Tobacco differentially affects the clinical-biological phenotypes of ANCA-associated vasculitides

OBJECTIVES

To describe the clinical-biological phenotype of ANCA-associated vasculitides (AAV) according to tobacco consumption.

METHODS

We conducted a descriptive study to describe that phenotype at diagnosis according to tobacco use. AAV patients entered in the French Vasculitis Study Group database with data on smoking habits were analysed. The clinical-biological phenotypes at diagnosis were compared according to current tobacco use (current smokers) or not (including previous and never smokers).

RESULTS

AAV diagnoses were: granulomatosis with polyangiitis (GPA) for 583 (50%), eosinophilic granulomatosis with polyangiitis (EGPA) for 326 (28%) and microscopic polyangiitis (MPA) for 256 (22%). Among them, 973 patients (84%) never smoked, 116 (10%) were previous smokers and only 76 (6%) were current smokers. Current smokers were younger age (p=0.01), male gender (p=0.004), less frequently EGPA (p=0.017) and MPA (p=0.036), and had less frequent kidney involvement (p=0.10). Among GPA patients, current smokers, compared to non-current smokers, were younger age (p=0.02), male gender (p=0.08), more frequent skin involvement (p=0.03) and less frequent ENT involvement (p=0.06). Among EGPA patients, current smokers, compared to non-current smokers, were also younger (p=0.028) and had less frequent constitutional symptoms (p=0.02), arthralgias (p=0.04), renal involvement (p=0.025) and MPO-ANCA (p=0.02). Finally, analysis of MPA patients was impossible because only 6 (2%) were current smokers.

CONCLUSIONS

These results suggest that tobacco use could differentially affect GPA and EGPA clinical-biological phenotypes, and support the role of environmental exposures in AAV development and its phenotype.

Mycophenolate mofetil in patients with anti-neutrophil cytoplasmic antibody-associated vasculitis: a prospective pharmacokinetics and clinical study

Anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) treatment strategy is based on immunosuppressive agents. Little information is available concerning mycophenolic acid (MPA) and the area under the curve (AUC) in patients treated for AAV. We evaluated the variations in pharmacokinetics for MPA in patients with AAV and the relationship between MPA-AUC and markers of the disease. MPA blood concentrations were measured through the enzyme-multiplied immunotechnique (C(0), C(30), C(1), C(2), C(3), C(4), C(6) and C(9)) to determine the AUC. Eighteen patients were included in the study. The median (range) MPA AUC(0-12) was 50·55 (30·9-105·4) mg/h/l. The highest coefficient of determination between MPA AUC and single concentrations was observed with C(3) (P < 0·0001) and C(2) (P < 0·0001) and with C(4) (P < 0·0005) or C(0) (P < 0·001). Using linear regression, the best estimation of MPA AUC was provided by a model including C(30), C(2) and C(4): AUC = 8·5 + 0·77 C(30) + 4·0 C(2) + 1·7 C(4) (P < 0·0001). Moreover, there was a significant relationship between MPA AUC(0-12) and lymphocyte count (P < 0·01), especially CD19 (P < 0·005), CD8 (P < 0·05) and CD56 (P < 0·05). Our results confirm the interindividual variability of MPA AUC in patients treated with MMF in AAV and support a personalized therapy according to blood levels of MPA.