Browsing by Author "Matchar, David B"

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Open Access
A Cost-Effectiveness Analysis of a Randomized Control Trial of a Tailored, Multifactorial Program to Prevent Falls Among the Community-Dwelling Elderly.
(Archives of physical medicine and rehabilitation, 2019-01) Matchar, David B; Eom, Kirsten; Duncan, Pamela W; Lee, Mina; Sim, Rita; Sivapragasam, Nirmali R; Lien, Christopher T; Ong, Marcus Eng Hock
Objective
To perform a cost-effectiveness analysis of a multifactorial, tailored intervention to reduce falls among a heterogeneous group of high-risk elderly people.
Design
Randomized control trial.
Settings
Communities.
Participants
Adults aged at least 65 years (N=354) seen at the emergency department (ED) for a fall or fall-related injury and discharged home.
Interventions
The intervention group received a tailored program of physical therapy focused on progressive training in strength, balance, and gait for a period of 3 months. They also received screening and referrals for low vision, polypharmacy, and environmental hazards. The Short Physical Performance Battery (SPPB) test was assessed at regular intervals to allocate participants into either a home-based or group center-based program. The control group received usual care prescribed by a physician and educational materials on falls prevention.
Main outcome measures
The incremental cost-effectiveness ratio (ICER) over the 9-month study period based on intervention costs and utility in terms of quality-adjusted life years (QALYs) calculated from EuroQol-5D scores.
Results
The ICER was 120,667 Singapore dollars (S$) per QALY gained (S$362/0.003 QALYs), above benchmark values (S$70,000). However, the intervention was more effective and cost-saving among those with SPPB scores of greater than 6 at baseline, higher cognitive function, better vision and no more than 1 fall in the preceding 6 months. The intervention was also cost-effective among those with 0-1 critical comorbidities (S$22,646/QALY).
Conclusion
The intervention was, overall, not cost-effective, compared to usual care. However, the program was cost-effective among healthier subgroups, and even potentially cost-saving among individuals with sufficient reserve to benefit.
Open Access
A new instrument for measuring anticoagulation-related quality of life: development and preliminary validation.
(Health Qual Life Outcomes, 2004-05-06) Samsa, Greg; Matchar, David B; Dolor, Rowena J; Wiklund, Ingela; Hedner, Ewa; Wygant, Gail; Hauch, Ole; Marple, Cheryl Beadle; Edwards, Roger
BACKGROUND: Anticoagulation can reduce quality of life, and different models of anticoagulation management might have different impacts on satisfaction with this component of medical care. Yet, to our knowledge, there are no scales measuring quality of life and satisfaction with anticoagulation that can be generalized across different models of anticoagulation management. We describe the development and preliminary validation of such an instrument - the Duke Anticoagulation Satisfaction Scale (DASS). METHODS: The DASS is a 25-item scale addressing the (a) negative impacts of anticoagulation (limitations, hassles and burdens); and (b) positive impacts of anticoagulation (confidence, reassurance, satisfaction). Each item has 7 possible responses. The DASS was administered to 262 patients currently receiving oral anticoagulation. Scales measuring generic quality of life, satisfaction with medical care, and tendency to provide socially desirable responses were also administered. Statistical analysis included assessment of item variability, internal consistency (Cronbach's alpha), scale structure (factor analysis), and correlations between the DASS and demographic variables, clinical characteristics, and scores on the above scales. A follow-up study of 105 additional patients assessed test-retest reliability. RESULTS: 220 subjects answered all items. Ceiling and floor effects were modest, and 25 of the 27 proposed items grouped into 2 factors (positive impacts, negative impacts, this latter factor being potentially subdivided into limitations versus hassles and burdens). Each factor had a high degree of internal consistency (Cronbach's alpha 0.78-0.91). The limitations and hassles factors consistently correlated with the SF-36 scales measuring generic quality of life, while the positive psychological impact scale correlated with age and time on anticoagulation. The intra-class correlation coefficient for test-retest reliability was 0.80. CONCLUSIONS: The DASS has demonstrated reasonable psychometric properties to date. Further validation is ongoing. To the degree that dissatisfaction with anticoagulation leads to decreased adherence, poorer INR control, and poor clinical outcomes, the DASS has the potential to help identify reasons for dissatisfaction (and positive satisfaction), and thus help to develop interventions to break this cycle. As an instrument designed to be applicable across multiple models of anticoagulation management, the DASS could be crucial in the scientific comparison between those models of care.
Open Access
A Smartphone Application to Deliver a Treat-to-Target Insulin Titration Algorithm in Insulin-Naive Patients With Type 2 Diabetes: A Pilot Randomized Controlled Trial.
(Diabetes Care, 2016-10) Bee, Yong Mong; Batcagan-Abueg, Ada Portia M; Chei, Choy-Lye; Do, Young Kyung; Haaland, Benjamin; Goh, Su-Yen; Lee, Phong Ching; Chiam, Priscilla Pei Sze; Ho, Emily Tse Lin; Matchar, David B
Open Access
An evaluation of patient self-testing competency of prothrombin time for managing anticoagulation: pre-randomization results of VA Cooperative Study #481--The Home INR Study (THINRS).
(Journal of thrombosis and thrombolysis, 2010-10) Dolor, Rowena J; Ruybalid, R Lynne; Uyeda, Lauren; Edson, Robert G; Phibbs, Ciaran; Vertrees, Julia E; Shih, Mei-Chiung; Jacobson, Alan K; Matchar, David B; THINRS Site Investigators
Prior studies suggest patient self-testing (PST) of prothrombin time (PT) can improve the quality of anticoagulation (AC) and reduce complications (e.g., bleeding and thromboembolic events). "The Home INR Study" (THINRS) compared AC management with frequent PST using a home monitoring device to high-quality AC management (HQACM) with clinic-based monitoring on major health outcomes. A key clinical and policy question is whether and which patients can successfully use such devices. We report the results of Part 1 of THINRS in which patients and caregivers were evaluated for their ability to perform PST. Study-eligible patients (n = 3643) were trained to use the home monitoring device and evaluated after 2-4 weeks for PST competency. Information about demographics, medical history, warfarin use, medications, plus measures of numeracy, literacy, cognition, dexterity, and satisfaction with AC were collected. Approximately 80% (2931 of 3643) of patients trained on PST demonstrated competency; of these, 8% (238) required caregiver assistance. Testers who were not competent to perform PST had higher numbers of practice attempts, higher cuvette wastage, and were less able to perform a fingerstick or obtain blood for the cuvette in a timely fashion. Factors associated with failure to pass PST training included increased age, previous stroke history, poor cognition, and poor manual dexterity. A majority of patients were able to perform PST. Successful home monitoring of PT with a PST device required adequate levels of cognition and manual dexterity. Training a caregiver modestly increased the proportion of patients who can perform PST.
Open Access
Assessing risk of breast cancer in an ethnically South-East Asia population (results of a multiple ethnic groups study).
(BMC cancer, 2012-11-19) Gao, Fei; Machin, David; Chow, Khuan-Yew; Sim, Yu-Fan; Duffy, Stephen W; Matchar, David B; Goh, Chien-Hui; Chia, Kee-Seng
Background
Gail and others developed a model (GAIL) using age-at-menarche, age-at-birth of first live child, number of previous benign breast biopsy examinations, and number of first-degree-relatives with breast cancer as well as baseline age-specific breast cancer risks for predicting the 5-year risk of invasive breast cancer for Caucasian women. However, the validity of the model for projecting risk in South-East Asian women is uncertain. We evaluated GAIL and attempted to improve its performance for Singapore women of Chinese, Malay and Indian origins.
Methods
Data from the Singapore Breast Screening Programme (SBSP) are used. Motivated by lower breast cancer incidence in many Asian countries, we utilised race-specific invasive breast cancer and other cause mortality rates for Singapore women to produce GAIL-SBSP. By using risk factor information from a nested case-control study within SBSP, alternative models incorporating fewer then additional risk factors were determined. Their accuracy was assessed by comparing the expected cases (E) with the observed (O) by the ratio (E/O) and 95% confidence interval (CI) and the respective concordance statistics estimated.
Results
From 28,883 women, GAIL-SBSP predicted 241.83 cases during the 5-year follow-up while 241 were reported (E/O=1.00, CI=0.88 to 1.14). Except for women who had two or more first-degree-relatives with breast cancer, satisfactory prediction was present in almost all risk categories. This agreement was reflected in Chinese and Malay, but not in Indian women. We also found that a simplified model (S-GAIL-SBSP) including only age-at-menarche, age-at-birth of first live child and number of first-degree-relatives performed similarly with associated concordance statistics of 0.5997. Taking account of body mass index and parity did not improve the calibration of S-GAIL-SBSP.
Conclusions
GAIL can be refined by using national race-specific invasive breast cancer rates and mortality rates for causes other than breast cancer. A revised model containing only three variables (S-GAIL-SBSP) provides a simpler approach for projecting absolute risk of invasive breast cancer in South-East Asia women. Nevertheless its role in counseling the individual women regarding their risk of breast cancer remains problematical and needs to be validated in independent data.
Open Access
At-Home Versus In-Clinic INR Monitoring: A Cost-Utility Analysis from The Home INR Study (THINRS).
(Journal of general internal medicine, 2016-09) Phibbs, Ciaran S; Love, Sean R; Jacobson, Alan K; Edson, Robert; Su, Pon; Uyeda, Lauren; Matchar, David B; writing for the THINRS Executive Committee and Site Investigators
Background
Effective management of patients using warfarin is resource-intensive, requiring frequent in-clinic testing of the international normalized ratio (INR). Patient self-testing (PST) using portable at-home INR monitoring devices has emerged as a convenient alternative. As revealed by The Home INR Study (THINRS), event rates for PST were not significantly different from those for in-clinic high-quality anticoagulation management (HQACM), and a cumulative gain in quality of life was observed for patients undergoing PST.
Objective
To perform a cost-utility analysis of weekly PST versus monthly HQACM and to examine the sensitivity of these results to testing frequency.
Patients/interventions
In this study, 2922 patients taking warfarin for atrial fibrillation or mechanical heart valve, and who demonstrated PST competence, were randomized to either weekly PST (n = 1465) or monthly in-clinic testing (n = 1457). In a sub-study, 234 additional patients were randomized to PST once every 4 weeks (n = 116) or PST twice weekly (n = 118). The endpoints were quality of life (measured by the Health Utilities Index), health care utilization, and costs over 2 years of follow-up.
Results
PST and HQACM participants were similar with regard to gender, age, and CHADS2 score. The total cost per patient over 2 years of follow-up was $32,484 for HQACM and $33,460 for weekly PST, representing a difference of $976. The incremental cost per quality-adjusted life year gained with PST once weekly was $5566 (95 % CI, -$11,490 to $25,142). The incremental cost-effectiveness ratio (ICER) was sensitive to testing frequency: weekly PST dominated PST twice weekly and once every 4 weeks. Compared to HQACM, weekly PST was associated with statistically significant and clinically meaningful improvements in quality of life. The ICER for weekly PST versus HQACM was well within accepted standards for cost-effectiveness, and was preferred over more or less frequent PST. These results were robust to sensitivity analyses of key assumptions.
Conclusion
Weekly PST is a cost-effective alternative to monthly HQACM and a preferred testing frequency compared to twice weekly or monthly PST.
Open Access
Benefits of Population Segmentation Analysis for Developing Health Policy to Promote Patient-Centred Care.
(Annals of the Academy of Medicine, Singapore, 2017-07) Chong, Jia Loon; Matchar, David B
Open Access
Cable externalization and electrical failure of the Riata family of implantable cardioverter-defibrillator leads: A systematic review and meta-analysis.
(Heart rhythm, 2015-06) Zeitler, Emily P; Pokorney, Sean D; Zhou, Ke; Lewis, Robert K; Greenfield, Ruth Ann; Daubert, James P; Matchar, David B; Piccini, Jonathan P
Background
The Riata class of defibrillator leads were placed under US Food and Drug Association (FDA) advisory as of November 2011 because of high rates of cable externalization (CE) and electrical failure (EF). The overall rates of these complications remain unknown.
Objective
The purpose of this study was to systematically search the literature for rates of Riata lead failure and to perform a meta-analysis to estimate failure rates.
Methods
We conducted a meta-analysis of observational studies examining the rates of EF, CE, and the interaction of the two. We identified 23 English language manuscripts addressing 1 or more of these questions.
Results
Across 23 studies, the overall CE rate was 23.1% (95% confidence interval [CI] 19.0%-27.6%). The overall EF rate was 6.3% (95% CI 4.7%-8.2%). The presence of CE was associated with a more than 6-fold increase in the rate of EF compared to no CE (17.3% [95% CI 11.2%-25.9%] vs 2.7% [95% CI 1.4%-5.2%], respectively). The rate of CE was 3-fold higher for 8Fr leads compared to 7Fr leads, but rates of EF were similar (4.6%; 95% CI 3.2-6.6] and 3.9%; 95% CI 2.4-6.1], respectively). Rates of both CE and EF were higher in dual coil vs single coil leads, but confidence intervals overlapped.
Conclusion
In clinical practice, rates of CE in Riata leads are substantial. While CE is associated with a significant increase in the risk of EF, the incidence of EF without externalization is not trivial.
Open Access
Can caregivers report their care recipients' post-stroke hospitalizations and outpatient visits accurately? Findings of an Asian prospective stroke cohort.
(BMC health services research, 2018-10-25) Tyagi, Shilpa; Koh, Gerald Choon-Huat; Luo, Nan; Tan, Kelvin Bryan; Hoenig, Helen; Matchar, David B; Yoong, Joanne; Finkelstein, Eric A; Lee, Kim En; Venketasubramanian, N; Menon, Edward; Chan, Kin Ming; De Silva, Deidre Anne; Yap, Philip; Tan, Boon Yeow; Chew, Effie; Young, Sherry H; Ng, Yee Sien; Tu, Tian Ming; Ang, Yan Hoon; Kong, Keng He; Singh, Rajinder; Merchant, Reshma A; Chang, Hui Meng; Yeo, Tseng Tsai; Ning, Chou; Cheong, Angela; Ng, Yu Li; Tan, Chuen Seng
Background
Health services research aimed at understanding service use and improving resource allocation often relies on collecting subjectively reported or proxy-reported healthcare service utilization (HSU) data. It is important to know the discrepancies in such self or proxy reports, as they have significant financial and policy implications. In high-dependency populations, such as stroke survivors, with varying levels of cognitive impairment and dysphasia, caregivers are often potential sources of stroke survivors' HSU information. Most of the work conducted on agreement analysis to date has focused on validating different sources of self-reported data, with few studies exploring the validity of caregiver-reported data. Addressing this gap, our study aimed to quantify the agreement across the caregiver-reported and national claims-based HSU of stroke patients.
Methods
A prospective study comprising multi-ethnic stroke patient and caregiver dyads (N = 485) in Singapore was the basis of the current analysis, which used linked national claims records. Caregiver-reported health services data were collected via face-to-face and telephone interviews, and similar health services data were extracted from the national claims records. The main outcome variable was the modified intraclass correlation coefficient (ICC), which provided the level of agreement across both data sources. We further identified the amount of over- or under-reporting by caregivers across different service types.
Results
We observed variations in agreement for different health services, with agreement across caregiver reports and national claims records being the highest for outpatient visits (specialist and primary care), followed by hospitalizations and emergency department visits. Interestingly, caregivers over-reported hospitalizations by approximately 49% and under-reported specialist and primary care visits by approximately 20 to 30%.
Conclusions
The accuracy of the caregiver-reported HSU of stroke patients varies across different service types. Relatively more objective data sources, such as national claims records, should be considered as a first choice for quantifying health care usage before considering caregiver-reported usage. Caregiver-reported outpatient service use was relatively more accurate than inpatient service use over shorter recall periods. Therefore, in situations where objective data sources are limited, caregiver-reported outpatient information can be considered for low volumes of healthcare consumption, using an appropriate correction to account for potential under-reporting.
Open Access
Changes in Informed Consent Policy and Treatment Delays in Stroke Thrombolysis.
(Journal of stroke and cerebrovascular diseases : the official journal of National Stroke Association, 2020-12-18) Xu, Hanzhang; De Silva, Deidre Anne; Woon, Fung Peng; Ong, Marcus Eng Hock; Matchar, David B; Bettger, Janet Prvu; Laskowitz, Daniel T; Xian, Ying
Objectives
The efficacy of thrombolytic therapy with tissue plasminogen activator (tPA) is highly time dependent. Although clinical guidelines do not recommend written informed consent as it may cause treatment delays, local policy can supersede and require it. From 2014 to 2017, three out of five public hospitals in Singapore changed from written to verbal consent at different time points. We aimed to examine the association of hospital policy changes regarding informed consent on door-to-needle (DTN) times.
Materials and methods
Using data from the Singapore Stroke Registry and surveys of local practice, we analyzed data of 915 acute ischemic stroke patients treated with tPA within 3 hours in all public hospitals between July 2014 to Dec 2017. Patient-level DTN times before and after policy changes were examined while adjusting for clinical characteristics, within-hospital clustering, and trends over time.
Results
Patient characteristics and stroke severity were similar before and after the policy changes. Overall, the median DTN times decreased from 68 to 53 minutes after the policy changes. After risk adjustment, changing from written to verbal informed consent was associated with a 5.6 minutes reduction (95% CI 1.1-10.0) in DTN times. After the policy changed, the percentage of patients with DTN ≤60 minutes and ≤45 minutes increased from 35.6% to 66.1% (adjusted OR 1.75; 95% CI 1.12-2.74) and 9.3% to 36.0% (adjusted OR 2.42; 95% CI 1.37-4.25), respectively.
Conclusion
Changing from written to verbal consent is associated with significant improvement in the timeliness of tPA administration in acute ischemic stroke.
Open Access
Chapter 11: challenges in and principles for conducting systematic reviews of genetic tests used as predictive indicators.
(Journal of general internal medicine, 2012-06) Jonas, Daniel E; Wilt, Timothy J; Taylor, Brent C; Wilkins, Tania M; Matchar, David B
In this paper, we discuss common challenges in and principles for conducting systematic reviews of genetic tests. The types of genetic tests discussed are those used to 1). determine risk or susceptibility in asymptomatic individuals; 2). reveal prognostic information to guide clinical management in those with a condition; or 3). predict response to treatments or environmental factors. This paper is not intended to provide comprehensive guidance on evaluating all genetic tests. Rather, it focuses on issues that have been of particular concern to analysts and stakeholders and on areas that are of particular relevance for the evaluation of studies of genetic tests. The key points include: The general principles that apply in evaluating genetic tests are similar to those for other prognostic or predictive tests, but there are differences in how the principles need to be applied or the degree to which certain issues are relevant. A clear definition of the clinical scenario and an analytic framework is important when evaluating any test, including genetic tests. Organizing frameworks and analytic frameworks are useful constructs for approaching the evaluation of genetic tests. In constructing an analytic framework for evaluating a genetic test, analysts should consider preanalytic, analytic, and postanalytic factors; such factors are useful when assessing analytic validity. Predictive genetic tests are generally characterized by a delayed time between testing and clinically important events. Finding published information on the analytic validity of some genetic tests may be difficult. Web sites (FDA or diagnostic companies) and gray literature may be important sources. In situations where clinical factors associated with risk are well characterized, comparative effectiveness reviews should assess the added value of using genetic testing along with known factors compared with using the known factors alone. For genome-wide association studies, reviewers should determine whether the association has been validated in multiple studies to minimize both potential confounding and publication bias. In addition, reviewers should note whether appropriate adjustments for multiple comparisons were used.
Open Access
Chapter 1: Introduction to the Methods Guide for Medical Test Reviews.
(Journal of general internal medicine, 2012-06) Matchar, David B
Evaluation of medical tests presents challenges distinct from those involved in the evaluation of therapies; in particular, the very great importance of context and the dearth of comprehensive RCTs aimed at comparing the clinical outcomes of different tests and test strategies. Available guidance provides some suggestions: 1) Use of the PICOTS typology for clarifying the context relevant to the review, and 2) use of an organizing framework for classifying the types of medical test evaluation studies and their relationship to potential key questions. However, there is a diversity of recommendations for reviewers of medical tests and a proliferation of concepts, terms, and methods. As a contribution to the field, this Methods Guide for Medical Test Reviews seeks to provide practical guidance for achieving the goals of clarity, consistency, tractability, and usefulness.
Open Access
Chapter 5: assessing risk of bias as a domain of quality in medical test studies.
(Journal of general internal medicine, 2012-06) Santaguida, P Lina; Riley, Crystal M; Matchar, David B
Assessing methodological quality is a necessary activity for any systematic review, including those evaluating the evidence for studies of medical test performance. Judging the overall quality of an individual study involves examining the size of the study, the direction and degree of findings, the relevance of the study, and the risk of bias in the form of systematic error, internal validity, and other study limitations. In this chapter of the Methods Guide for Medical Test Reviews, we focus on the evaluation of risk of bias in the form of systematic error in an individual study as a distinctly important component of quality in studies of medical test performance, specifically in the context of estimating test performance (sensitivity and specificity). We make the following recommendations to systematic reviewers: 1) When assessing study limitations that are relevant to the test under evaluation, reviewers should select validated criteria that examine the risk of systematic error, 2) categorizing the risk of bias for individual studies as "low," "medium," or "high" is a useful way to proceed, and 3) methods for determining an overall categorization for the study limitations should be established a priori and documented clearly.
Open Access
Chapter 7: grading a body of evidence on diagnostic tests.
(Journal of general internal medicine, 2012-06) Singh, Sonal; Chang, Stephanie M; Matchar, David B; Bass, Eric B
Introduction
Grading the strength of a body of diagnostic test evidence involves challenges over and above those related to grading the evidence from health care intervention studies. This chapter identifies challenges and outlines principles for grading the body of evidence related to diagnostic test performance.
Challenges
Diagnostic test evidence is challenging to grade because standard tools for grading evidence were designed for questions about treatment rather than diagnostic testing; and the clinical usefulness of a diagnostic test depends on multiple links in a chain of evidence connecting the performance of a test to changes in clinical outcomes.
Principles
Reviewers grading the strength of a body of evidence on diagnostic tests should consider the principle domains of risk of bias, directness, consistency, and precision, as well as publication bias, dose response association, plausible unmeasured confounders that would decrease an effect, and strength of association, similar to what is done to grade evidence on treatment interventions. Given that most evidence regarding the clinical value of diagnostic tests is indirect, an analytic framework must be developed to clarify the key questions, and strength of evidence for each link in that framework should be graded separately. However if reviewers choose to combine domains into a single grade of evidence, they should explain their rationale for a particular summary grade and the relevant domains that were weighed in assigning the summary grade.
Open Access
Cohort Profile: Panel on Health and Ageing of Singaporean Elderly (PHASE).
(International journal of epidemiology, 2019-12) Chan, Angelique; Saito, Yasuhiko; Matchar, David B; Østbye, Truls; Malhotra, Chetna; Ang, Shannon; Ma, Stefan; Malhotra, Rahul
Open Access
Community-Based Long-Term Care Services: If We Build It, Will They Come?
(Journal of aging and health, 2016-03) Liu, Chang; Eom, Kirsten; Matchar, David B; Chong, Wayne F; Chan, Angelique WM
Objective
This study examines the relationship between caregivers' perception of community-based long-term care (CBLTC) services and the service use.
Method
We used first two waves of the longitudinal data set of 1,416 dyads of care recipients and their caregivers in Singapore. Four perceived attributes of LTC services--service quality, convenience, social connectedness, and affordability--were measured on a 5-point scale.
Results
Among the four perceived attributes, perceived affordability was significantly associated with future utilization for all types of CBLTC services. Perceived service quality and convenience was significantly associated with center-based LTC services use.
Discussion
Caregivers are critically involved in the decision of using CBLTC services, and their perception of service characteristics is significantly associated with the uptake of CBLTC services. It is important to incorporate both care recipients' and caregivers' needs and preferences when designing and promoting integrated health care delivery models.
Open Access
Comorbid visual and cognitive impairment: relationship with disability status and self-rated health among older Singaporeans.
(Asia-Pacific journal of public health, 2014-05) Whitson, Heather E; Malhotra, Rahul; Chan, Angelique; Matchar, David B; Østbye, Truls
The objective of this study was to examine the prevalence and consequences of coexisting vision and cognitive impairments in an Asian population. Data were collected from 4508 community-dwelling Singaporeans aged 60 years and older. Cognition was assessed by the Short Portable Mental Status Questionnaire whereas vision, disability, and self-rated health (SRH) were determined by self-report. Vision impairment was present in 902 (18.5%) participants and cognitive impairment in 835 (13.6%), with 232 (3.5%) participants experiencing both impairments. Persons with the comorbidity experienced higher odds of disability than persons with either single impairment. The association of vision impairment with SRH was stronger among women (odds ratio [OR] = 6.79, 95% confidence interval [CI] = 4.64-9.92) than among men (OR = 1.71, 95% CI = 1.21-2.41). Concurrent cognitive and vision impairment is prevalent in older Singaporeans and is associated with high rates of disability. Gender differences in vision-dependent roles may affect the patient-perceived impact of this comorbidity.
Open Access
Cost Effectiveness of Universal Hepatitis B Virus Screening in Patients Beginning Chemotherapy for Sarcomas or GI Stromal Tumors.
(Journal of global oncology, 2016-08) Tan, Glorijoy; Zhou, Ke; Tan, Chee Hian; Matchar, David B; Farid, Mohamad; Quek, Richard; Ngeow, Joanne
Purpose
The value of screening for hepatitis B virus (HBV) infection before chemotherapy for nonhematopoietic solid tumors remains unsettled. We evaluated the cost effectiveness of universal screening before systemic therapy for sarcomas, including GI stromal tumors (GISTs).
Patients and methods
Drawing from the National Cancer Centre Singapore database of 1,039 patients with sarcomas, we analyzed the clinical records of 485 patients who received systemic therapy. Using a Markov model, we compared the cost effectiveness of a screen-all versus screen-none strategy in this population.
Results
A total of 237 patients were screened for HBV infection. No patients developed HBV reactivation during chemotherapy. The incremental cost-effectiveness ratio per quality-adjusted life-year (QALY) of offering HBV screening to all patients with sarcomas and patients with GISTs exceeded the cost-effectiveness threshold of SG$100,000 per QALY. This result was robust in one-way sensitivity analysis. Our results show that only changes in mortality rate secondary to HBV reactivation could make the incremental cost-effectiveness ratio cross the cost-effectiveness threshold.
Conclusion
Universal HBV screening in patients with sarcomas or GISTs undergoing chemotherapy is not cost effective at a willingness to pay of SG$100,000 per QALY and may not be required.
Open Access
Cost efficiency of anticoagulation with warfarin to prevent stroke in medicare beneficiaries with nonvalvular atrial fibrillation.
(Stroke, 2011-01) Mercaldi, Catherine J; Ciarametaro, Mike; Hahn, Beth; Chalissery, George; Reynolds, Matthew W; Sander, Stephen D; Samsa, Gregory P; Matchar, David B
Background and purpose
in controlled trials, anticoagulation with warfarin reduces stroke risk by nearly two thirds, but the benefit has been less pronounced in clinical practice. This report describes the extent of warfarin use, its effectiveness, and its impact on medical costs among Medicare patients with nonvalvular atrial fibrillation.
Methods
using claims from >2 million beneficiaries in the Centers for Medicare and Medicaid Services 5% Sample Standard Analytic Files, we identified patients with nonvalvular atrial fibrillation from 2004 to 2005. Warfarin use was inferred from 3 or more tests of the international normalized ratio within 1 year. Incidence of ischemic/hemorrhagic stroke and major bleeding was evaluated. Adjusted risk was calculated by Cox proportional-hazards regression. Medical costs (reimbursed amounts in 2006 US dollars) were estimated by multivariate linear regression.
Results
of patients with nonvalvular atrial fibrillation (N=119 764, mean age=79.3 years), 58.5% were categorized as warfarin users based on the study definition. During an average of 2.1 years' follow-up, the rate of ischemic stroke was 3.9 per 100 patient-years. After multivariate adjustment, ischemic stroke incidence was 27% lower in patients taking warfarin than in patients not taking warfarin (P<0.0001), with no increase in hemorrhagic stroke and a slightly elevated risk of a major bleed. Use of warfarin was independently associated with lower total medical costs, averaging $9836 per patient per year.
Conclusions
these results indicate that 41.5% of Medicare patients with nonvalvular atrial fibrillation are not anticoagulated with warfarin. The incidence of stroke and overall medical costs were significantly lower in patients treated with warfarin.
Open Access
Cost-Effectiveness of Drug-Coated Balloon Angioplasty Versus Conventional Balloon Angioplasty for Treating Below-the-Knee Arteries in Chronic Limb-Threatening Ischemia: The SINGA-PACLI Trial.
(Cardiovascular and interventional radiology, 2022-03-02) Sivapragasam, Nirmali; Matchar, David B; Zhuang, Kun Da; Patel, Ankur; Pua, Uei; Win, Hlaing Hlaing; Chandramohan, Sivanathan; Venkatanarasimha, Nanda; Chua, Jasmine ME; Tan, Glenn Wei Leong; Irani, Farah G; Leong, Sum; Tay, Kiang Hiong; Chong, Tze Tec; Tan, Bien Soo
Purpose
Drug-coated balloon angioplasty (DCBA) has been studied as a potentially superior option compared to conventional percutaneous transluminal angioplasty (PTA) in treating below-the-knee (BTK) arteries in chronic limb-threatening ischemia (CLTI). The aim of this study is to examine the cost-effectiveness of DCBA versus PTA in BTK arteries based on a randomized controlled trial.
Material and methods
A prospective economic study was embedded in a randomized controlled trial of 138 patients with CLTI. Resource use and health outcomes were assessed at baseline, and at 3, 6 and 12 months post-intervention. Costs were calculated from a societal perspective and health outcomes measured using quality-adjusted life years with probabilistic sensitivity analysis performed to account for subject heterogeneity.
Results
Compared with participants randomized to receive PTA, participants randomized to DCBA gained an average baseline-adjusted quality-adjusted life years (QALYs) of .012 while average total costs were USD$1854 higher; this translates to an incremental cost-effectiveness ratio (ICER) of US$154,500 additional cost per QALY gained. However, the estimate of ICER had substantial variance with only 48% of bootstrap ICERs meeting a benchmark threshold of US$57,705 (the average gross domestic product (GDP) per capita of Singapore).
Conclusion
The use of DCBA in BTK arteries in CLTI patients was not cost-effective compared with PTA.
Level of evidence
2, Randomized trial.

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