Epidemiology of Graves' orbitopathy (GO) and relationship with thyroid disease

Graves' orbitopathy: imperfect treatments for a rare disease

Graves' orbitopathy (GO) is the most frequent and invalidating extrathyroidal expression of Graves' disease. Its incidence and prevalence are, however, low. About three quarters of Graves' patients have no GO at diagnosis, and moderate-to-severe and severe forms represent no more that 5-6% of cases. Progression to severe forms occurs rarely, but it may be caused by risk factors, the most important being smoking and poor control of thyroid dysfunction. Lot of progress has been recently achieved in the understanding of GO pathogenesis, while the disease remains a therapeutic challenge and dilemma. Common treatments for moderate-to-severe and active forms of GO (glucocorticoids and orbital radiotherapy) frequently provide incomplete responses and may be followed by relapse or progression of GO. After the disease has been inactivated by medical treatment, many patients need rehabilitative surgery for residual manifestations (orbital decompression for exophthalmos, squint surgery for extraocular muscle dysfunction, eyelid surgery for eyelid malposition). Novel pharmacological treatments are on the horizon and might target pathogenetic mechanisms of the disease better than glucocorticoids. Clinical evidence concerning their efficacy and safety is presently lacking.

Prevalence and natural history of Graves' orbitopathy in the XXI century

Graves' orbitopathy (GO) is an autoimmune disorder and the main extrathyroidal expression of Graves' disease. There is a spectrum of ocular involvement in Graves' disease, from complete absence of symptoms and signs to sight-threatening conditions. The prevalence of GO varies in different published series of Graves' patients, due to confounding factors (new diagnosis vs long-lasting disease, way of defining and assessing ocular involvement, treatment of hyperthyroidism with potentially GO-modifying treatments, such as radioiodine). Recent studies, however, suggest that most Graves' patients have mild or no GO at presentation, while moderate-to-severe GO is rare, and sight-threatening GO (mostly due to dysthyroid optic neuropathy) is exceptional in non-tertiary referral centers. The natural course of GO is incompletely defined, particularly in patients with moderate- to-severe GO, because these patients require prompt and disease-modifying therapies for orbital disease. In patients with mild GO at presentation, progression to severe forms is rare, while partial or complete remission is frequent. Progression of pre-existing GO or de novo occurrence of GO is more likely in smokers. There seems to be a trend towards a decline in progression of GO, possibly due to a better control of risk factors (cigarette smoking, thyroid dysfunction, etc.) and a closer interaction between endocrinologists and ophthalmologists allowing an improved integrated management of thyroid and orbital disease.

Prevalence and natural history of Graves' orbitopathy in a large series of patients with newly diagnosed graves' hyperthyroidism seen at a single center

BACKGROUND

The prevalence and natural history of Graves' orbitopathy (GO) are poorly documented.

METHODS

A large series of 346 patients with newly diagnosed and recent onset Graves' hyperthyroidism seen at a single (nontertiary referral) center over an 8-year period were enrolled in an observational prospective study and evaluated for GO activity and severity according to the EUGOGO (European Group on Graves' Orbitopathy) criteria. After excluding patients immediately treated for moderate-to-severe GO, patients undergoing total thyroidectomy or radioactive iodine treatment, and patients lost to follow-up, 237 patients were submitted to antithyroid drug (ATD) treatment, with ocular evaluation at 6, 12, and 18 months.

RESULTS

Among the whole cohort, at presentation 255 (73.7%) had no ocular involvement, 70 (20.2%) had mild and inactive GO, 20 (5.8%) had moderate-to-severe and active GO, and 1 (0.3%) had sight-threatening GO with dysthyroid optic neuropathy. Of the 237 patients who completed the 18-month follow-up during or after ATD treatment, 194 (81.9%) had no GO at baseline. Progression to moderate-to-severe GO occurred in 5 (2.6%) of these patients. Of the 43 (18.1%) patients with mild and inactive GO at baseline, 1 (2.4%) progressed to moderate-to-severe GO, and 25 (58.1%) experienced complete remission.

CONCLUSIONS

Most patients with newly diagnosed Graves' disease have no ocular involvement. Moderate-to-severe and active GO or sight-threatening GO are rare at presentation and rarely develop during ATD treatment. Most patients (>80%) with no GO at baseline do not develop GO after an 18-month follow-up period. Remission of mild GO occurs in the majority of cases.