Subjects
Subjects were identified at 9 hospitals serving approx. 4,575,000 people by interrogating laboratory databases to identify individuals in three specific age bands with reduced eGFR calculated using the Modified Diet in Renal Disease (MDRD; 4 variable) or chronic kidney disease epidemiology (CKDEPI) equations. Thresholds were chosen empirically by estimating a feasible population size that could be sampled based on the distribution of eGFR results in a sample of data from Queen’s Hospital, Burton.
Laboratory database searches were performed using creatinine measurements over a maximum a 6-year time period interval limited by site-specific data access issues. Once provisionally identified, subjects were invited to take part in the study as they had been identified as having abnormal results in routine pathology testing. They were asked if they would meet with a research nurse to allow collection of a blood sample for lysosomal α-galactosidase activity. At the research visit, patients provided informed consent, and basic demographic details were collected. An EDTA blood sample was collected and single drops were spotted on a dried blood spot (DBS) collection card. Subjects indicated their preference for anonymity or if they wanted to receive a copy of their results.