Background/Purpose: Distal renal tubular acidosis (dRTA) involves impairment in the distal tubule, leading to insufficient renal acid secretion, which can result in metabolic acidosis, hypokalemia, nephrolithiasis, nephrocalcinosis and bone demineralization. While primary dRTA is caused by genetic factors, and additionally associated with poor growth and deafness, secondary dRTA may result from autoimmune disorders, such as Sjögren’s syndrome or systemic lupus erythematosus (SLE), which also attack the distal tubule. Some medications are also associated with secondary dRTA. While secondary dRTA is a rare disease, US prevalence may be under-reported.  This analysis utilizes administrative claims data to estimate the prevalence of secondary dRTA among patients with Sjogren’s syndrome or SLE in a US employer-sponsored insurance (ESI) population. 

Methods: Utilizing the Truven MarketScan^® Commercial and Medicare Supplemental Databases from Jan 1, 2016–Dec 31, 2016, secondary dRTA patients were identified using the following criteria: at least 1 inpatient or ≥2 outpatient claims ≥30 days apart for Sjögren’s syndrome (ICD-10-CM: M35.0x) or SLE (ICD-10-CM: M32.xx) or acidosis (ICD-10-CM: E87.2). To further delineate the sample, patients were also required either to have a claim for an alkalinizing agent or have a diagnosis of other disorders resulting from impaired renal tubular function (ICD-10-CM: N25.89).  MarketScan Commercial Insurance Weights were then applied to project the sample to the total US ESI population. 

Results: A total of 100,680 patients with ICD-10-CM diagnosis code of Sjögren’s syndrome, SLE, or Acidosis were identified in the 2016 Marketscan database.  Of these, 1,125 were prescribed an alkalinizing agent or had a diagnosis code of impaired renal tubular function.  Applying the insurance weights to the 1,125 identified sample, this projected to an estimated 6,716 secondary dRTA patients, which extrapolates to an estimated secondary dRTA patient prevalence rate of 3.88 per 100,000 in the 2016 US ESI population.

Conclusion: The ability to unequivocally identify secondary dRTA patients based on a diagnostic code is limited. This approach used claims data to provisionally identify and estimate the prevalence of secondary dRTA patients in the US ESI population. According to the Kaiser Foundation, ESI represents 49% of the total US population. Further research is needed to validate this approach to effectively identify and characterize the treatment experiences of dRTA patients. 

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/estimate-of-prevalence-of-secondary-distal-renal-tubular-acidosis-among-patients-with-sjogrens-syndrome-and-systemic-lupus-erythematosus-in-a-us-population-with-employer-sponsored-health-insu/