Introduction
Code | Drug regimens | Zidovudine (AZT) | Nevirapine (NVP) | ||
---|---|---|---|---|---|
mother
|
infant
|
mother
|
infant
| ||
A
| A short course AZT (practice in Thailand to 2004) | Starting from 32–34 week of gestation onward + intrapartum doses | From birth for 7 days (6 weeks in the case of the mother receiving <4 weeks AZT) | Not provided | Not provided |
B
| NVP alone (never adopted in the national policy) | Not provide | Not provide | Intrapartum single dose | Single dose after delivery |
C
| AZT or NVP (never adopted in the national policy) | Start at 32 but not latter than 34 weeks of gestations + intrapartum doses but not with NVP | From birth for 7 days (6 weeks in the case of the mother receiving <4 weeks AZT) – and given only the cases that mother received AZT | If mother know HIV status after 34 weeks then give single dose but not with AZT | Single dose after delivery if mother received NVP only |
D
| AZT and NVP (current practice, commencing from 2004) | Starting from 28 week of gestation onward + intrapartum doses | From birth for 7 days (6 weeks in the case of the mother receiving <4 weeks AZT) | In trapartum single dose | Single dose after delivery |
Design & Methods
Study model
Input parameters (table 2)
Parameters | Point estimate | 95%CI for sensitivity analysis | Parameter distribution | Data sources |
---|---|---|---|---|
Epidemiology
| ||||
Maternal HIV infection rate | 1.5% | Ref.19 | ||
ANC after gestational age 34 weeks | 7.4% | 6.7–8.0% | Beta | Ref.8 |
Rate of perinatal HIV transmission | 18.9% | 13.2–24.4% | Beta | Ref.3 |
Rate of transmission via breastfeeding | 12.0% | 7.0–17.0%* | Beta | Ref.22 |
Percent of HIV infection detected by second VCT | 4.7% | 2.70–7.5% | Beta | Ref.20 |
Rate of HIV infected mothers who, treated with NVP, developed HIV resistance to NVP | 17.4% | 12.0–22.7% | Beta | Ref.17 |
Rate of HIV infected mothers who need to be treated AIDS within a year after delivery | 33.9% | 29.6–38.3% | Beta | Ref.28 |
Efficacy of Antiretrovial therapy
| ||||
Odds of transmitting the virus when mother received AZT > = 4 weeks versus placebo | 0.46 | 0.35–0.60 | Normal | Ref.23 |
Odds of transmitting the virus when mother received AZT < 4 weeks versus receiving AZT > = 4 weeks | 1.40 | 0.82–2.38 | Normal | Ref.24 |
Risk of transmitting the virus with NVP regimen versus placebo | 0.51 | 0.33–0.79 | Normal | Ref. 23 |
Risk of transmitting the virus with AZT+NVP regimen versus receiving AZT > = 4 weeks | 0.23 | 0.05–0.41 | Normal | Ref.6 |
Compliance to the Programme
| ||||
Infected pregnant women who know their HIV status before or at 36 week of gestation and accept AZT | 75% | 70–90% | Beta | Ref.8 |
Infected pregnant women who know their HIV status after 36 week of gestation and accept AZT | 65% | 55–90%* | Beta | Assumption (see text) |
Infected pregnant women who know their HIV status before or at 36 week of gestation, do not accept AZT but accept NVP | 50% | 30–70%* | Beta | Assumption (see text) |
Infected pregnant women who know their HIV status before or at 36 week of gestation and accept NVP | 85% | 70–90%* | Beta | Assumption (see text) |
Infected pregnant women who know their HIV status after 36 week of gestation and accept NVP | 75% | 70–90%* | Beta | Assumption (see text) |
Infected pregnant women who know their HIV status before or at 36 week of gestation and accept AZT+NVP | 84% | 80–90% | Beta | Ref.17 |
Infected pregnant women who know their HIV status after 36 week of gestation and accept AZT+NVP | 75% | 70–80%* | Beta | Assumption (see text) |
Programme unit cost
|
US$ 2003
| |||
VCT for HIV negative pregnancy | 2.69 | 1.57–7.79 | Gramma | Ref. 8 |
VCT for HIV positive pregnancy | 7.10 | 3.82–14.54 | Gramma | Ref. 8 |
HIV testing for baby born by infected mother | 5.61 | 3.18–11.65 | Gramma | Ref. 8 |
Cost of antepartum AZT (per weeks) | 10.50 | Thai Department of Health | ||
Cost of intrapartum AZT | 2.30 | Thai Department of Health | ||
Cost of infant AZT (per week) | 17.20 | Thai Department of Health | ||
Cost of NPV for mother and infant | 3.10 | Price survey by authors | ||
Breast milk substitutes (per 1 year) | 175.90 | Thai Department of Health | ||
Incremental cost of switching from NNRTI-base treatment regimen to PI-based regimen | 497 | 147–847 | Gramma | Ref.29 |
Public sector health expenditure
| ||||
Life time pediatric HIV/AIDS treatment cost | 1,680 | 1,340–2,015 | Gramma | Ref.30 |
Uncertainty analysis
Results
Programme model | 1A | 1B | 1C | 1D | 2A | 2B | 2C | 2D |
---|---|---|---|---|---|---|---|---|
Programme cost | 560,000 | 500,000 | 580,000 | 600,000 | 840,000 | 770,000 | 880,000 | 880,000 |
Incremental cost of switching NNRTI-base treatment to PI-base treatment | 160,000 | 30,000 | 150,000 | 160,000 | 30,000 | 160,000 | ||
Total programme cost | 560,000 | 650,000 | 610,000 | 750,000 | 840,000 | 930,000 | 920,000 | 1,040,000 |
Life time treatment cost for pediatric HIV/AIDS | 390,000 | 430,000 | 460,000 | 560,000 | 410,000 | 450,000 | 500,000 | 590,000 |
Net programme cost
| 170,000 | 220,000 | 160,000 | 190,000 | 430,000 | 480,000 | 410,000 | 450,000 |
Number of infections averted by the program | 233 | 258 | 273 | 337 | 245 | 271 | 300 | 353 |
Cost-effectiveness ratio per averted infection
| 716 | 851 | 570 | 556 | 1,740 | 1,776 | 1,381 | 1,266 |