2 seen between intervention and control groups over the study period. All participants completed a questionnaire at enrollment, which included questions about out-of-pocket costs for seek- ing or receiving care at the clinic, time oﬀ work or school due to clinic visits, and time donated by others to allow the par- ticipant to attend clinic. These questions and the number of tests performed in clinic and at home in the trial are the focus of this analysis. The direct and indirect costs of receiving screening tests were calculated for women randomized to the intervention (testing at home) and for those in the control group (clinic testing). Direct costs of clinic-based testing were the costs for clinician time and for the test kit (nucleic acid ampliﬁcation for chlamydia and gonorrhea), along with required supplies. The Panel on Cost-Eﬀectiveness in Health and Medicine rec- ommends including the following as indirect costs of care: payments made by the patient in the course of seeking or re- ceiving care, and time required by the patient and others to allow care to be received [10]. In this analysis, indirect costs for the clinic visits included costs of parking or transporta- tion and of babysitting or childcare. Indirect costs for time missed from school or work to receive care and for time do- nated by others (e.g., for rides or babysitting) to allow care to occur were quantiﬁed based on patient responses, then valued based on the average hourly wage in 2005 for non- farm workers in the US [11] to avoid bias against interven- tion in this young population [10]; the eﬀects of other time costs were examined in sensitivity analyses. Direct costs for home screening were the cost of the test, packaging costs, and postage to and from the patient, costing a total of 25. Testing cost alone (including materials and technician time) in either setting was 21. These costs were then applied to clinic-based and home-based tests as quantiﬁed in the DAISY study, and costs compared between intervention and control groups. Alternative values for all cost components, varied individu- ally and collectively over plausible ranges, were examined in one-way and multiway sensitivity analyses. Direct costs per subject for the intervention group and the control group were calculated as follows: Direct cost (clinic test) ∗ clinic test frequency + Direct cost (Home test) ∗ home test frequency divided by the number of subjects in each group. Indirect costs were calculated similarly. Cost-eﬀectiveness calculations were performed to esti- mate the cost per additional test performed per subject, using the formula Total cost per subject (intervention) − Tests per subject (intervention) Total cost per subject (control) − Tests per subject (control) . The model assumes equal STD incidence and diagnosis with home- and clinic-based testing, as seen in the DAISY trial, and hence the advantage of home testing from a cost- eﬀectiveness standpoint (if any) is that, compared to the clinic testing group, more tests are performed overall due to testing at home (at a relatively low cost) while fewer tests are performed in clinic (at higher cost). (1) Infectious Diseases in Obstetrics and Gynecology Table 1: Demographic and economic questionnaire data from the DAISY study. All subjects Average age (years) 14–18 years old 19–25 years old Recruitment site Clinic Neighborhood No insurance Paid for parking/transportation Paid 5 or more Paid a babysitter Other person donated time Donated ≥1 hours Took time oﬀ from work or school ≥2 hours Clinic visit took ≥2 hours Travel time to clinic >30 minutes Frequency 388 18.9 181 207 198 190 86 136 49 25 143 115 136 86 99 86 Percent 100% — 46.6% 53.4% 51.0% 49.0% 22.2% 35.1% 12.6% 6.4% 36.9% 29.6% 35.1% 22.2% 25.5% 22.2% One-way and probabilistic sensitivity analyses were per- formed. Cost and time parameters were varied individu- ally to examine eﬀects on model results. In the probabilistic sensitivity analysis, these parameters were varied simultane- ously, along with testing frequencies from the DAISY study, through their 95% conﬁdence intervals, with values for each parameter randomly chosen from distributions 10,000 times and cost-eﬀectiveness ratios calculated for each parameter set chosen. Parameter distributions were selected based on the characteristics of each parameter. Uniform distributions, where all values in the range were equally likely to be cho- sen, were used for time cost per hour, nonclinician direct costs for clinic-based testing, and home-based testing costs. Gamma distributions, based on DAISY study mean and stan- dard deviation (SD) data, were used for indirect monetary costs, time required to receive care, and for clinician costs. Normal distributions were used for test frequencies. 3. RESULTS AND DISCUSSION Questionnaire results are summarized in Table 1. Responses to these questions were similar regardless of randomization group, therefore results are reported for 388 subjects (10 of the original 398 subjects had no questionnaire data avail- able). Slightly more than one-ﬁfth of subjects had no insur- ance, took more than 2 hours oﬀ school or work to attend clinic, or traveled more that 30 minutes to attend clinic; more than a third paid for parking/transportation or had another person donate time so that care could be obtained. Costs per test received are summarized in Table 2. Di- rect costs for clinic-based testing, including clinician and test costs, were estimated at 49 per test received. On average, sub- jects paid 2.97 for parking/transportation and childcare, and 3.7 hours were spent by the subject and others to allow care