Table 1.

Summary of Variables

Variable	Baseline Estimate	Range Used in Sensitivity Analysis	Source
EIA = enzyme immunosorbent assay; HIV = human immunodeficiency virus; PHI = primary HIV infection; CBC = complete blood count; G6PD = glucose-6-phosphate dehydrogenase; CMV = cytomegalovirus; RPR = rapid plasma reagin; PPD = purified protein derivative (tuberculin); NAAT = nucleic acid amplification test.
* Initial battery of laboratory tests includes: CBC, chemistry panel, G6PD assay, toxoplasmosis titer, CMV titer, RPR, PPD skin test, viral hepatitis panel, lipid panel, urinalysis, chest radiograph, urine NAAT for gonorrhea and chlamydia.
Costs ($)
p24 antigen EIA	24.65	12.33–49.30	Medicare fee schedule
HIV-1 RNA assay	118.89	59.45–237.78	Medicare fee schedule
Third-generation HIV-1 EIA	19.17	9.59–38.34	Medicare fee schedule
Western blot assay	27.05	13.53–54.10	Medicare fee schedule
CD4 cell count per microliter	90	45–180	Medicare fee schedule
Initial battery of laboratorys tests (new diagnosis)*	254	200–614	Medicare fee schedule
Expanded testing program costs	101.47	51–203	MMWR²⁰
Discounted lifetime medical costs (diagnosed with PHI and antiretroviral therapy started at CD4 cell count of 350/μL)	95,800	47,900–191,600	Freedberg et al²³
Discounted lifetime medical costs (PHI not diagnosed and antiretroviral therapy started when HIV diagnosed)	88,100	44,050–176,200	Freedberg et al²³
Return visit	52.53	40–67.86	Kaplan & Anderson²⁴
Test characteristics
p24 antigen EIA, sensitivity	0.887	0.770–0.957	Hecht et al,⁸ Daar et al⁹
Specificity	0.9996	0.9950–0.9999	Hecht et al,⁸ Daar et al⁹
HIV-1 RNA, sensitivity	1.000	—	Hecht et al,⁸ Daar et al⁹
Specificity	0.980	0.950–0.999	Hecht et al,⁸ Daar et al⁹
Third-generation HIV-1 EIA, sensitivity	0.790	0.600–0.920	Hecht et al⁸
Specificity	0.970	0.930–0.990	Hecht et al⁸
Probability of indeterminate Western blot	0.000004	—	Kleinman et al²²
Prevalence factors (%)
Patients lost to follow-up	31	16–62	MMWR²¹
Prevalence in screened population	0.66	0.53–0.92	Coco & Kleinhans¹⁶
Sexual transmission factors
Patients who change behavior to avoid infecting sexual partner	50	0–96	MMWR⁶
Patients that are sexually active	50	25–85	MMWR⁶
Infectivity (probability of sexual transmission during PHI period)	15	0–30	Yerly et al,²⁵ Pilcher et al²⁶
Utilities
Asymptomatic HIV infection	0.937	0.926–0.949	Schackman et al²⁷
Anxiety while waiting for confirmatory test results for patients with a positive screen	0.682	0.400–0.800	Kaplan & Anderson²⁴
Quality-adjusted life-expectancy (discounted), years
No PHI	24	—	NCHS¹⁵
Positive screening result, no PHI	23.9735	23.950–23.983	NCHS,¹⁵ Kaplan & Anderson²⁴
PHI diagnosed at screening with follow-up care and antiretroviral treatment started at CD4 cell count of 350/μL	11.9	11.832–11.952	Freedberg et al²³
PHI not diagnosed at screening or lost to care with antiretroviral treatment started when HIV diagnosed	11	—	Freedberg et al²³