Sixteen years of creatinine measurements among 460 000 individuals-The Funen Laboratory Cohort (FLaC), a population-based pharmacoepidemiological resource to study drug-induced kidney disease

Register-based administrative data comprise the backbone of pharmacoepidemiological research. However, information from these registers lacks biochemical details. The aim of our study was to describe the creation, coverage and content of the Funen Laboratory Cohort (FLaC). FLaC is a database comprising all inhabitants of Funen, Denmark, who in the study period of January 2000 to December 2015 had their creatinine levels measured. Data were linked to the Danish nationwide registers with information on vital status, redeemed prescriptions, discharge diagnoses, and socio-economic status. A total of 693 843 individuals lived on Funen during the study period, and we included 460 365 (66.4%) individuals with a creatinine measurement. In total, 7 742 124 creatinine measurements were performed during the study period. The coverage increased with increasing age, reaching 90%-100% of all 65-90 + year-olds in 2015. We found that an overall coverage of individuals recorded in FLaC with at least one creatinine measured redeeming prescriptions from public pharmacies was 83% (interquartile range [IQR] 75%-89%) compared to the entire Funen population. In total, 94.1% of all individuals with a discharge diagnosis of chronic kidney disease (CKD) were covered in FLaC, but only 16.5% (n = 3136) of all individuals with a laboratory-confirmed CKD also had a discharge diagnosis of CKD. We described the creation and content of the FLaC - a haven and a valuable resource for pharmacoepidemiological research using Danish nationwide administrative registers enriched with individual-level biochemical information in a population-based setting.