How methodologic differences affect results of economic analyses: a systematic review of interferon gamma release assays for the diagnosis of LTBI

• Published in: PloS one Vol. 8; no. 3; p. e56044
• Main Authors: Oxlade, Olivia, Pinto, Marcia, Trajman, Anete, Menzies, Dick
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 07.03.2013; Public Library of Science (PLoS)
• Subjects: Analysis; Biological response modifiers; Cost analysis; Cost effectiveness; Cost-Benefit Analysis; Decision analysis; Decision Support Techniques; Economic analysis; Economic aspects; Epidemiology; Health aspects; Humans; Impact prediction; Infection; Infections; Interferon; Interferon gamma; Interferon-gamma Release Tests - economics; Interferon-gamma Release Tests - methods; Latent Tuberculosis - diagnosis; Latent Tuberculosis - economics; Latent Tuberculosis - epidemiology; Mass Screening - economics; Mass Screening - methods; Mathematical models; Medical diagnosis; Medicine; Models, Statistical; Quality; Quality Control; Quality-Adjusted Life Years; Reviews; Science Policy; Skin tests; Studies; Systematic review; Tuberculin; Tuberculin Test - economics; Tuberculin Test - methods; Tuberculosis; γ-Interferon; Brazil; Canada; Montreal Quebec Canada; Rio de Janeiro Brazil
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0056044

Cost effectiveness analyses (CEA) can provide useful information on how to invest limited funds, however they are less useful if different analysis of the same intervention provide unclear or contradictory results. The objective of our study was to conduct a systematic review of methodologic aspects of CEA that evaluate Interferon Gamma Release Assays (IGRA) for the detection of Latent Tuberculosis Infection (LTBI), in order to understand how differences affect study results. A systematic review of studies was conducted with particular focus on study quality and the variability in inputs used in models used to assess cost-effectiveness. A common decision analysis model of the IGRA versus Tuberculin Skin Test (TST) screening strategy was developed and used to quantify the impact on predicted results of observed differences of model inputs taken from the studies identified. Thirteen studies were ultimately included in the review. Several specific methodologic issues were identified across studies, including how study inputs were selected, inconsistencies in the costing approach, the utility of the QALY (Quality Adjusted Life Year) as the effectiveness outcome, and how authors choose to present and interpret study results. When the IGRA versus TST test strategies were compared using our common decision analysis model predicted effectiveness largely overlapped. Many methodologic issues that contribute to inconsistent results and reduced study quality were identified in studies that assessed the cost-effectiveness of the IGRA test. More specific and relevant guidelines are needed in order to help authors standardize modelling approaches, inputs, assumptions and how results are presented and interpreted.