Accompanying autoimmune diseases may have a role in colchicine resistance in adult familial mediterranean fever patients

Colchicine is the primary treatment for familial Mediterranean fever (FMF); however, colchicine resistance poses a major challenge, affecting about 5–10% of patients. This study aimed to compare colchicine-response and colchicine-resistant patients and identify predictors of resistance. A retrospective analysis was performed in a tertiary rheumatology clinic. FMF patients (≥18 years) diagnosed per Tel-Hashomer criteria, on colchicine ≥6 months, compliant per the modified Morisky scale, with exon 10 mutations and complete data were included. Colchicine resistance was defined as ≥1 episode/month for >3 months despite maximum tolerated colchicine doses. Comparative analyses were performed. The study included 123 colchicine-response (65.9% female, median age 39) and 64 colchicine-resistant patients (62.5% female, median age 31.5). Colchicine-resistant patients were younger at diagnosis and symptom onset (p<0.05). In age-adjusted multivariate logistic regression, autoimmune comorbidity was the strongest predictor of colchicine resistance (OR: 19.17, 95% CI: 4.46-89.48, p<0.001), followed by age ≤7 years at symptom onset, current smoking, ≥ 3 day-long attack under colchicine, number of attacks/year before colchicine, International FMF Severity Score ≥ 4, and diarrhea during attack (OR=1.19–8.56, p<0.05). In the ROC analysis of laboratory parameters, C-reactive protein, fibrinogen, lymphocytes, erythrocyte sedimentation rate, neutrophils, and mean platelet volume predicted colchicine resistance with area under the curve values ranging from 0.769 to 0.995. Autoimmune comorbidities, early symptom onset, smoking, frequent and prolonged attacks, high disease severity, and diarrhea are important predictors of colchicine resistance in FMF. Laboratory parameters also aid in prediction, allowing earlier identification and personalized treatment approaches.