Occurrence and prognosis of chronic kidney disease in Denmark – a nationwide population-based cohort study

Background: Information on chronic kidney disease (CKD) epidemiology is essential for healthcare provision. Moreover, variation in CKD occurrence and prognosis may reveal unwarranted inequalities in healthcare. Therefore, we examined the nationwide incidence, prevalence, and mortality of laboratory-confirmed CKD in Denmark and assessed variation according to urbanicity. Methods: This nationwide cohort study utilized population-based laboratory data on estimated glomerular filtration rate (eGFR) and urine albumin-creatinine ratio (uACR) and included all adult (≥18 years) Danish residents without prevalent CKD on 1 January 2019. We estimated crude and standardized incidence rates, prevalences, and mortality rates of CKD overall and according to urbanicity categories. We standardized by age and sex, and by age, sex, diabetes, hypertension, and outpatient eGFR and uACR testing frequency. Results: The study included 4 157 059 adult Danish residents of whom 281 985 developed incident CKD during the 5-year study period. The CKD incidence rate was 14.5 [95% confidence interval (CI), 14.4-14.5] per 1000 person-years, and the CKD prevalence was 9.5% (95% CI, 9.5%-9.5%). The 5-year mortality was 24.9% (95% CI, 24.5%-25.3%). The crude CKD incidence, prevalence, and mortality varied across urbanicity categories; however, differences were largely accounted for by standardizing for age and sex. Conclusions: Chronic kidney disease affected nearly one in ten adults in Denmark, and one in four individuals with incident CKD died within 5 years. The occurrence and prognosis of CKD varied across urbanicity categories and was predominantly related to differences in demographics. This emphasizes the need for a targeted allocation of healthcare resources according to population demographics.