Lymphocyte counts in patients with ANCA-associated vasculitis

Lymphopenia and treatment-related infectious complications in ANCA-associated vasculitis

BACKGROUND AND OBJECTIVES

ANCA-associated vasculitis (AAV) is treated with potent immunosuppressive regimens. This study sought to determine risk factors associated with infections during first-intention therapy.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This retrospective study involved two separate cohorts of consecutive cases of AAV seen from 2004 to 2011 at two university hospitals. The following were assessed: vasculitis severity; therapy; and periods with no, moderate (lymphocyte count, 0.3-1.0× 10(9)/L), or severe (lymphocyte count ≤ 0.3×10(9)/L) lymphopenia and neutropenia (neutrophil count ≤ 1.5×10(9)/L).

RESULTS

One hundred patients had a mean age of 57±15 years and a Birmingham vasculitis activity score of 7.7±3.6. Therapy consisted of pulse methylprednisolone (59%), cyclophosphamide (85%), methotrexate (6%), and plasmapheresis (25%) in addition to oral corticosteroids. During follow-up, 53% of patients experienced infection and 28% were hospitalized for infection (severe infection). Only 18% experienced neutropenia, but 72% and 36% presented moderate and severe lymphopenia for a total duration of <0.1%, 73%, and 8% of the treatment follow-up, respectively. Lower initial estimated GFR, longer duration of corticosteroid use, and presence of lymphopenia were risk factors of infections. The rate was 2.23 events/person-year in the presence of severe lymphopenia compared with 0.41 and 0.19 during periods with moderate or no lymphopenia (P<0.001). Similarly, the rate of severe infections was 1.00 event/person-year with severe lymphopenia and 0.08 and 0.10 with moderate and no lymphopenia (P<0.001). This association remained independent of other risk factors.

CONCLUSIONS

Lymphopenia is frequent during the treatment of AAV, and its severity is associated with the risk of infectious complications.