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Biomedical subjects

J B Wong

Publications and source records attributed to J B Wong.

At least 19 recordsLinked to original sources
PubMed1997

Estimates of the cost-effectiveness of a single course of interferon-alpha 2b in patients with histologically mild chronic hepatitis C.

BACKGROUND: Chronic hepatitis C is a major cause of illness and death in the United States. Interferon-alpha 2b can induce clinical, biochemical, and virologic remission in some patients with chronic hepatitis C, but the long-term cost-effectiveness of this treatment, particularly in patients with histologically mild disease, is unknown. OBJECTIVE: To estimate the cost-effectiveness of interferon-alpha 2b in mild chronic hepatitis C. DESIGN: Meta-analysis of five prospective trials and cost-effectiveness analysis. Projection of the clinical and economic outcomes expected from loss of hepatitis C virus was done by using a Markov simulation. The potential effect of uncertainty in the model assumptions was tested by using sensitivity analyses. DATA SOURCES: Search of the MEDLINE database, opinions of expert panels, hospital cost data, and adjusted physician charges. PATIENTS: Hypothetical cohorts with histologically mild chronic hepatitis C. INTERVENTION: The model assumed a single 6-month course of recombinant interferon-alpha 2b. MEASUREMENTS: Life expectancy, quality-adjusted life expectancy, costs, and marginal cost-effectiveness ratios from a managed care perspective. RESULTS: In 27% of patients with mild chronic hepatitis C treated with interferon-alpha 2b for 6 months, serum alanine aminotransferase levels permanently returned to normal and viral status remained negative. The model estimated that interferon-alpha 2b treatment in this population should increase life expectancy by 3.1 years if given at 20 years of age, by 1.5 years at 35 years of age, and by 22 days at 70 years of age; discounted marginal cost-effectiveness ratios are $500, $1900, and $62,000 per year of life gained, respectively. Varying the long-term response rates and progression rates for mild and moderate chronic hepatitis to near zero in sensitivity analyses substantially affected the results: Ratios ranged from $31,000 for a 20-year-old patient to $640,000 for a 70-year-old patient. CONCLUSIONS: On the basis of estimations in this mathematical model of the natural history of chronic hepatitis C, treating mild chronic hepatitis with interferon-alpha 2b should prolong life expectancy at a reasonable marginal cost per year of life gained, particularly in younger patients.

Alanine Transaminase↗
PubMed1997

Patient-specific decisions about hormone replacement therapy in postmenopausal women.

OBJECTIVE: To examine the effect of hormone replacement therapy on life expectancy in postmenopausal women with different risk profiles for heart disease, breast cancer, and hip fracture. DESIGN: Decision analysis using a Markov model. Published regression models were used to link risk factors to disease incidence and to estimate the lifetime risks of developing coronary heart disease (CHD), breast cancer, hip fracture, and endometrial cancer. The impact of hormone therapy on disease incidence was estimated from published epidemiologic studies. SETTING: Mathematical model applicable to primary care. INTERVENTIONS: Treatment with hormone replacement therapy or no hormone replacement therapy. MAIN OUTCOME MEASURE: Life expectancy. RESULTS: Hormone replacement therapy should increase life expectancy for nearly all postmenopausal women, with some gains exceeding 3 years, depending mainly on an individual's risk factors for CHD and breast cancer. For women with at least 1 risk factor for CHD, hormone therapy should extend life expectancy, even for women having first-degree relatives with breast cancer. Women without any risk factors for CHD or hip fracture, but who have 2 first-degree relatives with breast cancer, however, should not receive hormone therapy. CONCLUSIONS: The benefit of hormone replacement therapy in reducing the likelihood of developing CHD appears to outweigh the risk of breast cancer for nearly all women in whom this treatment might be considered. Our analysis supports the broader use of hormone replacement therapy.

Aged↗
PubMed1997

Effect of failed extubation on the outcome of mechanical ventilation.

OBJECTIVE: To examine medical outcomes associated with reintubation for extubation failure after discontinuation of mechanical ventilation. DESIGN: Prospective cohort study of consecutive intubated medical ICU patients who underwent a trial of extubation at a tertiary-care teaching hospital. The failed extubation group consisted of all patients reintubated within 72 h or within 7 days (if continuous ICU care had been required) of extubation. All others were considered to be successfully extubated. Study end points included hospital death vs survival, the number of days spent in the ICU and in the hospital after the onset of mechanical ventilation, the likelihood of requiring > or = 7 or > or = 14 days of ICU care after extubation, and the need for transfer to either a long-term care or rehabilitation facility among the survivors. RESULTS: Of 289 intubated patients, 247 (85%) were successfully extubated, and 42 (15%) required reintubation for failed extubation (time to reintubation 1.5+/-0.2 days). Reintubation for extubation failure resulted in 12 additional days of mechanical ventilation. When compared with successfully extubated patients, reintubated patients were more likely to die in the hospital (43% vs 12%; p<0.0001), spend more time in the ICU (21.2+/-2.8 days vs 4.5+/-0.6 days; p<0.001) and in the hospital (30.5+/-3.3 days vs 16.3+/-1.2 days; p<0.001) after extubation, and require transfer to a long-term care or rehabilitation facility (38% vs 21%; p<0.05). Using multiple logistic regression, extubation failure was an independent predictor for death and the need for transfer to a long-term care facility. Compared with those successfully extubated, patients who failed extubation were seven times (p<0.0001) more likely to die, 31 times (p<0.0001) more likely to spend > or = 14 days in the ICU after extubation, and six times (p<0.001) more likely to need transfer to a long-term care or rehabilitation facility if they survived. CONCLUSION: After adjusting for severity of illness and comorbid conditions, extubation failure had a significant independent association with increased risk for death, prolonged ICU stay, and transfer to a long-term care or rehabilitation facility. Extubation failure may serve as an additional independent marker of severity of illness. Alternatively, poor outcomes may be etiologically related to extubation failure. If the latter proves to be the case, identifying patients at risk for poor outcomes from extubation failure and instituting alternative care practices may reduce mortality, duration of ICU stay, and need for transfer to a long-term care facility.

Case-Control Studies↗
PubMed1996

Modeling therapeutic benefit in the midst of uncertainty: therapy for hepatitis C.

Randomized, double-blind, controlled clinical trials are the gold standard for medical therapy. When a disease is rare or slowly progressive over many years, such a trial may not be feasible. Decision analysis provides a bridge between current studies with short-term surrogate markers and a large, longitudinal clinical trial. With decision analysis, results of current studies can be summarized and the outcome of a long-term study projected under explicit assumptions. Chronic hepatitis C is a disease that is slowly progressive, and the requirements of a longitudinal clinical study could be prohibitive. Therefore, we review the basic steps of decision analysis, apply these steps to two recent decision analyses evaluating the use of interferon-alpha2b (IFN) in the treatment of chronic hepatitis C, and discuss possible implications of decision modeling for this disease. The estimated marginal cost per year of life gained from IFN therapy ranged from approximately $3000 to $55,000 in these two studies. The wide range is based on different estimates of treatment costs and disease progression. This analysis has identified gaps in the current knowledge regarding the natural progression of hepatitis C and has established criteria to evaluate new developments and their impact on chronic hepatitis C.

Chronic Disease↗
PubMed1995

Revascularization for femoropopliteal disease. A decision and cost-effectiveness analysis.

OBJECTIVE: To evaluate the relative benefits and cost-effectiveness of revascularization for femoropopliteal disease using percutaneous transluminal angioplasty or bypass surgery. DESIGN: Decision analysis using a multistate transition simulation model (Markov process) and cost-effectiveness analysis from the perspective of the health care system. SETTING: Based on mortality, morbidity, patency, and cost data from a literature review. PATIENTS: Hypothetical cohort of patients with chronic femoropopliteal disease who desire revascularization. Subgroup analysis for patients defined by age, sex, indication, lesion type, and graft type. INTERVENTIONS: Percutaneous transluminal angioplasty, bypass surgery, and a strategies combining the two treatments. MAIN OUTCOME MEASURES: Five-year patency results, quality-adjusted life expectancy, lifetime costs, and incremental cost-effectiveness ratios. RESULTS: For 65-year-old men with disabling claudication and a femoropopliteal stenosis or occlusion and for 65-year-old men with chronic critical ischemia and a femoropopliteal stenosis, initial angioplasty increased quality-adjusted life expectancy by 2 to 13 months and resulted in decreased lifetime expenditures compared with bypass surgery. For patients with chronic critical ischemia and a femoropopliteal occlusion, initial bypass surgery increased quality-adjusted life expectancy by 1 to 4 months and resulted in decreased lifetime expenditures compared with angioplasty. Sensitivity analysis demonstrated that angioplasty would always be the preferred initial treatment if the angioplasty 5-year patency rate exceeds 30%. CONCLUSION: Angioplasty is the preferred initial treatment in patients with disabling claudication and a femoropopliteal stenosis or occlusion and in those with chronic critical ischemia and a stenosis. Bypass surgery is the preferred initial treatment in patients with chronic critical ischemia and a femoropopliteal occlusion.

Aged↗
PubMed1995

Cost-effectiveness of interferon-alpha 2b treatment for hepatitis B e antigen-positive chronic hepatitis B.

OBJECTIVE: To estimate the cost-effectiveness of interferon-alpha 2B for the treatment of patients with chronic hepatitis B infection who are positive for hepatitis B e antigen (HBeAg). DESIGN: Meta-analysis of nine randomized controlled trials and cost-effectiveness analysis, projecting the clinical and economic outcomes expected from changes in serologic markers of hepatitis B viral replication. DATA SOURCES: MEDLINE search, expert panel opinion, hospital cost data, and adjusted physician charges. PATIENTS: 552 patients with confirmed chronic hepatitis B infection who were positive for HBeAg. INTERVENTION: Interferon-alpha 2b. MEASUREMENTS: Lifetime incidence of cirrhosis and hepatocellular carcinoma; life expectancy; quality-adjusted life expectancy; and costs and marginal cost-effectiveness ratios from a societal perspective. RESULTS: Interferon-alpha 2b increases the likelihood of becoming negative for HBeAg from 9.1% to 45.6% (difference, 36.5%; 95% CI, 23.7% to 49.2%) and of becoming negative for hepatitis B surface antigen from 1.7% to 7.7% (difference, 6.0%; CI, 2.8% to 9.3%) in the first year. For a 35-year-old person with chronic hepatitis B who is HBeAg positive, our analysis suggests that interferon-alpha 2b will increase life expectancy by 3.1 years or 3.4 quality-adjusted life-years and will decrease projected lifetime costs, even if future savings are discounted; thus, interferon-alpha 2b is the dominant strategy. Even with the model biased strongly in favor of standard care, the marginal cost-effectiveness ratio of interferon did not exceed $12,000 per life-year gained. CONCLUSIONS: Interferon-alpha 2b should prolong life and lower costs for patients with chronic hepatitis B who are HBeAg positive.

Adolescent↗
PubMed1995

Foot infections in diabetic patients. Decision and cost-effectiveness analyses.

OBJECTIVE: To examine the cost-effectiveness of approaches to the diagnosis and treatment of patients with type II (non-insulin-dependent) diabetes mellitus (NIDDM) who have foot infections and suspected osteomyelitis. DESIGN: Decision and cost-effectiveness analyses were performed using a Markov model. We examined the prevalence of osteomyelitis, the major complications and efficacies of long-term antibiotic therapy and surgery, and the performance characteristics of four diagnostic tests (roentgenography, technetium Tc 99m bone scanning, indium in 111-labeled white blood cell scanning, and magnetic resonance imaging). Data were drawn from the English-language literature using MEDLINE searches and bibliographies from selected articles. SETTING: Primary care. PATIENTS: Patients with NIDDM who had foot infections and suspected osteomyelitis but no signs of systemic toxicity. INTERVENTIONS: Following hospitalization for surgical débridement and intravenous antibiotic therapy: (1) treatment for presumed soft-tissue infection, (2) culture-guided empiric treatment for presumed osteomyelitis, (3) 71 combinations of diagnostic tests preceding antibiotic therapy for osteomyelitis, (4) 71 combinations of tests preceding amputation, and (5) immediate amputation. MAIN OUTCOME MEASURES: Quality-adjusted life expectancy, average costs. RESULTS: Culture-guided empiric treatment for osteomyelitis with 10 weeks of oral antibiotic therapy has similar effectiveness to testing followed by a long course of antibiotic therapy if any test result is positive. However, empiric treatment is the least expensive strategy. CONCLUSIONS: Noninvasive testing adds significant expense to the treatment of patients with NIDDM in whom pedal osteomyelitis is suspected, and such testing may result in little improvement in health outcomes. In patients without systemic toxicity, a 10-week course of culture-guided oral antibiotic therapy following surgical débridement may be as effective as and less costly than other approaches.

Amputation, Surgical↗
PubMed1995

Prophylactic colectomy or surveillance for chronic ulcerative colitis? A decision analysis.

BACKGROUND & AIMS: The treatment of patients with long-standing ulcerative colitis involving the entire colon is controversial. The aim of this study was to examine the effectiveness of surveillance colonoscopy or prophylactic colectomy on colon cancer mortality in patients with chronic ulcerative colitis. METHODS: Using decision analysis, computer cohort simulation of patients with ulcerative colitis was performed to evaluate 17 strategies including no colonoscopic surveillance, surveillance at varying intervals, and prophylactic proctocolectomy with ileal pouch-anal anastomosis. The model examined which biopsy results (low-grade dysplasia, high-grade dysplasia, or cancer) should lead to proctocolectomy and ileal pouch-anal anastomosis. Published data on the incidence of cancer with ulcerative colitis, the sensitivity and specificity of colonoscopy with biopsy, the risks of colonoscopy and surgery, and the prognosis with colon cancer were used. RESULTS: For a 30-year-old patient with pancolitis for 10 years, the model suggests that prophylactic colectomy would increase life expectancy by 2-10 months compared with surveillance and by 1.1-1.4 years compared with no surveillance. Surveillance would improve life expectancy by 7 months to 1.2 years compared with no surveillance. In sensitivity analysis, results were most affected by the cumulative incidence of cancer in patients with chronic ulcerative colitis. CONCLUSIONS: Either surveillance or prophylactic colectomy should increase life expectancy in patients with ulcerative colitis.

Adult↗
PubMed1995

Screening for acquired cystic kidney disease: a decision analytic perspective.

Acquired cystic kidney disease (ACKD) increases the risk of renal malignancy, and many authors suggest routine screening of dialysis patients for ACKD and renal tumors. However, they have defined neither the target population, the optimal screening strategy, the magnitude of its benefit, nor its risk. We used decision analysis to evaluate strategies of performing either computed tomography (CT) or ultrasound every three years on all dialysis patients and annually on patients found to have cysts. We compared these strategies to a strategy of seeking cysts and cancer only if these are clinically suspected. The baseline analysis shows that both CT and ultrasound may decrease cancer deaths by half for patients with a life expectancy of 25 years. Screening for ACKD offers these patients as much as a 1.6 year gain in life expectancy. However, for the majority of patients beginning renal replacement therapy, age or comorbid disease substantially limits life expectancy. For such patients, the gain in life expectancy from an ACKD screening program is measured in days. Sensitivity analyses show that the benefit of screening depends on the rate of malignant transformation, which needs better definition. The gain in life expectancy does not appear to be large enough to justify an ACKD screening program for the entire ESRD population. However, for the youngest and healthiest patients, a screening program would be of benefit. The magnitude of this benefit is uncertain, because the analysis was consistently biased in favor of the screening strategies.

Decision Support Techniques↗
PubMed1995

A survey of current problems in meta-analysis. Discussion from the Agency for Health Care Policy and Research inter-PORT Work Group on Literature Review/Meta-Analysis.

The United States Agency for Health Care Policy and Research brought together representatives from each of the Patient Outcomes Research Teams (PORTs) as the Inter-PORT Meta-Analysis Work Group. The purpose of the meeting was to discuss a wide range of problems the panel had encountered in the area of meta-analysis. Several actual problems were presented, and tentative solutions to those problems were given. The PORTs had to consider issues such as quality assessment, survival analysis, rare events, sensitivity and specificity, and random effects models. The solutions presented represent the methods used by several researchers who are active in the area of meta-analysis.

Evaluation Studies as Topic↗
PubMed1994

Toward a peer review process for medical decision analysis models.

This paper presents a framework for a peer review process for medical decision analysis models. This framework is based on the collective experience of the members of the Inter-PORT Decision Modeling work group, a team of decision analysis experts comprising members from each of the Patient Outcomes Research Teams (PORTs), sponsored by the Agency for Health Care Policy and Research. Important general principles of correct model structure include choice of model type, perspective of the analysis, choice of utility scheme and identification of strategies that should be included and events that should be modeled. In addition, a set of rules for correct decision model structure may help to identify common errors. Although not necessarily exhaustive, this scheme provides an approach by which a reviewer may judge the adequacy of a decision model presented for publication or as the basis for a health policy.

Decision Support Techniques↗
PubMed1994

A guide for surveillance of patients with Barrett's esophagus.

OBJECTIVE: Barrett's esophagus (columnar metaplasia of the distal esophagus due to chronic gastroesophageal reflux) affects nearly 700,000 people in the United States, and carries a risk of esophageal adenocarcinoma that is 30-125 times that of an age-matched population. Patients who develop high grade dysplasia are at greatest risk. Current recommendations are for endoscopic surveillance to detect dysplasia and to diagnose carcinoma while it is in an early and possibly treatable stage. In addition, some authorities recommend esophagectomy for high grade dysplasia, whereas others reserve esophagectomy only for those with cancer. There are no controlled trials demonstrating that surveillance increases life expectancy in patients with Barrett's esophagus. Furthermore, endoscopic surveillance of this large group with Barrett's esophagus may be costly, and associated with considerable morbidity. Therefore, our objective was to assess the effectiveness and cost-effectiveness of endoscopic surveillance in patients with Barrett's esophagus. METHODS: Design--Decision analysis using a computer cohort simulation (Markov). We examined 12 strategies: (A) no endoscopic surveillance. Esophagectomy is performed only if cancer is detected by biopsy. (B) no surveillance. Esophagectomy is performed if high grade dysplasia is detected by biopsy: (C1-C5) surveillance at intervals from 1 to 5 yr, with esophagectomy if cancer is diagnosed, and (D1-D5) surveillance at intervals from 1 to 5 yr with esophagectomy if high grade dysplasia is diagnosed. We measured life expectancy, quality-adjusted life expectancy, and incremental cost-effectiveness ratios for each strategy. Data Sources--Medline Search and bibliographies of retrieved articles; expert opinion when published data were not available. RESULTS AND CONCLUSIONS: Annual surveillance with esophagectomy for high grade dysplasia prevents cancer and is the preferred strategy, if only length of life (life expectancy) is considered. For those who consider both length and quality of life, endoscopy every 2-3 yr will provide the greatest quality-adjusted life expectancy. When costs are considered, endoscopy every 5 yr also increases life expectancy and has an incremental cost-effectiveness ratio similar to common medical practices. The cumulative incidence of cancer and the quality of life with an esophagectomy had the greatest impact on the decision for surveillance and the optimal surveillance strategy.

Adenocarcinoma↗
PubMed1993

Who should be screened for HIV infection? A cost-effectiveness analysis.

BACKGROUND: The advent of effective prophylactic treatments for asymptomatic persons infected with human immunodeficiency virus has led to interest in widespread screening programs. However, the costs of screening programs and therapy are high, and the prevalence of infection above which screening becomes an appropriate use of scarce health care dollars remains undetermined. METHODS: To examine the cost-effectiveness of screening in populations with differing prevalences of infection, we developed a Markov model to compare costs and life expectancy for two strategies: (1) screening and prophylactic treatment for infected persons who have or who develop low CD4+ (T4) cell counts, and (2) no screening. Based on studies in the literature, we estimated the prevalence of HIV infection, the rate of T4-cell loss, the rates of developing the acquired immunodeficiency syndrome and Pneumocystis pneumonia stratified by T4 cell counts, the life expectancy with the acquired immunodeficiency syndrome, the efficacy of prophylactic therapies, and costs. RESULTS: In populations with a prevalence of infection more than 5%, which includes known risk groups, screening costs less than $11,000 per life-year gained. In populations with a prevalence as low as 0.15%, screening costs only $29,000 per life-year gained. Even when the efficacy of zidovudine is assumed to be limited to 3 years, screening still costs less than $40,000 per life-year gained in populations with a prevalence of 0.5% or greater. However, in populations with a very low prevalence of infection (two to 10/100,000), such as members of the general population without reported risk factors, screening costs rise to between $290,000 and $1,277,400 per life-year gained. CONCLUSIONS: When considering only direct medical benefits, screening for asymptomatic human immunodeficiency virus infection in the general population, without regard to reported risk factors or seroprevalence data, would be expensive. In populations with a prevalence of infection of 0.5% or greater, however, the cost-effectiveness of screening falls within the range of currently accepted medical practices. These results suggest that screening be offered routinely to all persons in defined populations, such as persons receiving care at hospitals or clinics, or residing in geographic areas, where the seroprevalence is 0.5% or more, and underscore the need to conduct seroprevalence studies to identify such populations.

AIDS Serodiagnosis↗
PubMed1993

Cost-effectiveness of radiofrequency ablation compared with other strategies in Wolff-Parkinson-White syndrome.

BACKGROUND: Patients with Wolff-Parkinson-White syndrome fall into four risk groups: those with (1) prior cardiac arrest, (2) paroxysmal supraventricular tachycardia or atrial fibrillation (PSVT/AF) with hemodynamic compromise, (3) PSVT/AF without hemodynamic compromise, and (4) no symptoms. METHODS AND RESULTS: For each group, we developed a cost-effectiveness analysis examining five clinical management strategies: (1) observation, (2) observation until a cardiac arrest dictates the need for therapy, (3) initial drug therapy guided by noninvasive monitoring, (4) initial radiofrequency ablation (RFA), and (5) initial surgical ablation. We used a Markov simulation model to estimate life expectancy and costs for patients whose ages are between 20 and 60 years. The model includes the risks of cardiac arrest, PSVT/AF, drug side effects, procedure-related complications and mortality, the efficacy of drugs and RFA, and costs. Based on literature and expert opinion, we assumed that the annual risks of cardiac arrest are 0.01%, 0.05%, and 0.5%, respectively, in patients who are asymptomatic, who had PSVT/AF without hemodynamic compromise, or who had PSVT/AF with hemodynamic compromise. We also assumed that RFA has an overall efficacy of 92% in preventing cardiac arrest and arrhythmias. Our model predicts that RFA should yield a life expectancy greater than or equal to other strategies. In cardiac arrest survivors and patients who have had PSVT/AF with hemodynamic compromise, our model suggests that RFA should both prolong survival and save resources. For patients with PSVT/AF without hemodynamic compromise, the marginal cost-effectiveness of attempted RFA (followed by conservative treatment if the RFA fails) ranges from $6600 per quality-adjusted life year (QALY) gained for 20-year-old patients to $19,000 per QALY gained for 60-year-old patients. For asymptomatic patients, RFA costs from $174,000 per QALY gained for 20-year-old patients to $540,000 per QALY gained for 60-year-old patients. CONCLUSIONS: Our analysis supports the emerging practice of performing RFA in patients with Wolff-Parkinson-White syndrome who survive cardiac arrest or who experience PSVT/AF but also supports the current practice of observing asymptomatic patients.

Adult↗