One-year Time Horizon Research Articles

Fast solution method for TCUC with long time horizon based on horizon splitting

Long-term transmission constrained unit commitment (LT-TCUC) is an important tool in generation expansion planning and has got much attention in recent years. When traditional Lagrangian relaxation (LR) and mixed integer programming (MIP) based methods are used to solve LT-TCUC problems, serious challenges related with the solution efficiency are encountered. This paper proposes a fast method for solving TCUC with long time horizon based on horizon splitting. The basic idea is to partition the whole horizon into several short time intervals, and then relax the coupling constraints between consecutive intervals (ramp rate constraints and minimum up/down time constraints). Sub-TCUC problem in each time interval is then solved independently (in parallel) with CPLEX and the solutions are further adjusted based on MIP to satisfy the relaxed coupling constraints. In this way, the feasibility of the solution is guaranteed and the solutions to the sub-TCUC problems are connected. Salient features of the method include that the solution efficiency is guaranteed and the solution quality can be estimated based on the optimality gap. The proposed method is tested on the modified IEEE 24-bus system, 118-bus systems, and a regional grid in China with one-month or one-year time horizon. Numerical results show that the solution method is efficient.

Survival and cost associated with chemotherapy and chemoradiotherapy among resected pancreas cancer patients.

351 Background: Pancreas cancer is expensive to treat, and the effectiveness of adjuvant chemotherapy (CT) and chemoradiation (CRT) following resection is debated. We compared both survival and healthcare costs by adjuvant therapy after curative-intent pancreaticoduodenectomy (PD) for pancreas adenocarcinoma (PC). Methods: All patients with resected PC in Ontario, Canada diagnosed 2004 to 2014 were identified and linked to administrative healthcare databases. Stratified Kaplan—Meier survival curves and log-rank test compared survival across treatment groups. Costs were assessed from the perspective of Ontario’s single-payer healthcare system and compared between CT and CRT. A one-year time horizon was used from the date of surgery. Results: 677 PC patients met all inclusion/exclusion criteria and underwent curative-intent PD with 77% receiving CT and 23% CRT. Median survival after resection was 21.7 and 18.9 months for CT and CRT groups, respectively. Patients receiving CRT were less likely to have high comorbidity burden (ADG ≥ 10), but were similar across other demographics. CRT patients were more likely to have margin positive disease. In a subgroup of 489 patients with margin negative disease, median survival in the node negative patients (n = 156) was 28.0 months for CRT and 24.7 months for CT (p = 0.8297, logrank). Median survival in the node positive patients (n = 333) was 20.6 months and 21.8 months for the CRT and CT patients, respectively (p = 0.9856, logrank). The median total one-year cost for CT was $52,575 (USD); CRT was $68,216 (Table 1). Conclusions: Patients who underwent adjuvant CT and CRT after PD for PC had similar overall survival, but healthcare expenditures were significantly higher in the CRT group. [Table: see text]

A Cost-Utility Analysis of Cryoballoon Ablation versus Radiofrequency Ablation for Paroxysmal Atrial Fibrillation.

The objective of this study was to evaluate the cost-effectiveness of the treatment with cryoballoon (CB) compared to the standard treatment with traditional irrigated radiofrequency (RF) ablation for pulmonary vein isolation in patients with paroxysmal atrial fibrillation (pAF) refractory to antiarrhythmic drug therapy. A decision tree model was developed to graphically depict the probabilities, utilities and costs of CB compared to RF therapy. Data from a conducted systematic literature review and meta-analysis of only RCTs were used to evaluate clinical outcomes of CB and RF treatments, including success rates after one year, complications and recurrence of atrial fibrillation. The cost-utility analysis estimated that, CB therapy had £1,747 higher cost, and 0.0114 more quality-adjusted life years (QALYs) compared to standard RF treatment over a one-year time horizon. The incremental cost per QALY of CB ablation compared to RF ablation was estimated to be £152,836/QALY. Based on current evidence, CB ablation for pulmonary vein isolation in patients with pAF is costeffective compared to RF if decision makers are willing to pay £152,836 or higher for a QALY.

Multi-objective optimization of district heating and cooling systems for a one-year time horizon

Besides lowering supply temperatures, the concept of fourth generation of district heating (4DH) also includes integration of heating, cooling and power sector. Due to their high interconnectivity, number of involved technologies and relatively long, but at the same time detailed temporal scale, optimization of such systems presents a challenging task. So far, only hourly district heating multi-objective optimization for a whole year period has been carried out, where detailed district heating and cooling multi-objective optimization has been reserved for small scale utilization and short temporal scale, usually covering specific days or weeks. The main objective of this paper was to develop an hourly based multi-objective optimization district heating and cooling model which is capable of defining supply capacities, including thermal storage size, and their operation for a whole year period. The objective functions are minimization of a total system cost, which includes discounted investment and operational costs, and minimization of environmental impact in terms of carbon dioxide emissions. By using multi-objective optimization, this research shows that for equal level of carbon dioxide emissions, combined district heating and cooling systems have lower total discounted cost when compared to district heating and cooling systems which operate separately.

Cost-effectiveness of procalcitonin testing to guide antibiotic treatment duration in critically ill patients: results from a randomised controlled multicentre trial in the Netherlands

BackgroundProcalcitonin (PCT) testing can help in safely reducing antibiotic treatment duration in intensive care patients with sepsis. However, the cost-effectiveness of such PCT guidance is not yet known.MethodsA trial-based analysis was performed to estimate the cost-effectiveness of PCT guidance compared with standard of care (without PCT guidance). Patient-level data were used from the SAPS trial in which 1546 patients were randomised. This trial was performed in the Netherlands, which is a country with, on average, low antibiotic use and a short duration of hospital stay. As quality of life among sepsis survivors was not measured during the SAPS, this was derived from a Dutch follow-up study. Outcome measures were (1) incremental direct hospital cost and (2) incremental cost per quality-adjusted life year (QALY) gained from a healthcare perspective over a one-year time horizon. Uncertainty in outcomes was assessed with bootstrapping.ResultsMean in-hospital costs were €46,081/patient in the PCT group compared with €46,146/patient with standard of care (i.e. − €65 (95% CI − €6314 to €6107); − 0.1%). The duration of the first course of antibiotic treatment was lower in the PCT group with 6.9 vs. 8.2 days (i.e. − 1.2 days (95% CI − 1.9 to − 0.4), − 14.8%). This was accompanied by lower in-hospital mortality of 21.8% vs. 29.8% (absolute decrease 7.9% (95% CI − 13.9% to − 1.8%), relative decrease 26.6%), resulting in an increase in mean QALYs/patient from 0.47 to 0.52 (i.e. + 0.05 (95% CI 0.00 to 0.10); + 10.1%). However, owing to high costs among sepsis survivors, healthcare costs over a one-year time horizon were €73,665/patient in the PCT group compared with €70,961/patient with standard of care (i.e. + €2704 (95% CI − €4495 to €10,005), + 3.8%), resulting in an incremental cost-effectiveness ratio of €57,402/QALY gained. Within this time frame, the probability of PCT guidance being cost-effective was 64% at a willingness-to-pay threshold of €80,000/QALY.ConclusionsAlthough the impact of PCT guidance on total healthcare-related costs during the initial hospitalisation episode is likely negligible, the lower in-hospital mortality may lead to a non-significant increase in costs over a one-year time horizon. However, since uncertainty remains, it is recommended to investigate the long-term cost-effectiveness of PCT guidance, from a societal perspective, in different countries and settings.

PRS38 - COST-CONSEQUENCE ANALYSIS OF FLUTICASONE FUROATE/VILANTEROL FOR ASTHMA MANAGEMENT IN SPAIN: AN ANALYSIS BASED ON THE SALFORD LUNG STUDY IN ASTHMA

The Salford Lung Study in asthma (SLS asthma) is a 12-month, open-label randomised clinical trial comparing clinical effectiveness and safety of initiating once-daily inhaled combination of either 92 mcg or 184 mcg fluticasone furoate with 22 mcg vilanterol (FF/VI), with continuing optimized usual care (UC) with inhaled corticosteroids (ICS) alone or in combination with a long-acting β2-agonist (ICS/LABA), in asthmatic patients followed in primary care in the UK. The objective of the present analysis is to estimate the economic impact of these results when applied to Spain. An Excel-based cost-consequence model with a one-year time horizon was populated with SLS asthma study results, adopting the Spanish National Health System (NHS) perspective. Total number of diagnosed asthmatic patients > 18 years old currently managed with UC in Spain were estimated with local data. Effectiveness data analysed were the percentage of patients per Asthma Control Test (ACT) category at 24- and 52-weeks from SLS asthma. Direct costs (pharmacological costs and per ACT category) were estimated from Spanish public sources and literature (€,2018). Base-case analysis assumed an increased use of FF/VI from 10% to 20% within one year and a 100% proportion of days covered. A series of sensitivity analyses from base-case settings were performed. At base-case, within 775,900 asthmatic patients analysed, substitution of UC with FF/VI was associated with reduced costs due to ACT improvement, leading to potential total annual savings of €4,927,672. Sensitivity analyses ranged from €6,012,975 up to €14,783,015 cost-savings associated with FF/VI, showing the robustness of base-case results. An analysis considering patients only on ICS/LABA showed €8,207,448 potential cost-savings. The improved asthma control with FF/VI compared with UC observed in SLS asthma, could be translated into potential healthcare-savings for the Spanish NHS. These results may be useful to inform decision-making processes.

PHP159 - PUBLIC HEALTH AND ECONOMIC VALUE OF A NATIONWIDE PATIENT BLOOD MANAGEMENT PROGRAM

Patient Blood Management (PBM) is an evidence-based, multidisciplinary approach aiming to optimize patients’ own blood in order to improve clinical outcomes and healthcare expenditure. This research set out to assess the public health and economic value of a nationwide PBM program in Portugal. A mathematical decision-model was developed to estimate the impact of a nationwide PBM program over a one-year time horizon. Hospital-attended patients from the following therapeutic areas were considered: surgery (orthopaedic/cardiac/urologic), cardiology, oncology, gastrointestinal bleeding, abnormal uterine bleeding, haemodialysis, inflammatory bowel disease and pregnancy. Model inputs, obtained from Portuguese national health databases and literature review, included effectiveness and cost data on PBM strategies, transfusion utilization, hospitalization, mortality, physician visits and drug use. Model structure and inputs were validated by a national expert panel. For an estimated 384,704 patients eligible for PBM strategies, a reduction in the proportion of red blood cell (RBC) transfused patients of 51.2% could be obtained (-17,202 patients), associated with a reduction in the number of transfused RBC units of 57.3% (-65,214 units). Due to an estimated 8.4% and 37.3% decrease in hospital length of stay and readmissions, respectively, 233,141 in-hospital days could be avoided. Furthermore, in-hospital mortality could reduce by 594 cases, resulting in 1,481 life-years gained. Although an increase in drug use and physician visits would lead to an estimated additional €24.1 million in costs, these would be counterbalanced by €91.9 million in savings, mainly due to €70.4 million in hospitalization costs and €17.6 million in RBC transfusions. Net savings of over €67.7 million could be expected, equivalent to a 6.3% reduction in the public expenditure of this population. The implementation of a nationwide PBM program in Portugal could result in a substantial improvement in public health outcomes with high economic value to the national health system.

Immediate versus delayed breast reconstruction in breast cancer patients in Colombia: A costutility analysis

Introduction. Breast reconstruction, either immediate or delayed, is part of the treatment of breast cancer. Each country and health system pays for and evaluates these procedures in different ways. Thus, it is important to determine which strategy is most cost-effective in Colombia. Objective: To evaluate the cost-utility of breast cancer treatment with immediate reconstruction compared with delayed reconstruction. Materials and methods: We used a decision tree model and a one-year time horizon from the perspective of the third-party payer; the cost data were taken from the Colombian Instituto de Seguros Sociales 2001 rate manual plus a 30% adjustment according to the methodology of the Instituto de Evaluación Tecnológica en Salud, IETS, and the billing model of the Centro Javeriano de Oncología at the Hospital Universitario San Ignacio. The transition probabilities and profits were obtained from medical specialists, patients, and the medical literature. We also conducted univariate and probabilistic sensitivity analyses. Results: The expected costs per capita were COP$ 26,710,605 (USD$ 11,165) for the immediate reconstruction and COP$ 26,459,557 (USD$ 11,060) for the deferred reconstruction. Immediate reconstruction generated an incremental cost of COP$ 251,049 (USD$ 105) and 0.75 quality-adjusted life years (QALY), while deferred reconstruction generated 0.63 QALYs, with an incremental cost-utility ratio of COP$ 2,154,675 per QALY (USD$ 901). Conclusions: The cost per QALY did not exceed the acceptability threshold of the Gross Domestic Product (GDP) per capita. The costs for the first year were similar. Both techniques are favorable for the Colombian health system, but the utility reported by patients and the literature is greater with the immediate reconstruction.

Cost-consequence analysis of fluticasone furoate/vilanterol 92/22 mcg for the management of COPD in the Spanish NHS.

ObjectivesThe Salford Lung Study in Chronic Obstructive Pulmonary Disease (SLS COPD) is a 12-month, open-label randomized clinical trial comparing clinical effectiveness and safety of initiating once-daily fluticasone furoate/vilanterol (FF/VI) 92/22 mcg with continuing usual care (UC) in patients with COPD followed in primary care in the UK. The objective of this analysis is to estimate the economic impact of these results when applied to Spain.Materials and methodsAn Excel-based cost–consequence model with a one-year time horizon was populated with SLS COPD results, adopting the Spanish National Health System (NHS) perspective. Patients analyzed were diagnosed COPD patients ≥40 years old, currently managed with maintenance treatment and with a history of exacerbations (total number estimated from Spanish data). Mean least squares annual rates of moderate/severe exacerbations after 1 year for the intention-to-treat population from SLS COPD were included in the model (1.50 [FF/VI] and 1.64 [UC]); serious adverse events were excluded from the analysis as no differences between treatment arms were found. Medication and exacerbation management costs in euros were estimated from Spanish public sources for 2016. Model base-case analysis assumed an increased usage of FF/VI from 4% to 10% within 1 year, and a 100% proportion of days covered with study medications. Deterministic sensitivity analyses were performed for mitigating uncertainty.ResultsAt base case, within 50,522 COPD patients analyzed, substitution of UC with FF/VI 92/22 mcg was associated with reduced medication and exacerbation management costs, leading to potential total annual savings of €353,623. Deterministic sensitivity results ranged from €218,333 up to €1,532,366 potential cost savings associated with FF/VI, showing the robustness of base-case results.ConclusionThe decreased rate of exacerbations with FF/VI 92/22 mcg compared with UC observed in SLS COPD could be translated into potential health care savings for the Spanish NHS. These results may be useful to inform decision-making processes.

Osteopathic care for low back pain and neck pain: A cost-utility analysis

ObjectivesThe aim was to examine the health and economic consequences of osteopathic care for low back pain and neck pain in addition to usual care compared to usual care alone. DesignA decision tree model considering a one-year time horizon was applied. The analysis occurred from a health insurance perspective only considering direct medical costs. The health effects were expressed as quality-adjusted life years (QALYs). Main outcomesThe main outcome was the incremental cost-effectiveness ratio (ICER). The uncertainty around key input parameters was addressed applying one-way and probabilistic sensitivity analyses (5000 simulations). ResultsFor low back pain, osteopathy resulted in cost savings (€385.1 vs €501.8/patient) at improved QALYs (0.666 vs. 0.614) compared to usual care. For neck pain, osteopathy resulted in additional costs (€577.3 vs. €521.0) and improved QALYs (0.639 vs. 0.609) resulting in an ICER of €1,870/QALY. The one-way sensitivity analysis identified the hospitalization cost (back) and osteopathy cost (neck) as major cost drivers. The probabilistic sensitivity analysis resulted in an average net saving of €163 (95%CI–€260, -€49.1) and a QALY gain of 0.06 (95%CI –0.06, 0.17) for low back pain and an average additional cost of €55.1 (95%CI €20.9, €129) and improved QALY gain of 0.03 (95%CI–0.06, 0.12) for neck pain. ConclusionsOsteopathy was found to be a ‘dominant’ (low back pain) and cost-effective strategy (neck pain) compared to usual care. Further health economic evaluation studies considering a broader range of cost items and longer time horizon are required.

Assessment of the Stability of Insurance Companies: The Case of Baltic Non-Life Insurance Market

Abstract The study gives an overview of the Baltic non-life insurance market. The purpose of the research is to summarise stability statistics on solvency ratios, risk profiles and capital surplus, which was contained in Solvency and Financial Condition reports (SFCR) in 2016 published first time by non-life insurance companies in European Union and Baltic market (Latvia, Estonia, and Lithuania). Solvency II came into effect in 2016, and these reports have been prepared using the new requirements of the Solvency II framework. All non-life insurance companies are required to have eligible own funds at least equal to solvency capital requirement (SCR) in order to avoid supervisory intervention (own funds divided by SCR are required to be at least 100 %). The SCR is based on well known risk measure value at risk with 99.5 % confidence level over a one-year time horizon. Baltic non-life insurance companies were strong capitalized (median 155 %) in 2016. It means that all Baltic companies can survive even if 1 in 200 years events have occurred although Baltic solvency coverage ratio is lower than the median ratio in European Union (209 %). For Latvian non-life insurance market, solvency ratio median is the lowest in European Union comparing by countries. The authors have analysed the historical development of the market and have calculated financial ratios, Gini’s concentration index, as well as dissimilarity index. The authors have investigated the current and future internal and external risks and issues for the Baltic non-life insurance market, such as political environment, low-yield environment, and market competition due to new mergers and acquisitions (M&A) activities, and a new rule for accounting for insurance companies IFRS17.

Physician Time Burden Associated with Querying Prescription Drug Monitoring Programs.

Prescription drug monitoring programs (PDMPs) enable prescribers to review patient prescription histories, and their use is mandatory in many states. We estimated the cost of physicians retrieving PDMP patient reports compared with a model where a delegate (i.e., administrative staff) retrieves reports. We performed a cost analysis with a one-year time horizon, from the perspective of physicians' employers. We obtained specialty-specific estimates of controlled substance prescribing frequency from the National Ambulatory Medical Care Survey, 2012-2014. We defined three PDMP usage cases based on the frequency of queries: comprehensive (before every Schedule II-IV controlled substance prescription), selective (before new Schedule II-IV prescriptions and every six months for continuing medications), and minimal (before new Schedule II or III prescriptions and annually for continuing medications). The delegate model was less costly for all specialties in the comprehensive usage case and most specialties in the selective usage case, and it was similar to physician model costs in the minimal usage case. Estimated annual costs of the physician model to a large health care system (1,000 full-time equivalent physicians) were $1.6 million for comprehensive usage, $1.1 million for selective usage, and $645,313 for minimal usage. The delegate model was less costly in the comprehensive (savings of $907,283) and selective usage cases (savings of $156,216). Relying on delegates vs physicians to retrieve reports is less costly in most cases. Automation and integration of PDMP data into electronic health records may reduce costs further. Physicians, health care systems, and states should collaborate to streamline access to PDMPs.

Backtesting an equity risk model under Solvency II

Backtesting is a technique for validating internal models under Solvency II, which allows for evaluating the discrepancies between the results provided by a model and real observations. This paper aims to establish various backtesting tests and to show their applications to equity risk in Solvency II. Normal and empirical models with a rolling window are used to determine VaR at the 99.5% confidence level over a one-year time horizon. The proposed methodology performs the backtesting of annualized returns arising from the accumulation of daily returns. The results show that even if a model is conservative when tested out of a sample, it may be inadequate when evaluated in a sample, thereby highlighting the problems inherent in the out-of-sample backtesting proposed by the regulator.

Analyzing the Impact of Time Horizon, Volatility and Profit Margins on Solvency Capital: Proposing a New Model for the Global Regulation of the Insurance Industry

The European Solvency II regime requires a solvency capital covering risks with a given shortfall probability of 1/200=0.5% on a one-year time horizon, which is extremely short compared to the contractual terms in traditional life insurances, as well as the settlement periods of several decades in some casualty branches. This approach undermines the importance of a high return margin and, given a risk-averse approach to management, may lead to an overall riskier business strategy in the long run. In light of this, we cannot help but ask whether such a short time horizon is capable of providing a meaningful guideline for a sustainable business and risk management that has a long-term perspective. In response to this question, we present a new model for assessing the evolution of the equity of an insurance company and calculating the probability that the initial equity of an insurance company will be depleted during a given time period. This model demonstrates that insolvencies mostly do not occur in the first year. Therefore, if one only considers a one-year window, as is the case under Solvency II, the risk will be underestimated. Even more serious is that the business will be managed too cautiously without aiming for a suitably high profit margin, which significantly reduces the risk only in the long term.

PD76 The Value Of Continuous Lateral Rotation Therapy In The ICU

Introduction:Mechanical ventilation in the intensive care unit (ICU) increases the risk of hospital-acquired conditions (HACs) such as ventilator-associated pneumonia (VAP) and pressure injuries (PrI). Continuous lateral rotation therapy (CLRT) has been shown to reduce VAP and PrI incidence, but the value of switching to CLRT over standard care is presently unknown. We evaluate the cost-effectiveness of CLRT beds compared to standard care in ICUs and determine the return on investment (ROI) associated with its implementation.Methods:A Markov model was constructed to predict health state transitions from the time of ventilation through 28 days using the healthcare sector perspective. Daily transition probabilities were extrapolated from prospective clinical studies comparing CLRT with standard care. Costs were estimated in 2014 USD. Utility scores were extracted from the published literature. Cost per quality-adjusted life-years (QALYs) was calculated and sensitivity analyses were conducted. A secondary analysis from a societal perspective with a one-year time horizon included the costs of patient and caregiver lost productivity. ROI analysis was performed to estimate the net benefit and breakeven point of the investment. Value of Information analysis was performed to determine whether further research is warranted.Results:From both perspectives, CLRT was dominant. From the healthcare sector perspective, the expected cost for CLRT per patient was USD 47,165 compared to standard care at USD 49,258 per patient, showing that CLRT saves cost per patient. The expected effectiveness of CLRT per patient was 0.0418 QALYs compared to 0.0416 QALYs for standard care. CLRT was dominant in 99.94 percent of Monte Carlo simulations. CLRT also reached the break-even point after 5 months. Expected Value of Perfect Information was equal to 0.019, indicating little value of additional evidence at the current level of parameter uncertainty.Conclusions:CLRT is highly cost-effective compared to standard care by preventing ventilator-associated infections and PrIs in an ICU setting.

An approximate multi-period Vasicek credit risk model

Abstract Financial institutions and regulators usually measure credit risk only over a one-year time horizon. Hence, current statistical models can generate closed-form expressions for the one-year loss distribution. Losses over longer horizons are considered using scenario analysis or Monte Carlo simulation. This paper proposes a simple multi-period credit risk model and uses Taylor expansion approximations to estimate the multi-period loss distribution. In this paper we extend the currently available second-order Taylor expansion approximations to credit risk with a third-order term and we use this new approximation to obtain the loss distribution in the multi-period framework. Our results show that the approximation is more accurate under recessions or for portfolios with high probability of default. We also show that, in general, the effect of this third-order adjustment is quite small.

Cost effectiveness of the addition of a comprehensive CT scan to the abdomen and pelvis for the detection of cancer after unprovoked venous thromboembolism

ImportanceUnprovoked venous thromboembolism (VTE) can be the first manifestation of cancer. It is unclear if extensive screening for occult cancer including a comprehensive computed tomography (CT) scan of the abdomen/pelvis is cost-effective in this patient population. ObjectiveTo assess the health care related costs, number of missed cancer cases and health related utility values of a limited screening strategy with and without the addition of a comprehensive CT scan of the abdomen/pelvis and to identify to what extent testing should be done in these circumstances to allow early detection of occult cancers. Participants and settingCost effectiveness analysis using data that was collected alongside the SOME randomized controlled trial which compared an extensive occult cancer screening including a CT of the abdomen/pelvis to a more limited screening strategy in patients with a first unprovoked VTE, was used for the current analyses. Main outcomes and measuresAnalyses were conducted with a one-year time horizon from a Canadian health care perspective. Primary analysis was based on complete cases, with sensitivity analysis using appropriate multiple imputation methods to account for missing data. ResultsData from a total of 854 patients with a first unprovoked VTE were included in these analyses. The addition of a comprehensive CT scan was associated with higher costs ($551 CDN) with no improvement in utility values or number of missed cancers. Results were consistent when adopting multiple imputation methods. Conclusions and relevanceThe addition of a comprehensive CT scan of the abdomen/pelvis for the screening of occult cancer in patients with unprovoked VTE is not cost effective, as it is both more costly and not more effective in detecting occult cancer.

Potential Cost-Effectiveness of an Influenza Vaccination Program Offering Microneedle Patch for Vaccine Delivery in Children.

ObjectiveThe influenza vaccine coverage rate of children is low in Hong Kong. Microneedle patches (MNPs) is a technology under development for painless delivery of vaccines. This study aimed to examine the potential clinical outcomes and direct medical costs of an influenza program offering MNP vaccine to children who have declined intramuscular (IM) vaccine in Hong Kong.MethodsA decision model was designed to compare potential outcomes between IM vaccine program and a program offering MNP vaccine to those declined IM vaccine (IM/MNP program) in a hypothetical cohort of children over one-year time horizon. The model outcomes included direct medical cost, influenza infection rate, mortality rate, and quality-adjusted life-years (QALYs) loss. Model inputs were retrieved from published literature. Sensitivity analyses were performed to examine the robustness of model results.ResultsIn base-case analysis, IM/MNP program was more costly per child (USD19.13 versus USD13.69; USD1 = HKD7.8) with lower influenza infection rate (98.9 versus 124.8 per 1,000 children), hospitalization rate (0.83 versus 1.05 per 1,000 children) and influenza-related mortality rate (0.00042 versus 0.00052 per 1,000 children) when compared to IM program. The incremental cost per QALY saved (ICER) of IM/MNP program versus IM program was 27,200 USD/QALY. Using gross domestic product (GDP) per capita of Hong Kong (USD40,594) as threshold of willingness-to-pay (WTP) per QALY, one-way sensitivity analysis found ICER of IM/MNP to exceed WTP when duration of illness in outpatient setting was <5.7 days or cost per MNP vaccine was >1.39-time of IM vaccine cost. In 10,000 Monte Carlo simulations, IM/MNP program was the preferred option in 57.28% and 91.68% of the time, using 1x and 3x GDP per capita as WTP threshold, respectively.ConclusionAcceptance of IM/MNP program as the preferred program was subject to the WTP threshold, duration of illness in outpatient settings, and cost of MNP vaccine.

Screening for acute HIV infection in community-based settings: Cost-effectiveness and impact on transmissions

To determine cost-effectiveness of three community-based acute HIV infection (AHI) testing algorithms compared to HIV antibody testing alone by focusing on the potential of averting new infections occurring within a one-year time horizon among men who have sex with men (MSM). Data sources for model parameters included actual cost and prevalence data derived from a community-based AHI screening program in San Diego, and published studies. Main outcome measure was costs per infection averted (IA). The lower end of the cost range of discounted lifetime costs of an HIV infection (i.e. $236,948) was used for defining cost-effectiveness. The most sensitive algorithm for AHI detection, which was based on HIV nucleic acid amplification testing, was estimated to prevent between 5 and 45 transmissions, with simulated costs per infection averted between $965 and $141,256 when compared to HIV antibody testing alone. AHI testing was cost-effective in preventing new HIV infections among at risk MSM in San Diego, and also among other MSM populations with similar HIV prevalence but lower proportions of AHI diagnoses. These results indicate that community-based AHI testing among MSM in the United States can pay for itself over the long run.

Modeling phytoplankton community in reservoirs. A comparison between taxonomic and functional groups-based models

In this paper we address the formulation of two mechanistic water quality models that differ in the way the phytoplankton community is described. We carry out parameter estimation subject to differential-algebraic constraints and validation for each model and comparison between models performance. The first approach aggregates phytoplankton species based on their phylogenetic characteristics (Taxonomic group model) and the second one, on their morpho-functional properties following Reynolds' classification (Functional group model). The latter approach takes into account tolerance and sensitivity to environmental conditions. The constrained parameter estimation problems are formulated within an equation oriented framework, with a maximum likelihood objective function. The study site is Paso de las Piedras Reservoir (Argentina), which supplies water for consumption for 450,000 population. Numerical results show that phytoplankton morpho-functional groups more closely represent each species growth requirements within the group. Each model performance is quantitatively assessed by three diagnostic measures. Parameter estimation results for seasonal dynamics of the phytoplankton community and main biogeochemical variables for a one-year time horizon are presented and compared for both models, showing the functional group model enhanced performance. Finally, we explore increasing nutrient loading scenarios and predict their effect on phytoplankton dynamics throughout a one-year time horizon.