Trends in renal function in Northern Sweden 1986-2014: data from the seven cross-sectional surveys within the Northern Sweden MONICA study

Objective The prevalence of chronic kidney disease (CKD) is increasing globally, and CKD is closely related to cardiovascular disease (CVD). CKD and CVD share several risk factors (RF), such as diabetes, hypertension, obesity and smoking, and the prevalence of these RF has changed during the last decades, and we aimed to study the effect on renal function over time. Design Repeated cross-sectional population-based studies. Setting The two Northern counties (Norr- and Vasterbotten) in Sweden. Participants Within the MONitoring Trends and Determinants of CArdiovascular Disease (MONICA) study, seven surveys were performed between 1986 and 2014, including participants aged 25-64 years (n=10 185). Interventions None. Measures Information on anthropometry, blood pressure and cardiovascular risk factors was collected. Creatinine and cystatin C were analysed in stored blood samples and the estimated glomerular filtration rate (eGFR) calculated using the creatinine-based Lund-Malmo revised and Chronic Kidney Disease Epidemiology Collaboration (eGFR(crea)) equations as well as the cystatin C-based Caucasian, Asian, Paediatric and Adult cohort (CAPA) equation (eGFR(cysC)). Renal function over time was analysed using univariable and multivariable linear regression models. Results Renal function, both eGFR(crea) and eGFR(cysC), decreased over time (both p<0.001) and differed between counties and sexes. In a multivariable analysis, study year remained inversely associated with both eGFR(crea) and eGFR(cysC) (both p<0.001) after adjustment for classical cardiovascular RF. Conclusion Renal function has deteriorated in Northern Sweden between 1986 and 2014.