Modelling the economic efficiency of using different strategies to control Porcine Reproductive & Respiratory Syndrome at herd level

PRRS is among the diseases with the highest economic impact in pig production worldwide. Different strategies have been developed and applied to combat PRRS at farm level. The broad variety of available intervention strategies makes it difficult to decide on the most cost-efficient strategy for a given farm situation, as it depends on many farm-individual factors like disease severity, prices or farm structure. Aim of this study was to create a simulation tool to estimate the cost-efficiency of different control strategies at individual farm level. Baseline is a model that estimates the costs of PRRS, based on changes in health and productivity, in a specific farm setting (e.g. farm type, herd size, type of batch farrowing). The model evaluates different intervention scenarios: depopulation/repopulation (D/R), close & roll-over (C&R), mass vaccination of sows (MS), mass vaccination of sows and vaccination of piglets (MS + piglets), improvements in internal biosecurity (BSM), and combinations of vaccinations with BSM. Data on improvement in health and productivity parameters for each intervention were obtained through literature review and from expert opinions. The economic efficiency of the different strategies was assessed over 5 years through investment appraisals: the resulting expected value (EV) indicated the most cost-effective strategy. Calculations were performed for 5 example scenarios with varying farm type (farrow-to-finish – breeding herd), disease severity (slightly – moderately – severely affected) and PRRSV detection (yes – no). The assumed herd size was 1000 sows with farm and price structure as commonly found in Germany. In a moderately affected (moderate deviations in health and productivity parameters from what could be expected in an average negative herd), unstable farrow-to-finish herd, the most cost-efficient strategies according to their median EV were C&R (€1′126′807) and MS + piglets (€ 1′114′649). In a slightly affected farrow-to-finish herd, no virus detected, the highest median EV was for MS + piglets (€ 721′745) and MS (€ 664′111). Results indicate that the expected benefits of interventions and the most efficient strategy depend on the individual farm situation, e.g. disease severity. The model provides new insights regarding the cost-efficiency of various PRRSV intervention strategies at farm level. It is a valuable tool for farmers and veterinarians to estimate expected economic consequences of an intervention for a specific farm setting and thus enables a better informed decision

Inventory management in railway sleepers: A simulation model for replacement strategies

This paper describes the development of a simulation model to assess the inventory requirements of alternative rail sleeper replacement strategies. The main aim of the model is to determine the optimal replacement strategy, given replacement costs and resultant train operating cost benefits. We consider the replacement problem under the following assumptions: The time to failure under constant stress follows a Weibull distribution and the scale parameter is a function of stress level and the three stress levels under normal (all adjacent units are good), medium-stress (one adjacent unit has failed) and high-stress conditions (two adjacent units are failed) are considered. The cumulative exposure model is used to model the failure distributions. The operational cost per unit time depends on the maximum number of consecutive failed units. The replacement cost consists of the fixed cost and variable cost proportional to the number of units replaced. A finite horizon is considered and total expected cost is a criterion for comparing the proposed policies. The model has been tested using rail system data and the results are presented in this paper

Development and implementation of preventive-maintenance practices in Nigerian industries.

A methodology for the development of PM using the modern approaches of FMEA, root-cause analysis, and fault-tree analysis is presented. Applying PM leads to a cost reduction in maintenance and less overall energy expenditure. Implementation of PM is preferable to the present reactive maintenance procedures (still prevalent in Nigeria

When is an ounce of prevention worth a pound of cure: The case of cardiovascular disease?

Objective: To provide decision makers with a tool to inform resource allocation decisions at the local level, using cardiovascular disease prevention as an example. Method: Evidence from the international literature was extrapolated to estimate the health and financial impacts in Central Sydney Area Health Service (CSAHS) of three different prevention programs; smoking cessation; blood pressure reduction and cholesterol lowering. The cost-effectiveness analysis framework was reconfigured to 1) estimate the risk of CVD in the community using local risk factor data, 2) estimate the number of CVD events prevented through investment in preventive programs and 3) estimate the local financial flow-on effects of prevention on acute care services. The model developed here estimates an upper bound of what local decision makers could spend on preventive programs whilst remaining consistent with their willingness to pay for one additional life-year gained. Results: The model predicted that over a five-year period the cumulative impact of the three programs has the potential to save 1245 life-years in people aged 40-79 years living in CSAHS. If decision-makers are willing to invest in cost-saving preventive programs only, the model estimates that they can spend up $12 per person in the target group per year. However, if they are willing to spend$70,000 per life-year gained, this amount rises to $201. Conclusions: Modelling the impact of preventive activities on the acute care health system enables us to estimate the amount that can be spent on preventive programs. The model is flexible in terms of its ability to examine these impacts in a variety of settings and therefore has the potential to be a useful resource planning tool.Resource allocation, cardiovascular disease, health promotion, Australia

The control of Corynebacterium pseudotuberculosis infection in sheep flocks : a mathematical model of the impact of vaccination, serological testing, clinical examination and lancing of abscesses

A mathematical model of Corynebacterium pseudotuberculosis infection in sheep flocks was used to evaluate strategies for control and elimination of caseous lymphadenitis (CIA). Control strategies tested were vaccination, serological testing and removal of seropositives, clinical examination and removal of sheep with abscesses, lancing abscesses, and appropriate combinations. Three different infection rates with and without replacement of culled ewes were used to evaluate the control options. Controls were either implemented immediately after infection was detected in a flock or once CIA was at endemic equilibrium, and with different frequencies of examination or testing. Elimination of infection was defined as 99% confidence that no sheep were infected with C. pseudo tuberculosis. The control strategies were evaluated by estimating the reduction in infection or probability of elimination and the number of ewes culled from the flock. Lancing abscesses reduced the prevalence of infection when the initial prevalence was 0.90, but vaccination combined with clinical examination reduced infection rapidly with little impact on lamb productivity. Further research is required to develop a diagnostic test with at least 0.90 specificity and sensitivity under field conditions before any methods of control can be recommended with confidence

Impact of generic alendronate cost on the cost-effectiveness of osteoporosis screening and treatment

Introduction: Since alendronate became available in generic form in the Unites States in 2008, its price has been decreasing. The objective of this study was to investigate the impact of alendronate cost on the cost-effectiveness of osteoporosis screening and treatment in postmenopausal women. Methods: Microsimulation cost-effectiveness model of osteoporosis screening and treatment for U.S. women age 65 and older. We assumed screening initiation at age 65 with central dual-energy x-ray absorptiometry (DXA), and alendronate treatment for individuals with osteoporosis; with a comparator of "no screening" and treatment only after fracture occurrence. We evaluated annual alendronate costs of $20 through$800; outcome measures included fractures; nursing home admission; medication adverse events; death; costs; quality-adjusted life-years (QALYs); and incremental cost-effectiveness ratios (ICERs) in 2010 U.S. dollars per QALY gained. A lifetime time horizon was used, and direct costs were included. Base-case and sensitivity analyses were performed. Results: Base-case analysis results showed that at annual alendronate costs of $200 or less, osteoporosis screening followed by treatment was cost-saving, resulting in lower total costs than no screening as well as more QALYs (10.6 additional quality-adjusted life-days). When assuming alendronate costs of$400 through $800, screening and treatment resulted in greater lifetime costs than no screening but was highly cost-effective, with ICERs ranging from$714 per QALY gained through $13,902 per QALY gained. Probabilistic sensitivity analyses revealed that the cost-effectiveness of osteoporosis screening followed by alendronate treatment was robust to joint input parameter estimate variation at a willingness-to-pay threshold of$50,000/QALY at all alendronate costs evaluated. Conclusions: Osteoporosis screening followed by alendronate treatment is effective and highly cost-effective for postmenopausal women across a range of alendronate costs, and may be cost-saving at annual alendronate costs of $200 or less. © 2012 Nayak et al