Noninflammatory thyroid eye disease in Indian subcontinent: Is it a departure from Rundle's curve?

Dear Editor,

We commend the sincere efforts of Muralidhar A, Das S, and Tiple S[1] in unearthing new information regarding the clinicodemographic profile of thyroid eye disease (TED) in Indian cohort. The authors wish to put forth their own observations regarding the presentation and epidemiology of TED in the Indian subcontinent.

Despite the fact that the natural course of the disease is not fully understood, most of the current literature derives its understanding of the disease from Rundle’s biphasic curve, which describes an initial steep phase of activity followed by a static period of inactive, quiescent disease.[2]

Striking differences in disease presentation and demography can be seen between patients from the Indian subcontinent (including our observations and those by Muralidhar et al.[1]) and those documented in western literature [Table 1].

Table 1

Comparison of demographic profile and incidence of noninflammatory disease

Parameters		Our Study (n=150)	Study by Muralidhar A, and Das S, Tiple S (n=106)	Western study[6] (n=152)
Female/Male		1.14:1	1.12:1	3.34:1
Age (in years) (Mean±SD)		38.58±13.35	41.30±14.76	49±13
Smokers		27.33%	25.5%	40%
Laterality	Unilateral	44.67%	17.9%	4%
Thyroid Status	Hyperthyroid	55.33%	46.23%	93%
	Euthyroid	26.67%	19.81%	3%
	Hypothyroid	17.33%	33.96%	4%
	Hashimoto Thyroiditis	0.67%	0%	0%
Inactive		76%	77.4%	40%
Active		24%	22.6%	60%
Noninflammatory (no preceding active clinical stage)		30.66% (46/150)	Not Specified	Not Specified
Late presentation of disease activity		5.33% (8/150)	Not Specified	Not Specified

Noninflammatory TED, a sparingly reported entity in the west,[3] is a frequent presentation in our clinic and has also been reported as “silent presenter” by Naik and Vasanthapuram.[4] A recent study from the west by Íñiguez-Ariza NM et al.[5] also acknowledges the existence of “Quiet” TED, a subgroup which presents atypically and departs from the Rundle’s curve. These patients do not require corticosteroids during the course of their disease and are more likely to benefit from supportive therapy and surgery, if indicated.

Inactive disease, unilateral presentation of TED, proptosis as the initial presenting sign, and orbitopathy with euthyroid status have more commonly been seen by us as well as other investigators from India. Also, delayed onset of disease activity, in patients initially presenting with inactive disease, is a deviation from the biphasic course and mandates identification as a distinct subgroup.

The above findings may suggest strong ethnic and genetic influences on the clinical course of the disease and enable us to acknowledge cases that deviate significantly from the clinical picture classically described through the Rundle’s curve. Studies focusing on the population prevalence and clinical course of noninflammatory TED in different ethnic groups of the world are needed. It would also be interesting to re-explore the pathophysiology of TED in this subtype of patients.

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Conflicts of interest

There are no conflicts of interest.