Outcomes of total hip arthroplasty in calcium pyrophosphate deposition disease patients

We aim to examine the demographics, clinical characteristics, outcomes, and resource utilization following total hip arthroplasty (THA) in patients with and without calcium pyrophosphate deposition (CPPD) disease. We queried the National Inpatient Sample database to identify patients who underwent THA between 2006 and 2014. The ICD-9 code 81.51 was used to determine the patients who underwent THA, and of those, we classified 2 groups of patients: (i) those with ICD-9 codes defining CPPD and (ii) those without any CPPD code. Data collection included patient demographics and comorbidities. Outcomes post-THA were mortality, length of stay (LOS), and costs. Associations between CPPD and specific morbidity were evaluated with chi-square tests. T tests were used for continuous variables. Among the 4,111,808 patients who underwent THA, 6198 (0.15 %) had CPPD, with a mean age of 77 years and 64.2 % were females. CPPD patients were more likely to be older (mean age 77 vs 72.7 years; p<0.001) than non-CPPD patients. The Charlson Comorbidity Index score ≥ 2 was more frequently seen in CPPD, however, the mortality post-THA was lower in the CPPD patients (0.7 % vs 1.7 %, OR 0.35, 95 % CI 0.26- 0.47). THA in CPPD patients was associated with a longer mean length of stay (LOS) (6.04 vs 5.15 days, OR 1.15, 95 % CI 1.09–1.22) while mean total charges were not statistically different between the 2 groups (p = 0.344). CPPD patients were more likely to be discharged to rehabilitation or other nursing facilities (42.5 % vs 35.3 %, p<0.001). The number of THA procedures increased in both CPPD and non-CPPD patients over time. CPPD patients who underwent THA were more likely to be older, with a greater comorbidity burden, longer LOS and discharged to a non-home setting.