Table 3.

Evidence supporting a negative effect of smoking habits on GO

Finding	Type of study	Ref.
Higher prevalence of smokers in Graves’ patients with GO than in those without GO	Observational study	19, 20
Smokers tend to have more severe GO	Consecutive entry case-control study	20
Smokers are more likely to have progression or de novo occurrence of GO after radioiodine treatment	Randomized clinical trial	21, 22
Smoking delays or worsens the outcome of immunosuppressive treatment for GO	Randomized clinical trial	23
	Prospective study	24
Refraining from smoking might reduce the risk of developing exophthalmos and diplopia	Retrospective study	25