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Feasible economic strategies to improve screening compliance for colorectal cancer in Korea |
Park S M, Yun Y H, Kwon S |
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Record Status 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. Health technology Fifteen strategies for the screening of colorectal cancer (CRC) were examined:
colonoscopy (COL) every 3, 5, or 10 years;
COL at age 55 years;
sigmoidoscopy (SIG) every 3, 5, or 10 years;
SIG at age 55 years;
faecal occult blood test (FOBT) every year or every 2 years;
double contrast barium enema (DCBE) every 3, 5, or 10 years;
FOBT every year plus SIG every 5 years; and
SIG every 5 years plus DCBE every 5 years.
Economic study type Cost-effectiveness analysis.
Study population The study population comprised a hypothetical cohort of 50-year-old Koreans in the general population.
Setting The setting was primary care. The economic study was carried out in Korea.
Dates to which data relate The effectiveness data were derived from studies published between 1951 and 2004. The dates to which the resource use data referred were not reported. The costs were derived from studies published between 1987 and 2004, but no price year was explicitly reported.
Source of effectiveness data The effectiveness evidence was derived from a synthesis of completed studies.
Modelling A Markov model was constructed to examine the natural history of a simulated cohort of 50-year-old Korean individuals with and without CRC screening until the age of 80 years. Cycles of one year were considered. Different health states defined by the presence or absence of a polyp or cancer (early or advanced) were considered. These were normal, early colon cancer, late colon cancer, polyp, death from colon cancer and death from other disease. After the initial screening, positive cases were worked up with a COL, and individuals diagnosed with polyp underwent polypectomy. COL was repeated every 3 years for surveillance after polypectomy. The structure of the model was depicted. The rates of perforation and mortality associated with the screening strategies were also considered.
Outcomes assessed in the review The outcomes estimated from the literature were:
the specificity and sensitivity of the screening tests,
the prevalence and incidence of polyps and cancer,
survival,
polyp recurrences,
rates of perforation, and
death.
Study designs and other criteria for inclusion in the review It was not stated whether a systematic review of the literature was undertaken to identify the primary studies. No information on the design and characteristics of the studies was provided. Age-specific mortality from causes other than CRC was estimated from national statistics.
Sources searched to identify primary studies Criteria used to ensure the validity of primary studies Methods used to judge relevance and validity, and for extracting data Number of primary studies included Twenty-eight primary studies provided clinical evidence.
Methods of combining primary studies The primary studies appear to have been combined using a narrative approach.
Investigation of differences between primary studies Results of the review The sensitivity of FOBT for polyps/cancer was 0.1/0.5.
The sensitivity of COL for polyps/cancer was 0.85/0.97.
The sensitivity of the colon study for polyps/cancer was 0.5/0.8.
The sensitivity of SIG for polyps/cancer was 0.67.
The specificity of FOBT was 0.9.
The specificity of COL was 1.
The specificity of the colon study was 0.9.
The specificity of SIG was 1.
The prevalence of polyps at age 50 was 0.25.
The annual polyp incidence rate was 0.005.
The proportion of cancers originating as polyps was 100%.
The annual cancer incidence of polyp with duration below 5 years was 0.005.
The annual cancer incidence of polyp with duration of 5 to 10 years was 0.01.
The annual cancer incidence of polyp with duration above 10 years was 0.016.
The dwelling time of cancer in early stages was 2 years.
The proportion of cancers detected in early stages with no screening was 5%.
The 5-year all-cause survival for early cancer was 90%.
The 5-year all-cause survival for advanced cancer was 54%.
The polyp recurrence rate after polypectomy in the first year was 0.11.
The polyp recurrence rate after polypectomy thereafter was 0.03.
The rate of perforation of the colon in COL was 0.002.
The rate of perforation of the colon in polypectomy was 0.004.
The rate of perforation from SIG was 0.0001.
The rate of perforation from the colon study was 0.00005.
The death rate from a perforated colon was 0.002.
Methods used to derive estimates of effectiveness The authors made some assumptions that were used in the decision model.
Estimates of effectiveness and key assumptions It was assumed that the longer the duration of polyp, the greater the probability of transformation from polyp to cancer.
At each particular screening event without NHI benefit coverage, 30% of the population underwent the initial screening test, independent of whether they were compliant with past tests.
The compliance of follow-up or surveillance colonoscopy was 20% higher than that of the initial screening.
If the NHI covered 50% and 100% of the screening cost, the compliance was 15% and 30% higher, respectively, than that in case of non-coverage, by reducing the financial barrier of patients.
Measure of benefits used in the economic analysis The summary benefit measure used was life expectancy. This was estimated using the modelling approach. Discounting was applied at an annual rate of 3%.
Direct costs The costs incurred in the long term were discounted at an annual rate of 3%. The unit costs were presented separately from the quantities of resources used. The health services included in the economic evaluation were screening strategies and cancer care, which depended on stage and time period. The cost/resource boundary of the NHI and the patient was used in the analysis. Given that the co-payments that the patients pay are about 50% of total medical expenses for CRC in Korea, it was assumed that the total medical costs of CRC treatment were twice that of the expenses that the NHI reimburses. The costs were estimated using data derived from the NHI in 2002 and 2004. Resource use reflected screening and subsequent treatment patterns in Korea. The price year was not reported.
Statistical analysis of costs The costs were treated deterministically.
Indirect Costs The indirect costs were not considered in the economic evaluation.
Currency The costs were estimated in Korean won (Won). The exchange rate from won to US dollars ($) was won 1,200 = $1.
Sensitivity analysis Alternative scenarios for reimbursement rates were considered. Univariate sensitivity analyses were carried out to assess the robustness of the base-case cost-effectiveness results to variations in compliance rates. The authors set the alternative values.
Estimated benefits used in the economic analysis In the absence of NHI coverage (screening compliance at 30%, follow-up compliance at 50%), the life expectancy was 6,161.9 with no screening. Life expectancy ranged from 6,164.1 with DCBE every 10 years to 6,181.1 with COL every 3 years.
In the scenario of reimbursement of COL set at 60% higher than the current level along with 50% NHI coverage and compliance rate of 55%, the life expectancy was:
6,173.1 with COL at 55 years,
6,179.1 with COL every 10 years,
6,184.0 with COL every 5 years, and
6,187.5 with COL every 3 years (the only non-dominated alternatives), versus
6,161.9 with no screening.
Cost results In the absence of NHI coverage (screening compliance at 30%, follow-up compliance at 50%), the estimated lifetime cost per patient was won 370,726 with no screening. It ranged from won 311,682 with COL every 5 years to won 435,775 with DCBE every 3 years.
The lifetime financial burden of NHI was won 185,236 with no screening. It ranged from won 128,757 with COL every 3 years to won 192,309 with FOBT every year.
In the scenario of NHI coverage at 50% (screening compliance at 45%, follow-up compliance at 65%), the lifetime cost per person (and the lifetime financial burden of NHI) was won 310,354 (won 178,233) with COL every 10 years, won 311,640 (won 188,051) with COL every 5 years, and won 336,101 (won 207,072) with COL every 3 years (the three non-dominated alternatives).
The authors noted that the financial burden of COL every 10 years was smaller than that associated with no screening.
In the scenario of NHI coverage at 100% (screening compliance at 60%, follow-up compliance at 80%), the lifetime cost per person (and the lifetime financial burden of NHI) was won 307,395 (won 226,848) with COL every 10 years, won 325,435 (won 267,054) with COL every 5 years, and won 374,192 (won 323,357) with COL every 3 years (the three non-dominated alternatives).
The authors noted that the financial burden of all three COL strategies was higher than that associated with no screening.
In the scenario of reimbursement of COL set at 60% higher than the current level along with 50% NHI coverage and compliance rate of 55%, the lifetime cost per person (and the lifetime financial burden of NHI) was won 339,486 (won 184,815) with COL at 55 years, won 362,230 (won 208,801) with COL every 10 years, won 402,824 (won 238,433) with COL every 5 years, and won 474,893 (won 281,257) with COL every 3 years. The total medical costs of COL at age 55 and COL every 10 years were less than that associated with no screening. In addition, the NHI's financial burden in the case of COL at 55 years was lower than that of no screening. COL every 10 years had relatively low incremental burden on the financial status of the NHI.
Synthesis of costs and benefits Incremental cost-effectiveness ratios (ICERs) were calculated to combine the costs and benefits of the alternative screening strategies. Dominated options were excluded.
In the absence of NHI coverage (screening compliance at 30%, follow-up compliance at 50%), COL every 5 years was the reference strategy and the ICER of COL every 3 years over COL every 5 years (the only non-dominated strategy) was won 160,965.
In the scenario of NHI coverage at 50% (screening compliance at 45%, follow-up compliance at 65%), the non-dominated alternatives were COL every 10 years (reference strategy), COL every 5 years (ICER won 93,440), and COL every 3 years (ICER won 2,113,350).
In the scenario of NHI coverage at 100% (screening compliance at 60%, follow-up compliance at 80%), the non-dominated alternatives were COL every 10 years (reference strategy), COL every 5 years (ICER won 1,371,670), and COL every 3 years (ICER won 5,656,770).
In the scenario of reimbursement of COL set at 60% higher than the current level along with 50% NHI coverage and compliance rate of 55%, the non-dominated alternatives were COL at age 55 years (reference strategy), COL every 10 years (won 1,401,600), COL every 5 years (won 2,992,270), and COL every 3 years (won 7,487,245).
The results of the sensitivity analysis confirmed the dominance of the COL strategies. In particular, the costs of COL every 10 years were always lower or slightly higher than those of no screening.
Authors' conclusions Colonoscopy (COL) strategies were the most cost-effective options for colorectal cancer (CRC) screening. In particular, screening with COL performed every 10 years was associated with lower total medical costs than the strategy of no screening at all compliance rates considered in the analysis. Moreover, the removal of the financial barrier to cancer screening by providing full insurance coverage increased screening compliance without increasing the financial burden of the Korean National Health Insurance (NHI).
CRD COMMENTARY - Selection of comparators The selection of the comparators was appropriate as all possible screening strategies for CRC were included in the comparison. Different time intervals were considered. A justification for the inclusion of specific screening options was provided and recommendations made in Korea were also reported. The authors stated that a strategy of FOBT every year was the primary method for screening in Korea. You should decide whether they are valid comparators in your own setting.
Validity of estimate of measure of effectiveness The effectiveness data came from published evidence. However, it would appear that primary studies providing clinical data were identified selectively and a systematic review of the literature was not performed. No information on the design and characteristics of the primary studies was provided. The methods used to extract the data from each study and to combine the primary estimates were not reported. Thus, it was not possible to assess the quality and robustness of the primary sources and to evaluate the approach used to pool clinical data in the decision model. Some assumptions were also made. The issue of uncertainty was not extensively addressed in the sensitivity analysis.
Validity of estimate of measure of benefit The summary benefit measure is comparable with the benefits of other health care interventions. The use of expected survival represents a common measure for cancer screening programmes. The impact of the health technologies on quality of life was not addressed, thus some potential benefits of screening might have been missed.
Validity of estimate of costs The choice of the perspective was a crucial issue of the analysis, which focused on different rates of screening cost reimbursement. The analysis was carried out in the scenario of no coverage of screening costs (which reflected the actual strategy) and in scenarios with 50% and 100% screening cost coverages. The unit costs were given for all screening tests, although the costs of cancer care were presented as macro-categories and a detailed breakdown of the cost items was not reported. This issue is very common to most studies assessing the long-term costs of cancer care. National sources were used to estimate the costs, while resource use was mainly derived using authors' assumptions, which reflected screening and treatment patterns in the authors' setting. The price year was not reported, which makes reflation exercises in other settings difficult. The cost estimates were treated deterministically and only the cost of COL was varied in the sensitivity analysis.
Other issues The authors did not make extensive comparisons of their findings with those from other studies. They also did not address the issue of the generalisability of the study results to other settings. Limited sensitivity analyses were performed, which reduces the external validity of the results of the study. Some limitations to the validity of the analysis were highlighted. First, the model employed to represent natural history of CRC was intentionally simple in order to reduce the need for assumptions not supported in the literature. Second, it was noted that clinical data from western countries were used, but epidemiological differences between races could be possible. The authors noted that if COL became the primary tool for CRC screening, the issue of sufficient available manpower could be problematic in Korea.
Implications of the study The study results supported the use of COL every 10 years as a primary screening for CRC in Korea. The authors suggested "health policy makers should understand the need to train medical, and possibly even non-medical, personnel to perform endoscopy and to find an effective policy to lead physicians to perform colonoscopy".
Bibliographic details Park S M, Yun Y H, Kwon S. Feasible economic strategies to improve screening compliance for colorectal cancer in Korea. World Journal of Gastroenterology 2005; 11(11): 1587-1593 Other publications of related interest Park SM, Chang YJ, Yun YH, et al. Cost-effectiveness analysis of colorectal cancer screening in Korean General Population. Journal of the Korean Academy of Family Medicine 2004;25:297-306.
Wagner JL, Herdman RC, Wadhwa S. Cost-effectiveness of colorectal cancer screening in the elderly. Annals of Internal Medicine 2001;115:807-17.
Kim TS, Kang YS, Jung SY, et al. Prospective evaluation of colorectal polyps in 1683 consecutive colonoscopies. Korean Journal of Gastrointestinal Endoscopy 1999;19:887-96.
Indexing Status Subject indexing assigned by NLM MeSH Aged; Aged, 80 and over; Colorectal Neoplasms /diagnosis /economics; Cost-Benefit Analysis; Feasibility Studies; Humans; Korea; Mass Screening /economics; Middle Aged; National Health Programs; Patient Compliance; Reimbursement Mechanisms AccessionNumber 22005000665 Date bibliographic record published 31/12/2005 Date abstract record published 31/12/2005 |
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