Renal Involvement in Granulomatosis With Polyangiitis Increases Economic Health Care Burden: Insights From the National Inpatient Sample Database

Background This study aims to compare outcomes of hospitalizations of granulomatosis with polyangiitis (GPA) with and without renal involvement. The primary outcome was inpatient mortality, whereas secondary outcomes were hospital length of stay (LOS) and total hospital charge. Methods Data were abstracted from the National Inpatient Sample (NIS) 2016 and 2017 databases. The NIS was searched for GPA hospitalizations with and without renal involvement as the principal or secondary diagnosis using International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10) codes. GPA hospitalizations for adult patients from the above groups were identified. Multivariate logistic and linear regression analyses were used to adjust for possible confounders for the primary and secondary outcomes, respectively. Results There were more than 71 million discharges included in the combined 2016 and 2017 NIS database, of which 23,670 were for adult patients who had either a principal or secondary ICD-10 code for GPA, and 8,265 (34.92%) of these GPA hospitalizations had renal involvement. Hospitalizations for GPA with renal involvement had similar inpatient mortality (3.8% vs. 3.7%; adjusted OR: 1.14; 95% CI: 0.84-1.56; p=0.406) compared to those without renal involvement. GPA with renal involvement hospitalizations had an increase in adjusted mean LOS of 1.36 days (95% CI: 0.82-1.91; p=0.0001) compared to those without renal involvement. GPA with renal involvement hospitalizations had an increase in adjusted total hospital charges of $18,723 (95% CI: 9,595-27,852; p=0.0001) compared to those without renal involvement. Conclusions GPA with renal involvement hospitalizations had similar inpatient mortality compared to those without renal involvement. However, LOS and total hospital charges were greater in those with renal involvement.