Socioeconomic Status and Mortality Among Type 2 Diabetics
Is socioeconomic status associated with all-cause, cardiovascular, diabetes-related, and cancer mortality in persons with type 2 diabetes?
Data collected from the Sweden National Diabetes Register were used for the present analysis. Individuals under the age of 70 years with type 2 diabetes between January 2003 and December 2010 were followed through December 31, 2012. Socioeconomic status variables obtained from the Longitudinal Integration Database for Health Insurance and Labour Market Studies, included income level, highest educational level obtained, country of birth, marital status, and occupation. Education was stratified into lower (≤9 years, with 9 years being the length of compulsory education in Sweden), intermediate (10-12 years, upper secondary), and higher (college/university). Income was stratified into quintiles. Country of birth was categorized into the following groups: Sweden, high-income Europe, low-income Europe, non-Western, and Nordic. Marital categories were single (never married or had a registered partner), married or had a registered partner, divorced, or widowed. Primary outcomes of interest included all-cause, cardiovascular disease (CVD), diabetes-related, and cancer mortality.
A total of 217,364 individuals were included in the study; the mean age was 58.3 years and 60.2% were male. During the follow-up, a total of 19,105 all-cause deaths occurred. Among these deaths, 11,423 (59.8%) were due to CVD; 6,984 (36.6%) were diabetes-related mortality, and 6,438 (33.7%) were cancer related. Being married was associated with lower all-cause mortality (hazard ratio [HR], 0.73; 95% confidence interval [CI], 0.70-0.77), lower CVD mortality (HR, 0.67; 95% CI, 0.63-0.71), and lower diabetes-related mortality (HR, 0.62; 95% CI, 0.57-0.67). Marital status was not associated with overall cancer mortality; however, married men had a 33% lower risk for prostate cancer mortality compared to single men (HR, 0.67; 95% CI, 0.50-0.90). Income was also associated with mortality. Comparing the lowest versus highest income quintiles, an increased risk was associated with lowest income quintile for all-cause mortality (HR, 1.71; 95% CI, 1.60-1.83); for CVD mortality (HR, 1.87; 95% CI, 1.72-2.05), for diabetes-related mortality (HR, 1.80; 95% CI, 1.61-2.01), and for cancer mortality (HR, 1.28; 95% CI, 1.14-1.44). Compared with native Swedes, HRs for all-cause, CVD, diabetes-related, and cancer mortality for non-Western immigrants were 0.55 (95% CI, 0.48-0.63), 0.46 (95% CI, 0.38-0.56), 0.38 (95% CI, 0.29-0.49), and 0.72 (95% CI, 0.58-0.88), respectively. Higher levels of education were associated with lower mortality. Comparing those with a college/university degree to those with ≤9 years of education, the HR for all-cause mortality was 0.85 (95% CI, 0.80-0.90); for CVD mortality was 0.84 (95% CI, 0.78-0.91); and for cancer mortality was 0.84 (95% CI, 0.76-0.93).
The investigators concluded that independent of risk factors, access to health care, and use of health care, socioeconomic status is a powerful predictor of all-cause and CVD mortality, but was not as strong as a predictor of death from cancer.
These data suggest that social support, education, income, and other factors which influence access to health care are important factors in mortality. Understanding how these findings are generalizable to other countries including the United States may have important public health implications.
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