Browsing by Author "Zhou, Ke"

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    ItemOpen 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.
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    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.
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    Detecting Germline PTEN Mutations Among At-Risk Patients With Cancer: An Age- and Sex-Specific Cost-Effectiveness Analysis.
    (Journal of clinical oncology : official journal of the American Society of Clinical Oncology, 2015-08) Ngeow, Joanne; Liu, Chang; Zhou, Ke; Frick, Kevin D; Matchar, David B; Eng, Charis

    Purpose

    Cowden syndrome (CS) is an autosomal dominant disorder characterized by benign and malignant tumors. One-quarter of patients who are diagnosed with CS have pathogenic germline PTEN mutations, which increase the risk of the development of breast, thyroid, uterine, renal, and other cancers. PTEN testing and regular, intensive cancer surveillance allow for early detection and treatment of these cancers for mutation-positive patients and their relatives. Individual CS-related features, however, occur commonly in the general population, making it challenging for clinicians to identify CS-like patients to offer PTEN testing.

    Patients and methods

    We calculated the cost per mutation detected and analyzed the cost-effectiveness of performing selected PTEN testing among CS-like patients using a semi-quantitative score (the PTEN Cleveland Clinic [CC] score) compared with existing diagnostic criteria. In our model, first-degree relatives of the patients with detected PTEN mutations are offered PTEN testing. All individuals with detected PTEN mutations are offered cancer surveillance.

    Results

    CC score at a threshold of 15 (CC15) costs from $3,720 to $4,573 to detect one PTEN mutation, which is the most inexpensive among the different strategies. At base-case, CC10 is the most cost-effective strategy for female patients who are younger than 40 years, and CC15 is the most cost-effective strategy for female patients who are between 40 and 60 years of age and male patients of all ages. In sensitivity analyses, CC15 is robustly the most cost-effective strategy for probands who are younger than 60 years.

    Conclusion

    Use of the CC score as a clinical risk calculator is a cost-effective prescreening method to identify CS-like patients for PTEN germline testing.
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    High Suspicion Sub-Centimeter Thyroid Nodules: Cost-Effectiveness of Active Surveillance versus Fine Needle Aspiration.
    (Journal of vascular and interventional radiology : JVIR, 2022-11) Woon, Tian Kai; Zhou, Ke; Tan, Bien Soo; Matchar, David B

    Purpose

    To compare the cost-benefit of active surveillance (AS) against immediate fine needle aspiration (FNA) of sonographically suspicious sub-centimeter thyroid nodules.

    Methods

    A Markov model was constructed to compare the cost-benefit of three strategies from point of discovery till death: 1) Surveillance of All Nodules; 2) Surveillance of Nodules with Positive Cytology; and 3) Surgery of Nodules with Positive Cytology. The reference case was a 40 year-old female with a sonographically suspicious sub-centimeter thyroid nodule. Transition probabilities, costs, and health utilities were derived from the literature. Sensitivity analyses were performed to evaluate model uncertainty. Willingness-to-pay threshold was set at $100,000/quality-adjusted life year (QALY).

    Results

    Surveillance of Nodules with Positive Cytology dominated in the reference scenario, and was cost-beneficial over Surveillance of All Nodules independent of the utility of AS. Surveillance of All Nodules was cost-beneficial only at life expectancy <2.6 years or surveillance duration <4 years.

    Conclusion

    While current guidelines recommend AS of sonographically suspicious sub-centimeter nodules, this study's results suggest immediate FNA (Surveillance of Nodules with Positive Cytology) is more cost-beneficial compared to AS (Surveillance of All Nodules). Patients with positive cytology on FNA may subsequently opt for AS (Surveillance of Nodules with Positive Cytology) or surgery (Surgery of Nodules with Positive Cytology) according to their level of comfort (i.e. utility) with AS.
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    Left Atrial Appendage Occlusion Versus Oral Anticoagulation in Atrial Fibrillation : A Decision Analysis.
    (Annals of internal medicine, 2022-08) Chew, Derek S; Zhou, Ke; Pokorney, Sean D; Matchar, David B; Vemulapalli, Sreekanth; Allen, Larry A; Jackson, Kevin P; Samad, Zainab; Patel, Manesh R; Freeman, James V; Piccini, Jonathan P

    Background

    Left atrial appendage occlusion (LAAO) is a potential alternative to oral anticoagulants in selected patients with atrial fibrillation (AF). Compared with anticoagulants, LAAO decreases major bleeding risk, but there is uncertainty regarding the risk for ischemic stroke compared with anticoagulation.

    Objective

    To determine the optimal strategy for stroke prevention conditional on a patient's individual risks for ischemic stroke and bleeding.

    Design

    Decision analysis with a Markov model.

    Data sources

    Evidence from the published literature informed model inputs.

    Target population

    Women and men with nonvalvular AF and without prior stroke.

    Time horizon

    Lifetime.

    Perspective

    Clinical.

    Intervention

    LAAO versus warfarin or direct oral anticoagulants (DOACs).

    Outcome measures

    The primary end point was clinical benefit measured in quality-adjusted life-years.

    Results of base-case analysis

    The baseline risks for stroke and bleeding determined whether LAAO was preferred over anticoagulants in patients with AF. The combined risks favored LAAO for higher bleeding risk, but that benefit became less certain at higher stroke risks. For example, at a HAS-BLED score of 5, LAAO was favored in more than 80% of model simulations for CHA2DS2-VASc scores between 2 and 5. The probability of LAAO benefit in QALYs (>80%) at lower bleeding risks (HAS-BLED score of 0 to 1) was limited to patients with lower stroke risks (CHA2DS2-VASc score of 2). Because DOACs carry lower bleeding risks than warfarin, the net benefit of LAAO is less certain than that of DOACs.

    Results of sensitivity analysis

    Results were consistent using the ORBIT bleeding score instead of the HAS-BLED score, as well as alternative sources for LAAO clinical effectiveness data.

    Limitation

    Clinical effectiveness data were drawn primarily from studies on the Watchman device.

    Conclusion

    Although LAAO could be an alternative to anticoagulants for stroke prevention in patients with AF and high bleeding risk, the overall benefit from LAAO depends on the combination of stroke and bleeding risks in individual patients. These results suggest the need for a sufficiently low stroke risk for LAAO to be beneficial. The authors believe that these results could improve shared decision making when selecting patients for LAAO.

    Primary funding source

    None.
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    Optimal management of Riata leads with no known electrical abnormalities or externalization: a decision analysis.
    (Journal of cardiovascular electrophysiology, 2015-02) Pokorney, Sean D; Zhou, Ke; Matchar, David B; Love, Sean; Zeitler, Emily P; Lewis, Robert; Piccini, Jonathan P

    Introduction

    Riata and Riata ST implantable cardioverter-defibrillator (ICD) leads (St. Jude Medical, Sylmar, CA, USA) can develop conductor cable externalization and/or electrical failure. Optimal management of these leads remains unknown.

    Methods and results

    A Markov model compared 4 lead management strategies: (1) routine device interrogation for electrical failure, (2) systematic yearly fluoroscopic screening and routine device interrogation, (3) implantation of new ICD lead with capping of the in situ lead, and (4) implantation of new ICD lead with extraction of the in situ lead. The base case was a 64-year-old primary prevention ICD patient. Modeling demonstrated average life expectancies as follows: capping with new lead implanted at 134.5 months, extraction with new lead implanted at 134.0 months, fluoroscopy with routine interrogation at 133.9 months, and routine interrogation at 133.5 months. One-way sensitivity analyses identified capping as the preferred strategy with only one parameter having a threshold value: when risk of nonarrhythmic death associated with lead abandonment is greater than 0.05% per year, lead extraction is preferred over capping. A second-order Monte Carlo simulation (n = 10,000), as a probabilistic sensitivity analysis, found that lead revision was favored with 100% certainty (extraction 76% and capping 24%).

    Conclusions

    Overall there were minimal differences in survival with monitoring versus active lead management approaches. There is no evidence to support fluoroscopic screening for externalization of Riata or Riata ST leads.
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    The relationship between workload and length of stay in Singapore.
    (Health policy (Amsterdam, Netherlands), 2018-07) Zhou, Ke; Vidyarthi, Arpana; Matchar, David; Cheung, Yin Bun; Lam, Shao Wei; Ong, Marcus
    Prior studies link higher workload with longer length of stay (LOS) in the US. Unlike U.S. hospitals, Singaporean hospitals, like other major hospitals in the Asia-Pacific, are partially occupied by patients with non-acute needs due to insufficient alternative facilities. We examined the association between workload and length of stay (LOS) and the impact of workload on 30-day re-hospitalization and inpatient mortality rates in retrospective cohort in this setting. We defined workload as the daily number of patients per physician team. 13,097 hospitalizations of 10,000 patients were included. We found that higher workload was associated with shorter LOS (coefficient, -0.044 [95%CI, -0.083, -0.01]), especially for patients with longer stays (hazard ratios, not significantly greater than 1 before Day 4, 1.04 [95%CI, 1.01, 1.07] at Day 4 and 1.16 [95%CI, 1.10, 1.24] at Day 10), without affecting inpatient mortality (odds ratio (OR), 1.03 [95%CI, 0.99, 1.05]) or 30-day re-hospitalization (OR, 1.01 [95%CI, 0.99, 1.04]). This result differs from studies in the US and may reflect regional differences in the use of acute hospital beds for non-acute needs.
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    Where to go if not the hospital? Reviewing geriatric bed utilization in an acute care hospital in Singapore.
    (Geriatrics & gerontology international, 2017-10) Zhou, Ke; Vidyarthi, Arpana R; Wong, Chek Hooi; Matchar, David

    Aim

    Singapore is one of the fastest-aging countries in the world, and the demand for acute hospital care for older adults is expected to triple in the next 25 years. Hence, it is crucial to understand the opportunities in reducing potentially avoidable bed days (PABD), which are days spent in acute hospitals delivering only non-acute services. We aimed to access the prevalence, causes and consequences of PABD among geriatric patients.

    Methods

    We examined all hospitalizations from 1 August through 31 December 2013 in the geriatric wards of an acute hospital in Singapore. PABD were identified using a modified Appropriateness Evaluation Protocol. Non-acute services were classified as subacute care, rehabilitative care, long-term care or social care. Hospitalization patterns were determined based on the presence or absence of non-acute services, and multinomial logistic regression was used to determine predictors of different patterns.

    Results

    Of the 273 bed days used by 254 patients, 49% were potentially avoidable. The most common non-acute services provided were rehabilitative care (19%), subacute care (12%) and long-term care (8%). New acute issues arose after the admission conditions subsided in 2.4% of hospitalizations, 61% of which were nosocomial infections. Being socially at risk as assessed on admission predicted the development of new acute issues (sensitivity = 62%; specificity = 88%).

    Conclusions

    In the present study, almost half of the bed days were potentially avoidable. New acute issues can arise after PABD, which are dangerous to these frail older adults. Proactive discharge planning and increasing access to intermediate and long-term care services are required to reduce PABD. Geriatr Gerontol Int 2017; 17: 1575-1583.