Prevalence, risk factors, and clinical features of thyroid-associated ophthalmopathy in multiethnic Malaysian patients with Graves' disease.

BACKGROUND

The prevalence of thyroid-associated ophthalmopathy (TAO) has been reported to be lower in several Asian populations than in Caucasians. The risk factors for TAO that have been demonstrated in Caucasians have not been studied in Asian populations. The aim of this study, therefore, was to determine the prevalence, risk factors, and clinical features of TAO in a cohort of multiethnic Malaysian patients with Graves' disease (GD).

METHODS

This was a cross-sectional study of 167 consecutive patients with GD who attended two endocrine clinics from October 2003 to September 2004. The patients were classified as Malay, Chinese, and Indian based on their ethnic characteristics as detailed in the national identity card. The patients were examined by a single individual for the presence and characteristics of TAO. Thyroid function tests were performed, and smoking history and the extent of smoking history were recorded.

RESULTS

The prevalence rate of TAO using the American Academy of Ophthalmology diagnostic criteria was 34.7%. This increased to 46.7% if lower lid retraction was added as an alternate criterion. The observed prevalence rate was higher than expected in the Chinese patient population based on a comparison with the Malay and Indian patients, but this was not statistically significant. Smokers with GD were at 2.75 times greater risk of TAO than nonsmokers (p = 0.019). Male gender was shown to confer higher risk of TAO on univariate analysis (p = 0.003), but not on multivariate analysis. The percentage of males who smoked in the study group was relatively high (79%). The most common presentation of TAO was exophthalmos, followed by lid retraction.

CONCLUSIONS

TAO has relatively high prevalence rate (34.7%) in three populations of Asian patients with GD. This is similar to that reported for Caucasian patients with GD. As in Caucasian patients, smoking increases the risk of TAO. In the Asian populations we studied, exophthalmos was the most common eye sign. However, lower lid retraction was also common and present in 60% of cases with other signs of TAO. In Chinese, Malay, and Indian Asians with GD, lower lid retraction should be a diagnostic criterion for TAO.