- Screening all hospitalized patients with HIV for tuberculosis (TB) using TB-LAM (lipoarabinomannan) urine tests would improve life expectancy and be cost-effective in places where TB is common.
- These findings could influence international guidelines on TB testing.
TB is the leading killer of people with HIV worldwide. Urine testing using the lipoarabinomannan (TB-LAM) and Xpert tests had been shown to improve TB detection in selected patients with HIV, but it has not been clear whether urine testing of all hospitalized patients with HIV would be useful and cost-effective.
In conjunction with the STAMP trial, a microsimulation model was used to estimate the effects on clinical outcomes and the cost-effectiveness of adding urine-based TB screening to sputum screening for hospitalised patients with HIV.
Two tuberculosis screening strategies were compared in Malawi and South Africa: a GeneXpert assay for Mycobacterium tuberculosis and rifampicin resistance (Xpert) in sputum samples (standard of care group) versus sputum Xpert combined with a lateral flow assay for M. tuberculosis in urine (Determine TB-LAM Ag test, by Abbott) and concentrated urine Xpert (intervention group). A modified intervention of adding only TB-LAM to the standard of care was also evaluated.
A cohort of simulated patients was modelled using selected characteristics of participants, tuberculosis diagnostic yields, and the use of hospital resources in the STAMP trial. Clinical and economic outcomes at 2 years, 5 years and over a lifetime were projected using 2-month model outputs from the trial.
The intervention increased life expectancy by 0.5–1.2 years and was cost-effective, with an incremental cost-effectiveness ratio (ICER) of $450 per year of life saved (YLS) in Malawi and $840/YLS in South Africa. The modified intervention was at least as cost-effective as the intervention. The ICERs decreased over time, but at lifetime horizon the intervention remained cost-effective under nearly all modelled assumptions.
Over 5 years, the intervention would save around 51,000 years of life in Malawi and around 171,000 years of life in South Africa. Health-care expenditure for screened individuals was estimated to increase by 10.8% and 2.8%, respectively.
Urine TB-LAM is especially attractive because of high incremental diagnostic yield and low additional cost compared with sputum Xpert.
Funding: UK Medical Research Council, UK Department for International Development, Wellcome Trust, US National Institutes of Health, Royal College of Physicians, Massachusetts General Hospital.