Different screening strategies (single or dual) for the diagnosis of suspected latent tuberculosis: a cost effectiveness analysis
Pooran A, Booth H, Miller RF, Scott G, Badri M, Huggett JF, Rook G, Zumla A, Dheda K
 
 
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.

CRD summary

This study aimed to compare the costs and effectiveness of single and dual screening tests for the identification of individuals with latent tuberculosis infection. The authors concluded that dual strategies were more cost-effective than single strategies. The lack of information regarding the quality of the clinical evidence makes the reliability of these results uncertain.

Type of economic evaluation

Cost-effectiveness analysis

Study objective

This study aimed to compare the costs and effectiveness of single and dual tests for the identification of individuals with latent tuberculosis infection.

Interventions

The interventions for the identification of individuals with latent tuberculosis infection were a single tuberculin skin test (TST) or interferon-gamma release assay (IGRA); and dual tests, consisting of a TST followed by an IGRA. The IGRAs were the T.SPOT.TB or QuantiFERON-Tuberculosis Gold In-Tube (QFT-GIT) tests. These interventions were also compared with no screening.

Location/setting

UK/primary care.

Methods

Analytical approach:

The study used a decision-tree model to estimate the clinical and economic outcomes for each of five screening strategies, by combining data from a range of sources. The time horizon in the base case was two years. The authors stated that their study was performed from the UK health care perspective.

Effectiveness data:

The effectiveness evidence came from a number of published clinical studies with varying methods. The main clinical parameters were the sensitivity and specificity of the screening tests, and the number of active tuberculosis cases prevented.

Monetary benefit and utility valuations:

Not applicable.

Measure of benefit:

The measure of benefit used was the number of active tuberculosis cases prevented and the number-needed-to-treat to prevent a case of active tuberculosis.

Cost data:

The direct costs included those of the tests, administration, treatment of adverse drug reactions, and treatment of active tuberculosis. These costs were from a range of sources including UK health technology assessments, standard reference costs, locally collected data, and published studies. The currency was UK pounds sterling (£) and the price year was 2008.

Analysis of uncertainty:

Univariate and deterministic sensitivity analyses were used to estimate the impact of parameter uncertainty on the conclusions.

Results

The dual screening strategies (TST and T-SPOT.TB £162,387; and TST and QFT-GIT £157,048) were cheaper than the single screening strategies (TST £199,589; T.SPOT.TB £203,983; and QFT-GIT £202,921). The cost of no screening was £57,148.

The number-needed-to-treat to prevent an active tuberculosis case was also lower for dual strategies (TST and T-SPOT.TB 61.7; and TST and QFT-GIT 63.6) than for the single strategies (TST 95.5; T.SPOT.TB 61.7; and QFT-GIT 69.7).

Compared with no screening, the incremental cost per active case avoided was £37,206 for TST and T.SPOT.TB; £37,699 for TST and QFT-GIT; £47,840 for TST; £39,712 for T.SPOT.TB; and £42,051 for QFT-GIT.

These results were most sensitive to variations in the change in prevalence of latent tuberculosis infection, the sensitivity and specificity of the IGRAs, and the cost of the IGRAs.

Authors' conclusions

The authors concluded that dual strategies were more cost-effective than single strategies in screening for latent tuberculosis infection.

CRD commentary

Interventions:

The screening strategies were adequately described and appear to have reflected the usual practice in the study setting. These results are likely to be generalisable to other settings.

Effectiveness/benefits:

The effectiveness data were from a range of published studies and some details of these studies were provided in a table with their references. The methods of a literature review were not reported and it is not possible to ascertain if the best available evidence was used. The quality of the studies that provided the clinical data was not reported. A time horizon of two years might not have been sufficient to fully capture the differences in the health outcomes.

Costs:

The authors stated that the perspective was that of the UK health care system and all those costs relevant to this perspective appear to have been included. The cost estimates were relevant to the population and setting and were fully referenced. The authors adjusted these costs to a base year using the Bank of England consumer price index, but the use of the health care component of the consumer price index might have been more appropriate, as inflation for health care is usually higher than that for the overall economy.

Analysis and results:

: The analytical approach was satisfactorily reported and the model structure was reported in full with diagrams. The results were also reported clearly. The incremental analysis compared each intervention with no screening, but a full incremental analysis should compare each intervention with the next most effective one. Significant sensitivity analyses were performed, but this type of sensitivity analysis cannot capture multiple parameter uncertainty. The reporting was adequate and the base-case estimates of the effectiveness and cost data were reported. The authors acknowledged and highlighted the limitations of their study.

Concluding remarks:

The lack of information on the quality of the clinical evidence makes the reliability of the results uncertain.

Funding

Supported by an award from the South African National Research Foundation and Department of Science and Technology South African Research Chairs Initiative, and European Union Framework Programme Seven.

Bibliographic details
Pooran A, Booth H, Miller RF, Scott G, Badri M, Huggett JF, Rook G, Zumla A, Dheda K. Different screening strategies (single or dual) for the diagnosis of suspected latent tuberculosis: a cost effectiveness analysis. BMC Pulmonary Medicine 2010; 10:7
PubMedID
20170555
DOI
10.1186/1471-2466-10-7
Original Paper URL
http://www.biomedcentral.com/1471-2466/10/7/abstract/
Indexing Status
Subject indexing assigned by NLM
MeSH
Contact Tracing /economics /methods; Cost-Benefit Analysis; Decision Trees; Enzyme-Linked Immunosorbent Assay /economics; Great Britain /epidemiology; Health Care Costs; Humans; Incidence; Interferon-gamma /metabolism; Mass Screening /economics /methods; Prevalence; Sensitivity and Specificity; Tuberculin Test /economics; Tuberculosis, Pulmonary /diagnosis /economics /epidemiology
AccessionNumber
22010000833
Date bibliographic record published
21/07/2010
Date abstract record published
29/09/2010
 
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