Colchicine-free remission in familial Mediterranean fever: featuring a unique subset of the disease-a case control study

BACKGROUND To demonstrate and clinically, genetically and demographically characterize familial Mediterranean fever (FMF) patients, maintaining remission despite colchicine abstinence. METHODS FMF patients were screened for an endurance of prolonged remission (≥ 3 years), despite refraining from colchicine. Clinical, demographic and genetic parameters were collected. Data were compared with those of consecutive control FMF subjects, coming to the clinic for their periodic follow up examination. RESULTS Of 1000 patients screened over 5 years, 33 manifested colchicine-free remission. The mean duration of the remission period was 12.6 ± 8.1 years. Patients in the remission group had milder severity of FMF, compared to the control group (22 vs. 11 patients with mild disease, respectively, p=0.003) and a longer diagnosis delay (21 ± 15.7 vs. 13.4 ± 13.5 years, respectively, p=0.04). Patients experiencing remission suffered mostly of abdominal attacks, low rate of attacks in other sites and low rate of chronic and non-attack manifestations. When the disease resumed activity, it responded well to colchicine, despite using a lower dose, as compared to the control subjects (p<0.001). None of the patients in this group was homozygous for the M694V mutation (p=0.0008). CONCLUSIONS Prolonged colchicine-free remission defines a rare and milder form of FMF with unique clinical, demographic, and molecular characteristics.