Objective: To describe initial clinical symptoms attributable to microscopic polyangiitis (MPA) or polyarteritis nodosa (PAN).
Methods: We retrospectively reviewed the medical files of 72 patients (mean followup 6.7 years) with biopsy-proven MPA (n = 36) or PAN (n = 36).
Results: Initial manifestations were similar in both entities except for peripheral neuropathy (P = 0.02) and gastrointestinal tract involvement (P = 0.006), which were significantly more frequent in PAN, and general signs alone in MPA (8%; P = 0.02). The mean time to diagnosis was 9.8 +/- 19.4 months; 35% of the patients died and 26% relapsed; significantly more MPA than PAN patients relapsed (P = 0.03). Time to diagnosis >/=90 days was associated with a trend toward more patients relapsing (P = 0.12), but not with an increased risk of mortality.
Conclusion: Initial symptoms of MPA and PAN are usually nonspecific and last for several months before the diagnosis is made. A longer time to diagnosis is associated with a tendency to a higher relapse rate.