Impact of Socioeconomic Status on Cardiovascular Disease and Mortality in 24,947 Individuals With Type 1 Diabetes

Diabetes Care, Jul 2015

OBJECTIVE Socioeconomic status (SES) is a powerful predictor of cardiovascular disease (CVD) and death. We examined the association in a large cohort of patients with type 1 diabetes.

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Impact of Socioeconomic Status on Cardiovascular Disease and Mortality in 24,947 Individuals With Type 1 Diabetes

araz. . Received 20 January 2015 and accepted 28 March 2015. This article contains Supplementary Data online at http://care.diabetesjournals.org/lookup/ suppl/doi:10.2337/dc15 Impact of Socioeconomic Status on Cardiovascular Disease and Morta lity in 24,947 Individua ls With Type 1 Diabetes 0 Araz Rawshani Socioeconomic status (SES) is a powerful predictor of cardiovascular disease (CVD) and death. We examined the association in a large cohort of patients with type 1 diabetes. RESEARCH DESIGN AND METHODS Clinical data from the Swedish National Diabetes Register were linked to national registers, whereby information on income, education, marital status, country of birth, comorbidities, and events was obtained. Patients were followed until a first incident event, death, or end of follow-up. The association between socioeconomic variables and the outcomes was modeled using Cox regression, with rigorous covariate adjustment. - We included 24,947 patients. Mean (SD) age and follow-up was 39.1 (13.9) and 6.0 (1.0) years. Death and fatal/nonfatal CVD occurred in 926 and 1378 individuals. Compared with being single, being married was associated with 50% lower risk of death, cardiovascular (CV) death, and diabetes-related death. Individuals in the two lowest quintiles had twice as great a risk of fatal/nonfatal CVD, coronary heart disease, and stroke and roughly three times as great a risk of death, diabetesrelated death, and CV death as individuals in the highest income quintile. Compared with having £9 years of education, individuals with a college/university degree had 33% lower risk of fatal/nonfatal stroke. Immigrants had 19%, 33%, and 45% lower risk of fatal/nonfatal CVD, all-cause death, and diabetes-related death, respectively, compared with Swedes. Men had 44%, 63%, and 29% greater risk of all-cause death, CV death, and diabetes-related death. CONCLUSIONS Low SES increases the risk of CVD and death by a factor of 2–3 in type 1 diabetes. Socioeconomic status (SES) is a complex construct, often conceptualized as the social standing or class of an individual. It is commonly measured as a combination of education, income, and occupation but may include age, sex, ethnicity, and marital status (1). SES may profoundly affect health. It is a powerful predictor of cardiovascular disease (CVD) and death (2–5). The impact of SES on CVD and mortality in type 2 diabetes has been examined (6), but studies in type 1 diabetes are scarce. Available data, which are hampered by small samples and inadequate adjustment for confounders, suggest either a modest effect or no significant effect of SES on death and CVD (7–9). Consequently, no reliable studies relating SES to CVD and mortality in type 1 diabetes have been conducted. This might explain why socioeconomic variables have not been considered in recent risk prediction models for type 1 diabetes (10,11). We used the Swedish National Diabetes Register (NDR), which provides almost complete national coverage of type 1 diabetes, to investigate how income, education, marital status, immigrant status, and sex relate to CVD and death (12,13). It is important to examine this relationship, as it may reveal easily accessible risk markers. RESEARCH DESIGN AND METHODS The NDR was initiated in 1996 as a caregiver tool for local quality assurance and as a feedback tool in diabetes care. Roughly 95% of all individuals age 18 years and older with type 1 diabetes in Sweden are included (12). Data provided by nurses and physicians trained in register procedures are obtained at visits in outpatient clinics of hospitals and primary health care centers nationwide. Clinical information and various measurements are updated at least once a year. The study was approved by the regional ethics review board at the University of Gothenburg. All patients give their informed consent before being included in the NDR. Study Cohort We included 24,947 individuals (220,281 appointments) with type 1 diabetes who had at least one listing in the NDR between 1 January 2006 and 31 December 2008. This excluded 2,186 individuals with a history of CVD (as defined below), who were listed in the NDR during the same period. Type 1 diabetes was defined on the basis of epidemiologic data: treatment with insulin and a diagnosis at the age of 30 years or younger. This definition has been validated as accurate in 97% of the cases listed in the register (14). Socioeconomic Data Data on annual income in Swedish kronor, highest educational level, country of birth, marital status, and occupation were obtained from Statistics Sweden. Education was stratified into lower (#9 years, the length of compulsory education in Sweden), intermediate (10–12 years, upper secondary) and higher (col lege/university). Income was stratified into quintiles (Q1 [lowest] to Q5 [highest]). Immigrant status was defined as immigrant or native Swede depending on country of birth. Marital categories were single (defined as never married and (...truncated)


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Araz Rawshani, Ann-Marie Svensson, Annika Rosengren, Björn Eliasson, Soffia Gudbjörnsdottir. Impact of Socioeconomic Status on Cardiovascular Disease and Mortality in 24,947 Individuals With Type 1 Diabetes, Diabetes Care, 2015, pp. 1518-1527, 38/8, DOI: 10.2337/dc15-0145