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Table 1 Parameters used for input into a model of cost-effectiveness of tenofovir for PMTCT in South Africa, based on a simulated cohort of 10,000 antenatal women and their babies

From: Modelling cost-effectiveness of tenofovir for prevention of mother to child transmission of hepatitis B virus (HBV) infection in South Africa

Parameter Point estimate Uncertainty (Lower bound - Upper bound) Source (references)
p1: Probability of mother being HBsAg+ 3.6% 3.1–7.4%b [21, 25,26,27]
p2: Probability of mother who is HBsAg+ being HBeAg+ 23% 16.7–42.9%b [21, 25,26,27]
p3: Probability of mother who is HBsAg+ and HBeAg+ having child who is HBsAg+ (no PMTCT) 38.3% 7.0–74.4%b [22]
p4: Probability of mother who is HBsAg+ and HBeAg- having child who is HBsAg+ (no PMTCT) 4.8% 0.1–13.3%b [22]
Relative risk reduction (efficacy) of TDF 71% 26–89% [15]
Antiviral adherence 73.5% 69.3–77.5% [28]
S2: Cost of diagnostics: laboratory test for HBsAg $9.1 per mother   [29]
S3: Cost of diagnostics: laboratory test for HBsAg and HBeAg $9.1 per mother (HBsAg test) + $9.1 for HBsAg+ mother
(HBeAg test)
  [29]
S2: Cost of diagnostics: POCT for HBsAg $2 * all mothers   [29]
S3: Cost of diagnostics: POCT for HBsAg+ and laboratory test for HBeAg+ $2 * for all mothers (HBsAg test) + $ 9.1 * for all HBsAg+ mothers (HBeAg test)   [29]
Treatment cost: monthly cost of TDF, applied to all HBsAg+ women (S2) or only to HBsAg+/HBeAg+ women (S3) $2.48a/month   [30]
POCT sensitivity 97.6%   [21]
Estimated relative risk reduction (efficacy) of TDF when combined with birth dose vaccine and HBIg 90% 85–95% [9]
Prevalence of TDF resistance 0.08%   [31]
  1. a To cover the cost of TDF treatment from 28 weeks’ gestation to 4 weeks post-delivery, we multiplied the cost for one month by four. A triangular distribution allows for uncertainty in all probabilities (except cost which we assume is fixed)
  2. b The uncertainty values for p1 and p2 were derived from studies that had the lowest and highest HBsAg prevalence rates, representing lower and higher bounds respectively; whereas uncertainly values for P3 and P4 were from 95% confidence intervals around the mean value