Hydralazine-associated vasculitis: Overlapping features of drug-induced lupus and vasculitis

Introduction: Hydralazine is an antihypertensive medication that has been associated with drug-induced lupus erythematosus (DIL) as well as ANCA-associated vasculitis (AAV). Although rare, early diagnosis is critical since drug cessation is the mainstay of therapy. This retrospective study aims to characterize the clinical, laboratory, and histopathologic features of this disease.

Methods: Once approval was obtained from the Institutional Review Board at the University of Iowa, all patients carrying a diagnosis of vasculitis (ICD9 code: 447.6 or ICD10 code: I77.6, I80, L95, M30, or M31) and positive ANCA lab results over the past 15 years were identified. Age, gender, comorbid conditions, medications taken over the prior 6 months, laboratory data, including electrolytes, urine studies and serologies, chest x-rays, CT scans, and pathologic biopsy records were abstracted from the electronic medical record.

Results: 323 cases of AAV were identified, of which 12 were exposed to hydralazine, all at the time of diagnosis. The average duration of hydralazine therapy was 22 months and mean cumulative dose was 146g. Patients were typically older (70.3 years old) with slight female preponderance (7 females). Eleven patients presented with dyspnea, fatigue, and unintentional weight loss. Five had polyarthralgias and 8 had lower extremity petechiae. All 12 patients were both ANA and ANCA positive. ANA titers ranged from 1:160 and 1:2560. Ten were of diffuse pattern while 2 were nucleolar. ANCA titers ranged from 1:320 to 1:2560. Eleven had a pANCA pattern while one had cANCA. All 12 patients were positive for histone and 11 were positive for myeloperoxidase antibodies. Eleven also had dsDNA antibodies, and 4 had anti-cardiolipin IgG or IgM antibodies. Nine patients were also hypocomplementemic (mean C3 level: 88.4mg/dL; mean C4 level: 16.5mg/dL). All patients had variable levels of proteinuria (1+ to 3+) and eleven had active urine sediment. Urine protein:creatinine ratios ranged from 0.2 to 1.7. Of the 6 patients who underwent kidney biopsy, all 6 showed pauci-immune crescentic glomerulonephritis. Seven patients had bilateral pulmonary interstitial infiltrates and four had pleural effusions on CT scan. Four had pericardial effusions as demonstrated by echocardiography.

Conclusions: Hydralazine-associated vasculitis is a drug-associated autoimmune syndrome that presents with interstitial lung disease, hypocomplementemia, and pauci-immune glomerulonephritis. Patients have elements of both DIL and DIV, as manifested by high ANA and ANCA titers as well as the presence of histone and MPO antibodies. Further research is needed to understand the etiopathogenesis of this condition.