Background/Purpose: Calcium pyrophosphate deposition disease (CPDD) is a crystal arthropathy caused by calcium pyrophosphate (CPP) crystals. Individuals with CPDD also have increased risks for other manifestations of disordered mineralization, including osteoporosis and vascular calcification. To our knowledge, there are no prior studies investigating the potential association of CPDD and nephrolithiasis. Using data from the United States national Veterans Health Administration, we investigated this prevalence of nephrolithiasis in individuals with CPDD. Rates were compared with age and sex-matched controls. We also investigated the contribution of co-existing gout in patients with mixed crystal disease.

Methods: We performed a retrospective cohort analysis utilizing the Veterans Health Administration Corporate Data Warehouse, 2010 – 2014. CPDD was identified by ICD-9 code according to a previously validated rule, and nephrolithiasis and gout were also identified by ICD-9 codes. Each CPDD patient was age- and sex-matched to 4 controls. All subjects were required to have ≥2 encounters in the 365 days before and including the index date. Univariable analysis among CPDD, nephrolithiasis, and gout were performed using Chi Square.

Results: The study population was comprised of 110,796 individuals including 23,470 CPDD patients and 87,326 matched controls. The average age was 70.76 years, and 96.01% were male. More CPDD patients had nephrolithiasis (8.06% vs 4.88%; p< 0.0001) and gout (26.72% vs 9.15%; p< 0.0001) than controls. Nephrolithiasis rates were slightly higher when gout was present (6.89% vs 5.36%; p < 0.0001), but probably not to a level of clinical importance.

Conclusion: We show here that the prevalence of nephrolithiasis is positively associated with CPDD and was the presence of gout did not have a major impact on rates. Interestingly, the widely-distributed membrane protein known as ANKH, which is linked to familial CPDD, has recently been shown to transport factors important in nephrolithiasis, such as citrate. This observational study lends credence to the idea that abnormal mineralization occurs in multiple tissues in CPDD and the association with nephrolithiasis warrants further study.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/calcium-pyrophosphate-deposition-disease-is-associated-with-an-increased-prevalence-of-nephrolithiasis/