Table 3. Sensitivity analysis–effect of varying (selected) assumptions and values, on estimated national STI prevalence and numbers of new infections for adult men or women (15–49 years) in South Africa, in 2017.
| Scenario & STI | Syphilis | Gonorrhea | Chlamydia | Syphilis | Gonorrhea | Chlamydia | |||
|---|---|---|---|---|---|---|---|---|---|
| Metric | Prevalence | Incident cases | |||||||
| Sex | Women | Men | Women | Men | Women | Men | Men | Men | Men |
| Default scenario | 0.50% (0.32–0.80) |
0.97% (0.19–2.38) |
6.6% (3.8–10.8) |
3.5% (1.7–6.1) |
14.7% (9.9–21) |
6.0% (3.8–10.6) |
47,500 (5,100–173,000) |
2.2 (1.1–3.8) million |
3.9 (2.2–6.3) million |
| Including sex-specific blood donor screening data from 2015 to 2018 (see S1 File) | 0.38% (0.25–0.69) |
0.35% (0.19–0.52) |
− | − | − | − | 16,000 (4,900–49,800) |
− | − |
| All gonorrhea & chlamydia data points assigned the same statistical weight | − | − | 8.4% (4.7–13.4) |
2.7% (1.1–5.6) |
17.3% (11.7–23.9) |
5.1% (2.4–9.3) |
− | 1.8 (0.70–3.2) million |
3.2 (1.5–6.5) million |
| Scenario 4. All 3 STIs: Assume that treatment coverage stays at 35% throughout 2017 (instead of improving to 65%; for syphilis in M&F and for NG and CT in M) | − | − | − | − | − | − | 39,100 (4,200–142,700) |
1.8 (0.75–3.1) million |
3.4 (2.2–5.9) million |
‘−‘ means: Not assessed, because the outcome was not affected by the scenario.