Biomedical subjects

D Machin

Publications and source records attributed to D Machin.

At least 37 records · Page 2Linked to original sources

PubMed2002

Measuring health-related quality of life in Singapore: normal values for the English and Chinese SF-36 Health Survey.

OBJECTIVE: To determine norms for assessing Health-related Quality of Life (HRQOL) in Singapore using the Short Form 36 Health Survey (SF-36). MATERIALS AND METHODS: Mean SF-36 scores were calculated for 24 population subgroups (categorised by age, gender, ethnicity and questionnaire language) and for subjects with self-reported co-morbid conditions using data from a community-based survey in Singapore. RESULTS: The English and Chinese SF-36 was completed by 4122 and 1381 subjects, respectively, 58% (n = 3188) of whom had self-reported co-morbid conditions. SF-36 scores varied in subgroups differing in age, gender and ethnicity. In general, subjects with self-reported co-morbid conditions had lower SF-36 scores than those without these conditions, the magnitude of which exceeded 20 points in several instances. A method for calculation of SF-36 scores adjusted for age, gender, ethnicity and questionnaire language is described. CONCLUSION: We present norms for English and Chinese SF-36 versions in Singapore and describe potential uses for these data in assessing HRQOL in Singapore.

Adult↗

PubMed2002

Angular regression and the detection of the seasonal onset of disease.

BACKGROUND: In examining the seasonality of onset of a disease over the year, investigators attempt to identify the peak of onset, and its magnitude. A second objective is to see if the day in which the disease manifests itself is related to subject-specific characteristics or environmental factors. METHOD: This paper describes appropriate statistical methodology for the situation where seasonality can be summarised by either a single peak or several peaks, possibly determined by patient characteristics or external influences. The circular, rather than linear, nature of the day of onset of a disease (irrespective of year) requires angular regression techniques to assess these relations, and the von Mises distribution replaces the normal distribution in this context. RESULTS: The methods outlined are illustrated by a national study of those experiencing an attack of acute primary angle-closure glaucoma in Singapore. CONCLUSIONS: We recommend re-analyses of already published work on seasonality of disease using this angular methodology. We anticipate that this may provide both useful further insight into aspects of aetiology and case studies for the methods themselves.

Acute Disease↗

PubMed2001

A competing risk approach to the analysis of trials of alternative intra-uterine devices (IUDs) for fertility regulation.

The methods of survival analysis have had a profound influence on the way that studies concerned with the safety and efficacy of intra-uterine devices (IUDs) for fertility control have been designed, conducted, analysed and reported. For example, the Kaplan-Meier technique has been used to summarize the results of controlled clinical trials of alternative devices and the logrank test used to make any comparisons. A particular feature of IUD studies is the large number of possible causes of failure (reasons for discontinuation of the device). These lead to considerations of competing risks, where in this framework, the discontinuations are considered as competing causes of contraceptive failure. In this context, we compare the net and crude probability estimates of discontinuation rates using continuous time and argue for the routine use of the latter. We use data from a randomized multi-centre trialon the long-term safety and efficacy of two IUDs, TCu220C and TCu380A, for illustration.

Contraception↗

PubMed2001

Seasonal variation in breast cancer diagnosis in Singapore.

This study investigates seasonality in the diagnosis of 3219 female breast carcinoma cases reported between 1995-8 in Singapore. There is little evidence of marked seasonal variation. Angular regression suggested that observed differences in peak diagnosis with respect to menopausal status, tumour size, ER and PR status may be chance.

Adult↗

PubMed2001

Competing risks analysis of patients with osteosarcoma: a comparison of four different approaches.

In failure time studies involving a chronic disease such as cancer, several competing causes of mortality may be operating. Commonly, the conventional statistical technique of Kaplan-Meier, which is only meaningfully interpreted by assuming independence of failure types and the censoring mechanism, is employed in clinical research involving competing risks data. Some authors have advocated the use of a cause-specific cumulative incidence function which takes into account the existence of other events within a competing risks framework, without making any assumption about independence. Lunn and McNeil have proposed an approach based on an extension of the Cox proportional hazards regression, which enables direct comparisons between failure types. We have extended this approach to estimate cause-specific cumulative incidence. As it is often not easy to follow competing risks methodology in the literature, this paper sets out systematically the assumptions made and the steps taken to implement four different methods of analysing competing risks data using cumulative incidence rates or the Kaplan-Meier estimates of cause-specific failure probabilities. The data obtained from a randomized trial of patients with osteosarcoma were used to compare these four approaches. As illustrated using the osteosarcoma data, the estimates of the classical Kaplan-Meier methods have larger numerical values than the cause-specific cumulative incidence. On the other hand, estimates of the cause-specific cumulative incidence rates from the conventional method and the modified Cox method are highly comparable.

Adolescent↗

PubMed2001

Evaluating the role of alternative therapy in burn wound management: randomized trial comparing moist exposed burn ointment with conventional methods in the management of patients with second-degree burns.

CONTEXT: Moist exposed burn ointment (MEBO), from China, has been said to revolutionize burn management. OBJECTIVE: Our study was conducted to compare MEBO with conventional management (C) with respect to the rate of wound healing, antibacterial and analgesic effect, and hospital costs. DESIGN: This is a prospective, randomized, controlled clinical trial conducted between 1 March 1997 and 24 October 1998. SETTING: The trial was conducted in a specialized burn facility located in a tertiary referral hospital in a developed and industrialized island-state in Southeast Asia. PATIENTS: We randomly assigned 115 consecutive patients between the ages of 12 and 80 who had partial-thickness thermal burns covering less than 40% of body surface area (BSA) to receive either MEBO or C. Fifty-seven patients were assigned to MEBO and 58 patients to C. The latter group received twice-daily dressing changes; MEBO patients received MEBO every 4 hours. MAIN OUTCOME MEASURES: Patients were hospitalized until 75% BSA had healed. BSA was determined by visual inspection and charted on Lund and Browder charts regularly. Wound healing rate, bacterial infection rate, pain score, and hospitalization costs were recorded. RESULTS: The median time to 75% healing was 17.0 and 20.0 days with MEBO and C, respectively (HR = 0.67, 95% CI = 0.41-1.11, P =.11), suggesting similar efficacy between the 2 modalities. Bacterial infection rates were similar between the 2 groups (HR = 1.10, 95% CI = 0.59-2.03, P =.76). MEBO imparted a greater analgesic effect in the first 5 days of therapy and reduced hospital costs by 8%. CONCLUSIONS: MEBO is as effective as conventional management but is not the panacea for all burn wounds. The use of MEBO eases the management of face and neck burns and facilitates early institution of occupational therapy in hand burns. It confers better pain relief such that fewer opiates are used during the first 5 days after burn injury.

Adult↗

PubMed2001

Seasonality of suicide in Singapore: data from the equator.

BACKGROUND: Studies in the northern and southern hemispheres consistently identify seasonal patterns in suicidal deaths. In many such studies, bimodal yearly peaks have been described for females as against unimodal ones for males. The current study examines the monthly variation in suicidal deaths in Singapore to determine if any seasonal patterns exist in an equatorial region. METHODS: Monthly suicidal death data over the decade 1989-98 were examined for the whole sample and for gender- and age-specific subgroups. Both von Mises' distribution and harmonic analysis techniques were used to interpret the data. RESULTS: Among the 2013 male and 1382 female suicides, there was minimal variation in patterning of suicidal deaths. We found a weak suggestion of a later peak for the females in mid-May as opposed to mid-February for the males, and the peaks for those less than 25 years of age were 5-6 months later than for the older age groups. The magnitude of all peaks was, however, very small suggesting chance variation. The harmonic analyses confirmed that patterning was 'randomly' rather than 'seasonally' determined. CONCLUSION: In an equatorial region, there was no evidence of any 'seasonal' patterning of suicidal deaths.

Adult↗

PubMed2001

A community-based study of scaling assumptions and construct validity of the English (UK) and Chinese (HK) SF-36 in Singapore.

Scaling assumptions and validity of the English (UK) and Chinese (HK) short form 36 health survey (SF-36) were assessed in a community-based survey of 5,503 Chinese, Malays and Indians in Singapore using the international quality of life assessment project approach of item and scale level validation. Missing data for SF-36 items and scales occurred in less than 1.0% of subjects. Item level validation of both versions generally supported assumptions underlying Likert scoring and hypothesised item-order clustering. Item level factor analysis supported the eight-scale structure of the SF-36. In scale level validation, SF-36 scale scores showed wide variability and acceptable internal-consistency reliability (Cronbach's alpha > 0.70 for six English and seven Chinese scales), conformed to hypothesised patterns and generally varied according to hypotheses in subjects known to differ in quality of life. Scale level factor analysis of both versions yielded very similar patterns of factor correlation, comparable to that found in Japan, but differing from that seen in Western populations. Taken together, these results support the validity of the English (UK) and Chinese (HK) SF-36 versions in the multi-ethnic Asian socio-cultural context of Singapore.

Adult↗

PubMed2001

Health-related quality of life of patients with endometrial cancer who are disease-free following external irradiation.

Health-related quality of life (HQoL) is assessed through the patients' own evaluation of the impact that a disease and its treatment may have on some of the physical, psychological and social aspects of their lives. The purpose of this study is to describe the HQoL of patients with endometrial cancer who are free of disease after undergoing external irradiation. An HQoL questionnaire was designed and validated, and consisted of the EORTC QLQ-C30 and 80 additional questions. The patients provided self-reported assessments at the end of radiotherapy, and 1, 3, 6, 12, 18 and 24 months later. Forty-nine out of 66 potential subjects participated in the study, which was confined to the period during which the, women were disease free. Most patients experience physical side effects at the end of treatment and up to 6 months thereafter; 10% of the patients have chronic local symptoms and a large number of the patients think about their treatment even two years later. The patients' overall evaluation of their quality of life is lower than that of a matched population of healthy women.

Adult↗

PubMed2000

Preface.

Explore the source record for details and available documents.

Journal Article↗

PubMed2000

Received dose and dose-intensity of chemotherapy and outcome in nonmetastatic extremity osteosarcoma. European Osteosarcoma Intergroup.

PURPOSE: To examine the relationship between received dose, received dose-intensity (RDI), and survival in patients with osteosarcoma. PATIENTS AND METHODS: Between 1983 and 1993, the European Osteosarcoma Intergroup (EOI) conducted two randomized trials involving patients with high-grade, nonmetastatic, biopsy-proven osteosarcoma of the extremity. These trials shared a common treatment arm of doxorubicin (DOX) 75 mg/m(2) and cisplatin (CDDP) 100 mg/m(2) planned for six cycles at 3-week intervals. Definitive surgery was scheduled at week 9, after three cycles. Survival time was calculated from 122 days, the scheduled end of chemotherapy. RESULTS: A total of 287 patients randomized to DOX/CDDP received at least one cycle of chemotherapy, and 232 (81%) received all six cycles. On average, 79% of the intended dose of DOX and 80% of the intended dose of CDDP was given. Mean time to completion of chemotherapy was 1.27 times that specified by the protocol. Mean RDI was 0.64 for DOX (SD = 0.19) and 0.65 for CDDP (SD = 0.18). Progression-free survival was lower for those who received one to five cycles compared with those who completed all six cycles (hazards ratio, 1.69; 95% confidence interval, 1.03 to 2.78). Survival and progression-free survival were lowest for patients with RDI less than 0.6, although these differences were not statistically significant at the 5% level. There was no clear evidence of preoperative dose or dose-intensity influencing histologic response. CONCLUSION: This analysis did not establish a clear survival benefit for increasing received dose or dose-intensity in the context of this two-drug regimen. The hypothesis that increasing dose-intensity may improve survival in osteosarcoma requires prospective evaluation.

Adolescent↗

PubMed2000

Anterior chamber depth measurement as a screening tool for primary angle-closure glaucoma in an East Asian population.

OBJECTIVE: To evaluate anterior chamber depth measurement as a method of screening for primary angle-closure glaucoma in an East Asian population. DESIGN: Two-phase, cross-sectional, community-based study. SETTING: Rural and urban locations in the Hovsgol and Omnogobi provinces, Mongolia. PARTICIPANTS: Nine hundred forty-two (94.2%) of 1000 individuals in Hovsgol(1995) and 775 (96.9%) of 1000 individuals in Omnogobi (1997) aged 40 years or older were examined. MAIN OUTCOME MEASURES: Anterior chamber depth was measured by optical pachymetry, slitlamp-mounted A-mode ultrasound, and handheld ultrasound. Gonioscopy was used to detect occludable angles, defined as one in which the trabecular meshwork was visible for less than 90 degrees of angle circumference. Primary open-angle glaucoma was diagnosed in subjects with an occludable angle and glaucomatous optic neuropathy with visual morbidity. The area under the curve in a receiver operating characteristic plot was used to compare test performance. RESULTS: Optical pachymetry outperformed the slitlamp-mounted ultrasound method of anterior chamber depth measurement (area under the curve, 0.93 and 0.90, respectively; z test, P = .001). Handheld ultrasound (area under the curve, 0.86) was inferior to optical measurement (z test, P = .001) but did not differ significantly from slitlamp ultrasound (z test, P = .06). The optical method gave sensitivity of 85% and specificity of 84% at a screening cutoff of less than 2.22 mm for detecting occludable angles. CONCLUSIONS: Measurement of axial anterior chamber depth can detect occludable angles in this Asian population and therefore may have a role in population screening for primary angle-closure glaucoma.

Adult↗

PubMed2000

The prevalence of glaucoma in Chinese residents of Singapore: a cross-sectional population survey of the Tanjong Pagar district.

BACKGROUND: Data on prevalence of glaucoma in East Asia are scarce. OBJECTIVE: To determine the prevalence and clinical characteristics of glaucoma in adult Chinese Singaporeans. METHODS: A group of 2000 Chinese people, aged 40 to 79 years, were selected from the electoral register of Tanjong Pagar district in Singapore using a disproportionate, stratified, clustered, random-sampling procedure. Glaucoma was diagnosed in people with an excavated optic neuropathy and a reproducible visual field defect or on the basis of severe structural disc abnormality alone, if reliable field results could not be obtained. The diagnosis was also made in blind subjects with raised intraocular pressure or previous glaucoma surgery. RESULTS: Of 1717 eligible subjects, 1232 were examined, with a response rate of 71.8%. There were 45 cases of glaucoma: 27 were men and 18 were women. The main diagnoses were primary open-angle glaucoma (n = 22 [49%]), primary angle-closure glaucoma (n = 14 [31%]), and secondary glaucoma (n = 7 [16%]). It was not possible to determine the mechanism in 2 (4%). CONCLUSIONS: The age-standardized prevalence of glaucoma was 3.2% (95% confidence interval, 2.3-4.1) in the population 40 years and older. Glaucoma was the leading cause of blindness. Primary angle-closure glaucoma and secondary glaucoma were the most visually destructive forms of the disease. Our findings suggest current projections of glaucoma prevalence among ethnic Chinese are a substantial underestimate. Arch Ophthalmol. 2000;118:1105-1111

Adult↗

PubMed2000

Obstructive sleep apnea syndrome in obese Singapore children.

We set out to determine the prevalence of obstructive sleep apnea syndrome (OSAS) among obese Singapore school children and identify risk factors for OSAS. This study was designed as a prospective study in three phases. Parents completed a questionnaire with regards to sleep and daytime symptoms in Phase 1. Children suspected to have OSAS based on the questionnaire and all with a percent ideal body weight (IBW) >/=180 were called for clinic visits in Phase 2. All whose percent IBW >/=180 and those in whom the physicians strongly suspected OSAS were subjected to a polysomnogram in phase 3. The children were recruited from the School Health Nutritional Clinic for obese children. The investigations were carried out at Tan Tock Seng Hospital. In all, 3,671 children were screened with the questionnaire. Of these, 146 were selected to undergo polysomnography. Twenty-six had abnormal sleep studies with apnea/hypoxia indices (AHIs) >5/hr. The significant clinical feature which correlated with OSAS was sleep sitting up (P = 0.005). The risk is higher in morbidly obese (IBW >/=180), with a prevalence of 13.3% (8/60), than in less obese children (IBW <180). One in eight (12.5%) of these children was asymptomatic and would have been missed based on the questionnaire. Presence of adenotonsillar hypertrophy led to increased risk of OSAS. The prevalence of OSAS was 0.7% (26/3,671) among the obese schoolchildren in Singapore, which is similar to the prevalence reported by others. Using discriminant analysis, the estimated prevalence increased to 5.7%. In the morbidly obese (IBW >/=180), the prevalence rate is higher at 13.3%.

Adenoids↗

PubMed2000

Neoadjuvant and adjuvant therapy for operable hepatocellular carcinoma.

OBJECTIVES: To determine the efficacy and adverse effects of different neoadjuvant and adjuvant therapies compared to surgery alone or surgery and placebo/supportive therapy when given to improve relapse and survival rates for operable hepatocellular carcinoma. SEARCH STRATEGY: Electronic databases, conference proceedings, bibliographies of identified publications. SELECTION CRITERIA: All truly randomised and quasi-randomised clinical trials that compared hepatocellular carcinoma patients who were given and not given neoadjuvant/adjuvant therapy as a supplement to curative liver resection. DATA COLLECTION AND ANALYSIS: Study data was extracted independently by two reviewers and discrepancies were resolved by consensus. A total of eight randomised controlled clinical trials were identified, totaling 548 randomised patients. Seven of the eight trials reported survival and disease-free survival curves and the results of hypothesis testing (log-rank test). The remaining trial reported only the mean survival times. None reported the hazard ratio and only one did a sample size calculation. The survival and disease-free survival curves were compared using their one, two and three-year survival rates, median survival times and the result of the hypothesis tests. MAIN RESULTS: The size of the randomised clinical trials ranged from 40 to 115 subjects. Both preoperative (neoadjuvant) and postoperative (adjuvant), systemic and locoregional (+/- embolization), chemo- and immunotherapy interventions were tested. None were comparable in terms of both treatment regimen and participants selected, so no pooling was done. Only one regimen using preoperative transcatheter arterial chemoembolization with doxorubicin was approximately duplicated. Seven of the eight trials reported no survival benefit from adjuvant therapy. Only one trial reported a statistically significant difference for survival and disease-free survival for the treatment arm, but the results of both its arms were very poor when compared to other studies. Two of the trials that did not report any absolute survival advantage reported statistically significant differences in disease-free survival. Five of the eight trials did not perform intention-to-treat analysis. The highest toxicity rate was in a trial using oral 1-hexylcarbamoyl 5-fluorouracil which resulted in 12 out of 38 subjects stopping because of adverse events. REVIEWER'S CONCLUSIONS: There is no evidence for efficacy of any of the adjuvant protocols reviewed. In order to detect a realistic treatment advantage, larger trials will have to be conducted.

Antineoplastic Agents↗

PubMed2000

Life after radiotherapy: the psychological and social effects experienced by women treated for advanced stages of cervical cancer.

PURPOSE: The aim of this study was to describe the psychological and social reactions of women with advanced stages of cancer of the cervix during and after radiotherapy. METHODS: A questionnaire about health-related quality of life was used, which consisted of the EORTC QLQ-C30 and additional specific questions. One-hundred eighteen patients filled out the questionnaire at the end of treatment and 1, 3, 6, 12, 18, and 24 months later. The scores from the disease-free patients were compared to those from 236 healthy controls. RESULTS: Many patients experience psychological and social consequences at the end of treatment and 1 to 3 months later. Patients continue to think about their illness and treatment throughout the 24-month study period, but find it increasingly hard to share their worries with others. Their score on overall quality of life never reaches that of the controls. CONCLUSION: Disease-free patients treated for cancer of the cervix with radiotherapy have psychological reactions. The interpretation of the results should take into consideration that the patients change their personal frame of reference over the course of time. Professionals should be aware of patients' needs to talk about their disease long after treatment. Patients should be informed about the risk of psychological reactions. The more information about possible symptoms they receive the better their ability to cope with them should they arise.

Adaptation, Psychological↗

PubMed2000

Accuracy of clinical estimates of intraocular pressure in Chinese eyes.

PURPOSE: To investigate the validity of clinical estimates of intraocular pressure (IOP) in Chinese people. DESIGN: Prospective, cross-sectional, hospital-based in vivo study. PARTICIPANTS: Twenty-three ethnic Chinese adults (aged 35-82 years) undergoing routine phacoemulsification surgery were examined. TESTING: "True" IOP was measured with a solid-state hemodynamic monitor through a cannula in the anterior chamber. IOP was set successively to 10, 20, and 30 mmHg in each subject, using a reservoir of balanced salt solution. Intraocular pressure was simultaneously estimated by use of a hand-held applanation tonometer (Perkin's) and a Tono-Pen. The association between ocular biometric variables and measurement error was examined. MAIN OUTCOME MEASURES: The median of three readings at each IOP level was taken as the IOP estimate of each instrument. Measurement error was calculated as the mean difference (tonometer minus direct measurement). RESULTS: The error for the hand-held applanation tonometer was -1.6, -4.3 and -5.7 at 10, 20, and 30 mmHg, respectively. For the Tono-Pen the measurement error was +0.4, -2.0, and -4.1 at 10, 20, and 30 mmHg, respectively. We could identify no association between measurement error and corneal thickness or curvature, anterior chamber depth, or axial length. CONCLUSIONS: The applanation tonometer and Tono-Pen underestimate the true IOP in Chinese eyes. Error increases as true IOP increases. These tonometers do not give an accurate estimate of IOP in East Asians.

Adult↗

PubMed2000

A clinical model for quality of life assessment in cancer patients receiving chemotherapy.

BACKGROUND: The pattern of symptoms experienced by cancer patients during chemotherapy is very complex. Consequently, quality of life (QOL) assessment has to be carefully planned to capture clinically relevant changes. PATIENTS AND METHODS: A clinical model of changes in symptoms experienced by symptomatic metastatic patients during several courses of chemotherapy has been developed. The model differentiates cancer-related symptoms, acute side-effects, chronic side-effects and symptoms not related to cancer. The model was used to predict changes in each of these four symptom groups. Three time points were selected (post-cycle 2, pre-cycle 3, post-cycle 5) and an appropriate window around each time point was set. The model predictions were tested empirically with 56 patients with advanced ovarian cancer who completed the EORTC QLQ-C30 plus disease specific items during a six-cycle course of chemotherapy. RESULTS: The changes observed in the sample were in accordance with the changes predicted by the clinical model. Results from patients who did not complete the questionnaire within the specified time windows tended to dilute the findings from the group who did. CONCLUSIONS: A clinical model is useful in the planning of QOL assessments in order to capture clinically relevant effects. Such models also facilitate the interpretation of QOL studies, particularly when cyclic short-term effects and chronic side-effects are overlaid on disease symptoms, as is the case with chemotherapy for cancer.

Antineoplastic Agents↗