Background/Purpose: Progressive multifocal leukoencephalopathy (PML), a rare, usually fatal, central nervous system demyelinating disorder that occurs in immunocompromised hosts, results from reactivation of the JC virus. We undertook this study to determine the frequency of rheumatic and other diseases associated with an immunocompromised state in a national cohort of PML hospitalizations derived from the Nationwide Inpatient Sample (NIS).

Methods: The NIS, established as part of the Healthcare Cost and Utilization Project, is a 20% sample of all US hospital discharges weighted to represent the entire US population. Data collected and analyzed from January 1^st 1998 until December 31^st 2011. A NIS sampling design change in 2012 precluded reliably including the data from 2012 to 2014. International Classification of the Diseases, Ninth Revision, Clinical Modification codes were used to identify the total number of hospitalizations for PML and diseases of interest (rheumatic diseases, multiple sclerosis (MS), human immunodeficiency virus (HIV) infection, hematologic and solid organ malignancies, and bone marrow and solid organ transplants). Information on demographics and hospital characteristics (region and type of hospital) was also collected. All analyses were performed using SAS enterprise guide, version 7.13 (SAS Institute, Cary, NC).

Results: A total of 17,268 hospitalizations for PML was identified over the 14 year period. The frequency of hospitalizations for PML among the diseases of interest is presented in Table 1. Details of demographics and hospital characteristics are presented in Table 2. Among the rheumatic diseases, there were 145 (0.84%) PML hospitalizations with SLE, 103 (0.60%) PML hospitalizations with RA, 11 (0.06%) PML hospitalizations with granulomatosis with polyangiitis, and no PML hospitalizations with microscopic polyangiitis. Hospitalization rates for PML per 100,000 hospitalizations among patients with rheumatic diseases are presented in Table 3.

Conclusion: PML is a rare complication even among diseases at high risk for JC virus reactivation. The frequency of PML hospitalizations among rheumatic diseases was reassuringly low. Only among rheumatic disease patients with HIV, MS, or a hematologic malignancy did the rate of PML hospitalizations increase substantially.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/occurrence-of-rheumatic-diseases-in-a-national-cohort-of-hospitalizations-for-progressive-multifocal-leukoencephalopathy/