OBJECTIVES

Primary distal renal tubular acidosis (dRTA) is caused by genetic defects leading to impaired renal acid secretion, which can result in nephrolithiasis, nephrocalcinosis, bone demineralization, poor growth and possibly deafness. While primary dRTA is a rare disease, US prevalence may be under-reported. This analysis utilizes administrative claims data to estimate the prevalence of primary dRTA among the US employer-sponsored insurance (ESI) population.

METHODS

Utilizing the Truven MarketScan^® Administrative Claims data from Jan 1, 2016–Dec 31, 2016, primary dRTA patients were identified: at least 1 inpatient or ≥2 outpatient claims ≥30 days apart containing ICD-10-CM code N25.89. To further delineate the sample, those prescribed an alkalinizing agent, had ≥1 visit with a nephrologist, urologist or pediatrician, and did not have a diagnosis of Sjogren’s syndrome, systemic lupus erythematosus, scleroderma, cystinosis, Fanconi syndrome, hypophosphatemia, Bartter syndrome, mitochondrial disorders or urolithiasis were identified. MarketScan Commercial Insurance Weights were applied to project the sample to the total US ESI population.

RESULTS

We identified 1084 patients with ICD-10 code N25.89; 117 were identified as primary dRTA using the additional criteria. Using this proportion of primary dRTA to the larger identified sample (117/1084) and applying the insurance weights, this projected to an estimated 665 primary dRTA patients, which translates to an estimated primary dRTA patient prevalence rate of 0.38 per 100,000 in the 2016 US ESI population.

CONCLUSIONS

The ability to unequivocally identify primary dRTA patients based on a diagnostic code is limited. This approach used claims data to provisionally identify and estimate the prevalence of 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.