Table 1

Variables and constants from other sources

Name of variable (units, if applicable)SymbolValue95% CI (or range*)DistributionSource
Life-time probability of developing disease following infection P 0.1(0.08 to 0.12)BetaSloot et al 24
Efficacy PT in adults Embedded Image 0.6(0.49 to 0.70)BetaSmieja et al 25
Efficacy PT in children Embedded Image 0.4(0.16 to 0.57)BetaAyieko et al 26
Average number of cases per year N 2790N/AN/ALTBR
Fraction of all adult cases that have ETB Embedded Image 0.545N/AN/ALTBR
Fraction of those tested for active TB that have active TB Embedded Image 0.2N/AN/AMears et al 23
Case fatality ratio μ 0.0363N/AN/AMears et al 23*and LTBR
Relative average treatment length of non-completed PT Embedded Image 0.33N/AN/AAssumption
Contact tracing, per contact traced, £ Embedded Image 244N/AN/ASee online supplementary appendix part 1
Further tests if case is suspected to have active disease, £ Embedded Image 497N/AN/ASee online supplementary appendix part 1
Cost per full course PT (3 month rifampicin and isoniazid, with pyridoxine), £ Embedded Image 852N/AN/ASee online supplementary appendix part 1
Cost per full course (6 months) of treatment of TB disease, £ Embedded Image 1694N/AN/ASee online supplementary appendix part 1
Average utility of a healthy person, given age structure of TB cases in London Embedded Image 0.876N/AN/ACalculated from Kruijshaar et al via Mears et al
Symptom onset to diagnosis Embedded Image 0.68Embedded Image N/AN/AKruijshaar et al via Jit et al
On treatment Embedded Image 0.79Embedded Image N/AN/AKruijshaar et al via Jit et al
Utility preventive therapy Embedded Image 0.9992Embedded Image N/AN/AKruijshaar et al via Mears et al
Average # of QALYs at death for someone living in UK Embedded Image 72.6N/AN/ACalculated from Mears et al and LTBR
Average # of QALYs at death for someone living in UK with TB as cause of death Embedded Image 52.2N/AN/ACalculated from Mears et al and LTBR
  • Note that some CIs differ slightly from those in the literature due to the use of beta distributions. Following current treatment guidance (NICE 2016), we used the following references to calculate cost values: NICE 2011, Pareek et al 2011, Reference costs 2016, Dowdy et al 2008, Dinnes et al 2007, BNF 2017; where necessary, we inflated costs according to inflation to the base year 2016. See online supplementary appendix part 1 and 6 for details of cost and utility calculations.

  • *This was calculated using the age-specific case-fatality ratios given in Mears et al and the age-structure of cases calculated from the LTBR.

  • BNF, British National Formulary; ETB, non-pulmonary and non-laryngeal TB; LTBR, London TB register; NICE, National Institute for Health & Care Excellence; PT, preventive therapy; QALY, quality-adjusted life-years.