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COMPARISON OF TWO HEALTH RELATED QUALITY OF LIFE QUESTIONAIRES IN MALAY CHILDREN WITH

STRABISMUS AND THEIR PARENT PROXY

BY

DR TAN JIN POI (MBBch BAO, National University of Ireland)

DISSERTATION SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER

OF MEDICINE (OPHTHALMOLOGY)

SCHOOL OF MEDICAL SCIENCES UNIVERSITI SAINS MALAYSIA

2015

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DISCLAIMER

I hereby certify that the work in this dissertation is my own except for the quotations and

summaries which have been duly acknowledged.

Date : 26th May 2015 ……………………….. Tan Jin Poi PUM 0148/ 09

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ACKNOWLEDGEMENT

I would like to express my deepest gratitude and appreciation to my supervisor,

Professor Dr. Shatriah Ismail. You have been an inspiring mentor, a supportive friend

and a respectful model, all at the same time to me. I cherish the full effort, your kind

patience and precious time that you have given me throughout this study and provided

me generously stimulating suggestions and aspiring encouragement as well. It is

undeniable that you have played such important role in maintaining my progress in

track and making this study possible. Thank you for all the experience, the knowledge,

and the unfailing encouragement that you have ever so ready to provide and share. I will

forever cherish this experience.

Furthermore, I would also like to acknowledge with much appreciation to Miss

Norsuhana Mohd. Noor, Staff Nurse Sarimah Samsudin, Staff Nurse Che Hasmah Che

Said, Miss Norhaniza Harun. All of you played a crucial role in the process of my data

collection. I would never have been able to finish my dissertation if it wasn’t for your

unselfish dedication. It has been such a wonderful pleasure working with all of you.

A warm thanks to lecturer Dr Sarimah Abdullah and Miss Tengku Mardhiah. Both of

you have patiently answered all my qualms on statistical issues and jargons. I deeply

appreciate the time that both of you are willing to allocate despite of your busy

schedule. Your constructive advices were very helpful indeed.

Most importantly, I am in debt to my loving and supportive family. You have been my

comforters, always welcoming me and providing me a place of refuge whenever I feel

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overwhelmed with the work load and when I was unwell. Your sacrifice in nursing me

back to health has deeply touched my heart and sustained me throughout my career. All

that you have done unconditionally had changed my view in life. No words can express

my gratitude to all of you.

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TABLE OF CONTENTS

PAGE

TITLE 1

DISCLAIMER 2

ACKNOWLEDGEMENT 3

TABLE OF CONTENTS

LIST OF TABLES

LIST OF FIGURES

ABSTRAK (BAHASA MALAYSIA)

ABSTRACT (ENGLISH)

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CHAPTER 1: INTRODUCTION 19

1.1 Strabismus

1.1.1 Prevalence of strabismus

1.1.2 Functional effects of strabismus

1.1.3 Psychosocial effects of strabismus

1.2 Health Related Quality of Life Questionnaires

1.2.1 Intermittent Exotropia Questionnaires (IXTQ)

1.2.2 Adult Strabismus-20 (AS-20) Questionnaires

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1.3 Rationale of Study 36

CHAPTER 2: STUDY OBJECTIVES

2.1 General objective

2.2 Specific objectives

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CHAPTER 3: METHODOLOGY

3.1 Study design

3.2 Population, place of study and duration of study

3.2.1 Study population

3.2.2 Place of study

3.2.3 Duration of study

3.3 Sampling and sample size

3.3.1 Sampling method

3.3.2 Sample size calculation

3.3.2.1 Sample size calculation for objective one

3.3.2.2 Sample size calculation for objective two

3.4 Selection criteria

3.4.1 Inclusion criteria

3.4.1.1 Inclusion criteria for child

3.4.1.2 Inclusion criteria for parent

3.4.2 Exclusion criteria

3.4.2.1 Exclusion criteria for child

3.4.2.2 Exclusion criteria for parent

3.5 Ethical approval

3.6 Financial support

3.7 Definition of terms

3.7.1 Strabismus / Tropia

3.7.2 Exotropia

3.7.3 Esotropia

3.7.4 Health Related Quality Of Life (HRQOL)

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3.7.5 Likert type scale answer

3.7.6 Malay (Melayu)

3.7.7 Intermittent Exotropia Questionnaire (IXTQ)

3.7.8 Adult Strabismus-20 (AS-20) Questionnaire

3.7.9 Cronbach’s alpha coefficient

3.8 Study tools and instruments

3.9 Details of methodology

3.9.1 Phase 1: From the Questionnaire’s Translation to the

Pretest

3.9.2 Recruitment of patients

3.9.3 Orthoptic assessment

3.9.4 Anterior segment and posterior segment examination

3.9.5 Written consent

3.9.6 Sampling procedures

3.10 Methods to minimize study error

3.11 Statistical analysis

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CHAPTER 4: RESULTS

4.1 Demographics for phase one

4.1.1 Demographic data

4.1.1.1 Age distribution

4.1.1.2 Gender distribution

4.1.1.3 Parents distribution

4.1.2 Clinical characteristics

4.1.2.1 BCVA

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4.1.2.2 Types of strabismus

4.2 Reliability Analysis of the translated IXTQ and AS-20

Questionnaires

4.3 Demographics for phase two

4.3.1 Demographic data

4.3.1.1 Age distribution

4.3.1.2 Gender distribution

4.3.1.3 Parents or guardians distribution

4.3.2 Clinical characteristics

4.3.2.1 BCVA

4.3.2.2 Types of strabismus

4.4 Malay version of IXTQ and AS-20 in children

4.4.1 Mean scores of Malay version of IXTQ in

Children

4.4.2 Mean scores of Malay version of AS-20 in

Children

4.4.3 Comparison between Malay version of IXTQ

and AS-20 Questionnaires in Children

4.5 Malay version of IXTQ and AS-20 in parent proxy

4.5.1 Mean scores of Malay version of IXTQ in parent proxy

4.5.2 Mean scores of Malay version of AS-20 in parent proxy

4.5.3 Comparison between Malay version of IXTQ and AS-

20 Questionnaires in children and parent proxy

4.6 Comparison between the children and their parent proxy

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4.6.1 Comparison between Malay version of IXTQ in

children and proxy

4.6.2 Comparison between Malay version of AS-20 in

children and proxy

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CHAPTER 5: DISCUSSION

5.1 Evaluation of content validity of Malay version of IXTQ and

AS-20 questionnaires

5.2 Total mean score of IXTQ and AS-20 in Malay children with

strabismus and their parent proxy

5.3 Comparison of mean scores between the Malay version of

IXTQ and the Malay version of AS-20 questionnaires in the

children and parent proxy

5.4 Comparison of mean scores between the children and their

parent proxy

5.5 Limitations and recommendations

CHAPTER 6: CONCLUSION

CHAPTER 7: REFERENCES

CHAPTER 8: APPENDICES

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Appendix A: Flow chart of the study 125

Appendix B: Patient consent form (English and Malay Versions) 127

Appendix C: Data collection form 129

Appendix D: Patient information sheet (English and Malay Versions) 143

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Appendix E: Ethical approval 155

LIST OF TABLES

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Table 3.1 Items in the IXTQ concerning the subject’s eye 51

Table 3.2 Items in the AS-20 concerning the subject’s eye 52 Table 4.1 Age distribution for the respondents in the phase one study 65

Table 4.2 Distribution of parents in the phase one study 67

Table 4.3 BCVA distribution in phase one study population 68

Table 4.4 Types of strabismus in phase one study population 69

Table 4.5 Reliability statistic 70

Table 4.6 Distribution of demographic characteristics for the respondents 71

Table 4.7 Distribution of the parents 73 Table 4.8 BCVA 74

Table 4.9 Types of Strabismus 75

Table 4.10 Total mean score and subscale mean scores of IXTQ in Children 76

Table 4.11 Individual item mean scores of IXTQ in Children 77

Table 4.12 Total mean score and subscale mean scores of AS-20 in Children 78

Table 4.13 Individual item mean scores of AS-20 in Children 79

Table 4.14 Comparison between mean scores of Malay version of IXTQ and 80

AS-20 Questionnaires in children

Table 4.15 Total mean score and subscale mean scores of IXTQ in proxy 81

Table 4.16 Individual item mean scores of IXTQ in parent proxy 82

Table 4.17 Total mean score and subscale mean scores of AS-20 in proxy 83

Table 4.18 Individual item mean scores of AS-20 in parent proxy 84

Table 4.19 Comparison between total mean score of IXTQ and AS-20 85

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Questionnaires in parent proxy

Table 4.20 Comparison between mean scores of Malay version of Child 86

IXTQ and Proxy IXTQ

Table 4.21 Comparison between individual item mean scores of Malay 87

version of Child IXTQ and Proxy IXTQ

Table 4.22 Comparison between total mean score of Malay version of 88

Child AS-20 and Proxy AS-20 Questionnaires

Table 4.23 Comparison between individual item mean scores of Malay 89

version of Child AS-20 and Proxy AS-20 Questionnaires

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LIST OF FIGURES

PAGE

Figure 3.1 Slit Lamp Biomicroscope 53

Figure 3.2 Binocular indirect ophthalmoscope 53

Figure 3.3 Goldmann Applanation Tonometer 53 Figure 3.4 Airpuff tonometer 53 Figure 3.5 a) Topical Phenylephrine 54

b)Topical Tropicamide c) Topical Cyclopentolate

d) Topical Proparacaine e) Fluorescein Sodium paper strip Figure 3.6 Snellen Chart 54

Figure 3.7 Kay pictures acuity test 55 Figure 3.8 Smart system optosmart 55 Figure 3.9 Fixation target 55 Figure 3.10 Transparent occluder 55 Figure 3.11 Block prism set 56

Figure 3.12 Frisby stereotest 56 Figure 3.13 Retinoscopy trial lenses and retinoscope 56

Figure 3.14 Retinoscope 56

Figure 4.1 Phase One Study - Gender distribution 66

Figure 4.2 Gender Distribution 72

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PERBANDINGAN DI ANTARA DUA JENIS BORANG SOAL SELIDK KUALITI KEHIDUPAN DI KALANGAN KANAK-KANAK MELAYU DENGAN JULING DAN PROKSI IBU BAPA MEREKA ABSTRAK

Pengenalan: Juling merupakan satu penyakit mata yang boleh menyebabkan

masalah-masalah kosmetik, fungsi dan psikososial. Penilaian Kualiti Kehidupan

Berkaitan dengan Kesihatan (HRQoL) semakin diiktirafkan sebagai satu faktor penting

dalam rawatan juling dan merupakan satu instrumen yang penting dalam bidang

penyelidikan klinikal. Tetapi, tidak banyak alat penilaian HRQoL juling yang khusus,

terutamanya untuk kanak-kanak dan dalam pengetahuan kami, tidak ada penerjemahan

Bahasa Malaysia untuk soal selidik juling juga. Dalam kajian kami, IXTQ dan AS-20

versi Inggeris telah diterjemahkan kepada Bahasa Malaysia dan mencapai pengesahan

linguistik. Kami harap dua-dua borang soal selidik ini dapat diperkenalkan ke dalam

amalan klinikal kami. Selain itu, kajian ini juga membandingkan borang soal selidik

IXTQ dan AS-20 versi Melayu yang baru di kalangan kanak-kanak Melayu dengan

juling dan proksi ibu bapa mereka.

Objektif: Untuk membandingkan dua jenis borang soal selidik kualiti kehidupan

(HRQoL) dalam aspek fungsi dan psikososial di kalangan kanak-kanak Melayu dengan

juling dan proksi ibu bapa mereka.

Metodologi: Soal selidik telah diterjemahkan dari Inggeris ke Bahasa Malaysia

sebelum diberikan kepada 30 kanak-kanak Melayu dengan juling dan ibu bapa mereka

untuk menentukan kebolehpercayaan konsistensi dalaman. Ujian alfa Cronbach telah

digunakan. Ini diikuti oleh kajian keratan rentas komparatif yang telah dijalankan di

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Klinik dan Wad Oftalmologi, Hospital Universiti Sains Malaysia dari Jun 2012 hingga

Jun 2014. Seramai 57 kanak-kanak Melayu berusia 5 hingga 17 tahun dan ibu bapa

telah dikumpulkan untuk kajian ini. Kanak-kanak dan ibu bapa kemudiannya diminta

untuk mengisi borang soal selidik IXTQ dan AS-20 versi Melayu. Kanak-kanak dan ibu

bapa diberikan arahan lisan dan bertulis yang mudah oleh personel terlatih dan diminta

untuk menjawab berasaskan pengalaman mereka bulan sebelumnya. Soal selidik terdiri

daripada jawapan skala 5 titik jenis Likert. Jumlah purata skor, purata skor sub-skala

fungsi dan psikososial telah dikira dan dibandingkan di antara dua-dua soal selidik.

Keputusan: Penilaian konsistensi dalaman untuk semua soal selidik versi

Melayu yang baru diterjemahkan kecuali IXTQ Kanak-kanak melebihi nilai alfa 0.90.

Nilai alfa untuk AS-20 Kanak-kanak ialah 0.909, 0.912 untuk IXTQ Proksi, 0.948 untuk

AS-20 Proksi dan 0.651 untuk IXTQ Kanak-kanak. Terdapat perbezaan yang signifikan

dalam jumlah purata skor dan purata skor sub-skala fungsi di antara kedua-dua IXTQ

dan AS-20 di kalangan kanak-kanak Melayu dengan juling (p < 0.001). Tetapi, didapati

tiada perbezaan yang signifikan antara purata skor sub-skala psikososial dua-dua soal

selidik dalam kanak-kanak (p = 0.122). Semua skor soal selidik IXTQ dan AS-20 Proksi

mempunyai perbezaan signifikan (p < 0.05). Kajian kami juga mencatatkan skor yang

lebih rendah dalam soal selidik IXTQ dibandingkan dengan skor soal selidik AS-20.

Kesimpulan: Jumlah purata skor dan purata skor sub-skala fungsi adalah lebih

tinggi dalam soal selidik AS-20 versi Melayu berbanding dengan IXTQ versi Melayu

dalam kanak-kanak Melayu dengan juling. Perbezaan ini juga didapati signifikan.

Tetapi, perbezaan dalam purata skor sub-skala psikososial di antara dua soal selidik

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dalam kanak-kanak didapati tidak signifikan. Untuk ibu atau bapa atau penjaga proksi

kanak-kanak Melayu dengan juling, didapati semua purata skor adala lebih rendah di

soal selidik IXTQ versi Melayu berbanding dengan AS-20 versi Melayu Proksi.

Perbezaan ini didapati signifikan.

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COMPARISON OF TWO HEALTH RELATED QUALITY OF LIFE QUESTIONAIRES IN MALAY CHILDREN WITH STRABISMUS AND THEIR PARENT PROXY

ABSTRACT

Introduction: Strabismus is an eye condition associated with cosmetic,

functional and psychosocial circumstances. Evaluation of Health Related Quality of

Life (HRQoL) is increasingly recognized as an important factor in strabismus

management and a crucial tool for clinical research. However, there are not many

strabismus-specific HRQoL assessment tools, especially for children and to our

knowledge, no Malay translation for strabismus specific questionnaires. The English

versions of IXTQ and AS-20 questionnaires were translated into Malay language and

achieved linguistic validation in our study in a hope to apply the questionnaires into our

clinical practice. This study also compared the newly developed Malay version of IXTQ

and AS-20 HRQoL questionnaires in Malay children with strabismus and their parent

proxy.

Objective: To compare two health related quality of life (HRQoL)

questionnaires for functional and psychosocial aspects in Malay children with

strabismus and their parent proxy.

Methodology: The questionnaires were translated forward and backward before

they were administered to 30 Malay children with strabismus and their parents to

determine the internal consistency reliability. The test for Cronbach’s alpha was

performed. This was then followed by a comparative cross sectional study conducted in

Ophthalmology Clinic and Ward, Hospital Universiti Sains Malaysia from June 2012

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until June 2014. A total of 57 Malay children aged 5 to 17 years and their parents were

recruited for this study. The children and their parents were then asked to complete the

translated Malay version of IXTQ and the AS-20 questionnaires. Children and their

parents were given simple verbal and written instructions by a trained personnel and

asked to base their responses on their experiences over the previous month.

Questionnaires consist of 5 point Likert type scale answer. The total mean scores,

functional subscale scores and psychosocial scores were calculated and compared

between both questionnaires.

Result: The evaluation of the internal consistency for all our newly translated

Malay version questionnaires except for Child IXTQ exceeded an alpha of 0.90. The

alpha value was 0.909 for Child AS-20, 0.912 for Proxy IXTQ, 0.948 for Proxy AS-20

and 0.651 for Child IXTQ. There was a significant difference noted in the total mean

scores and the functional subscale mean scores between both IXTQ and AS-20

questionnaires in the Malay children with strabismus (p < 0.001). There was no

significant difference between the psychosocial subscale mean scores of the two

questionnaires in the children (p = 0.122). In the comparison between the Proxy IXTQ

and AS-20, there was a significant difference noted in the total mean scores, the

functional subscale and the psychosocial subscale mean scores between both

questionnaires (p < 0.05). All the scores in AS-20 questionnaires are higher when

compared to the scores from all IXTQ.

Conclusion: The total mean score and functional subscale mean score were

significantly lower in the Malay version of IXTQ compared to the Malay version of AS-

20 in the Malay children with strabismus. There was no significant difference in the

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psychosocial subscale mean score between the two questionnaires in the children. The

total mean score, functional and psychosocial subscale mean score were significantly

lower in the Malay version of IXTQ compared to the Malay version of AS-20

questionnaires in the parent of Malay children with strabismus.

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Chapter 1 Introduction

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1.0 INTRODUCTION

1.1 Strabismus

1.1.1 Prevalence of Strabismus

Strabismus, also known as heterotropia or squint, is defined as misalignment of the

eyes. In other words, the eyes do not point in the same direction. It is an eye

condition with cosmetic and functional circumstances (Carlton et al., 2008). Carlton

et al performed a systemic literature review in 2008 on the prevalence and natural

history, the screening methods used, effectiveness of treatment options, and health-

related quality of life issues relating to amblyopia and strabismus. They also reported

that if strabismus is left untreated, it would persist into adulthood.

Few population-based studies have reported the prevalence of strabismus in children

to be in the range of 0.01% to 3.3% globally. Some studies from Malaysia reported a

strabismus prevalence of 1.4%-2.2% (Teoh and Yow, 1982; Goh et al., 2005),

whereas, it was reported to be 0.8% in Singaporean Chinese children (Chia et al.,

2010), 1.9%-3% in China (He et al., 2004), 1.28% in Japan (Matsuo and Matsuo,

2007), up to 3.3% in United States (Chew et al., 1994), 2.8% in Australia (Robaei et

al., 2006), and 2.3% in United Kingdom (Williams et al., 2008).

Teoh and Yow (1982) conducted the study in Petaling Jaya, Malaysia, involving 650

school children aged 7. Fourteen (2.2%) of them were found to have strabismus, of

which 86% were exotropia, 7% alternating esotropia and 7% hypertropia. Another

population-based, cross-sectional survey was done by Goh et al. (2005) on 4634

children, aged 7 to 15 years, living in a suburban area near Kuala Lumpur city. They

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reported strabismus in 1.4% of the children in which mostly (up to 85%) were

exotropia.

Chia et al. (2010) carried out a door to door survey in the South-Western region of

Singapore, recruiting 3009 children aged 6 to 72 months. They observed a lower

prevalence of strabismus (0.8%) among young Singaporean Chinese children.

Majority of the strabismic children had intermittent exotropia (58%), followed by

constant exotropia (25%) and constant esotropia (12%).

In Guangzhou, China, He et al. (2004) studied on 5053 children aged 5 to 15 years

and reported prevalence of strabismus to be 1.9% to 3.0%. Most of them were

exotropia (80% with near and 86% with distant fixation). Matsuo and Matsuo (2007)

carried out a large-scale population-based survey in Okayama Prefecture, Japan.

Questionnaires were mailed to elementary schools and a total 86531 children, aged 6

to 12 years participated in the surgey. They observed 1.28% of the children were

found to have strabismus where 0.69% were exotropia and 0.28% were esotropia.

In the United States, the Baltimore Paediatric Eye Disease Study examined 2546

white and African American children aged 6 through 71 months and revealed that

3.3% of white and 2.1% of African American children had manifest strabismus.

(Friedman et al., 2009). Robaei et al. (2006) reported a 2.8% prevalence of

strabismus in a population-based cross-sectional study in Sydney. 1739 children aged

6 years was recruited and reported that 54% had esotropia and 29% had exotropia.

Whereas in the United Kingdom, Williams et al. (2008) reported a 2.3% prevalence of

strabismus in 7825 seven year-old children. And it was also reported that 73.4% were

esotropia, 21.4% were exotropia and 5.2% had a vertical component.

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There are four types of strabismus. They are the horizontal strabismus: esotropia and

exotropia; and the vertical strabismus: hypertropia and hypotropia. Esotropia is an

inward turning of the eyes or also known as "crossed eyes". Exotropia is an outward

deviation of the eyes forming a divergent angle of the eyes or also known as "wall

eyes". Hypertropia is an upward deviation of the eyes whereas hypotropia is a

downward turning of the eyes. Strabismus is equally common in boys and girls and

sometimes runs in families.

The prevalence of the type of strabismus varies based on racial and ethnic

background. Exotropia occurs more commonly in the Middle East, subequatorial

Africa and the Asian populations than in the United States as quoted from Noorden

(1996). Jenkins (1992) made the interesting observation that the nearer a country is to

the equator the higher the prevalence of exodeviations. Whereas Europeans,

Australians and Americans are predominantly diagnosed with esotropia. The basis of

this difference may be in part linked with population-based differences in refractive

error. Cotter et al. (2011) investigated the risk factors associated with esotropia or

exotropia in a population-based cross-sectional prevalence study where 9970 children

ages 6 to 72 months from California and Maryland participated. They reported that

esotropia is commonly associated with hyperopia, whereas exotropia is more

associated with myopia. Yu et al. (2002) also reported a higher prevalence of

exotropia in Hong Kong as the population becomes less hyperopic.

Sometimes, the child cannot use both eyes together but has to fixate with one or the

other. The eye that looks straight at a given time is the fixing eye. Visual acuity

diminishes with diminished use of an eye, and suppression amblyopia may develop.

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Early treatment usually improves vision and appearance. Generally, the most

satisfactory results are achieved if the condition is corrected before the age of seven

years old. However, if strabismus is left untreated, it may result in loss of binocularity

and depth perception.

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1.1.2 Functional effects of Strabismus

In strabismus, there is disruption of binocular vision which leads to images forming in

non-corresponding points in both retinae. This causes overlapping of different foveal

images from the fixating eye and the deviating eye. Noorden published an article in

1985, explaining that in order to minimize the disorganization and confusion, there is

an active inhibition within the retino-cortical pathways of visual input which

originates from the fovea of the deviating eye (Noorden, 1985). This mechanism

prevents diplopia or confusion due to visual adaptation via anomalous retinal

correspondence or known as visual suppression. This will result in poor vision in the

non-fixating eye causing amblyopia.

Amblyopia is defined as unilateral or less commonly, bilateral reduced best corrected

visual acuity (BCVA) in the absence of organic abnormality of the eye (Noorden,

1985). If left untreated or inadequately treated, it can cause permanent loss of vision.

Although amblyopia generally develops in children aged less than seven years, it can

still happen at any age prior to visual maturation. But early accurate diagnosis and

treatment of amblyopia should be carried out. Birch and Wang (2009) did a review on

the normal maturation of stereoacuity, the stereoacuity deficits associated with

infantile and accommodative esotropia and strategies for improving stereoacuity

outcomes. They concluded early diagnosis and treatment may result in improved

vision, leading to a better prognosis for binocular vision development, a more stable

alignment for surgery if required and improved long term quality of life.