PUK18 DISTAL RENAL TUBULAR ACIDOSIS, A RARE RENAL CONDITION THAT IS OFTEN UNDIAGNOSED: UK STUDY USING CPRD DATABASE

Abstract

Distal renal tubular acidosis (dRTA), or RTA type 1, a rare genetic or acquired disease, is a disorder of the distal tubule, causing acid excretion to collect in the kidney duct system, elevating acidity levels in the blood and alkalising urine. Due to associated conditions and non-specific symptoms it may be under-reported and undiagnosed. This analysis aims to estimate the prevalence of dRTA, the use of healthcare resources and pathway of dRTA patients in the UK. A retrospective analysis was carried out using the CPRD GOLD UK database and linked HES data to identify diagnosed, potentially undiagnosed or miscoded patients. First patient records with at least one event of RTA or dRTA recorded between January 1987 and November 2017 were obtained. This population was analysed on the following aspects: demographics, GP consultations, specialist referrals, treatment patterns, outpatient visits, hospitalisations. Then records of patients without RTA but with associated conditions were analysed. Algorithms based on a sequence of inclusion criteria were developed and validated by clinical experts to identify suspected dRTA cases. Prevalence rates for 2017 were calculated. 216 patients diagnosed with RTA/dRTA were identified in the database, of whom 98 had a linkage to hospital data. 447 patients were identified as having suspected dRTA through the algorithm. The dRTA prevalence was estimated to between 0.46 (diagnosed, 22% inherited) and 1.60 (diagnosed and suspected) per 10,000 Health records of diagnosed patients revealed that pharmacological treatment was required to manage associated symptoms, patients frequently visited a wide range of specialist physicians, and although hospitalisations rates were low, they often incurred long lengths of stay. The study adds to the literature by providing a new estimate of dRTA prevalence and further shows that patients are often undiagnosed or miscoded, and experience complications as a result of their disease.