|CT colonography to screen for colorectal cancer and aortic aneurysm in the Medicare population: cost-effectiveness analysis
|Pickhardt PJ, Hassan C, Laghi A, Kim DH
This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn.
The objective was to assess the cost-effectiveness of computed tomography colonography (CTC) screening for colorectal cancer and abdominal aortic aneurysms. The authors concluded that CTC was a highly cost-effective screening strategy. The methods were adequate, but could have been reported in more detail, particularly for the cost calculations. Assuming that the best clinical evidence was used, the conclusions appear to be valid.
Type of economic evaluation
The objective was to assess the cost-effectiveness of computed tomography colonography (CTC) screening for colorectal cancer and abdominal aortic aneurysms (AAA) in a Medicare population.
The interventions were no screening; CTC screening every five years; CTC screening every 10 years; and optical colonoscopy every 10 years.
USA/out-patient secondary care.
: A Markov state-transition model was used to simulate the costs and outcomes for a hypothetical cohort of 100,000 patients aged 65 to 100 years. This model had been validated for younger adult populations (Pickhardt, et al. 2007, and Hussan, et al. 2008, see 'Other Publications of Related Interest' below for bibliographic details). The time horizon the lifetime of the patient and the perspective was not explicitly reported.
The clinical and effectiveness data were from published studies. The main effectiveness estimate was the performance of optical colonoscopy and CTC in detecting polyps and colorectal cancer. This information was from published trials.
Monetary benefit and utility valuations:
Measure of benefit:
Life-years gained were the measure of benefit and they were discounted at an annual rate of 3%.
The costs were those relating to screening; radiologic workup; adverse consequences of optical colonoscopy; treatment for colorectal cancer; and surgery for AAA. The authors also included indirect costs for CTC and optical colonoscopy. These indirect costs were estimated using median hourly incomes. The medical costs were from Medicare reimbursement data. All costs were updated to 2008 prices using the medical component of the Consumer Price Index. The currency was the US dollar ($) and future costs were discounted at an annual rate of 3%.
Analysis of uncertainty:
A sensitivity analysis was performed by assigning probability distributions to all the model parameters, which were then varied simultaneously in 10,000 Monte Carlo simulations. The results of this analysis were presented as 5th to 95th percentiles around the incremental cost-effectiveness ratio. A one-way sensitivity analysis was also performed by varying the screening parameters for colorectal cancer and AAA.
For 100,000 individuals 29,925 life-years were lost due to colorectal cancer without screening. Compared with no screening, 7,786 life-years were gained with five-yearly CTC, 7,027 with 10-yearly CTC, and 6,032 with 10-yearly optical colonoscopy. The total costs were $204,638,692 with no screening, $252,044,138 with five-yearly CTC, $213,430,059 with 10-yearly CTC, and $211,297,150 with 10-yearly optical colonoscopy.
Compared with no screening, 10-yearly optical colonoscopy was associated with an incremental cost-effectiveness ratio (ICER) of $1,104, 10-yearly CTC had an ICER of $1,251, and five-yearly CTC had an ICER of $6,088. Compared with 10-yearly optical colonoscopy, 10-yearly CTC was associated with an ICER of $2,144, and five-yearly CTC had an ICER of $23,234. Compared with 10-yearly CTC, five-yearly CTC was associated with an ICER of $50,875.
The results of the sensitivity analysis showed that in all of the 10,000 simulations CTC was found to be cost-effective compared with optical colonoscopy, using a cost-effectiveness threshold of $50,000 per life-year gained.
The authors concluded that CTC was a highly cost-effective screening strategy.
The interventions were reported clearly.
The authors reported that the clinical and effectiveness data were from published studies, which were referenced, but the details of how they were identified were not reported. More information was available in other publications that used the same model. As a result, it is not possible to determine from this article if all the relevant information was included.
The perspective was not explicitly reported, but indirect costs were included and it appears that a societal perspective was adopted. The authors did not report the categories of costs, either for direct or indirect costs, which makes it impossible to determine if all categories relevant to a societal perspective were included. The medical costs were from Medicare reimbursement data. The time horizon, price year, and discount rate were all reported.
Analysis and results:
A Markov model was used to synthesise all the available cost and outcome information and appropriate details of this model, including a diagram were provided. The impact of uncertainty on the model’s results was adequately tested using a probabilistic sensitivity analysis. The authors reported the limitations of their study, which were that the inputs and assumptions could profoundly affect the results, as in any modelling study.
: The methods were adequate, but could have been reported in more detail, particularly for the cost calculations. Assuming that the best clinical evidence was used, the conclusions appear to be valid.
Pickhardt PJ, Hassan C, Laghi A, Kim DH. CT colonography to screen for colorectal cancer and aortic aneurysm in the Medicare population: cost-effectiveness analysis. American Journal of Roentgenology 2009; 192(5): 1332-1340
Other publications of related interest
Pickhardt PJ, Hassan C, Laghi A, Zullo A, Kim DH, Morini S. Cost-effectiveness of colorectal cancer screening with computed tomography colonography: the impact of not reporting diminutive lesions. Cancer 2007; 109: 2213-2221.
Hassan C, Pickhardt P, Laghi A, et al. Computed tomographic colonography to screen for colorectal cancer, extracolonic cancer, and aortic aneurysm. Archives of Internal Medicine 2008; 168: 696-705.
Subject indexing assigned by NLM
Aged; Aged, 80 and over; Aortic Aneurysm /economics /epidemiology /radiography; Colonography, Computed Tomographic /economics; Colonoscopy /economics; Colorectal Neoplasms /economics /epidemiology /radiography; Cost-Benefit Analysis /economics; Female; Humans; Male; Markov Chains; Medicare /economics; Prevalence; United States /epidemiology
Date bibliographic record published
Date abstract record published