Disease severity in adult patients of Turkish ancestry with familial mediterranean fever living in Germany or Turkey. Does the country of residence affect the course of the disease?

BACKGROUND: The environment may affect the course of familial Mediterranean fever (FMF).
OBJECTIVE: The objective of this study was to compare disease severity between adult FMF patients in Turkey (TR) and Germany (G).
METHODS: Adult FMF patients of Turkish ancestry on colchicine living in Turkey (n = 40) or G (n = 35) were compared. Disease severity, C-reactive protein (CRP), and erythrocyte sedimentation rate were assessed.
RESULTS: Groups differed significantly in the following aspects: age at onset of disease (TR: 15.6, G: 10.8 years; P = 0.02), delay between onset and initiation of colchicine treatment (TR: 6.8 years, G: 14.9 years; P < 0.001), female gender (TR: 80%, G: 57.1%; P = 0.04), and duration of disease (TR: 14.4 years, G: 23.4 years; P < 0.001). There was no significant difference in colchicine treatment concerning average dosing and duration of therapy. No significant difference could be found between the 2 groups in CRP and disease severity as assessed by the score of Pras et al. (Am J Med Genet. 1998;75:216-219) even after adjusting for potential confounding variables. Mean erythrocyte sedimentation rate was significantly higher among patients living in G (TR: 13.2 mm/first hour, G: 26.3 mm/first hour; P < 0.001). Among patients living in Germany, there was a significant difference in age at FMF onset depending on their country of birth (born in TR: 14.9 years, born in G: 6.9 years; P = 0.0001).
CONCLUSIONS: In adult FMF patients living in Turkey or Germany, no difference in disease activity or CRP could be found. German patients were younger at onset of disease and had a longer delay between onset and initiation of colchicine treatment.