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Biomedical subjects

Yin-Bun Cheung

Publications and source records attributed to Yin-Bun Cheung.

At least 19 recordsLinked to original sources
PubMed2006

Are Asians comfortable with discussing death in health valuation studies? A study in multi-ethnic Singapore.

BACKGROUND: To characterize ease in discussing death (EID) and its influence on health valuation in a multi-ethnic Asian population and to determine the acceptability of various descriptors of death and "pits"/"all-worst" in health valuation. METHODS: In-depth interviews (English or mother-tongue) among adult Chinese, Malay and Indian Singaporeans selected to represent both genders and a wide range of ages/educational levels. Subjects rated using 0-10 visual analogue scales (VAS): (1) EID, (2) acceptability of 8 descriptors for death, and (3) appropriateness of "pits" and "all-worst" as descriptors for the worst possible health state. Subjects also valued 3 health states using VAS followed by time trade-off (TTO). The influence of sociocultural variables on EID and these descriptors was studied using univariable analyses and multiple linear regression (MLR). The influence of EID on VAS/TTO utilities with adjustment for sociocultural variables was assessed using MLR. RESULTS: Subjects (n = 63, 35% Chinese, 32% Malay, median age 44 years) were generally comfortable with discussing death (median EID: 8.0). Only education significantly influenced EID (p = 0.045). EID correlated weakly with VAS/TTO scores (range: VAS: -0.23 to 0.07; TTO: -0.14 to 0.11). All subjects felt "passed away", "departed" and "deceased" were most acceptable (median acceptability: 8.0) while "sudden death" and "immediate death" were least acceptable (median acceptability: 5.0). Subjects clearly preferred "all-worst" to "pits" (63% vs. 19%, p < 0.001). CONCLUSION: Singaporeans were generally comfortable with discussing death and had clear preferences for several descriptors of death and for "all-worst". EID is unlikely to influence health preference measurement in health valuation studies.

Adult↗
PubMed2005

Variability and sample size requirements of quality-of-life measures: a randomized study of three major questionnaires.

PURPOSE: To compare the variability and sample size requirements of the global quality-of-life (QOL) scores of the following three major QOL instruments: the Functional Assessment of Cancer Therapy-General (FACT-G), Functional Living Index-Cancer (FLIC), and European Organisation for Research and Treatment of Cancer Core Quality of Life Questionnaire C30 (EORTC QLQ-C30). PATIENTS AND METHODS: Cancer patients were randomly assigned to answer two of the three instruments using an incomplete block design (n = 1,268). The instruments were compared in terms of coefficient of variation, effect size in detecting a difference between patients with different performance status, and correlation coefficient between scores at baseline and follow-up. RESULTS: The FACT-G and FLIC had significantly smaller coefficients of variation than the EORTC QLQ-C30 (both P < .05). The FLIC also had significantly larger correlation coefficients between scores at baseline and follow-up than the EORTC QLQ-C30 (P < .05). The FACT-G and the FLIC had a larger effect size in a cross-sectional and longitudinal setting, respectively, than the EORTC QLQ-C30 in differentiating patients with different performance status (both P < .05). CONCLUSION: In some aspects, the FACT-G and FLIC global QOL scores had smaller variability and larger discriminative ability than the EORTC QLQ-C30. Further research using other criteria to compare the three instruments is recommended.

Female↗
PubMed2005

Order effects: a randomised study of three major cancer-specific quality of life instruments.

BACKGROUND: In methodological studies and outcomes research, questionnaires often comprise several health-related quality of life (HRQoL) measures. Previous psychological studies have suggested that changing the sequential order of measurement scales within a questionnaire could alter the pattern of responses. Yet, information on the presence or absence of order effects on the assessment of HRQoL in cancer patients is limited. METHODS: An incomplete block design was used in this study of 1277 cancer patients. Each patient filled out a questionnaire package that contained two of the three major cancer-specific HRQoL instruments, namely the Functional Assessment of Cancer Therapy--General, the European Organization for the Research and Treatment of Cancer Core Quality of Life Questionnaire and the Functional Living Index--Cancer. Within a questionnaire package the sequential order of the instruments contained were randomised. Measurement properties of the instruments, including the number of missing values, mean HRQoL scores, known-groups validity and internal consistency were compared between samples of different presentation orders. RESULTS: No effect of presentation order on the four properties aforementioned was found. CONCLUSION: Presentation order is unlikely to alter the responses to these HRQoL instruments administered in cancer patients when any two of them are used together.

Activities of Daily Living↗
PubMed2005

Phase II study of irinotecan (CPT-11) as salvage therapy for advanced nasopharyngeal carcinoma.

BACKGROUND: This Phase II study was designed to evaluate the efficacy and safety of irinotecan in patients with advanced nasopharyngeal carcinoma (NPC). METHODS: Patients with disseminated, undifferentiated NPC that progressed during or within 3 months of platinum-based and/or taxane-based regimen were eligible. Irinotecan at a dose of 100 mg/m(2) was administered on Days 1, 8, and 15 every 28 days, up to a maximum of 6 cycles, until disease progression or the appearance of intolerable toxicity. RESULTS: Twenty-eight patients were evaluable for toxicity and response. Patient characteristics were as follows: The median age was 46.5 years (range, 40.3-71.6 years), the median number of prior lines of chemotherapy was 2 (range, 1-9), the majority of patients (89%) had good Eastern Cooperative Oncology Group performance status (0-1), and the majority of patients (82.1%) had >/= 2 sites of distant metastases. A total of 79 cycles of irinotecan with a median of 3 cycles per patient were administered. Toxicity > Grade 3 included neutropenia in 5 patients (17%), anemia in 5 patients (17%), and diarrhea in 4 patients (14%). The best response outcomes were 4 patients (14%) who achieved partial responses and 1 patient (4%) who achieved stable disease. Global quality-of-life scores were stable during treatment. Using the Kaplan-Meier method, the median progression-free survival was 3.9 months, and the median overall survival was 11.4 months. The partial responders had a durable response (range, 5.7-12.2 months). CONCLUSIONS: Results from this trial suggest that irinotecan is an active salvage agent with modest toxicity in patients with advanced NPC who are refractory to platinum/taxane-based chemotherapy. Studies combining irinotecan with other active agents in the first-line setting are warranted.

Adult↗
PubMed2005

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?

BACKGROUND: Diabetes 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). METHODS: Using 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. RESULTS: Among 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. CONCLUSION: DM 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.

Adult↗
PubMed2005

Does being bilingual in English and Chinese influence changes in quality of life scale scores? Evidence from a prospective, population based study.

BACKGROUND: Bilinguals differ from monolinguals in language use, but the influence of bilingualism on changes in Health-Related Quality of Life (HRQoL) scores is not known. OBJECTIVE: To determine the influence of bilingualism on changes in HRQoL scores. RESEARCH DESIGN: A prospective cohort study of a population-based, disproportionately stratified random sample of monolingual or bilingual ethnic Chinese who completed the Short-Form 36 Health Survey (SF-36) in English or Chinese twice in 2 years. Least squares regression models were used to assess the influence of bilingualism on SF-36 scores, while adjusting for the influence of questionnaire language and determinants of HRQoL. RESULTS: Usable English and Chinese questionnaires were returned by 1013 and 910 subjects respectively (aged 21-65 years, 48.5% female, 52.8% bilingual). Bilinguals differed from monolinguals in known determinants of HRQoL (being younger and better educated), changes in determinants of HRQoL over 2 years (more bilinguals had changes in work or marital status) and had mean SF-36 scores that were up to 10 points higher than monolinguals. After adjusting for these differences, bilingualism did not influence 2 year change scores for any of 8 SF-36 scales. CONCLUSION: Bilingualism did not influence changes in HRQoL scores over 2 years in this large, population-based study of subjects fluent in English and/or Chinese (representing an alphabet and/or pictogram based language respectively).

Adult↗
PubMed2005

Adrenal insufficiency in intestinal obstruction from carcinomatosis peritonei--a factor of potential importance in symptom palliation.

Corticosteroids are used in the management of intestinal obstruction (IO) in carcinomatosis peritonei. There is considerable overlap in the symptoms experienced in IO and functional adrenal insufficiency (AI). The success of symptom palliation in IO may be related to the presence of AI. The aim of this preliminary study was to evaluate the incidence of functional adrenal insufficiency in patients with IO and its relation to clinical outcome and symptom control. Twenty-nine consecutive patients with IO and carcinomatosis peritonei from gastrointestinal cancers admitted to our inpatient service between January and October 2002 were analyzed. They were screened for AI using the short corticotropin stimulation test. Thirteen patients (45%) had functional AI. Differences in characteristics of patients with normal adrenal function (Group 1) and adrenal insufficiency (Group 2) were not statistically significant. Time taken to control symptoms in Group 2 was longer. Mean duration of hospitalization per month of survival was two times longer in Group 2 relative to Group 1 (7.9 versus 4.0 days, P=0.011). Functional AI may be caused by cytokines produced in advanced cancer mediating direct adrenal suppression. Prompt corticosteroid therapy in the presence of AI may facilitate IO symptom palliation.

Adrenal Cortex Hormones↗
PubMed2005

Pharmacogenetic profiling across the irinotecan pathway in Asian patients with cancer.

AIMS: The aim of this exploratory study was to investigate associations between irinotecan pharmacokinetic parameters and allelic variants in genes encoding for drug transporters and drug metabolizing enzymes that are involved in irinotecan disposition in Asian patients with cancer. METHODS: Irinotecan was administered at 100 mg m(-2) over 90 min on a weekly schedule to 29 nasopharyngeal carcinoma patients and pharmacokinetic analysis was performed during the first cycle. All patients were genotyped for allelic variants in genes encoding drug metabolizing enzymes (CYP3A4, CYP3A5, UGT1A1) and drug transporters (ABCB1, ABCC2 and ABCG2) that are involved in irinotecan disposition. RESULTS: Of the six candidate genes that were analyzed, 11 genetic variants were found. Significant genotypic-phenotypic associations were apparent only for transporter genes. The C(max) of irinotecan was significantly lower in patients carrying the CC genotype at exon 26 of the ABCB1 gene compared with those harbouring at least one variant allele (P = 0.047). Patients harbouring the wild type ABCG2 CTCA genotype were associated with significantly higher values for relative extent of conversion (REC) of irinotecan to SN-38 compared with patients carrying at least one deletion CTCA allele (P = 0.019). CONCLUSIONS: The present exploratory study shows that genetic polymorphisms in drug transporter genes, particularly in ABCB1 and ABCG2 genes, may be important in influencing the pharmacokinetics of irinotecan and its metabolites. The predictive value of the identified allelic variants in the ABCG2 and ABCB1 genes on irinotecan disposition should be further investigated in a larger patient population as well as in other ethnic populations.

ATP Binding Cassette Transporter, Subfamily G, Mem↗
PubMed2004

The equivalence and difference between the English and Chinese versions of two major, cancer-specific, health-related quality-of-life questionnaires.

BACKGROUND: English and Chinese are two of the most widely used primary languages in the world. Patients in many cancer centers have a variety of ethnic backgrounds and primary languages. The comparability of version 4 of the English and Chinese versions of the Functional Assessment of Cancer Therapy-General (FACT-G) and version 3 of the European Organization for the Research and Treatment of Cancer Core Quality of Life Questionnaire (EORTC QLQ-C30) have not been established. METHODS: In total, 1136 ethnic Chinese patients with cancer were recruited from the National Cancer Centre of Singapore. Patients chose to answer an English or Chinese questionnaire, according to their own preference. Multiple regression analysis was used to adjust for differences in demographic and health characteristics. Equivalence was confirmed if the 90% confidence intervals of the adjusted mean difference fell completely within an equivalence zone of +/- 0.25 standard deviations (SD). RESULTS: The English and Chinese versions of the Total, Emotional, and Functional Well Being Scales of the FACT-G and the Physical and Emotional Functioning Scales of the EORTC QLQ-C30 were equivalent. Scores for the other scales on the two questionnaires, at most, had a small differences that did not exceed 0.5 SD. Nevertheless, the Chinese translation of the question "I have a lack of energy" in the Physical Well Being Scale of the FACT-G produced results that differed from the results produced by the original English version. CONCLUSIONS: Data collected from English-speaking and Chinese-speaking respondents were capable of being pooled, and either version could be used for bilingual respondents. Nevertheless, the authors recommend modification of the Physical Well Being question that produced different results ("I have a lack of energy").

Asian People↗
PubMed2004

Does the 12-item General Health Questionnaire contain multiple factors and do we need them?

BACKGROUND: The 12-item General Health Questionnaire (GHQ-12) is widely used as a unidimensional instrument, but factor analyses tended to suggest that it contains two or three factors. Not much is known about the usefulness of the GHQ-12 factors, if they exist, in revealing between-patient differences in clinical states and health-related quality of life. METHODS: We addressed this issue in a cross-sectional survey of out-patients with psychological disorders in Singapore. The participants (n = 120) completed the GHQ-12, the Beck Anxiety Inventory, and the Short-Form 36 Health Survey. Confirmatory factor analysis was used to compare six previously proposed factor structures for the GHQ-12. Factor scores of the best-fitting model, as well as the overall GHQ-12 score, were assessed in relation to clinical and health-related quality of life variables. RESULTS: The 3-factor model proposed by Graetz fitted the data better than a unidimensional model, two 2-factor models, and two other 3-factor models. However, the three factors were strongly correlated. Their values varied in a similar fashion in relation to clinical and health-related quality of life variables. CONCLUSIONS: The 12-item General Health Questionnaire contains three factors, namely Anxiety and Depression, Social Dysfunction, and Loss of Confidence. Nevertheless, using them separately does not offer many practical advantages in differentiating clinical groups or identifying association with clinical or health-related quality of life variables.

Adult↗
PubMed2004

Concurrent chemoradiotherapy in locoregionally recurrent nasopharyngeal carcinoma.

PURPOSE: To analyze the results of concurrent chemoradiotherapy in patients with locoregional recurrent nasopharyngeal carcinoma. METHODS AND MATERIALS: We performed a retrospective analysis of 35 patients with locoregional recurrent nasopharyngeal carcinoma referred to our department between March 1994 and November 2002. Most patients were male (77%), Chinese (97%), and had undifferentiated carcinoma (89%). Most had extensive locally recurrent Stage rT3-T4 disease (66%) with a median age at recurrence of 49 years (range, 35-69 years). A repeat course of radiotherapy was given concurrently with cisplatin, with cisplatin/5-fluorouracil as consolidation treatment. Significant morbidities were present, including cranial nerve palsies due to extensive recurrent local disease before treatment of the recurrence. RESULTS: The response rate to concurrent chemoradiotherapy was 58% (29% complete response and 29% partial response). The 5-year progression-free and overall survival rate, calculated using the Kaplan-Meier method, was 15% and 26%, respectively. Only 3 patients developed systemic metastases. Grade 3-4 acute toxicities included emesis (9%) and neutropenia (14%), and Grade 3-4 late toxicities consisted of temporal lobe necrosis (3%), cranial neuropathy (6%), and endocrine abnormalities (14%). CONCLUSION: Concurrent chemoradiotherapy is feasible in a selected group of patients with locoregional recurrent NPC, but the risk of major late toxicities is significant.

Adult↗
PubMed2004

On the definition of gestational-age-specific mortality.

The "fetuses at risk" concept of gestational-age-specific mortality proposed by Yudkin et al. (Lancet 1987;1:1192-4) and extended by various researchers is becoming popular in perinatal and pediatric epidemiology. However, the definitions using this concept have led to a puzzling phenomenon in which mortality rates appear to increase monotonically with advancing gestational age. While proponents of this concept have highlighted the rationale for using as the denominator the number of fetuses at risk rather than that of fetuses delivered at a particular gestational week, many have not discussed how the numerator is derived. This article reviews various definitions of gestational-age-specific mortality rates. It points out that the definitions based on the concept of Yudkin et al. are indicators of short-term risk only. Furthermore, the seemingly monotonic positive association between mortality rates and gestational age is a misinterpretation. All of the definitions are valid when used and interpreted correctly. The choice of which definition to adopt depends on the specific issues one attempts to address. Calls for abandoning the conventional definitions are not justified.

Canada↗
PubMed2004

Are English- and Chinese-language versions of the SF-6D equivalent? A comparison from a population-based study.

OBJECTIVE: The goal of this study was to assess the equivalence of English- and Chinese-language versions of the SF-6D (a 6-dimensional health classification system based on the 36-Item Short Form Health Survey) using a model of equivalence proposed previously. METHODS: We analyzed data from a previously published, cross-sectional, population-based survey of ethnic Chinese in Singapore, using linear regression models to adjust for the influence of potential confounding variables. Based on equivalence clinical trial methods, measurement (ie, scale) and item equivalence were assessed by comparing 90% CIs of differences in scores due to language with predefined equivalence margins, that corresponded to the minimum clinically important difference for SF-6D utility and item scores. RESULTS: Data from 2,558 respondents (aged 21-65 years; 48.8% completed the English-language version) were analyzed. The utility scores of respondents using the English- or Chinese-language versions of the SF-6D had similar distribution patterns, with a mean (SD) utility score of 0.8 (0.12). Adjusted 90% CIs for differences in utility and item scores due to language fell within predefined equivalence margins, suggesting measurement and item level equivalence. The 90% CI for scale scores was -0.0089 to 0.0065 (range, 0.0154; equivalence margin, 0.033); the 90% CI for item scores varied from -0.0046 to -0.0020 (range, 0.0026; equivalence margin, 0.0036) for vitality to -0.0024 to 0.0037 (range, 0.0061; equivalence margin, 0.0088) for social functioning. Functional equivalence was suggested because the various aspects of equivalence proposed previously were demonstrated in this study. CONCLUSIONS: English- and Chinese-language versions of the SF-6D demonstrated item, measurement, and functional equivalence in this population-based study comparing 2 widely used languages with very different linguistic structures. This suggests that English and Chinese SF-6D scores can be pooled, thus increasing the representativeness and power of studies using the SF-6D, and providing a basis for studies to value health by obtaining SF-6D utility scores in Asian populations.

Adult↗
PubMed2004

Order effects in the assessment of quality of life in cancer patients.

Methodological studies and outcome research often include several health-related quality of life (HRQoL) measurement scales in one questionnaire. Psychological studies have previously demonstrated that changing the sequential order of measurement scales within a questionnaire can alter the pattern of responses. Little is known, however, about whether there are order effects on the assessment of HRQoL in cancer patients. Here we address this issue in a study of 190 Singaporean cancer patients who were assessed using two different HRQoL instruments placed in alternating sequence within a questionnaire package. Measurement properties of the instruments, including the number of missing values, means, variability, known-group validity and internal consistency, were compared in the two samples representing different presentation orders. The HRQoL instruments administered in different sequential orders appeared to be equivalent in several aspects. No major effect of presentation order on outcomes was shown. The reasons and implications of the absence of an order effect are discussed. We conclude that presentation order is unlikely to alter the responses to the two HRQoL instruments.

Analysis of Variance↗
PubMed2003

Elicitation of prior distributions for a phase III randomized controlled trial of adjuvant therapy with surgery for hepatocellular carcinoma.

A randomized, controlled clinical trial of radioactive iodine tagged with lipiodol in patients with resected hepatocellular carcinoma was criticized for its early stopping and resulting small sample size. To clarify its results, a new, larger multicenter trial was therefore proposed. This paper describes the elicitation of the pretrial opinions of the investigators involved in the new trial and the construction of appropriate clinical and skeptical prior distributions based on their responses. The prior distributions provide a useful tool in assessing the state of equipoise before the start of the trial. They can also be used in Bayesian analyses, both at the interim stage(s) as well as at the end of the trial. We illustrate these analyses, assuming that the data resulting from the new trial was the same as that obtained in the earlier trial when it was stopped.

Bayes Theorem↗
PubMed2003

Quick-FLIC--a short questionnaire for assessing quality of life of cancer patients.

Health-related quality of life instruments tend to include a great many items. This imposes a burden on the respondents as well as undermining response rate and data quality. In this study we developed a shortened version of the Functional Living Index-Cancer (FLIC), now called Quick-FLIC, and examined its measurement properties. A questionnaire package, self-administered by 140 patients, included the FLIC and the Functional Assessment of Cancer Therapy-General. A factor analysis and clinical judgement were used to shorten the FLIC, which included 22 items. Each subscale of FLIC was shortened to include two or three items only. The Quick-FLIC included a total of only 11 items. Nevertheless, the measurement properties of the Quick-FLIC and its subscales were comparable to those of the original FLIC. It is concluded that the shortening of established health-related quality of life instruments is viable in oncology research.

Adult↗
PubMedDate not supplied

The influence of ethnicity on health-related quality of life in diabetes mellitus: a population-based, multiethnic study.

OBJECTIVES: The aims of this study were to evaluate the influence of ethnicity on health-related quality of life (HRQoL) in diabetic participants using both profile [the Short-Form 36 (SF-36)] and single-index (the SF-6D) instruments and to evaluate the usefulness of the SF-6D as a summary measure for the SF-36. RESEARCH DESIGN AND METHODS: Using data from a cross-sectional, population-based survey of Chinese, Malay, and Indians in Singapore, we analyzed the influence of ethnicity and other variables on each SF-36 scale and SF-6D scores using linear regression models to adjust for the influence of known determinants of HRQoL. RESULTS: Data from 309 diabetic respondents were analyzed. Compared with other ethnicities, Indians were most likely to report impaired HRQoL. The unadjusted influence of ethnicity on HRQoL exceeded the minimum clinically important difference (MCID) for all SF-36 scales (MCID: 5 points) and the SF-6D (MCID: 0.033 points). After adjusting for gender, age, and education, the influence of Chinese ethnicity exceeded the MCID for all SF-36 scales, except vitality (VT) and mental health (MH), as well as for the SF-6D. The influence of Malay ethnicity exceeded the MCID only for the SF-36 MH scale and the SF-6D. The influence of ethnicity on HRQoL persisted after adjusting further for other determinants of HRQoL. The SF-6D reflected the ethnic trends for some but not all SF-36 scales. CONCLUSIONS: After adjusting for demographic, socioeconomic, and other factors known to influence HRQoL, ethnicity remained an important factor influencing HRQoL in this population-based multiethnic sample of diabetic Asians. Further studies to identify modifiable factors explaining the ethnic disparities in HRQoL among diabetic participants are needed. The SF-6D may be a useful summary measure for the SF-36.

Adult↗