Methods: We recruited patients from the University of North Carolina Endoscopy Center at Meadowmont scheduled to undergo screening colonoscopy. Participants were asked to keep a diary recording time requirements for the screening colonoscopy process, including time spent in preparation, travel, waiting, colonoscopy, and recovery. We assigned values to two specific time intervals: “occupied time” started with taking the prep medication, included travel time, waiting time, colonoscopy time, on-site recovery time, and ended upon returning home; “dedicated time” started with departure from home and ended upon returning home. We used two economic techniques, the human capital method and contingent valuation (willingness to pay), to estimate the value of patients' time. For the human capital method, we multiplied time spent by the average value of the subject's time based on national wage averages from the Bureau of Labor Statistics (2004). For the contingent valuation method, subjects were asked to complete an open-ended question asking the maximum amount they would theoretically be willing to pay to avoid the colonoscopy while still receiving its benefits and having its risks.
Results: We enrolled 107 subjects. The sample was 57% female, 86% Caucasian, 90% insured (39% Medicare, 4% Medicaid), 46% employed, and 39% retired. Their annual household income was $45,000 or greater for 73%. Mean “occupied time” required was 23.2 hours and mean “dedicated time” was 4.3 hours. Using the human capital method, the mean value of patients' occupied time” was $420 and “dedicated time” was $78. Using contingent valuation, the mean value of patient time required for screening colonoscopy was $265. Willingness to pay was sensitive to number of work days missed, difficulty of the prep, having Medicare, reporting bad effects from the colonoscopy, employment status, age, and out-of-pocket cost. We estimate that including patient time costs in cost-effectiveness analysis could increase the cost per life year saved with screening colonoscopy from $20,900 up to as much as $30,600, compared with no screening.
Conclusions: Patient time constitutes an important cost in colonoscopy screening and should be included in cost-effectiveness analyses.