ORIGINAL ARTICLE

Evaluation of thyroid eye disease: quality-of-life questionnaire (TED-QOL) in Korean patients Byeong Jae Son, MD, Sang Yeul Lee, MD, Jin Sook Yoon, MD, PhD ABSTRACT ● RÉSUMÉ Objective: To assess impaired quality of life (QOL) of Korean patients with thyroid eye disease (TED) using the TED-QOL questionnaire, to evaluate the adaptability of the questionnaire, and to assess the correlation between TED-QOL and scales of disease severity. Design: Prospective, cross-sectional study. Participants: Total of 90 consecutive adult patients with TED and Graves’ disease were included in this study. Methods: TED-QOL was translated into Korean and administered to the patients. The results were compared with clinical severity scores (clinical activity score, VISA (vision loss (optic neuropathy); inflammation; strabismus/motility; appearance/exposure) classification, modified NOSPECS (no signs or symptoms; only signs; soft tissue; proptosis; extraocular muscle; cornea; sight loss) score, Gorman diplopia scale, and European Group of Graves’ Orbitopathy Classification). Results: Clinical scores indicating inflammation and strabismus in patients with TED were positively correlated with overall and visual function–related QOL (Spearman coefficient 0.21–0.38, p o 0.05). Clinical scores associated with appearance were positively correlated with appearance-related QOL (Spearman coefficient 0.26–0.27, p o 0.05). In multivariate analysis, age, softtissue inflammation, motility disorder of modified NOSPECS, and motility disorder of VISA classification had positive correlation with overall and function-related QOL. Sex, soft-tissue inflammation, proptosis of modified NOSPECS, and appearance of VISA classification had correlation with appearance-related QOL. In addition, validity of TED-QOL was proved sufficient based on the outcomes of patient interviews and correlation between the subscales of TED-QOL. Conclusions: TED-QOL showed significant correlations with various objective clinical parameters of TED. TED-QOL was a simple and useful tool for rapid evaluation of QOL in daily outpatient clinics, which could be readily translated into different languages to be widely applicable to various populations. Objet : Évaluation d'une baisse de la qualité de vie (QDV) chez des patients coréens ayant une maladie oculaire thyroïdienne (MOT), en utilisant le questionnaire QDV-MOT, évaluant l'adaptabilité du questionnaire et estimant la corrélation entre la QDVMOT et les degrés de gravité de la maladie. Nature : Étude prospective transversale. Participants : En tout, 90 patients adultes consécutifs ayant une MOT et une maladie de Graves ont fait l'objet de l'étude. Méthodes : Le questionnaire de QDV-MOT a été traduit en coréen et administré aux patients. L'on a comparé les résultats aux degrés cliniques de sévérité [notes d'activité clinique, classification VISA, résultats NOSPECS modifiés, degré de diplopie selon l'échelle Gorman et classification de l'orbitopathie selon le Groupe européen d'orbitopathie Graves]. Résultats : Les données cliniques indiquant l'inflammation et le strabisme chez les patients ayant une MOT étaient corrélées positivement avec la QDV reliée à la fonction visuelle (coefficient de Spearman 0,21-0,38, po0,05). Les résultats cliniques associés à l'apparence étaient corrélés positivement avec la QDV liée à l'apparence (coefficient de Spearman 0,26-0,27, po0,05). Dans l'analyse multivariée, l'âge, l'inflammation des tissus mous et les troubles de motilité des NOSPECS modifiés et la classification VISA des troubles de motilité avaient une corrélation positive avec la QDV globale et fonctionnelle. Le genre, l'inflammation des tissus mous et l'exophtalmie des NOSPECS modifiés et l'apparence de la classification VISA avaient une corrélation avec la QDV reliée à l'apparence. En outre, la validité QDV-MOT a été prouvée suffisante selon les résultats des entrevues avec les patients et le rapport entre les sous-échelles QDV-MOT. Conclusion : La QDV-MOT a montré des corrélations significatives avec divers paramètres cliniques objectifs de MOT. La QDVMOT était un outil simple et utile d'évaluation de la QDV dans les cliniques externes et elle pourrait être facilement traduite dans diverses langues pour être grandement applicable chez diverses populations.

Thyroid eye disease (TED) is a chronic, inflammatory, and autoimmune condition that causes various complicated symptoms and impairments. These changes associated with TED have a negative impact on patients’ quality of life (QOL).1 Terwee et al.2 developed the first QOL questionnaire (Graves’ Ophthalmopathy-QOL [GOQOL]) specific for TED in 1998, which consisted of 16 questions on visual function and appearance. This group,

and many other subsequent studies, found that the GOQOL was valid and reliable enough to assess QOL of patients with TED, showing good correlations with clinical activity and severity of TED, even among different populations and in different languages.3–6 In 2006, the European Group on Graves’ Orbitopathy (EUGOGO) recommended using GO-QOL as subjective parameters for assessing response to interventions in clinical trials.7

From the Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea.

Can J Ophthalmol 2014;49:167–173 0008-4182/14/$-see front matter & 2014 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jcjo.2013.12.007

Originally received Jul. 29, 2013. Final revision Nov. 12, 2013. Accepted Jan. 3, 2014 Correspondence to: Jin Sook Yoon, MD, Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-ku, 120-752, Seoul, Korea; [email protected]

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Evaluation of thyroid eye disease using TED-QOL—Son et al. Our group previously reported on the QOL of TED measured with the Korean version of GO-QOL.5 GOQOL scores of Korean patients were significantly correlated with disease severity and activity measured by modified NOSPECS (no signs or symptoms; only signs; soft tissue; proptosis; extraocular muscle; cornea; sight loss) and clinical activity scores (CASs).5 Although GO-QOL is commonly used to assess QOL of TED, it can be time consuming and often unfeasible to use in clinics because of its large number of questions. Fayers and Dolman8 recently developed a simpler 3-item questionnaire in English called TED-QOL and found it quick and easy to complete, score, and analyze, with similar validity and reliability compared with GO-QOL. In addition, TED-QOL was moderately correlated VISA (vision loss (optic neuropathy); inflammation; strabismus/ motility; appearance/exposure) classification scores. The aim of this study was therefore to assess impaired QOL of Korean patients with TED using the TED-QOL questionnaire and evaluate correlations between TED-QOL scores and other various established scales of disease severity and activity.

METHODS After obtaining approval from the Yonsei University College of Medicine Institutional Review Board and informed consent from the participants, a total of 90 consecutive adult patients with TED and Graves’ disease were included in this study. This was a prospective, crosssectional study, consisting of all Korean patients who were followed from November 2012 to January 2013. Patients who had other ocular or orbital diseases that could affect the QOL were excluded. All patients received the TEDQOL self-administered questionnaires at the outpatient clinic and completed them before medical investigation. Clinical data collected are listed in Table 1. The data on the thyroid-stimulating hormone receptor autoantibodies (TSHR Ab), including both thyroid bindinginhibiting immunoglobulin and thyroid-stimulating immunoglobulin (TSI), were collected within 1 month of the study initiation. All clinical observations and objective measurements were performed by 1 ophthalmologist (J.S.Y.). The disease-specific TED-QOL questionnaire developed by Fayers and Dolman8 was modified to the Korean language using forward and backward translation.9 The TED-QOL contained 3 single-item questions: how TED impacted on the patient’s appearance, visual functioning, and overall QOL in the patient’s life. The TED questions were scored from 0 to 10, where 0 ¼ TED did not interfere with QOL and 10 ¼ TED completely interfered with QOL. After completion, participants were asked whether any of the items were confusing or difficult to grade, and whether the questions were relevant and inclusive.

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Table 1—Characteristics of patients with thyroid eye disease at the time of survey (n ¼ 90) Characteristics

Values

Mean age ⫾ SD (range), y 42.9 ⫾ 13.6 (20–74) Sex (F/M), n (%) 65 (72.2%)/25 (27.8%) Duration of TED ⫾ SD (range), mo 19.9 ⫾ 26.4 (1–180) Duration of GD ⫾ SD (range), mo 36.2 ⫾ 58.2 (1–360) Bilateral:unilateral manifestation, n (%) 75 (83.3%):15 (16.7%) Other autoimmune disease, n (%) 6 (6.7%) History of smoking, n (%) 24 (26.7%) Family history of thyroid disease, n (%) 15 (16.7%) Best corrected visual acuity ⫾ SD (range) Right eye 0.9 ⫾ 0.2 (0.3–1.2) Left eye 0.9 ⫾ 0.2 (0.03–1.2) Lid traction from normal position of lid ⫾ SD (in patients with lid retraction, n ¼ 60) (range) Upper lid (from 2 mm below limbus) 2.3 ⫾ 0.9 (1–5) Lower lid (from limbus) 1.2 ⫾ 0.6 (0.5–3) Total 2.0 ⫾ 1.0 (0.5–5) Exophthalmos ⫾ SD (range), mm Right eye 17.6 ⫾ 2.7 (11–24) Left eye 17.4 ⫾ 2.6 (11–23) Site difference 1 ⫾ 1 (0–5) Treatment of GD, n (%) Antithyroid drugs 67 (74.4%) Radioiodine therapy 4 (4.4%) Thyroidectomy 10 (11.1%) Treatment of TED, n (%) Steroid (oral/intravenous) 52 (57.8%)/23 (25.6%) Local triamcinolone injection 26 (28.9%) Radiotherapy 2 (2.2%) Decompression 12 (13.3%) Eye muscle surgery 0 Eye lid surgery 6 (6.7%) Clinical feature of patients with TED Mean CAS ⫾ SD (range) 1.99 ⫾ 1.4 (0–6) Mean modified NOSPECS score ⫾ SD 5.1 ⫾ 2.5 (1–12) (range) Active TED (CAS Z 4) 13 (14.4) Optic nerve involvement, n (%) 5 (5.6%) Severity by EUGOGO classification (mild/ 26 (28.9%) /59 (65.6%)/5 moderately severe/sight-threatening), n (%) (5.6%) Current Gorman score of diplopia (score 0/ 44 (48.9%)/21 (23.3%)/12 1/2/3), n (%) (13.3%)/13 (14.4%) Mean VISA score ⫾ SD (range) 5.7 ⫾ 2.9 (1–13) Mean TSI ⫾ SD (range), SRR% 437.2 ⫾ 221.6 (37.4–991.3) Positive, n (%) 79 (87.8%) Mean TSHR Ab ⫾ SD (range), IU/ml 8.5 ⫾ 10.4 (0–40) Positive, n (%) 67 (74.4%) Thyroid function, n (%) Euthyroid 60 (66.7%) Hyperthyroid 27 (30%) Hypothyroid 3 (3.3%) TED, thyroid eye disease; GD, Graves’ disease; CAS, clinical activity score; NOSPECS, no signs or symptoms, only signs, soft tissue, proptosis, extraocular muscle, cornea, sight loss; EUGOGO, European Group on Graves’ Orbitopathy; VISA, vision loss (optic neuropathy), inflammation, strabismus/motility, appearance/exposure; TSI, thyroid-stimulating immunoglobulin; SRR, specimen-to-reference ratio; TSHR Ab, thyroid-stimulating hormone receptor autoantibodies.

Soft-tissue inflammation and activity of TED were evaluated by the CASs ranging from 0 to 7.10 TED was classified as an active state when CAS was greater than 3. The severity of TED was evaluated according to the following classification scores.11–13 The VISA classification was graded as follows: vision (0 or 3 points), inflammation (0–8 points), S1 (diplopia), S2 (motility restriction), and appearance/exposure (0–3 points). The sum of the VISA classification scores ranged from 0 to 20 (most severe). We used the modified NOSPECS score used by Choi et al.5

Evaluation of thyroid eye disease using TED-QOL—Son et al. Table 2—Thyroid Eye Disease Quality-of-Life questionnaire scores Subscale Overall Function Appearance

First Quartile

Second Quartile (median)

Third Quartile

Range

Mean ⫾ SD

Patients at Ceiling, n (%)

Patients at Floor, n (%)

7 6 6

8 8 9

10 10 10

0–10 0–10 0–10

7.67 ⫾ 2.5 7.32 ⫾ 2.6 8.0 ⫾ 2.7

31 (34.4%) 25 (27.8%) 43 (47.8%)

3 (3.3%) 3 (3.3%) 3 (3.3%)

based on Eckstein et al.12 The modified NOSPECS was graded as: lid retraction (0 or 1 point), soft-tissue inflammation, proptosis, site difference, extraocular muscle involvement (0–3 points), corneal defects (0 or 1 point), and optic nerve compression (0 or 3 points). The total modified NOSPECS score ranged from 0 to 17 (most severe). EUGOGO severity classification divided patients with TED into 3 groups: mild, moderate-to-severe, and sightthreatening groups. Motility disorders were classified according to the Gorman diplopia scale (0–3 points).14 All data were analyzed using SPSS version 20.0 software (SPSS, Chicago, Ill.). Using 2-sided p values, a p value less than 0.05 was considered statistically significant. We regarded TED-QOL scores as a dependent variable and the following as independent variables: age, sex, bilaterality, history of smoking, duration of TED and Graves’ disease, activity and severity scores of TED, and abnormality of TSI and TSHR Ab. To analyze relationships between each subscale of TEDQOL and continuous variables, we calculated the Spearman correlation coefficient. According to Cohen et al.’s recommendations, correlations were considered low (r o 0.2), moderate (0.2 o r o 0.5), or high (r 4 0.5).15 The relationship between TED-QOL and categorical variables was calculated by the Mann–Whitney U test or Kruskal– Wallis test. To determine which component of the clinical severity score was a significant predictor of QOL scores, we performed multiple linear regression analysis (stepwise regression) with possible confounders (age and sex). To assess floor and ceiling effects, we calculated the fraction of patients scoring 0 (minimum value) and 10 (maximum value) for each of the items of TED-QOL. According to Bradley et al.,16 more than 15% and more than 30% of maximum value were considered significant and substantial ceiling effects, respectively. Significant and substantial floor effects were defined in the same way. Content validity dealt with whether TED-QOL covered all health-related qualities of life relevant for the intended purpose. This was evaluated through patient interviews about the coverage and relevance of TEDQOL. Convergent validity and discriminant validity, procedures to measure the construct validity, were assessed by correlation between the subscales of TED-QOL.

RESULTS All 90 participants completed every item of the TEDQOL and interview, and all participants completed the

questionnaire within 2 minutes. Table 1 shows demographic data and clinical characteristics of consecutive patients with TED. The mean CAS was 1.99, and 13 (14.4%) patients had active TED. Five patients (5.6%) had optic neuropathy at the time of the survey. More than half of the patients with TED had diplopia with moderately severe TED, according to the EUGOGO severity classification. Patients demonstrated moderately severe impaired QOL as measured by the TED-QOL questionnaire (Table 2). Mean and median scores for overall (7.67, 8), function (7.32, 8), and especially appearance (8, 9) were measured, and the distribution was negatively skewed, with most scores deviated toward worst QOL. Therefore, a substantial ceiling effect was observed for overall (34.4%) and especially for appearance-related QOL (47.8%). A significant ceiling effect was observed for visual function–related QOL (27.8%). However, a significant floor effect was not observed for any subscale of TED-QOL. In interviews, most participants stated that the questionnaire was easy to understand because of their obvious meanings and simplified answers. The patients also said that the questionnaire covered all aspects of TED. Three patients said it was somewhat difficult to score each item separately because of selection of one point among a broad range of 11 scales, so they scored each item relative to the results of the other items. Two respondents mentioned a need for additional items about ocular discomfort, such as ocular irritation, tearing, and photophobia. Convergent validity and discriminant validity were assessed by correlation between the subscales of TEDQOL. TED-QOL had good convergent validity because there were high positive correlations between overall and visual function–related QOL (r ¼ 0.88, p o 0.001), and overall and appearance-related QOL (r ¼ 0.71, p o 0.001). Although the correlation between visual functioning and appearance was high, the discriminant validity was thought to be good to have a relatively weaker correlation (r ¼ 0.57, p o 0.001). In addition, content validity of TED-QOL was proved sufficient through patient interviews, and TED-QOL was indirectly estimated as valid based on the outcomes of correlations between questionnaires and correspondent clinical scores. Table 3 shows correlations between items of TEDQOL and clinical scores. Clinical scores indicating the inflammatory degree of TED, such as CAS, I of VISA classification, and soft-tissue inflammation of NOPECS, were moderately positively correlated with overall (all p o 0.01) and visual function–related QOL (all p o 0.05). Clinical scores indicating strabismus of TED, such as S1 CAN J OPHTHALMOL — VOL. 49, NO. 2, APRIL 2014

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Evaluation of thyroid eye disease using TED-QOL—Son et al. Table 3—Correlations between Thyroid Eye Disease Quality-of-Life questionnaire and clinical severity scores TED-QOL Overall Spearman Coefficient (95% CI) CAS scores VISA scores I S1 S2 A Total NOSPECS Soft-tissue inflammation Proptosis Site difference EOM Total Gorman scores

0.28 (0.09 0.45)*

Appearance

Function p

Spearman Coefficient (95% CI)

0.009*

0.24 (0.07 0.43)*

p 0.020*

Spearman Coefficient (95% CI)

p

0.19 (-0.03  0.37)

0.068

0.28 0.21 0.34 0.14 0.39

(0.09–0.45)* (0.02–0.40)* (0.14–0.51)* (–0.07 to 0.34) (0.19–0.55)*

0.008* 0.047* 0.001* 0.186 o0.001*

0.24 0.24 0.33 0.14 0.38

(0.07–0.42)* (0.07–0.42)* (0.13–0.50)* (–0.07 to 0.34) (0.19–0.54)*

0.021* 0.023* 0.001* 0.181 o0.001*

0.20 0.10 0.17 0.27 0.30

(–0.02 to 0.38) (–0.11 to 0.30) (–0.04 to 0.36) (0.08–0.45)* (0.10–0.47)*

0.055 0.347 0.111 0.012* 0.005*

0.384 0.130 0.025 0.340 0.35 0.22

(0.18–0.54)* (–0.08 to 0.33) (–0.18 to 0.23) (0.14–0.51)* (0.15–0.51)* (0.03–0.41)*

o0.001* 0.220 0.817 0.001* 0.001* 0.040*

0.372 0.112 0.02 0.341 0.34 0.24

(0.17–0.53)* (–0.10 to 0.31) (–0.19 to 0.23) (0.14–0.51)* (0.14–0.51)* (0.07–0.43)*

o0.001* 0.294 0.855 0.001* 0.001* 0.022*

0.267 0.260 –0.102 0.175 0.26 0.07

(0.08–0.43)* (0.08–0.44)* (–0.30 to 0.11) (–0.03 to 0.37) (0.08–0.44)* (–0.15 to 0.27)

0.011* 0.013* 0.34 0.098 0.014* 0.526

TED, thyroid eye disease; QOL, quality of life; CAS, clinical activity score; VISA, vision loss (optic neuropathy), inflammation, strabismus/motility, appearance/exposure; I, inflammation; S1, diplopia; S2, motility restriction; A, appearance; NOSECS, no signs or symptoms, only signs, soft tissue, proptosis, extraocular muscle, cornea, sight loss; EOM, extraocular muscle involvement. *p o 0.05.

and S2 of VISA classification, extraocular muscle involvement of NOSPECS, and Gorman scores, were moderately positively correlated with overall (all p o 0.05) and visual function–related QOL (all p o 0.05). As expected, clinical scores associated with appearance, such as A of VISA classification and proptosis of NOSPECS, were moderately positively correlated with appearance-related QOL (all p o 0.05). In addition, total scores of VISA classification and modified NOPSECS were moderately positively correlated with all items of TED-QOL (all p o 0.05). All mean values of TED-QOL were significantly different between patients with mild TED and moderate-tosevere TED (Fig. 1; p o 0.05). However, there was no

statistical difference between sight-threatening TED and others because of the small number of patients with sightthreatening TED (Fig. 1; p 4 0.05). There were no statistical differences in all items of TED-QOL scores regarding sex, bilaterality, lid retraction, smoking behaviour, disease activity, dysthyroid optic neuropathy, and abnormal TSI or TSHR Ab (p 4 0.05). Moreover, no significant correlations were observed between all items of TED-QOL scores and age, duration of Graves’ disease, duration of TED, and trend of TSI or TSHR Ab (p 4 0.05). Multiple linear regression analysis with stepwise regression for each component of clinical severity and the possible confounders (age and sex) was performed (Table 4). In cases of the modified NOSPECS score,

Fig. 1 — Effect of European Group on Graves’ Orbitopathy (EUGOGO) severity classification on quality-of-life scores. *p o 0.05.

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Evaluation of thyroid eye disease using TED-QOL—Son et al. Table 4—Association of thyroid eye disease quality-of-life with clinical severity scores and the possible confounders (age and sex) by multiple linear regression analyses

Overall QOL

Function QOL

Appearance QOL

NOSPECS Age Soft-tissue inflammation EOM VISA Age S2 NOSPECS Age Soft-tissue inflammation EOM VISA S2 NOSPECS Sex Soft-tissue inflammation Proptosis VISA Sex A

β Coefficient ⫾ SE

95% CI of β

p

0.048 ⫾ 0.019 1.011 ⫾ 0.327 0.983 ⫾ 0.262

0.011–0.086 0.360–1.662 0.462–1.504

0.013 0.003 o0.001

0.046 ⫾ 0.02 1.121 ⫾ 0.284

0.006–0.085 0.556–1.686

0.026 o0.001

0.04 ⫾ 0.02 1.087 ⫾ 0.337 0.906 ⫾ 0.27

0.001–0.079 0.417–1.757 0.37–1.443

0.045 0.002 0.001

0.836 ⫾ 0.272

0.294–1.377

0.003

1.57 ⫾ 0.582 0.865 ⫾ 0.369 0.797 ⫾ 0.3

0.414–2.727 0.131–1.599 0.201–1.393

0.008 0.022 0.009

1.285 ⫾ 0.599 0.945 ⫾ 0.316

0.093–2.476 0.317–1.574

0.035 0.004

SE, standard error; QOL, quality of life; EOM, extraocular muscle involvement; S2, motility restriction; A, appearance.

overall and function scores of QOL were positively correlated with scores of soft-tissue inflammation (regression coefficient B ¼ 1.011 ⫾ 0.327 and 1.087 ⫾ 0.337, respectively; p o 0.01) and motility disorder (B ¼ 0.983 ⫾ 0.262 and 0.906 ⫾ 0.27; p o 0.01), and weakly positively correlated with age (B ¼ 0.048 ⫾ 0.019 and 0.04 ⫾ 0.02; p o 0.05). Appearance scores of QOL were correlated with scores of soft-tissue inflammation (B ¼ 0.865 ⫾ 0.369) and proptosis (B ¼ 0.797 ⫾ 0.3), and showed higher scores in female patients (B ¼ 1.57 ⫾ 0.582; p o 0.05). Similarly, in cases of VISA scores, overall and function scores of QOL were positively correlated with motility disorder (S2, B ¼ 1.121 ⫾ 0.284 and 0.836 ⫾ 0.272; p o 0.01), and weakly positively correlated with age (B ¼ 0.046 ⫾ 0.02 and 0.038 ⫾ 0.02; p o 0.05). Appearance scores of QOL were correlated with appearance (A, B ¼ 0.945 ⫾ 0.316) and showed higher scores in females (B ¼ 1.285 ⫾ 0.599; p o 0.05).

DISCUSSION The correlation between the GO-QOL survey for different populations and various objective clinical scores of TED were evaluated in previous studies.2,4–6 The visual function and appearance score of GO-QOL showed good correlations with motility disorder scores and grades of proptosis, respectively. Similarly, Fayers and Dolman8 reported that TED-QOL and GO-QOL scores were moderately correlated with VISA assessment. Likewise, the Korean overall and function-related TED-QOL were moderately correlated with objective grades of inflammation, diplopia, and motility restriction in all clinical classification scores. And the objective signs related to appearance (proptosis in NOSPECS, A in VISA) were

correlated only with QOL related to appearance. Because TED-QOL correlated with expected objective clinical measures and all types of clinical classification systems, we believe that this questionnaire may provide reliable QOL information about patients with heterogeneous TED, no matter which methods of assessment for TED are used. In the study of Fayers and Dolman,8 although there was no information about the mean and the range of TEDQOL, a significant ceiling effect was observed for the function scale (19%), and a significant floor effect was observed for the appearance scale (21%). In this study, even if the clinical disease severity of participants seemed similar to that of Fayers and Dolman,8 there were no significant floor effects for any items of the Korean TEDQOL, although significant or substantial ceiling effects (27.8%–47.8%) were observed in all items (Table 2). The following theories may explain possible causes for such differences. Some social psychological researchers found self-critical tendencies in self-evaluation and underestimation of daily life satisfaction among Asians who rated themselves as relatively worse compared with the Westerners.17 In contrast, they found self-enhancement among the Westerners, who rated themselves as relatively better compared with the others. Another cultural difference that could influence QOL is approach versus avoidance orientation. Asians who think themselves as part of a group tend to focus on the negative consequences (avoidance), whereas Westerners who think of themselves as an independent self tend to focus on the positive consequences (approach).18 Another difference could be in communication styles: Asian cultures highly value the harmony in interpersonal relationships and do not promote open expression of a full range of emotions including negative, as well as positive, but prefer more subtle, nonverbal communication.19 Patients with TED often CAN J OPHTHALMOL — VOL. 49, NO. 2, APRIL 2014

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Evaluation of thyroid eye disease using TED-QOL—Son et al. suffer from disfiguration like proptosis and lid retraction, and this interferes with social interaction. In other words, these changes of appearance may disrupt eye contact and blinking, which play an important part in sustaining the flow of social interaction, and the disfiguration can make the patients unintentionally appear to present with facial expressions associated with aggression, surprise, or fear.20 Therefore, it is not surprising that the Asians who prefer indirect and nonverbal expression in human communication are more affected psychologically by TED than are the Westerners. These cross-cultural differences could have had more negative influence on the QOL in Asians. Moreover, psychological morbidity may persist and become chronic, although severity of TED may decline with passage of time and as a result of treatment.20 Therefore, the longer the duration of TED, the higher the TED-QOL scores may be, compared with the predicted results from clinical scores. This may explain why the TED-QOL of patients in this study with longer duration of TED showed relatively higher scores than scores reported by Fayers and Dolman.8 A ceiling effect occurs when the patients who score the maximum value of test items cannot be assessed beyond the examined criteria because of the limited number of items to select.21 It leads to limitation in the discriminative ability of the questionnaire to identify deterioration in patients who already have a poor QOL. A floor effect is an opposing notion to the ceiling effect, which inhibits the questionnaire from identifying improvement in patients who already have a good QOL. Because there was a significant ceiling effect of TED-QOL in our study group, the questionnaire might be insensitive in detecting aggravated change of QOL in relatively severe cases. However, because the floor effect of all items of the questionnaire was rare, TED-QOL could be used as the instrument for measuring improvement of QOL with treatment. GO-QOL was originally developed in Dutch and translated into 8 languages, and it has been widely used for many different populations. There were some difficulties in cross-cultural adaptation with GO-QOL, especially in terms of visual functioning. Because GO-QOL consists of questions about particular activities, the importance and meaning perceived by the patients might be dependent on the population characteristics. For example, limitations in bicycling are important for Dutch patients, but may be less important for patients in other countries. Moreover, multiple items of GO-QOL may cause more missing responses than TED-QOL; 79%–85% of the patients completed all of the GO-QOL questionnaire, but missing response rates of some questions were up to 15%.4–6 However, because TED-QOL was composed of only 3 questions, it was easier to translate into many other languages, and cross-cultural variations were lower than GO-QOL. In addition, missing responses on TED-QOL were rare, as 100% of the patients completed all the questions for TED-QOL in both English and Korean.8

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In addition, both the study by Fayers and Dolman8 and our study showed that completion times for TED-QOL were shorter than those for GO-QOL: less than 2 minutes compared with approximately 3 minutes.8 Furthermore, interpretation would be much faster for TED-QOL because GO-QOL has multiple item scales and it takes more time to convert numerical values and exclude missing values. Our study has several limitations. First, we collected data of patients in the tertiary orbital centre of a single academic institution. Referred patients from the other clinics might have had above-average disease severity. Second, this crosssectional study did not allow an evaluation of the responsiveness of changes of the TED-QOL in TED patients over time and with treatment. Third, because a small number of patients (n ¼ 5) had sight-threatening TED, the most severe complication of TED, these complications did not statistically influence TED-QOL. In summary, TED-QOL had good correlation with clinical severity scores comparable with GO-QOL. It could be used in different populations and would be useful in objective clinical assessment, because of the convenience of cross-cultural translation and good correlation with various specific clinical parameters of TED. Moreover, TED-QOL is quick and easy to score, and offered operational efficiency for data entry and data analysis. For these reasons, TED-QOL would be more clinically useful in rapid QOL evaluation of patients in a daily outpatient clinic, in making decisions for treatment method including psychosocial supports by identifying psychosocial impairment, and in measuring improvement of QOL after treatment.

Disclosure: The authors have no proprietary or commercial interest in any materials discussed in this article.

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Evaluation of thyroid eye disease: quality-of-life questionnaire (TED-QOL) in Korean patients.

To assess impaired quality of life (QOL) of Korean patients with thyroid eye disease (TED) using the TED-QOL questionnaire, to evaluate the adaptabili...
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