Socio-economic gradients in the presence of musculoskeletal and other chronic diseases: results from a cross-sectional study in the Netherlands.

Socio-economic gradients in occurrence of diseases have been reported for many chronic conditions. However, whether the magnitude of socio-economic gradients differs across diseases and the extent to which lifestyle mediates such relationships are not known. Cross-sectional data from The National Monitor on Musculoskeletal System was used. Respondents (> 18 years) completed a questionnaire including gender, education, social status, lifestyle, and physician-diagnosed diseases. Logistic regressions investigated the relationship between education and the major chronic diseases (musculoskeletal diseases (MSKD), diabetes, cardiovascular (CVD), cancer, mental, respiratory, any disease). Next, analyses were repeated in individuals with potential to have paid work (i.e., those < 65 having paid work, being unemployed, or receiving living allowance (minimum income)). The mediating role of smoking and BMI between education and occurrence of diseases was assessed by testing indirect effects. From 8904 individuals (mean age 54 years, 46% male), 4378 (49%) had at least one disease. Gradients in occurrence of disease by education were present for all diseases except cancer and mental disease, with the strongest gradient in diabetes (OR 2.0 [95%CI 1.4;2.8]). Unemployment and especially living on minimum income were associated with increased odds to have MSKD and mental and respiratory disease, after adjusting for education. Smoking and obesity mediated part of the relationship between education and disease, with obesity playing more pronounced role. Association between deprivation and occurrence of all major chronic diseases is of comparable magnitude, with education having most consistent contribution. Our results support the notion of the generic (i.e., non-disease specific) mechanisms underlying socio-economic gradients in health.