Background/Purpose: Autoinflammatory diseases (AIDs) cause chronic systemic inflammation that can damage multiple organs. Recently, the ADDI index has been developed and validated in the four most common monogenic AIDs, Cryopyrin-associated Periodic Syndrome (CAPS), Familial Mediterranean Fever (FMF), Mevalonate Kinase Deficiency (MKD) and Tumor Necrosis Factor Receptor-associated Periodic Fever Syndrome (TRAPS). The use of ADDI index could also be of great value in other AIDs. We sought to assess the application of ADDI in patients with the four most common monogenic diseases and other AIDs. To accomplish this objective a detailed cohort of patients with different AIDs is presented.

Methods: All patients with AIDs followed in the Pediatric Rheumatology Unit from Hospital Universitari Vall d’Hebron were identified. A cross- sectional, descriptive study was performed applying ADDI by two pediatric rheumatologists (EM, ML). CRP mg/dl, amyloid protein (AP) mg/L, ESR mm/h and protein/creatinine rate (mg/g Cr) were performed at the moment ADDI was applied. Disease duration and current treatment were assessed. The continuous variables are presented as mean and standard deviation (mean ± SD) and categorical variables are presented by percentages.  Kappa (k) coefficient was calculated. Differences between two groups (sex and GC intake) was compared using Student’s t-test and a significance level of < 0.05 was considered. Results: A total of 41 patients with AIDs were included, 61% were female, with a median age of 20 ± 11.9 years at inclusion. Disease duration was 11 ± 8.2 years. AIDs included were 11 patients with FMF (26.8%), TRAPS n=4 (9.8%), MKD  n=3 (7.3%), CAPS n= 2 (4,9%), Blau syndrome n= 7 (17.1%), SAVI syndrome n=3 (7.3%), CRMO n=4 (9.8%), PFAPA n=2 (4.9%), APLAID n=1 (2.4%), Stickler syndrome n=1 (2.4%), and 3 unknown AIDs with genetic test negative n=3 (7.3%). Current treatment is variable among patients, 6 (15.8%) are taking DMARDs, 9 (23.7%) Colchicine, 8 (21.1%) Anakinra, 13 anti-TNF therapy (34.2%), 1 (2.6%) Ruxolitinib and 1 (2.6%) Abatacept.  Only 6 patients were receiving steroids with mean prednisone dose of 7.5 mg/day. The global ADDI mean score was 2.3 ± 2.2. No differences were found between gender and ADDI (male 2.19, female 1.9, P= 0.68). Musculoskeletal domain (MSK) shown the highest score with 1.02, followed by the ocular domain with 0.42. The patient with APLAID syndrome had the highest score of 6 followed by Blau syndrome with 4.71. FMF has the lowest score with 0.83. Patients with GC intake had a highest ADDI score than patients without GC treatment (3.7 vs 1.63 P=0.0018). Laboratory test results were mean ESR 27.2 ± 26.7mm/h, CRP 0.7 ± 1.3 mg/dl, AP 13.9 ± 18.6mg/L. Proteinuria was present in 2 patients with mean 286.5 ± 246.1mg/g. The k statistic showed an excellent agreement between two rheumatologist (k=0.98, P< 0.001). EM and ML applied ADDI in 5-10 minutes average. Conclusion: ADDI is a feasible index suitable to measure damage in a single patient. In our cohort the mean ADDI index was low and MSK has the highest score. GC intake was associated with a higher ADDI score. Knowing the difficulties of applying an unified index for all diseases, ADDI may be supportive in other AIDs and longitudinal cohorts.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/application-of-the-autoinflammatory-disease-activity-index-addi-to-a-cohort-of-patients-in-a-tertiary-hospital/