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Objective: The aim of this study was to examine how calibration uncertainty affects the overall uncertainty of a mathematical model and to evaluate potential drivers of calibration uncertainty. Methods: A lifetime Markov model of the natural history of human papillomavirus (HPV) infection and cervical disease was developed to assess the cost effectiveness of a hypothetical HPV vaccine. Published data on cervical cancer incidence and mortality and prevalence of pre-cursor lesions were used as endpoints to calibrate the age- and HPV-type-specific transition probabilities between health states using the Nelder-Mead simplex method of calibration. A conventional probabilistic sensitivity analysis (PSA) was performed to assess uncertainty in vaccine efficacy, cost and utility estimates. To quantify the uncertainty around calibrated transition probabilities, a second PSA (calibration PSA) was performed using 25 distinct combinations of objective functions and starting simplexes. Results: The initial calibration produced an incremental cost-effectiveness ratio (ICER) of $US4300 per QALY for vaccination compared with no vaccination, and the conventional PSA gave a 95% credible interval of dominant to $US9800 around this estimate (2005 values). The 95% credible interval for the ICERs in the calibration PSA ranged from $US1000 to $US37 700. Conclusions: Compared with a conventional PSA, the calibration PSA results reveal a greater level of uncertainty in cost-effectiveness results. Sensitivity analyses around model calibration should be performed to account for uncertainty arising from the calibration process. [ABSTRACT FROM AUTHOR]

Background: A recent study found fewer hospitalizations for congestive heart failure (CHF) patients receiving high-dose versus low-dose statin therapy. Objective: To examine the cost effectiveness of high-dose versus low-dose statin therapy in CHF patients. Methods: Two scenarios (literature-based [base-case scenario] vs trial-based post-event mortality [alternative scenario]) assessed the cost effectiveness of atorvastatin 80mg/day (A80) versus atorvastatin 10 mg/day (A10) in patients with both CHF and coronary heart disease (CHD) [CHF/CHD], using a lifetime Markov model. The model predicts treatment-specific probabilities of major and minor cardiovascular events and death, based on clinical trial data. The quality of life and costs were literature based. Measures included costs per life-year saved (LYS) and QALY gained. Health consequences and costs were discounted at 3.0% annually. Analyses were conducted from the payer perspective and valued in $US, year 2006-7 values. Results: Literature-based mortality estimates (base case) increased life-years and QALYs for A80 compared with A10 (incremental cost-effectiveness ratios [ICERs]: $US9600 per LYS; $US13 600 per QALY). At a willingness to pay of $US100 000 per QALY, A80 was cost effective in 80% of simulations. A10 dominated A80 when using trial-based mortality estimates (alternative scenario). At a willingness to pay of $US100 000 per QALY, A80 was cost effective in 48% of simulations. Conclusions: Intensive A80 treatment may be cost effective versus A10 in cardiovascular prevention in CHF/CHD patients in the US, due to projected gains in life expectancy and health-related quality of life. However, the results are highly sensitive to assumptions about the mortality rate in the model. When using the mortality rate observed in the trial, A10 dominates A80. [ABSTRACT FROM AUTHOR]

The Treating to New Targets (TNT) clinical trial found that intensive 80 mg atorvastatin (A80) treatment reduced cardiovascular events by 22% when compared to 10 mg atorvastatin (A10) treatment. We evaluated the cost-effectiveness of intensive A80 vs A10 treatment in the United Kingdom (UK), Spain, and Germany. A lifetime Markov model was developed to predict cardiovascular disease-related events, costs, survival, and quality-adjusted life-years (QALYs). Treatment-specific event probabilities were estimated from the TNT clinical trial. Post-event survival, health-related quality of life, and country-specific medical-care costs were estimated using published sources. Intensive treatment with A80 increased both the per-patient QALYs and corresponding costs of care, when compared to the A10 treatment, in all three countries. The incremental cost per QALY gained was € 9,500, € 21,000, and € 15,000 in the UK, Spain, and Germany, respectively. Intensive A80 treatment is estimated to be cost-effective when compared to A10 treatment in secondary cardiovascular prevention. [ABSTRACT FROM AUTHOR]