The nonmedical costs of colorectal cancer screening using CT colonography (CTC) are significant but lower than those of colonoscopy, according to a study published in the December issue of the Journal of the American College of Radiology .
Nonmedical costs are important because they may influence screening uptake and the results of cost-effectiveness analyses of colorectal cancer screening, according to the authors. “Although the nonmedical costs of CRC screening are known for fecal occult blood testing, flexible sigmoidoscopy and colonoscopy, they are unknown for CTC,” they wrote.
Therefore, Steven J. Heitman, MD, and colleagues from the University of Calgary in Alberta, undertook the study to determine the nonmedical costs of CTC.
The researchers approached 481 consecutive individuals presenting for CRC screening using CTC at a radiology clinic in Calgary, Alberta, to participate in the study. Of these, 197 agreed to have a questionnaire mailed to them. Subjects completed the questionnaire, including items on time off from work, both for the subject and any accompanying caregiver; travel details; and direct out-of-pocket expenses. They valued time costs at government of Canada wage rates. They also included travel costs estimated costs for travel by car and actual parking costs and taxi and public transportation fares. Car user's costs were calculated using a Canadian Automobile Association estimate of motoring costs per kilometer. Costs are reported in 2010 Canadian dollars.
The authors found that 132 subjects returned the questionnaire (mean age, 57 years; 65 percent men; 67 percent employed). Ten subjects traveled more than 200 km for their CTC. The nonmedical costs (subject with or without caregiver) for the 122 subjects who resided within 200 km of the clinic averaged $101 per CTC exam. In comparison, the nonmedical costs of colonoscopy using a similar analysis were estimated at $308.
The nonmedical costs of CTC seem “substantially lower” than they are for colonoscopy, according to the authors. However, there are other factors to consider, said Heitman and colleagues. The researchers noted the following points:
- The reported costs are for a single screening encounter. After an exam with negative results, CTC has been recommended at five-year intervals compared to every 10 years for colonoscopy. Therefore, over a comparable time period, the nonmedical costs that an individual might face when screened with CTC would be closer to $200.
- If one assumes that only polyps more than 5 mm are significant, approximately 15 percent of average-risk individuals may require follow-up colonoscopy according to the findings of the National CT Colonography Trial. Ideally, same day colonoscopies would be possible for all individuals with positive results, but if this were not feasible, some patients would have to bear the nonmedical costs of both procedures when performed on different days. The need to undergo both procedures would at least lengthen the time off work for individuals and caregivers.
“[E]ven though the nonmedical costs of CTC are lower than they are for colonoscopy, they are likely more than 30 percent of the costs when … [these] factors are considered,” the authors wrote.
Among its limitations, the study authors listed the potential for recall errors with surveys, as well as the fact that all of the data was collected from one single, private radiology clinic.
Nevertheless, based on the data, Heitman and colleagues concluded that patients should be aware of these differential costs, and they should be incorporated into economic analyses of CRC screening.