Background IgG4-related disease (IgG4-RD) is a recently recognized systemic inflammatory disorder that can affect many organs . In IgG4-RD, relapse including recurrence of existing organ involvement (REOI) and new development of organ involvement (NDOI) easily occurs during the clinical course, and its predictors have been suggested [2, 3]. However, differences between risk factors of REOI and those of NDOI have not been clarified.
Objectives This study aimed to clarify the respective risk factors of REOI and NDOI in IgG4-RD.
Methods We retrospectively investigated factors related to REOI and NDOI in 86 IgG4-RD patients whose follow-up period was more than 12 months. For assessment of factors related to REOI and NDOI, we performed uni- and multivariate Cox regression analysis. On stepwise multivariate analysis, we applied the variables with P<0.1 in univariate analysis and the predictors of relapse suggested in past reports (age, sex, serum IgG4, IgG, and IgE levels, eosinophil counts, and RF positivity) [2, 3], and used the forward selection method (including factors presenting with P<0.05).
Results The patients comprised 57 men and 29 women (mean age 65.9 years). Mean follow-up period was 63.1 months (range 14–150). At diagnosis, their mean serum IgG4 level was 718 mg/dL (range 10.7–3,610). Seventy-one patients were treated with glucocorticoid (GC). REOI was detected at 52.3 months (range 1.0–120) after the diagnosis in 20 patients, including 4 not receiving GC at that time. On the other hand, NDOI was detected at 37.6 months (range 5.0–120) after the diagnosis in 15 patients, including 8 not receiving GC then. In multivariate Cox regression analysis, blood eosinophil counts [per 100/μL, hazard ratio (HR) 1.072, 95% confidence interval (CI) 1.018–1.129, P=0.008] and continuation of GC (vs discontinuation or observation without GC, HR 0.245, 95% CI 0.076–0.793, P=0.019) had a significant impact on the time to NDOI, whereas age (per year, HR 0.942, 95% CI 0.899–0.986, P=0.011) and ANA positivity (vs negativity, HR 6.632, 95% CI 1.892–23.255, P=0.003) had a significant impact on the time to REOI.
Conclusions The present study suggests that the risk factors of REOI and NDOI in IgG4-RD are different.
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Disclosure of Interest None declared
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