Socio-economic status and chronic renal failure:: a population-based case-control study in Sweden

Background. Low socio-economic status is associated with the occurrence of several different chronic diseases, but evidence regarding renal disease is scant. To explore whether the risk of chronic renal failure varies by socio-economic status, we performed a population-based case-control study in Sweden. Methods. All native residents from May 1996 to May 1998, aged 18-74 years, formed the source population. Cases (n = 926) were incident patients with chronic renal failure in a pre-uraemic stage. Control subjects (n = 998) were randomly selected within the source population. Exposures were assessed at personal interviews and relative risks were estimated by odds ratios (OR) in logistic regression models, with adjustment for age, sex, body mass index (BMI), smoking, alcohol consumption and regular analgesics use. Results. In families with unskilled workers only, the risk of chronic renal failure was increased by 110% [OR = 2.1; 95% confidence interval (CI), 1.1-4.0] and 60% (OR = 1.6; 95% CI, 1.0-2.6) among women and men, respectively, relative to subjects living in families in which at least one member was a professional. Subjects with 9 years or less of schooling had a 30% (OR = 1.3; 95% CI, 1.0-1.7) higher risk compared with those with a university education. The excess risk was of similar magnitude regardless of underlying renal disease. Conclusions. Low socio-economic status is associated with an increased risk of chronic renal failure. The moderate excess was not explained by age, sex, BMI, smoking, alcohol or analgesic intake. Thus, socioeconomic status appears to be an independent risk indicator for chronic renal failure in Sweden.