|
Costs and consequences of additional chest X-ray in a tuberculosis prevention program in Botswana |
Samandari T, Bishai D, Luteijn M, Mosimaneotsile B, Motsamai O, Postma M, Hubben G |
|
|
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 examined the cost-effectiveness of adding a chest radiograph to symptom screening alone, before starting isoniazid, to reduce the risk of tuberculosis in patients with HIV. The authors concluded that, in Botswana, symptom screening alone prevented more tuberculosis cases and deaths, for less money, because the addition of a chest X-ray resulted in fewer patients completing screening and receiving treatment. The methods were valid and key areas of uncertainty were addressed. The authors’ conclusions seem robust. Type of economic evaluation Cost-effectiveness analysis Study objective This study examined the cost-effectiveness of adding a chest radiograph to symptom screening alone, before starting isoniazid, to reduce the risk of tuberculosis in patients with HIV. Interventions Three strategies were considered: symptoms only, symptoms plus chest X-ray, and symptoms plus X-ray plus tracking. For symptoms only, isoniazid was given based on symptom screening alone. For symptoms plus X-ray, isoniazid was given based on symptoms and a chest X-ray. With tracking, there was an intensive effort to prevent any loss to treatment (attrition) due to refusal to have a chest X-ray, non-availability of a chest X-ray, or the patient not returning for the X-ray. Methods Analytical approach:The analysis was based on a decision model, with a three-year time horizon. The authors stated that it took the perspective of the health care system. Effectiveness data:Most of the data were from published sources, including clinical trials. One trial conducted in several Botswana clinics was a primary source of accuracy data and the attrition rate for the symptom plus chest X-ray strategy. The efficacy of isoniazid was from an intention-to-treat analysis of clinical trial data. The rate of attrition and tuberculosis incidence were key inputs for the model. Monetary benefit and utility valuations:Not considered. Measure of benefit:Two summary benefit measures were used: the number of new tuberculosis cases (including the number of new isoniazid-resistant tuberculosis cases) and the number of deaths. Cost data:The economic analysis included the direct medical costs of screening and treatment, such as personnel, tests, and drugs. The unit costs and quantities of resources were presented separately for most items. Most costs were from official Botswanan sources. All costs were expressed in US $ and the price year was 2008. A 3% annual discount rate was applied. Analysis of uncertainty:One-way sensitivity analyses were carried out on all the model inputs. Published ranges of values were used for the clinical inputs, while the costs were varied from 75% to 125% of their starting value. Worst- and best-case scenarios were considered for all three strategies. Results In a hypothetical cohort of 10,000 people with HIV, the total costs were $395,100 with symptoms alone, $522,200 with symptoms plus X-ray, and $607,600 with symptoms, X-ray and tracking. The number of isoniazid-resistant tuberculosis cases was 21.63 with symptoms alone, 5.61 with symptoms plus X-ray, and 6.84 with symptoms, X-ray and tracking. The number of new tuberculosis cases was 618.50 with symptoms alone, 716.20 with symptoms plus X-ray, and 618.50 with symptoms, X-ray and tracking. The number of deaths was 116.53 with symptoms alone, 131.11 with symptoms plus X-ray, and 116.45 with symptoms, X-ray and tracking. Compared with symptoms alone, the incremental cost per isoniazid-resistant tuberculosis case averted was $7,933 with symptoms plus X-ray and $14,368 with symptoms, X-ray and tracking. With the number of tuberculosis cases as the outcome, symptoms plus X-ray was dominated by symptoms alone as it was less effective and more expensive, due to attrition from the isoniazid programme. Compared with symptoms alone, the incremental cost per death averted was $2,816,061 with symptoms, X-ray and tracking, while symptoms plus X-ray was dominated. These results held in almost all scenarios in the sensitivity analysis. The strategy of symptoms plus X-ray produced fewer deaths than symptoms alone, when the attrition rate was less than 0.2%. Authors' conclusions The authors concluded that, in Botswana, a policy of symptom screening only before isoniazid preventive therapy prevented more tuberculosis cases and deaths, for less money, because the addition of a chest X-ray resulted in fewer patients completing screening and receiving treatment. CRD commentary Interventions:The selection of the comparators was appropriate because in Botswana the usual care was symptom screening alone, without a chest X-ray. Effectiveness/benefits:The sources for the clinical inputs were not fully described, but the key estimates, such as attrition rate and isoniazid prevention efficacy, were from clinical trials that should have had high internal validity. The data for the symptom plus chest X-ray strategy were from a study conducted in Botswana. Uncertainty in the key model parameters was investigated in the sensitivity analysis. The benefit outcomes were specific to the disease, but the outcome of deaths might allow comparisons with other diseases. Costs:The economic analysis was consistent with the perspective stated and was well carried out and satisfactorily reported. The unit costs, quantities of resources, price year, and data sources were clearly reported, enhancing the transparency of the analysis. Typical sources from the authors’ setting were used and described. The cost estimates were appropriately varied in the sensitivity analyses. The price year was reported allowing reflection exercises. Analysis and results:An incremental method was appropriately used to combine the projected costs and benefits of the strategies. A deterministic approach was used to investigate the uncertainty, and this focused on variations in individual inputs, as well as scenarios with simultaneous changes of key inputs. The results of both the main analysis and the sensitivity analyses were clearly presented and discussed. The authors acknowledged some limitations of their analysis due to the lack of published data for some model inputs, but the results were stable in the sensitivity analysis. The results were specific to the authors’ setting in Botswana and appear to be difficult to transfer to other settings. Concluding remarks:The cost-effectiveness methods were valid and key areas of uncertainty were addressed. The authors’ conclusions appear to be robust. Funding Supported by a grant from the Centers for Disease Control and Prevention, USA. Bibliographic details Samandari T, Bishai D, Luteijn M, Mosimaneotsile B, Motsamai O, Postma M, Hubben G. Costs and consequences of additional chest X-ray in a tuberculosis prevention program in Botswana. American Journal of Respiratory and Critical Care Medicine 2011; 183(8): 1103-1111 Indexing Status Subject indexing assigned by NLM MeSH Antitubercular Agents /economics /therapeutic use; Botswana /epidemiology; Cost-Benefit Analysis; Drug Resistance, Multiple, Bacterial; Health Care Costs /statistics & Humans; Isoniazid /economics /therapeutic use; Mass Chest X-Ray /economics; Models, Economic; Tuberculosis, Pulmonary /drug therapy /economics /prevention & control /radiography; numerical data AccessionNumber 22011000848 Date bibliographic record published 06/07/2011 Date abstract record published 19/11/2012 |
|
|
|