Long-term followup of polyarteritis nodosa, microscopic polyangiitis, and Churg-Strauss syndrome: Analysis of four prospective trials including 278 patients

Rates of mortality due to PAN (related or unrelated to HBV), MPA, and CSS reflected disease severity and were higher than the mortality rate in the general population (P < 0.0004). Rates of relapse, more common in MPA than HBV-related PAN patients, did not reflect disease severity. Survival rates were better among the more severely ill patients who had received first-line CYC. Based on these findings, we recommend that the intensity of the initial treatment be consistent with the severity of the disease. The use of the FFS and BVAS scores improved the ability to evaluate the therapeutic response.