Clinical and laboratory markers associated with relapse in cutaneous polyarteritis nodosa

IMPORTANCE In cutaneous polyarteritis nodosa (CPAN), less aggressive treatments can be selected, because CPAN is not associated with life-threatening or progressive outcomes. Although patients with a recurrent clinical course may require additional immunosuppressive therapies, no pretreatment factors associated with a worse prognosis in CPAN have been reported. OBJECTIVE To identify clinical or laboratory markers associated with relapse of CPAN. DESIGN, SETTING, AND PARTICIPANTS This retrospective case series was performed at a dermatology clinic of a tertiary referral center in Okayama, Japan, from October 1, 2001, through April 30, 2017. Of 30 patients identified with CPAN, the 21 with histopathologic evidence of disease were eligible and enrolled in the study. MAIN OUTCOMES AND MEASURES The medical database was examined for sex, age at diagnosis, affected anatomical sites, type and extent of skin lesion, laboratory data, initial therapies, duration of follow-up, and current status. Relapse was defined as the first reoccurrence or new onset of cutaneous disease that required further escalation of treatment with prednisolone at a dosage of greater than 20 mg/d and/or add-on use of immunosuppressant therapy, more than 6 months after initial treatment. The pretreatment factors were statistically evaluated between the groups without and with relapse. RESULTS The 21 patients included 5 males and 16 females with a median age of 49 years (range, 11-74 years) at diagnosis. The median follow-up was 42 months (range, 8-374 months). Pretreatment cutaneous ulcer was significantly associated with relapse between the 2 groups (0 of 11 in the nonrelapse group vs 4 of 10 in the relapse group; χ₁ ² = 4.67; P < .05). In the laboratory test results, significantly higher mean (SD) values were observed in the relapse group for C-reactive protein level (0.23 [2.00] vs 6.03 [3.10] mg/dL; standard error of the mean [SEM], 3.40 mg/dL; 95% CI, 0.01-10.8 mg/dL; P = .01), absolute neutrophil count (ANC) (3.4 × 10³/μL [1.1 × 10³/μL] vs 6.0 × 10³/μL [3.2 × 10³/μL]; SEM, 2.9 × 10³/μL; 95% CI, 1.9 × 10³/μL to 14.6 × 10³/μL; P = .001), neutrophil-to-lymphocyte ratio (1.4 [0.8] vs 2.8 [0.9]; SEM, 1.2; 95% CI, 1.1-4.9; P = .002), and systemic immune-inflammation index (5.1 × 10⁵ [3.9 × 10⁵] vs 11.7 × 10⁵ [7.7 × 10⁵]; SEM, 7.3 × 10⁵; 95% CI, 3.3 × 10⁵ to 31.1 × 10⁵; P = .007). The estimated 2-year cumulative relapse rate was significantly high in the patients with blood ANC of greater than 4.9 × 10³/μL compared with 4.9 × 10³/μL or less (9 of 10 [90%] vs 2 of 11 [18%]; 95% CI, 6%-72%). CONCLUSIONS AND RELEVANCE Pretreatment status of cutaneous ulcer, the serum C-reactive protein level, the blood ANC, the neutrophil-to-lymphocyte ratio, and the systemic immune-inflammation index are associated with a worse prognosis in CPAN.