on schizophrenia and its treatment (age of onset, duration of illness, psychotropic drugs and duration of their use, and current global assessment of functioning scores), history of diabetes and its treatment, and the most recent venous fasting plasma glucose (FPG) levels documented within six months prior to the audit. Any recorded comorbid physical health problems in general, and cardiovascular and hepatic diseases in particular were noted; and a family history of relevant physical illnesses including diabetes was gathered. The recorded blood pressure, morphometric measurements (height and weight), and the most recent laboratory test results on other metabolic parameters (FPG, HbA1c, serum insulin, triglycerides, HDL and LDL) were also noted. The cumulative daily amount of time (recorded in minutes) spent in physical activity, and details of nutrition and dietary habits (nutritional assessments, dietary prescriptions or counseling) were gathered when available. The latter information was limited to the recorded information in the psychiatric case files, which was reported by patients and other informants including various health care professionals.
3. Data analysis
Information gathered from the charts was entered into a database and further analyses were performed with SPSS Version 14 (SPSS Inc., 2005). Means and standard deviations were calculated for the continuous variables.
Data from patients with missing FPG values were compared to the data for patients with an available FPG level using analysis of variance (ANOVA) for continuous variables and chi-square tests for categorical variables. Other analyses excluded people with established diagnosis of type 2 diabetes mellitus and were limited to people with a recorded FPG. The latter were categorized into those who were “euglycemic” (i.e. had a FPG below 5.6mmol/l), and those who were “dysglycemic” (FPG >5.6mmol/l) (The expert committee on the diagnosis and classification of diabetes mellitus, 2003). Logistic regression models were calculated, in which dysglycemia was the dependent variable. The multivariate models were adjusted for important determinants of dysglycemia, including demographic variables; schizophrenia-related variables; and clinical measures.
4. Results
4.1. Sample description
A total of 1123 subjects' case records were reviewed. The subjects were aged 44.4±12.67years, and predominantly male (62.8%); single or unmarried (76.3%); unemployed (92.4%); of European ancestry (81.8%); and living in supported housing (78.7%). Psychiatric profiles revealed a long history of schizophrenia or schizoaffective disorder (mean duration 20.08±10.08years; treatment with second-generation (atypical) antipsychotics (78.9%); and adjunctive antipsychotic, antidepressant and mood stabilizing drugs (50.5%). Physical profiles indicated a known history of type 2 diabetes mellitus among 39 (3.5%) subjects; the presence of other chronic comorbid physical disorders (22.8%); and moderate functional impairment (mean global assessment of functioning score 50.15±11.08).
4.2. Screening practices
The frequency of screening for metabolic abnormalities was: a) triglycerides in 658 (58.6%); b) HDL in 560 (49.8%); c) LDL in 542 (48.2%); d) total cholesterol in 480 (42.7%); and e) hemoglobin A1C in 390 (34.7%). Relevant physical indices were recorded as following: a) blood pressure in 721 (64.2%); b) weight in 562 (50%); c) height in 452 (40.2%); d) hip circumference in 413 (36.7%) and e) waist circumference in 413 (36.7%). Daily or weekly levels of physical activity were recorded in 398 (35.4%) people. Nutritionists' assessments were available in 14 (1.2%) individuals and inquiry into dietary habits (e.g. cooking at home or the frequency of eating fast food) was noted in 78 (7%).
4.3. Prevalence of an elevated glucose level
Fasting plasma glucose (FPG) levels were available in 845 (78%) people. Individuals with a missing FPG level were more likely to be female and to not have a family history of diabetes than those who had a recorded FPG level (Table 1). The frequency and extent of FPG measurements varied significantly between individual sites (P0.001).
Table 1.
Comparative profiles of people with or without fasting plasma glucose monitored
Population with FPGa / Population without FPG a / Statistical significanceN=845 / N=239
1. Socio-demographic factors
a. Age (years) / 44.2±12.6 / 44.78±12.7 / P=0.54
b. Educational attainment (years) / 11.50±2.25 / 11.60±2.29 / P=0.55
c. Ethnicity (European:others) / 693 (82%):152 (18%) / 193 (80%):46 (20%) / P=0.62
d. Family history of diabetes / 102 (12%):743 (88%) / 5 (2%):234 (98%) / P=0.0001
e. Living arrangement independent:otherwise / 186 (22%):659 (78%) / 58 (22%):181 (78%) / P=0.61
f. Gender (male:female) / 546 (65%):299 (35%) / 135 (56%):104 (44%) / P=0.023
2. Clinical risk factors
a. Duration of illness (years) / 20.17±10.04 / 14.20±4.65 / P=0.18
b. Severity of disability (GAF) / 50.03±11.04 / 58.0±12.16 / P=0.11
c. Daily physical activity (minutes per day) / 45.4±36.1 / 61.6±69.7 / P=0.20
d. Body mass index (kg/m2) / 29.12±5.11 / 28.9±7.01 / P=0.9
aContinuous variables are expressed as mean±SD and categorical variables are expressed as N (%).
Among those with a FPG, it was <5.6mmol/l in 474 (56%), ≥5.6–6.9mmol/l in 268 (31%) and ≥7mmol/l in 103 (12.2%) subjects (Fig. 1).
Fig. 1.Overview of the study population and their glycemic status. 1T2DM: Type 2 diabetes mellitus. 2FPG = fasting plasma glucose.
4.4. Risk factors for dysglycemia in people with schizophrenia and no history of diabetes
Several risk factors were significantly associated with dysglycemia in the univariate logistic regression analysis (Table 2), of which family history of diabetes mellitus (OR=8.8; 95% CI 5.25–14.2, P0.001), age (OR=1.03 per year; 95% CI 1.01–1.04, P0.001), longer duration of schizophrenia (OR=1.06; 95% CI 1.03–1.08, P0.001), and low physical activity level (OR=0.958; 95% CI 0.94–0.97, P0.001) were significant.
Table 2.
Univariate risk factors for dysglycemia in people with schizophrenia and no previous diabetes
Euglycemic group (n=474) FPG <5.6mmol / Dysglycemic group (n=371) FPG ≥5.6mmol / Estimated odds ratios, confidence intervals and significance1. Socio-demographic factors
a. Age (years) / 42.2±12.9 / 46.9±11.8 / 1.031 (1.01–1.04)
b. Educational attainment (years) / 11.5±2.2 / 11.5±2.3 / 1.008 (0.77–1.35)
c. Ethnicity (European) / 84.4% / 79.2% / 0.706 (0.5–0.99)
d. Family history of diabetes / 3.6% / 24.9% / 8.877 (5.25–14.2)
e. Living arrangement Independent housing / 17.0% / 26.8% / 1.779 (1.28–2.46)
f. Gender (female) / 35.3% / 35.8% / 1.025 (0.77–1.35)
2. Clinical risk factors
a. Duration of schizophrenia (years) / 17.1±9.9 / 22.8±9.5 / 1.062 (1.03–1.08)
b. Severity of disability (GAFa) / 50.0±13.6 / 50.1±8.3 / 1.000 (0.98–1.02)
c. Primary antipsychotic drug
i. No antipsychotic drugs / 3.8% / 2.6% / 1.000
ii. Neuroleptics / 14.0% / 16.1% / 1.683 (0.72–3.89)
iii. Risperidone / 11.6% / 9.1% / 1.147 (0.47–2.74)
iv. Olanzapine / 17.4% / 13.2% / 1.114 (0.48–2.58)
v. Quetiapine / 13.8% / 9.4% / 0.991 (0.41–2.35)
vi. Clozapine / 39.3% / 49.6% / 1.852 (0.83–4.08)
d. Polypharmacy / 50.5% / 49.9% / 0.975 (0.74–1.27)
3. Morphometric correlates
a. Weight (pounds) / 176.9±32.2 / 190.3±31.2 / 1.014 (1.0–1.02)
b. Body mass index (BMI) (kg/m2) / 28.12±5.09 / 29.97±4.98 / 1.081 (1.03–1.12)
4. Physical activity (minutes/day) / 58.6±41.4 / 27.5±14.6 / 0.958 (0.94–0.97)
5. Other metabolic correlates
a. Serum triglycerides (mmol/l) / 2.06±1.33 / 2.67±1.88 / 1.289 (1.15–1.43)
b. Cholesterol (mmol/l) / 5.11±1.12 / 5.19±1.21 / 1.059 (0.90–1.23)
c. LDL (mmol/l) / 2.92±1.04 / 2.87±0.97 / 0.946 (0.79–1.12)
d. HDL (mmol/l) / 1.22±0.56 / 1.22±0.56 / 1.015 (0.74–1.37)
e. HDL/cholesterol ratio / 4.73±1.77 / 4.94±1.63 / 1.076 (0.92–1.21)
0.05P0.001; 0.001≥P.
aGlobal assessment of functioning scale; score ranges between 0–90.
The independent contribution of these risk factors to the presence or absence of dysglycemia was explored in 3 different multivariate models. As noted in Table 3, people with dysglycemia (impaired fasting glucose or diabetes) were more likely to be older, have a family history of diabetes, or lived on their own than normoglycemic individuals. When psychiatric variables were added to the model, the duration of mental illness but not antipsychotic drug use was an independent determinant. Physical activity, but not weight or body mass index also emerged as a significant determinant.
Table 3.
Risk of dysglycemia in schizophrenia — results of the multivariate logistic regression analyses
Model 1 (n=845) / Model 2 (n=327) / Model 3 (n=268)1. Socio-demographic factors
a. Age (years) / 1.038 (1.02–1.05) / 1.009 (0.97–1.05) / 1.048 (1.01–1.09)
b. Educational attainment (years) / 1.005 (0.94–1.07) / 0.964 (0.65–1.94) / 0.975 (0.83–1.15)
c. Ethnicity (European) / 0.745 (0.51–1.11) / 0.671 (0.32–1.41) / 1.317 (0.40–4.36)
d. Family history of diabetes / 9.832 (5.7–1.68) / 7.238 (3.31–15.84) / 5.239 (1.42–19.36)
e. Living arrangement Independent housing / 1.712 (1.21–2.45) / 2.318 (1.20–4.47) / 3.859 (1.18–12.58)
f. Gender (female) / 0.896 (0.65–1.21) / 1.127 (0.65–1.94) / 1.041 (0.37–2.92)
2. Psychiatric illness factors
a. Duration of mental illness (years) / 1.061 (1.00–1.12)
b. Severity of disability (GAF) / 1.012 (0.99–1.03)
c. Primary antipsychotic drug / 1.852 (0.53–6.49)
d. Polypharmacy / 0.762 (0.46–1.25)
3. Clinical measures
a. Weight (pounds) / 0.991 (0.96–1.02)
b. Body mass index (kg/m2) / 1.055 (0.88–1.26)
c. Physical activity / 0.972 (0.95–0.99)
0.05P0.001 0.001≥P.
4.5. Prevalence of diabetes and care profile
A total of 39 people (3.5%) in the sample had a previous diagnosis of diabetes. Of the 39 known cases with known diabetes, 12 had had an FPG performed within the preceding 6months. Only 8 of them had information on their diabetes care (meal plan, drug therapy, glucose monitoring, and involvement of endocrinologist, nutritionist or family physician) recorded in their psychiatry charts.
5. Discussion
This audit of the psychiatric records of a representative sample of community-dwelling adults treated for schizophrenia revealed a lack of uniformity in screening procedures for diabetes and other metabolic disorders as well as varied data collection practices on risk factors within and between the psychiatric care settings studied. 3.5% of this population was already diagnosed and treated for diabetes, while significantly greater proportions of people (12.2% and 31% respectively) were dysglycemic with a FPG in the pre-diabetes (5.6–6.9mmol/l) or diabetes range (≥7mmol/l), and not formally diagnosed. Dysglycemia was found to be associated with various non-modifiable (family history, ethnicity and older age) and modifiable risk factors (low physical activity, increased weight and body mass index, and independent living status).
These data on screening practices confirm the existence of varied knowledge and attitudes among mental health professionals towards the significance of metabolic abnormalities observed during the course of treating people with schizophrenia ([Buckley et al., 2005] and [Newcomer et al., 2004]). The inconsistency in screening practices across centers may have reflected varying degrees of awareness, lack of clarity with regard to psychiatric care providers' role in monitoring physical ailments, lack of necessary infrastructure and adequate resources, and the arrival of an array of consensus protocols in the absence of evidence-based guidelines for monitoring physical health status among people treated for schizophrenia.
The prevalence of known type 2 diabetes (3.5%) in this survey was significantly lower than the Canadian national and regional prevalence rates for the corresponding age group (6.19%) (Hux et al., 2003). The significantly lower rates of recorded diabetes in the study population, coupled with the evidence of a two-fold increase in the prevalence of dysglycemia suggests a pattern of substantial under-diagnosis of diabetes among people with schizophrenia (Kisely et al., 2007). Also, the higher rates of dysglycemia noted in the DiSCO study confirm earlier findings that prevalence of diabetes is higher in those with schizophrenia than in the general population ([Cohen et al., 2006a], [Cohen et al., 2006b], [Dixon et al., 2000], [Meyer et al., 2006], [Mukherjee et al., 1996] and [Philippe et al., 2005]) and people with schizophrenia are at a high risk of having or developing diabetes ([Citrome et al., 2006] and [De Hert et al., 2006]).
The risk factors for diabetes identified in this population were similar to those observed in other studies, and included older age ([Dixon et al., 2000], [Hung et al., 2005], [Philippe et al., 2005] and [Subramaniam et al., 2003]), non-European ethnicity ([Dixon et al., 2000], [Henderson et al., 2005] and [Tabata et al., 1987]), and family history of diabetes ([Hung et al., 2005], [Lamberti et al., 2005], [Thonnard-Neumann, 1968] and [Waitzkin, 1966]). These risk factors, however, are largely non-modifiable and offer little scope for developing preventive strategies. Less consistently reported risk factors include increased BMI ([Cavazzoni et al., 2004], [Hung et al., 2005], [Sernyak et al., 2003] and [Tabata et al., 1987]) and the use of second-generation antipsychotic drugs (Sernyak et al., 2002). The fact that DiSCO has identified an association between dysglycemia and modifiable risk factors such as physical activity, weight, body mass index and type of living arrangement, may facilitate the development of appropriate preventive strategies. Interventions focused on preventing diabetes as opposed to treating this metabolic condition and its complications once they are present, will not only reduce costs but will provide sufferers with the most effective tools for maintaining and improving their health and well-being.