Cost-Effectiveness of Latent Tuberculosis Screening Before Steroid Therapy for Idiopathic Nephrotic Syndrome in Children

Background Guidelines differ on screening recommendations for latent tuberculosis infection (LTBI) prior to immunosuppressive therapy. We aimed to determine the most cost-effective LTBI screening strategy before long-term steroid therapy in a child with new-onset idiopathic nephrotic syndrome. Study Design Markov state-transition model. Setting & Population 5-year-old boy with new-onset idiopathic nephrotic syndrome. Model, Perspective, & Timeframe The Markov model took a societal perspective over a lifetime horizon. Intervention 3 strategies were compared: universal tuberculin skin testing (TST), targeted screening using a risk-factor questionnaire, and no screening. A secondary model included the newer interferon γ release assays (IGRAs), requiring only one visit and having greater specificity than TST. Outcomes Marginal cost-effectiveness ratios (2010 US dollars) with effectiveness measured as quality-adjusted life-years (QALYs). Results At an LTBI prevalence of 1.1% (the average US childhood prevalence in our base case), a no-screening strategy dominated ($2,201; 29.3356 QALYs) targeted screening ($2,218; 29.3356 QALYs) and universal TST ($2,481; 29.3347 QALYs). At a prevalence >10.3%, targeted screening with a risk-factor questionnaire was the most cost-effective option. Higher than a prevalence of 58.5%, universal TST was preferred. In the secondary model, targeted screening with a questionnaire followed by IGRA testing was cost-effective compared with no screening in the base case when the LTBI prevalence was >4.9%. Limitations There is no established gold standard for the diagnosis of LTBI. Results of any modeling task are limited by the accuracy of available data. Conclusions Prior to starting steroid therapy, only patients in areas with a high prevalence of LTBI will benefit from universal TST. As more evidence becomes available about the use of IGRA testing in children, the assay may become a component of cost-effective screening protocols in populations with a higher burden of LTBI.