Table 1

Epidemiologic parameter estimates

ParameterBase case estimateUnivariable analysis rangeReference(s)
Initiation rateIqaluit LTBI program11 28
 9H0.790.72–0.80
 3HP0.7910.72–0.80*
Completion rates
 9HIqaluit LTBI programme
 Probability of stopping isoniazid before 3 months among all those who initiated treatment0.1030.077–1.37
 Probability of stopping isoniazid at 3 months among all those who completed at least 3 months of treatment0.0880.063–0.122
 Probability of stopping isoniazid at 6 months among all those who completed at least 6 months of treatment0.0780.054–0.112
 Probability of completing 9 months of treatment among all persons who initiated treatment†0.750
3HP11
 Probability of stopping 3HP before 4 weeks among all those who initiated treatment0.0820.038–0.168
 Probability of stopping 3HP at 4 weeks among all those who completed at least 4 weeks of treatment0.0750.032–0.163
 Probability of stopping 3HP at 8 weeks among all those who completed at least 8 weeks of treatment0.0320.009–0.110
 Probability of completing 12 weeks of treatment among all persons who initiated treatment†0.820
Mild AE‡‡7
 9H0.0910.082–0.100
 3HP0.0770.069–0.085
Severe AEs‡‡7
 9H0.0650.058–0.073
 3HP0.0570.050–0.064
Fatal AEs‡6 31
 9H0.000140.00004–0.00057
 3HP0.0001410.00004–0.000571
Risk of reactivation of LTBI16 32 33
 First 2 years0.0250.01–0.05
 Subsequent years0.0010–0.0016
Reduction in risk of TB disease‡6 34
 9H0.93
 3HP0.931
Risk of death following TB disease diagnosis0.0820.070–0.09435–43
Health Utilities (QALYs)
 LTBI without treatment1Assumed
 LTBI treatment10.99–144
 Mild AE10.99–145
 Severe AE0.750.65–0.8523
 TB disease0.880.86–0.9044
 Death0Assumed
  • Iqaluit LTBI programme: retrospective data from the Iqaluit LTBI programme, 2010–2016, unpublished.

  • *Assumed identical values for 9H and 3HP in base case analysis.

  • †Overall completion rates among initiators are given for reference. Only the component probabilities provide were used in the model.

  • ‡Values for partially completed regimens were interpolated assuming a linear relationship between duration of treatment and parameter values.

  • AEs, adverse events; 9H, 9 months of twice weekly isoniazid; 3HP, once weekly rifapentine and isoniazid for 12 weeks; LTBI, latent tuberculosis infection; QALYs, quality-adjusted life years; TB, tuberculosis.