Tuesday, October 25, 2011: 10:00 AM
Grand Ballroom CD (Hyatt Regency Chicago)
Category Reference
BECBehavioral Economics ESPApplied Health Economics, Services, and Policy Research
DEC Decision Psychology and Shared Decision Making METQuantitative Methods and Theoretical Developments

  * Candidate for the Lee B. Lusted Student Prize Competition

Session Chairs:
Matt Stevenson, PhD and Allison B. Rosen, MD, ScD
10:00 AM
Emily Burger, MPhil1, Jesse D. Ortendahl, BS2, Stephen Sy, BS2, Ivar Sønbø Kristiansen, MD, PhD, MPH1 and Jane J. Kim, PhD2, (1)University of Oslo, Oslo, Norway, (2)Harvard School of Public Health, Boston, MA

Purpose: Since 1991, the Norwegian Coordinated Cervical Cancer Screening Program has invited women to cytology-based screening every three years. Although a reduction in cervical cancer has been observed, it remains among the top three most frequent cancers for women aged 25-49 and may be further reduced by new screening technologies. In addition, vaccination against human papillomavirus, the necessary cause of cervical cancer, may impact optimal screening strategies. We evaluated the cost-effectiveness of alternative primary screening strategies for vaccinated and unvaccinated women to inform policy recommendations in Norway.

Method: We used likelihood-based methods to calibrate a first-order Monte Carlo simulation model to reflect the natural history of HPV-induced cervical cancer in Norway. The current screening strategy involving cytology only was compared to a strategy involving cytology at younger ages, followed by a switch to primary HPV-based screening, an option being actively considered by the Norwegian government. Pre-switch screening strategies included varying the management protocols for mildly abnormal results. Post-switch screening strategies included varying the age at which women switch to primary HPV testing (31 or 34 years), screening interval (3-6 years), and triage strategies for women with HPV-positive results. All costs were considered from the societal perspective. Additional sensitivity analysis included varying screening laboratory costs to reflect potential discrepancies between published reimbursement rates and true economic costs.  

Result: Current cytology-only screening was less effective and more costly than proposed strategies that involve switching to primary HPV testing in older ages. For unvaccinated women, switching at age 31 to primary HPV testing every 4 years with cytology as a triage for HPV-positive results was most cost effective at 460,000NOK/YLS (≈$72,000/YLS) given a Norwegian cost-effectiveness threshold of approximately 500,000NOK/YLS (≈$78,000/YLS). For vaccinated women, the preferred screening strategy was the same, but with intervals widened to every 6-years after the switch age of 31. Strategies involving immediate diagnostic referral of young women with mildly abnormal cytology results were not cost-effective. By using published reimbursement rates for laboratory costs that were lower than our base-case estimates, we found that the optimal strategy for vaccinated women allowed for more intensive follow-up of HPV-positive women.

Conclusion: Strategies involving a switch to HPV testing for primary screening in older women is expected to be cost-effective, compared with current screening recommendations in Norway.

10:15 AM
María Clara Mendoza Arango, MD1, Shihchen Kuo, RPh, MSCP1, Carlos H. Morales Uribe, MD, MS2, Juan C. Puyana, MD1 and Kenneth J. Smith, MD, MS1, (1)University of Pittsburgh, Pittsburgh, PA, (2)University of Antioquia, Medellin, Colombia

Purpose: Tranexamic acid (TXA) is an antifibrinolytic agent that decreased mortality in trauma patients with increased bleeding risk. We sought to determine cost effectiveness of general implementation of this pharmacological strategy in trauma patients with significant bleeding.

Methods: We developed a decision-analytical model to compare implementation of TXA infusion with no TXA infusion in trauma patients, modeling the clinical and economic consequences of these strategies in patients with significant bleeding risk early in their post-trauma care. Events included in the model were death, bleeding, vascular occlusion, drug-related adverse events and post-injury health status. Intervention costs fluctuations were modeled from the least expensive generic drug to the most expensive therapeutic brand; other costs were assumed to be equal between strategies, potentially biasing against TXA. Probabilities mainly came from the CRASH-2 study, a large placebo controlled trial of the effects of early administration of a short course of TXA on death, vascular occlusive events, and the receipt of blood transfusion. This trial recruited 20,211 patients from 274 hospitals in 40 countries. Health state utilities were obtained from medical literature, reflecting the effect of possible adverse events due to antifibrinolytic treatment. The time horizon for the model was one year. Sensitivity analyses were performed to identify variables whose variation impacted base case model results.  

Results: In the base case analysis, TXA gained 0.0381 more quality-adjusted life-years (QALYs) at an added cost of $160, or $4,199/QALY. In sensitivity analyses, TXA cost $2,205/QALY when drug costs were at the lower limit ($84, base case $160) and cost $32,018/QALY at the upper limit ($1,220). Results were also sensitive to variation of adverse events risk related to TXA, with the incremental cost-effectiveness ratio increasing to $65,570/QALY when this risk was fixed at 80% (base case 5%). 

Conclusions: Our results favor TXA therapy in trauma patients over no TXA. The economic benefit of TXA is substantial in an analysis biasing against its use. Based on favorable clinical trial and economic analysis data, adoption of TXA in trauma treatment protocols should be recommended. *Funded by FIC NIH grant D43 TW007560 01

10:30 AM
Toshitaka Morishima, MD, Hiroshi Ikai, MD, PhD and Yuichi Imanaka, MD, PhD, Kyoto University Graduate School of Medicine, Kyoto, Japan

Purpose: Omalizumab, a recombinant humanized monoclonal anti-IgE antibody, reduces risk of exacerbations and improves health-related quality of life (HRQoL) among patients with moderate to severe persistent asthma. Several economic evaluations of omalizumab have been reported previously. Our objective was to evaluate cost-effectiveness of omalizumab, using results of a randomized controlled trial which enrolled Asian population for the first time and was conducted in Japan.

Method: We developed a Marcov model comparing omalizumab plus standard therapy with standard therapy alone, on the basis of efficacy data from the randomized placebo-controlled double-blind trial and cost data of Japan. Our model had a lifetime horizon in which five-year omalizumab plus standard therapy was followed by standard therapy alone. The study cohort matched the clinical trial population with an average age of 50 and 50% men. Omalizumab provides different benefits for patients with persistent asthma, although no predictive factor for response has been found. Non-responders who represented little effect of omalizumab reverted back to standard therapy after 16-week omalizumab therapy. We assumed that patients could transition every week among symptom-free state, day-to-day state, and exacerbation state, and that patients in asthma-related hospitalization state were at risk of dying from asthma exacerbation. We derived preference-based utility values from another study examining relationship between asthma control level and HRQoL because the clinical trial in Japan failed to measure HRQoL convertible into utilities. Costs from a societal perspective included estimates for drugs, medical resource uses, and lost productivity.

Result: The mean lifetime discounted costs and quality-adjusted life years (QALYs) were $118,000 and 16.097 for omalizumab plus standard therapy, and $47,000 and 16.003 for standard therapy alone. The incremental cost-effectiveness ratio (ICER) was $751,000/QALY. One-way sensitivity analyses indicated that the results were sensitive to asthma-related mortality, exacerbation rates, symptom-free rates, and omalizumab price.

Conclusion: The result of the base case analysis suggested that omalizumab was not cost-effective given a willingness to pay of $54,000 in Japan. However, omalizumab possesses a unique mechanism and is required for the treatment of persistent asthma. The cost-effectiveness of omalizumab would be improved if the price of omalizumab is cut down and omalizumab therapy is confined to patients with higher asthma mortality or exacerbation risk.

10:45 AM
Joyce Lee, MD, MPH and Achamyeleh Gebremariam, MS, University of Michigan, Ann Arbor, MI

Purpose: To evaluate the effectiveness and cost-effectiveness of four screening strategies for identifying overweight and obese adolescents with dysglycemia (prediabetes or diabetes) from a single-payer and societal perspective.

Method: We assumed that 2.5 million US children qualify for screening, with a 15% prevalence of dysglycemia(n=375,000 children). Test performance was based on a clinical study of nonfasting test performance. We calculated direct costs (testing costs) using Medicare reimbursement rates, and indirect costs (patient time costs) using data from the Bureau of Labor Statistics. Costs were expressed in $US2010. The 4 strategies considered included: (1)2-hour oral glucose tolerance test (2-hr OGTT)(positive greater than or equal to 140 mg/dl) only, or nonfasting initial screening tests [(2)HbA1c greater than or equal to 5.7%); (3)random glucose(positive greater than or equal to 100 mg/dl); or (4)1-hour glucose tolerance test(1-hr OGTT) (positive greater than or equal to 110 mg/dl)], followed by a 2-hr OGTT only if the initial test is positive. Outcomes included the proportion of cases identified, total screening costs, and cost per case identified. We also conducted sensitivity analyses assuming a 50% lower adherence for the 2-hr OGTT only strategy, and increases or decreases in the prevalence of dysglycemia(±25%).

Result: Compared with the other strategies, HbA1c was associated with a lower number of true positives, a higher number of missed cases, and higher total costs and a higher cost per case detected (direct and direct combined with indirect). This is highlighted in the figure which shows the "efficiency frontier", plotting effectiveness (% of cases of dysglycemia missed) against efficiency (cost per case). An ideal test is located near the origin. Although the 2-hr OGTT only strategy had high effectiveness and a lower cost per case identified, when we assumed only 50% adherence, screening effectiveness dropped to 50% with lower overall costs, but the same cost per case identified. At higher and lower estimates of prevalence, test effectiveness and overall costs did not change, but the cost per case increased or decreased by 25%.

Conclusion: HbA1c was an inferior test compared with the other test strategies. 1-hr OGTT and random glucose were intermediate regarding efficiency and effectiveness, and therefore may be viable strategies for dysglycemia screening in adolescents.

11:00 AM
Elisa F. Long, PhD, Yale University, New Haven, CT and Robert R. Stavert, MD, MBA, Yale School of Medicine, New Haven, CT

Purpose:   With more than 400,000 annual new HIV infections in South Africa, scaling up prevention is an urgent priority.  Many experts believe a portfolio of interventions is the best strategy for controlling the epidemic.  We aimed to evaluate the cost-effectiveness of HIV intervention portfolios in South Africa, to maximize health benefits given limited resources.   

Methods:   We developed a dynamic HIV transmission model to evaluate combinations of HIV screening, antiretroviral therapy (2010 guidelines), male circumcision, vaccination, and vaginal microbicide use.  The model includes disease transmission, progression, morbidity, and mortality among adults aged 15-49 in South Africa.  Initial conditions were based on demographic, epidemiologic, and behavioral data, and parameters were adjusted using trial data on intervention efficacy.  Three trials in sub-Saharan Africa indicated that male circumcision reduced transmission in heterosexual men by 48-60%; a 2009 Thailand trial found a vaccine regimen conferring 31% protection; a 2010 South Africa vaginal tenofovir microbicide trial indicated a 39% transmission reduction in women. Calculated outcomes include incidence, prevalence, quality-adjusted life years (QALYs), and cost-effectiveness.  We extended our deterministic results to include a Monte Carlo simulation and probabilistic cost-effectiveness analysis to account for uncertainty in each intervention's efficacy.   

Results:   Under the status quo, 1.43 million (men) and 1.64 million (women) new infections occur over 10 years.  Increased male circumcision is cost-saving, reducing infections by 19% (men) and 7% (women).  Broad use of a vaginal microbicide reduces incidence by 30% (women) and 11% (men) due to reduced secondary transmission, for $750/QALY assuming an annual microbicide cost of $100.  Extensive vaccination reduces cases by 26%, for $880/QALY assuming $500 per vaccination series.  A program offering circumcision, microbicides, and vaccination has diminishing returns, preventing 43% of cases.  Alternatively, increased screening and antiretroviral therapy reduces incidence by 45%, for $800/QALY.  A portfolio with all five interventions averts 69% of infections, and is cost-effective at $1,860/QALY.  Monte Carlo simulation results suggest that such a strategy costs <$5,000/QALY in 87% of trials, and <$10,000/QALY in 94% of trials.   

Conclusions:   A comprehensive portfolio of expanded HIV screening, antiretroviral therapy, male circumcision, vaccination, and microbicide use prevents the greatest number of infections and is cost-effective.  Male circumcision is cost-saving, but differentially benefits men.  Given resource constraints, the model can help identify the optimal portfolio of interventions. 

11:15 AM
Thomas J. Best, MSc, Burhaneddin Sandikci, PhD, David O. Meltzer, MD, PhD and Donald D. Eisenstein, PhD, The University of Chicago, Chicago, IL

Purpose: Many teaching hospitals with strained inpatient bed capacity struggle to maintain a mix of patients that satisfies their teaching, research, and financial needs. Even an increase in bed capacity is unlikely to address the patient mix problem. We investigate one such hospital that received special dispensation from the government to partition its inpatient beds into wings.  Each wing is allocated a fixed number of beds and is restricted to a fixed set of clinical specialties.  An admission request is granted only if a bed is available in the appropriate wing. We develop a modeling framework to investigate how best to form wings so as to optimize some function of patient mix.

Method: A dynamic programming (DP) model is formulated to optimize the wing configurations from the perspective of the hospital administrator. The model assumes a heterogeneous patient population that demands hospital services in a stochastic manner. The model maximizes the average DRG (Diagnosis Related Grouping) relative weights of admitted patients. Parameters are calibrated with data from the hospital and from national databases. In addition, we model length-of-stays as decreasing when a wing becomes more heavily demanded.  This model of length-of-stays is supported with empirical evidence. The associated DP is too large to solve using standard methods. However, we are able to exploit special structures of the model that enables us to obtain near optimal solutions very quickly.

Result: If the total demand for hospital beds per day is, on average, sufficiently less than bed capacity, then the optimal solution is to avoid forming specialized wings. As average total demand for beds increases it becomes more advantageous to form multiple wings. In particular, our model shows that forming wings when the hospital services are heavily demanded will increase the average DRG relative weight, decrease the average overall occupancy, yet increase the number of patients admitted. The increase in patient flow is due to a decrease in length-of-stays for highly utilized wings.

Conclusion: Forming wings can be an effective strategy to deal with strained bed capacity. Our dynamic programming model informs hospital administrators about how to form wings that achieve a patient mix that better matches the mission of the hospital. The solutions are fast to obtain and easy to communicate.