Objective: Smoking has been associated with an increased incidence of endocrine ophthalmopathy (EO). In this study we examined the relation between smoking severity and the incidence of EO symptoms in patients with Graves' hyperthyroidism.
Design: Patients were prospectively followed for at least one year after the onset of hyperthyroidism. Smoking and EO status were evaluated at 3-6- months intervals.
Patients: Two hundred and fifty-three ambulatory patients with recent onset of Graves' hyperthyroidism were studied.
Measurements: The incidence of total EO symptoms, proptosis, and diplopia at any time point before and after the occurrence of Graves' hyperthyroidism was assessed by interview and physical examination.
Results: Smoking was associated with a 1.3-fold increase in the overall incidence of symptomatic EO, and a 2.6 and 3.1-fold increase in the incidence of proptosis and diplopia, respectively. The relative risk increased in parallel with the current number of cigarettes smoked per day. In contrast, lifetime tobacco use was not an independent risk factor for the development of EO symptoms. Former smokers had a significantly lower risk for the occurrence of proptosis and diplopia than active smokers with a comparable lifetime cigarette consumption.
Conclusions: Our data suggest that current, but not lifetime, tobacco consumption constitutes a risk for the incidence of proptosis and diplopia in patients with Graves' hyperthyroidism, and that this risk increases with smoking severity.