# Table 1 Summary of STI cost estimates (in 2006 US dollars) and selected parameter values applied in the formulas

Parameter Value applied   Range applied
Direct medical costs Females Males
Average cost per case of PID [23–25] \$1,995 not applicable ± 50%
Average cost per case of epididymitis [26] not applicable \$274 ± 50%
Average sequelae costs per case of syphilis [5] \$572* \$572* ± 50%
Average cost per case of chlamydia [5] \$315 \$26 ± 50%
Average cost per case of gonorrhea [5] \$343 \$68 ± 50%
Average cost per case of syphilis [5] \$572* \$572* ± 50%
Average cost per case of HIV [6] \$198,471 \$198,471 ± 50%
Average cost per case of congenital syphilis [1,64,65] \$6,738 \$6,738 ± 50%
Indirect (lost productivity) costs
Average cost per case of HIV [6] \$831,614 \$831,614 ± 50%
Average cost per untreated case of chlamydia [85] \$148 \$13 ± 50%
Average cost per untreated case of gonorrhea** \$171 \$34 ± 50%
Average cost per untreated case of syphilis** \$112* \$112* ± 50%
Average cost per case of chlamydia** \$47 \$10 ± 50%
Average cost per case of gonorrhea** \$47 \$10 ± 50%
Average cost per case of syphilis** \$112* \$112* ± 50%
Average cost per case of congenital syphilis** \$60,421 \$60,421 ± 50%
Other parameters
Absolute reduction in probability of sequelae due to treatment: chlamydia** 0.16 0.03 ± 90%
Absolute reduction in probability of sequelae due to treatment: gonorrhea** 0.14 0.03 ± 90%
Adjustment to chlamydia costs averted to account for gonorrhea coinfection** 0.925 0.925 ± 5%
Adjustment to gonorrhea costs averted to account for chlamydia coinfection** 0.79 0.90 ± 5%
Adjustment to account for reinfection: gonorrhea and chlamydia** 0.70 0.70 ± 25%
Probability of congenital syphilis given untreated syphilis in mother [63] 0.50 not applicable ± 50%
Number of cases of STI averted in population per STI case treated** 0.50 0.50 ± 90%
Probability of a new case of HIV attributable to chlamydia [70] 0.0011 0.0011 ± 90%
Probability of a new case of HIV attributable to gonorrhea [70] 0.0007 0.0007 ± 90%
Probability of a new case of HIV attributable to syphilis [70] 0.02386 0.02386 ± 90%
Adjustment for time frame for STI-attributable HIV infections** 0.25 0.25 ± 90%
Adjustment for partner overlap (heterosexuals) [67] 0.75 0.75 ± 25%
Adjustment for partner overlap (MSM)** not applicable 0.50 ± 25%
Additional adjustment for averted HIV costs for MSM** not applicable 0.25 not varied
HIV cases averted per person counseled and tested [78,81] 0.00045 0.00045 ± 90%
Adjustment for repeat counseling and testing** 0.875 0.875 ± 10%
1. *The average sequelae cost per case of syphilis was set equal to the average cost per case of syphilis (and the indirect cost per case of syphilis was set equal to the indirect cost per case of untreated syphilis), because when calculating the costs of syphilis we allowed for the possibility that treatment of syphilis would have occurred (even in the absence of the STI program) before the onset of sequelae.
2. **See text for sources, assumptions, and additional information.