Hwee Lin Wee

The impact of diabetes mellitus and other chronic medical conditions on health-related Quality of Life: Is the whole greater than the sum of its parts?

BackgroundDiabetes mellitus (DM) is an important public health concern, the impact of which is increased by the high prevalence of co-existing chronic medical conditions among subjects with DM. The aims of this study were therefore to (1) evaluate the impact of DM and co-existing chronic medical conditions on health-related quality of life (HRQoL) (which could be additive, synergistic or subtractive); (2) to determine the extent to which the SF-6D (a single-index preference measure) captures the multidimensional information provided by the SF-36 (a profile measure).MethodsUsing data from a cross-sectional, population-based survey of Chinese, Malay and Indians in Singapore, we developed 9 separate multiple linear regression models, with each SF-36 scale or SF-6D index score being the dependent variable for one model. The influence of DM and a second chronic medical condition (hypertension (HTN), heart disease (HD), musculoskeletal illnesses (MS)) and their interactions were studied after adjusting for the influence of potential confounding variables.ResultsAmong 5,224 subjects, the prevalence of DM, HTN, HD and MS were 5.9%, 10.7%, 2.4% and 26.6% respectively. DM lowered SF-36 scores by more than 2 points on 3 SF-36 scales and lowered SF-6D scores by 0.03 points. Subjects with DM and HTN, DM and HD or DM and MS experienced further lowering of SF-36 scores exceeding 2 points on at least 6 scales and further lowering of SF-6D scores by 0.05, 0.08 and 0.10 points respectively. Generally, DM and co-existing medical conditions exerted additive effects on HRQoL, with the exception of DM and heart disease, where a subtractive effect was noted. SF-6D index scores generally reflected the patterns of influence of DM and chronic medical conditions on SF-36 scores.ConclusionDM and chronic medical conditions generally reduced HRQoL in this multiethnic general population in an additive, rather than synergistic or subtractive fashion. In this study, the SF-6D was a reasonably good summary measure for the SF-36.

Usefulness of the Audit of Diabetes-Dependent Quality-of-Life (ADDQoL) Questionnaire in Patients with Diabetes in a Multi-Ethnic Asian Country

AbstractIntroduction: Asia will be at the forefront of the current epidemic of diabetes mellitus. Quality of life (QOL) is an important outcome measure in the assessment of diabetes care. However, few QOL instruments are culturally suitable for use in Asian countries. The Audit of Diabetes-Dependent Quality-of-Life (ADDQoL) questionnaire is a third-generation individualised QOL instrument. Individualised instruments such as the ADDQoL have the potential to be useful and less costly alternatives to computerised adaptive testing (CAT), which may not be practical in developing countries. Objective: To evaluate and validate the ADDQoL questionnaire in Englishspeaking patients with diabetes in Singapore, a multi-ethnic Asian country. Methods: The ADDQoL and EQ-5D were administered to English-speaking respondents with type 1 or 2 diabetes (aged ≥18 years) recruited from a tertiary acute-care referral hospital by convenience sampling. The usefulness of the key design features of the ADDQoL were assessed by measuring the number of zeroimportance responses, the change in item ranking with and without weighting for importance, and the frequency of utilisation of the ‘not applicable’ (NA) options. The acceptability, factor structure and internal consistency (Cronbach’s α) of the ADDQoL were also assessed. Data were subjected to unforced factor analysis with oblimin rotation and then the condition was set to force a one-factor solution.The validity of the ADDQoL was tested with the following hypotheses: those with moderate or severe problems on the EQ-5D would have worse ADDQoL average weighted impact (AWI) scores than those with a perfect health rating on the EQ-5D; those with better Present QOL scores on the ADDQoL would have better EQ-5D utility and visual analogue scale (VAS) scores; on the ADDQoL, AWI scores would correlate better with diabetes-dependent QOL than with Present QOL scores; and female respondents, those who required insulin or had longer duration of known diabetes would have worse ADDQoL AWI scores (known-group validity). Results: We analysed data from 152 respondents (49% Chinese, 34% Indian; 45% female; mean age 52 years, range 18–80; mean duration of known diabetes 10 years, range 0–62). There were few missing data. Weighted scoring and NA options were shown to be necessary, thus supporting the usefulness of individualised health-related QOL measures. Factor structure of the ADDQoL was supported and internal consistency was high (α = 0.94). All hypotheses were fulfilled except for one that was partially fulfilled; respondents with longer duration of known diabetes did not report worse ADDQoL AWI scores. Conclusions: The ADDQoL is culturally appropriate, valid, reliable and well accepted among Singaporean patients with diabetes. Individualised measures such as the ADDQoL allow one to obtain precise score estimates and may offer developing countries a useful alternative to CAT.

Progression of Parkinson's disease as evaluated by Hoehn and Yahr stage transition times

This study was carried out to evaluate progression in Parkinsons disease (PD) by analyzing time taken to transit from one Hoehn and Yahr (H&Y) stage to the next stage and to investigate the variables that would be associated with H&Y transition times using a large PD database that contained prospectively collected information. Data were obtained from the movement disorder database of the National Neuroscience Institute in Singapore. Kaplan‐Meier (KM) survival analysis was adopted to investigate the time taken to progress through various H&Y stages. Cox regression analysis was used to examine the association between the baseline variables at the entry point of each H&Y stage and the progression to the next stage. A total of 695 patients (mean age: 65.2, male: 57.3%) were studied. Using KM analysis, the median time taken to transit from H&Y stage 1 to 2, 2 to 2.5, 2.5 to 3 were 20, 62, and 25 months, respectively; whereas the median time taken to progress from stage 3 to 4 and 4 to 5 were 24 and 26 months, respectively. Cox regression analysis revealed that older age‐at‐diagnosis, longer PD duration, and higher Unified Parkinsons Disease Rating Scale (UPDRS) motor scores at baseline were associated with a significantly faster progression through various H&Y stages. Gender and ethnicity were not associated with disease progression. In conclusion, H&Y transition time is a useful measure of disease progression in PD and may be utilized in clinical studies evaluating therapeutic interventions and prognostic factors in PD.

Validation of the English version of the KINDL® generic children's health-related quality of life instrument for an Asian population : results from a pilot test

ObjectivesTo evaluate the psychometric properties of the KINDL questionnaire in an Asian population. Methods: Consecutive patients with diabetes mellitus (DM) and healthy subjects were recruited to complete the English KINDL questionnaire. The inclusion criteria for patients were age 8–16 years, English-speaking, diagnosed with DM and absence of co-morbid conditions. Results:Thirty children with DM (mean age: 10.7 ± 1.35 years; 11M) and 39 healthy subjects (mean age: 10.6 ± 1.23 years, 17M) completed the child version whereas 31 adolescents with DM (mean age: 14.5 ± 1.48 years; 15M) and 32 healthy subjects (mean age: 14.3 ± 0.87 years, 16M) completed the adolescent version. Overall, children with DM reported better HRQoL than healthy children. Although this appeared counter-intuitive, several explanations are possible: (1) the development of resilience to the disease over time, (2) our subjects are well-managed, (3) response shift, (4) the provision of high quality medical care, (5) compared to normal children, diabetic subjects and their family pay greater attention to health issues. The reliability coefficients were (overall, scales): KINDL-Kid DM (0.79, 0.44–0.65), KINDL-Kid Healthy (0.71, 0.60–0.80), KINDL-Kiddo DM (0.77, 0.37–0.74) and KINDL-Kiddo Healthy (0.84, 0.21–0.79). Conclusions: The KINDL questionnaire appeared promising for use in Asian children. However, further validation in a sample more representative of the general population is required.

Vision Impairment, Ocular Conditions, and Vision-specific Function: The Singapore Malay Eye Study

OBJECTIVE To validate the VF-11, a vision-specific function scale and determine the relationship among vision impairment, ocular conditions, and vision-specific functioning in an Asian Malay population. DESIGN Population-based cross-sectional study. PARTICIPANTS Persons aged 40 to 80 years of Malay ethnicity in Singapore. METHODS Of the 3280 participants, 3267 answered the VF-11 scale. Participants underwent an extensive and standardized examination procedure, which included visual acuity testing. Sociodemographic and medical data were recorded using a standardized questionnaire. Rasch analysis was initially used to validate the VF-11 and determine its measurement characteristics. Analyses were performed to explore the relationship between the overall functioning score and the presenting unilateral and bilateral vision and ocular conditions using linear regression models. MAIN OUTCOME MEASURE Vision-specific functioning score. RESULTS The mean presenting visual acuity values in the better and worse eyes were 0.21 (+/-0.23) and 0.36 (+/-0.27) logarithm of the minimum angle of resolution, respectively. Some 46.4% of participants had some form of visual impairment in either eye, and 1.8% of participants had severe visual impairment in both eyes. By using Rasch analysis, it was shown that a modified VF-11 is a unidimensional, reliable, and valid scale to assess vision-specific functioning in this population. Participants with unilateral or bilateral visual impairment had significantly lower vision functioning scores. The independent association between severe vision loss in one or both eyes and functioning was considered to be clinically meaningful. Eye conditions were not independently associated with overall visual function with bilateral visual impairment in the model with the exception of glaucoma (P<0.05 and beta = -1.08). Compared with people with normal vision, people with mild/moderate visual impairment were 1.6 (95% confidence intervals [CI], 1.2-2.2; P = 0.01) and 2.2 (95% CI, 1.6-3.0; P = 0.007) times more likely to have moderate and poor vision function, respectively. Similarly, participants with severe visual impairment were 3.5 (95% CI, 1.1-12.7; P<0.001) and 13.6 (CI, 4.0-45.4; P<0.001) times more likely to have moderate and poor vision function, respectively. CONCLUSIONS Presenting unilateral and bilateral vision impairment is significantly associated with poor vision-specific functioning across the spectrum of mild to severe vision impairment in this Asian Malay population.

Association of body mass index with Short-Form 36 physical and mental component summary scores in a multiethnic Asian population.

Objectives:To investigate the association between body mass index (BMI) and physical and mental health-related quality of life (HRQoL) in a multiethnic Asian population in Singapore, and explore whether there were gender and ethnic differences in this association.Methods:We conducted cross-sectional analyses using data from 5027 Chinese, Malay and Indian participants (2403 men and 2624 women) aged 24–95 years. These subjects were from four previous cross-sectional surveys carried out in Singapore (from 1982 to 1998) who attended a follow-up examination (including both a questionnaire and a clinic examination) between 2004 and 2007, during which HRQoL was assessed. Participants were classified as underweight (<18.5 kg m−2), normal weight (18.5 to <23 kg m−2), overweight (23 to <25 kg m−2), moderate obese (25 to <30 kg m−2) and severe obese (⩾30 kg m−2). HRQoL was measured using the Short-Form 36-item questionnaire (SF-36) physical component summary score (PCS) and mental component summary score (MCS). Linear regressions with and without adjusting for other covariates were used to evaluate the association between BMI and SF-36 PCS and MCS.Results:Compared with participants with normal weight, moderate or severe obesity was associated with 0.8 points (95% confidence interval (CI): −1.5 to −0.1, P=0.03) and 2.1 points lower PCS (95% CI: −3.1 to −0.1, P<0.001), respectively, after adjustment for sociodemographic variables, family functioning measure scores and the presence of chronic diseases. These associations were greater in women than in men. In contrast, being underweight was associated with 1.3 points lower MCS (95% CI: −2.3 to −0.3, P=0.014).Conclusions:In this study (one of few studies in the Asia-Pacific region), obesity was associated with lower PCS and the effect was modified by gender but not ethnicity, such that the association was greater in women than in men. However, obesity was not associated with MCS. Underweight was associated with reduced MCS but not PCS.

The association of body mass index with health-related quality of life: an exploratory study in a multiethnic Asian population

OBJECTIVES To evaluate the association between body mass index (BMI) and health-related quality of life (HRQoL) in a multiethnic Asian population in Singapore, and to explore if the World Health Organization (WHO) recommendation of alternative BMI cutoffs for Asians could be further strengthened by evidence of higher risk of impaired HRQoL using these criteria. METHODS Consenting English, Chinese, Malay and Tamil-speaking primary care patients (age >or= 21 years) were interviewed using English/their respective mother tongue versions of the EQ-5D/EQ-VAS, Health Utilities Index (HUI2 & HUI3) and the SF-6D. We first evaluated the relationship between BMI and HRQoL (overall and individual attributes for each instrument) using multiple linear/logistic regression (where appropriate) to adjust for factors known to affect HRQoL. We next reorganized BMI into five categories (reflecting the differences in cutoffs between International/Asian classifications) and evaluated if median HRQoL scores were significantly different across these categories. RESULTS Among 411 participants [response rate: 87%; median age: 51 years; obese: 19% (International); 33% (Asian)], after adjusting for sociodemographic and other factors, a tendency for underweight and obese subjects to report lower overall HRQoL scores was observed for most instruments. At the individual attribute level, obese subjects reported significantly lower HUI2 pain scores (regression coefficient: -0.035, P = 0.029) and greater odds of reporting problems for SF-6D role-limitations (odds ratio: 2.9, P = 0.005). Median overall HRQoL scores were not significantly different across the five BMI categories. CONCLUSION Consistent with available studies, obese subjects reported worse HRQoL than normal-weight subjects. That underweight subjects also reported worse HRQoL is interesting and requires confirmation. HRQoL was similar in Asians using either WHO criteria.

The impact of corrected and uncorrected refractive error on visual functioning: the Singapore Malay Eye Study.

PURPOSE To determine the impact of corrected and uncorrected myopia and hyperopia on visual functioning in an urban Malay population. METHODS The Singapore Malay Eye Study is a population-based, cross-sectional study of Singaporean Malays aged 40 to 80 years. Myopia was defined as spherical equivalence (SE) <or= -0.50 D, hyperopia as SE > 1.0 D, and emmetropia as SE -0.5 to 1.0 D in the better eye. Uncorrected myopia and hyperopia were defined as at least a 2-line difference between habitual and best corrected VA in persons with myopia or hyperopia, respectively. Visual functioning was assessed with the VF-11 scale. RESULTS Of 2912 participants, 441 (15.1%) and 213 (7.3%) had corrected or uncorrected hyperopia and 333 (11.4%), and 131 (4.5%) had corrected or uncorrected myopia, respectively. Of those, 249 (8.6%) participants were considered emmetropic with a >2-line difference between habitual and best corrected vision, and 1543 (53.1%) participants had a <or=2-line difference. In linear regression models adjusted for age, sex, educational attainment, ocular conditions, and nonocular comorbidity, only uncorrected myopia was independently associated with poorer overall visual functioning (beta regression coefficient = -0.34; P <or= 0.001) and with activities such as reading street signs (beta = -0.47; 95% CI: -0.62 to -0.33; P < 0.001), recognizing friends (beta = -0.52; 95% CI: -0.67 to -0.37; P < 0.001), and watching television (beta = -0.33; 95% CI: -0.44 to -0.22; P < 0.001). These findings were replicated in a healthy subsample with no other eye conditions and nonocular comorbidities (n = 1112). CONCLUSIONS Adequate myopia correction can improve participation in daily living and visual functioning in people with myopia. Correction of hyperopia does not have this effect.

Factor structure of the Singapore English version of the KINDL® children quality of life questionnaire

BackgroundQuality of life (QoL) outcomes are useful in the assessment of physical, mental and social well-being and for informed healthcare decision making. However, few studies have evaluated QoL issues among Asian children due largely to the lack of culturally valid and reliable QoL questionnaires. Hence, we aimed to report the psychometric properties, in particular factor structure, of KINDL (Singapore) questionnaires among school-going children.MethodsStudents aged 8–16 years from participating schools were selected by convenience sampling. Subjects self-completed KINDL-Kid (Singapore) and KINDL-Kiddo (Singapore) questionnaires, which were cross-culturally adapted from KINDL (Germany English) for use in Singapore. We evaluated floor and ceiling effects, internal consistency and performed factor analysis.ResultsA total of 328 respondents (mean (SD) age: 9.6 (1.31) years; 67% female; 75% Chinese, 16% Malays, 9% Indians and others) completed KINDL-Kid while 1,026 respondents (mean (SD) age: 14.0 (1.00) years; 82% female; 82% Chinese, 12% Malays; 6% Indians and others) completed KINDL-Kiddo. Mean (SD) TOTAL QoL score was 65.5 (12.76) and 56.6 (11.92) for KINDL-Kid and KINDL-Kiddo, respectively. Floor and ceiling effects were important in five of six KINDL-Kid and two of six KINDL-Kiddo subscales. Reliability coefficients ranged from 0.40 to 0.71 (KINDL-Kid) and 0.44 to 0.84 (KINDL-Kiddo). Factor analysis generated eight and seven factors in KINDL-Kid and KINDL-Kiddo, respectively.ConclusionKINDL-Kiddo exhibited good psychometric properties and may be used to assess QoL in this multi-ethnic English-speaking Asian population. However, psychometric properties of KINDL-Kid may need to be improved either by developing new items or modifying existing items.

The EQ-5D (Euroqol) is a valid generic instrument for measuring quality of life in patients with dyspepsia

BackgroundThere is little information of the validity of generic instruments in measuring health-related quality of life (HRQOL) in patients with dyspepsia. We aimed to assess the reliability and validity of the EQ-5D, a brief and simple instrument, in measuring HRQOL in adult patients with dyspepsia.MethodsConsecutive adults with dyspepsia attending the Gastroenterology clinic in a tertiary referral center were interviewed with the EQ-5D (both English and Malay versions), the short-form Nepean Dyspepsia Index (SF-NDI), the SF-36 and Leeds Dyspepsia Questionnaire (LDQ). Known-groups and convergent construct validity were investigated by testing hypotheses at attribute and overall levels. A repeat telephone interview was conducted 2 weeks later to assess test-retest reliability.ResultsA total of 113 patients (mean (SD) age: 53.7 (14) years; 49.5% male; 24.8% Malays, 37.2% Chinese; 70.8% functional dyspepsia) were recruited. Response rate was 100% with nil missing data. Known-groups validation revealed 20/26 hypotheses fulfillment. Patients with more severe dyspepsia reported more problems with their usual activity (p = 0.07) and pain (p = 0.06) and demonstrated lower median VAS scores (60 vs 70, p = 0.002) and EQ-5D utility scores (0.72 vs 0.78, p = 0.002). Those reporting problems in various EQ-5D dimensions had significantly lower scores in relevant SF-36 and SF-NDI dimensions. The overall EQ-5D utility score also demonstrated good correlation with the SF-36 summary physical and mental scores and the SF-NDI total score. Intraclass correlation coefficient for test-retest reliability was 0.66 (95% CI = 0.55 – 0.76).ConclusionThe EQ-5D is an acceptable, valid and reliable generic instrument for measuring HRQOL in adult patients with dyspepsia.