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Cost-effectiveness of vaccinating for invasive pneumococcal disease in the elderly in the Lazio region of Italy |
Merito M, Giorgi Rossi P, Mantovani J, Curtale F, Borgia P, Guasticchi G |
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Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. Health technology The study compared pneumococcal vaccination for an elderly population against no vaccination. The 23-valent polysaccharide vaccine was used.
Economic study type Cost-effectiveness analysis.
Study population As this was a modelling study, the target population comprised a cohort of 921,281 people of the general population, who were older than the age of 64. Further inclusion and exclusion criteria were not reported.
Setting The setting was the community. The economic study was carried out in Lazio, Italy.
Dates to which data relate The demographic and effectiveness data were obtained from sources published between 1991 and 2005. The resource use data were based on actual data from the year 2003-2004. The cost data were from 2001 and 2004. All costs were reported for the price year 2001.
Source of effectiveness data The effectiveness data were derived from a review and synthesis of published sources.
Modelling A model was constructed to assess the health benefits and costs of the pneumococcal programme. The time horizon selected for the model was 5 years since data in the literature indicated that levels of antibodies, and hence protection due to the vaccine, significantly decrease after this time. However, further relevant details of the model were not provided.
Outcomes assessed in the review Numerous epidemiological and clinical parameters were used in the model. Those related specifically to the vaccine were vaccine efficacy according to age-group during the first 3 years and during the following 2 years.
Study designs and other criteria for inclusion in the review Sources searched to identify primary studies Criteria used to ensure the validity of primary studies Methods used to judge relevance and validity, and for extracting data Number of primary studies included Overall, the authors used 6 primary studies as sources of effectiveness data.
Methods of combining primary studies Investigation of differences between primary studies The authors do not appear to have investigated differences between the primary studies.
Results of the review During the first 3 years, aggregate efficacy against invasive pneumococcal infections was 80% in the age group 65 to 74 years, 67% in the age group 75 to 84 years, and 46% in the age group 85 years and older.
For the following 2 years, vaccine efficacy decreased to 71% in the age group 65 to 74 years, 53% in the 75 to 84 years, and 22% in the age group 85 years and older.
Measure of benefits used in the economic analysis The authors used invasive pneumococcal disease (IPD) episodes averted and life-years gained (LYG) as the measures of benefit in the economic analysis. These were obtained from the model.
Direct costs The health service costs were included in the analysis. These comprised the costs of vaccination, treatment of IPD and hospitalisation for pneumococcal pneumonia and pneumococcal meningitis. Vaccination costs included the administrative costs of the vaccination programme, the vaccine dose and the general practitioner's (GP) charges for vaccine delivery. Treatment costs included GP visit, pneumological visit and chest radiography. Hospitalisation costs included room and board, nursing care, physician services, standard pharmacotherapy, laboratory tests, radiology, surgery and intensive care. The costs and the quantities were not reported separately and only summary costs were reported for inpatient treatment costs. All costs were derived from official published sources (e.g. Lazio Region's Agency of Public Health data on Diagnosis-Related Groups) or were based on actual data from the authors' setting. All costs were reported for the price year 2001, but adjustments for inflation were not performed. As the time horizon of the model was 5 years, all costs were appropriately discounted at a rate of 3%.
Statistical analysis of costs The costs were treated deterministically.
Indirect Costs The indirect costs were not included in the analysis.
Sensitivity analysis One-way sensitivity analyses were performed on the age-specific incidence of vaccine coverage, incidence rate of bacteraemic pneumococcal pneumonia (BPP), BPP case-fatality rate, discount rate and vaccine efficacy in order to investigate the robustness of the results to variability in the input parameters. The benefits (LYG) were discounted at the same rate as the costs. A multi-way sensitivity analysis, in which the above parameters were set at the most and least favourable values in order to obtain best-and worst-case scenarios, was conducted. The ranges used were obtained from the literature. A probabilistic sensitivity analysis was also performed, using distributions of the model parameters and Monte-Carlo simulations to obtain the confidence intervals (CIs) for incremental costs per LYG. Distributions were reported.
Estimated benefits used in the economic analysis Within 5 years, one-time vaccination would result in 4.5 IDP episodes averted per 10,000 vaccinated persons and in a gain of 0.2 days of life per person vaccinated.
Cost results The total costs were not reported. It was reported that the implementation of the vaccination programme would result in a cost of EUR 0.9 million, while cost-savings due to averted hospitalisations were EUR 1.2 million.
Synthesis of costs and benefits An incremental cost-effectiveness analysis was performed. The costs and benefits of the vaccination were compared against those of no vaccination.
The incremental cost per IPD episode averted was EUR 34,681 (95% CI: 28,699 to 42,929).
The incremental cost per LYG was EUR 23,361 (95% CI: 16,419 to 38,297).
The one-way sensitivity analyses demonstrated that the results were most sensitive to changes in vaccine effectiveness, percentage of BPP and BPP case-fatality rate.
Using higher and lower values of age and year-specific vaccine effectiveness resulted in changes in the incremental cost-effectiveness ratio of +218% to -31% compared with baseline.
The worst case-scenario resulted in an incremental cost of EUR 285,400 per LYG, while the best-case scenario resulted in an incremental cost of EUR 4,249 per LYG.
Assuming a willingness-to-pay threshold of EUR 35,000 per LYG, the probability of the vaccination programme being cost-effective in comparison with no vaccination was 0.9.
Authors' conclusions The authors acknowledged that the sensitivity of the cost-effectiveness results to variability in the data meant that they were unable to derive robust conclusions.
CRD COMMENTARY - Selection of comparators The authors compared the vaccination programme administered to the general elderly population against no vaccination. This allowed for the active value of the intervention to be evaluated. No vaccination seems to have represented standard practice in the authors' setting. You should decide if this is a valid health technology in your own setting.
Validity of estimate of measure of effectiveness The authors did not indicate whether a systematic review of the literature was undertaken. Although this is common practice with models, it does not always ensure that the best available data are used in the model. In most cases, the authors appear to have used data from the available sources they identified. In addition, the impact of differences between the studies was not considered when estimating effectiveness. However, the authors carried out a number of sensitivity analyses relating to efficacy estimates. These analyses improve both the internal validity and the generalisability of the study by demonstrating the variability of the results to changes in the base-case estimates.
Validity of estimate of measure of benefit The authors used IPD episodes averted and LYG as the measures of benefit in the economic analyses. These measures were obtained from the model. LYG is an appropriate measure with which to express survival and can be compared with the benefits of other health care interventions.
Validity of estimate of costs Given the perspective of the public health service paying for the vaccination programme, it appears that all the relevant categories of costs have been included in the economic analysis. The unit costs and the resource quantities were not reported separately, and the use of summary hospitalisation costs will not enable the analysis to be easily reworked for other settings. In addition, the authors used diagnosis-related group reimbursement fees, which do not reflect true opportunity costs. These facts may limit the generalisability of the authors' results. The costs were treated deterministically and, even though it was reported that uncertainty around the cost estimates was investigated in sensitivity analyses, the results of the analysis and the ranges used were not reported. The costs of long-term care for meningitis, medication before and after hospitalisation, ambulatory visits and tests were omitted from the analysis. Although it was reported that the omitted costs accounted for less than 15% of the total direct health care costs, it is difficult to determine whether their omission has affected the authors' conclusions. Discounting was appropriately performed and the price year was reported, which will aid future reflation exercises.
Other issues The authors compared their results with those from other studies which, in general, showed the findings to be in agreement. The issue of generalisability of the results to other settings was not directly addressed. The authors do not appear to have presented their results selectively. However, the results from the sensitivity analyses were not reported in full and the costs were not summarised.
The authors reported a number of limitations to their study. The indirect costs and direct costs for care-giving were not included in the analysis, although their inclusion might have strengthened the authors' conclusions. The impact of vaccination on quality of life was not accounted for because of a lack of relevant data. Although the adverse effects of vaccination were not taken into consideration, their exclusion is unlikely to have affected the authors' conclusions. Data on the incidence of BPP were not available, thus the authors indirectly derived them using an algorithm and data on pneumonia incidence from the literature.
Implications of the study The authors did not make explicit recommendations for changes in policy or practice. However, they called for further research to derive robust estimates of vaccine efficacy amongst the elderly and of IPD incidence. They also suggested that future trials should account for all IPD syndromes other than meningitis. Such research would be further facilitated through the establishment of case definition. In future trials, IPD should be more tightly defined and the definition should include meningitis, bacteraemic pneumonia and sepsis.
Bibliographic details Merito M, Giorgi Rossi P, Mantovani J, Curtale F, Borgia P, Guasticchi G. Cost-effectiveness of vaccinating for invasive pneumococcal disease in the elderly in the Lazio region of Italy. Vaccine 2007; 25(3): 458-465 Other publications of related interest Because readers are likely to encounter and assess individual publications, NHS EED abstracts reflect the original publication as it is written, as a stand-alone paper. Where NHS EED abstractors are able to identify positively that a publication is significantly linked to or informed by other publications, these will be referenced in the text of the abstract and their bibliographic details recorded here for information.
Indexing Status Subject indexing assigned by NLM MeSH Aged; Aged, 80 and over; Cost-Benefit Analysis; Costs and Cost Analysis; Female; Humans; Italy /epidemiology; Male; Middle Aged; Monte Carlo Method; Pneumococcal Infections /economics /epidemiology /prevention & Pneumococcal Vaccines /economics /immunology; control AccessionNumber 22007000020 Date bibliographic record published 31/05/2007 Date abstract record published 31/05/2007 |
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