Analytical approach:
A decision-analytic Markov model (with annual cycles) was used to assess the costs and outcomes associated with each screening intervention. The time horizon of the study was 20 years. The authors did not report a study perspective.
Effectiveness data:
Clinical and effectiveness data were derived from previously published studies and the authors’ own assumptions. The main measures of effectiveness were sensitivity and specificity of TST and IGRA which were derived from previously published studies including data from two meta-analyses (Menzies et al. 2007 and Pai et al. 2008, see Other Publications of Related Interest)
Monetary benefit and utility valuations:
Not relevant
Measure of benefit:
Healthy life years gained (defined as the years of life healthcare workers were free from tuberculosis or hepatitis).
Cost data:
The direct costs included those for screening (including TST, IGRA and chest radiograph), tuberculosis treatment, contact tracing, latent tuberculosis infection treatment and hepatitis treatment. Indirect costs included time spent by healthcare workers attending for treatments and contact tracing. Costs of screening interventions were derived from data supplied by the National Institute for Health and Clinical Excellence (NICE) 2011 (see Other Publications of Related Interest). Other direct and indirect costs were obtained from the Cambridge tuberculosis service and NHS national tariffs and pay scales. The price year was 2010/11. All costs were reported in UK pounds sterling (£). Future costs were discounted using an annual rate of 5%.
Analysis of uncertainty:
A probabilistic sensitivity analysis was undertaken by fitting probability distributions in all model parameters and then carrying out a Monte Carlo simulation using 100,000 iterations. A series of one-way sensitivity analyses was undertaken by varying model parameters.