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A computer simulation model for cost-effectiveness analysis of mass screening for type 2 diabetes mellitus |
Chen T H, Yen M F, Tung T H |
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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 Two 10-year mass screening programmes for Type 2 diabetes mellitus (DM) were examined. The programmes were biennial and 5-yearly screening.
Economic study type Cost-effectiveness analysis and cost-utility analysis.
Study population The study population referred to a hypothetical cohort of individuals aged over 30 years, in Taiwan.
Setting The setting was the community. The economic study was conducted in Taiwan.
Dates to which data relate The effectiveness and resource use data were derived from studies published from 1988 to 1999. No price year was reported.
Source of effectiveness data The effectiveness evidence came from published studies.
Modelling A decision model based on a Markov Monte Carlo simulation process was used to model the disease natural history. In addition, to evaluate the costs and benefits of the two screening programmes in comparison with no screening. The model had a time horizon of 30 years and applied to a hypothetical cohort of 30,000 individuals aged over 30 years. Further details of the model were not provided. Sub-group analyses were performed for the age groups 30 - 39 years, 40 - 49 years, 50 - 59 years, 60 - 69 years, and over 70 years.
Outcomes assessed in the review The outcomes assessed from published studies were as follows.
The incidence of Type 2 DM.
The transition rates of complications for retinopathy: from NDR (not defined) to non-proliferative, from non-proliferative to proliferative, for non-proliferative to macula oedema, from proliferative to blindness, and from macula oedema to blindness.
The transition rates of complications for nephropathy and CVD (not defined) mortality: no nephropathy to MA (not defined), from MA to proteinuria, from proteinuria to ESRD (not defined), from ESRD to CVD, and from CVD to death.
The transition rates of complications for neuropathy: from no neuropathy to symptomatic neuropathy and from symptomatic neuropathy to LEA (not defined).
The CVD mortality rate for a non-ESRD patient.
The utility values for no Type 2 DM, screen-detected Type 2 DM, blindness, ESRD and LEA.
Study designs and other criteria for inclusion in the review 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 The effectiveness evidence was obtained from 13 primary studies.
Methods of combining primary studies Primary study estimates were combined using narrative methods.
Investigation of differences between primary studies Results of the review The incidence of Type 2 DM was 0.0107.
For retinopathy, the transition rates of complications were:
0.0730 for NDR to non-proliferative,
0.0103 for non-proliferative to proliferative,
0.1928 for non-proliferative to macula oedema,
0.0148 for proliferative to blindness, and
0.0330 for macula oedema to blindness.
For nephropathy and CVD mortality, the transition rates of complications were:
0.0267 for no nephropathy to MA,
0.1572 for MA to proteinuria,
0.0042 for proteinuria to ESRD,
0.5 for ESRD to CVD, and
0.2 for CVD to death.
For neuropathy, the transition rates of complications were:
0.0144 for no neuropathy to symptomatic neuropathy, and
0.0280 for symptomatic neuropathy to LEA.
The CVD mortality rate for a non-ESRD patient was 0.02.
The utility values were 1 for no Type 2 DM, 0.95 for screen-detected Type 2 DM, 0.69 for blindness, 0.61 for ESRD and 0.80 for LEA.
Measure of benefits used in the economic analysis The summary benefit measures used in the economic analysis were the life-years saved and quality-adjusted life-years (QALYs). Both were derived from modelling and a 3% discount rate was applied. The utility values used to calculate the QALYS were based on data derived from the literature. The cumulative incidence rates of micro-vascular complications were also reported for each option under study.
Direct costs A 3% discount rate was used since the time horizon of the model was 30 years. The unit costs were reported, but the quantities of resources used were not. The costs of health services included in the economic analysis were for screening tests, routine treatment drugs and complications. Screening tests included the fasting plasma glucose test, haemoglobin test and oral glucose tolerance test. Routine treatment drugs covered insulin and oral agents, self-testing, outpatient services insulin users and case management. Complications considered blindness, photocoagulation treatment, eye examination, renal examination, end-stage renal disease, lower extremity amputation and cardiovascular disease. The cost/resource boundary adopted in the study was not reported. Both the resource consumption and the unit costs were estimated using data originating from published studies and official prices. No price year was reported.
Statistical analysis of costs The costs were treated deterministically.
Indirect Costs The indirect costs were not included in the economic analysis.
Sensitivity analysis Sensitivity analyses were not conducted.
Estimated benefits used in the economic analysis The average age at diagnosis was 49.40 years for biennial screening, 49.86 years for 5-yearly screening, and 54.15 years for no screening.
The cumulative incidence rates were 3.06% with biennial screening, 3.13% with 5-yearly screening, and 4.37% with no screening for blindness. The corresponding rates were 0.19% (biennial screening), 0.19% (5-yearly screening) and 0.54% (no screening) for ESRD, and 0.97% (biennial screening), 0.99% (5-yearly screening) and 1.43% (no screening) for LEA.
These results suggested that there was a small difference between the two screening strategies with respect to the efficacy of reducing complications.
The life-years gained with both screening programmes over no screening were 0.8. The QALYs gained were 0.12 with biennial screening and 0.13 with 5-yearly screening.
Cost results The increased cost due to screening was $2,140 with biennial screening and $1,369 with 5-yearly screening.
Synthesis of costs and benefits Incremental cost-effectiveness and cost-utility ratios were calculated to combine the costs and benefits of the two screening strategies in comparison with no screening.
The incremental cost per additional life-year gained was $26,750 with biennial screening and $17,113 with 5-yearly screening.
The incremental cost per additional QALY gained was $17,833 with biennial screening and $10,531 with 5-yearly screening.
The incremental cost per life-year gained was $17,238 for the age group 30 - 39 years, $11,400 for 40 - 49 years, $11,842 for 50 - 59 years, $18,788 for 60 - 69 years, and $54,700 for over 70 years.
The QALYs gained were $9,193 for the age group 30 - 39 years, $7,600 for 40 - 49 years, $8,881 for 50 - 59 years, $16,700 for 60 - 69 years, and $36,467 for over 70 years
Authors' conclusions Mass screening for Type 2 diabetes mellitus (DM) with a 5-year inter-screening interval represented a cost-effective option in Taiwan, especially among young persons.
CRD COMMENTARY - Selection of comparators The authors compared the two screening programmes with the no-screening option to evaluate the extra costs and benefits of the interventions under study. However, no explication was given for the choice of the two screening programmes. You should decide whether they are appropriate alternative interventions in your own setting.
Validity of estimate of measure of effectiveness The analysis of effectiveness used published studies. However, a formal review of the literature does not appear to have been performed. Neither the search methods used, nor the design of the primary studies used as the source of the effectiveness data, were reported. The data were combined using narrative methods. It was not stated whether the authors considered the impact of differences in the studies when estimating effectiveness. No sensitivity analyses were conducted to take into account uncertainty around the estimates used in the analysis. These issues tend to limit the internal validity of the analysis.
Validity of estimate of measure of benefit Survival and QALYs were used as the summary benefit measures in the economic analysis. Both were appropriate to estimate the impact on the health of the two screening strategies. In addition, they ensured the comparability of the benefits of the present study interventions with those from the benefits of other programmes. The benefits were calculated from published data through a decision model, which was not described in detail. Appropriate discounting was performed.
Validity of estimate of costs The perspective adopted in the study was not reported, and as such, it was unclear whether all the relevant categories of costs were included in the analysis. The indirect costs were not accounted for in the study. The unit costs were reported, but details concerning resource consumption were not given. No price year was reported, thus making reflation exercises in other settings difficult. The costs appear to have been treated deterministically and sensitivity analyses were not conducted. The costs were derived from a variety of different sources, including US data. The lack of concise reporting may limit the reproducibility of the study in other settings.
Other issues The authors compared their findings with the evaluations of the cost-effectiveness of other screening strategies, such as breast cancer, cervical cancer and hypertension screening. The issue of the generalisability of the study results to other settings was not addressed and sensitivity analyses were not conducted. Thus, the external validity of the analysis was low. The authors pointed out some limitations of their analysis.
Implications of the study The study suggests that mass screening for Type 2 DM may be a cost-effective option in countries with 6 - 12% prevalence, such as Taiwan. However, caution is required when interpreting this conclusion due to the limitations of the present analysis.
Bibliographic details Chen T H, Yen M F, Tung T H. A computer simulation model for cost-effectiveness analysis of mass screening for type 2 diabetes mellitus. Diabetes Research and Clinical Practice 2001; 54(Supplement 1): S37-S42 Indexing Status Subject indexing assigned by NLM MeSH Computer Simulation; Cost-Benefit Analysis; Diabetes Mellitus, Type 2 /prevention & Humans; Markov Chains; Mass Screening /economics; Models, Theoretical; Monte Carlo Method; Quality-Adjusted Life Years; control AccessionNumber 22001002083 Date bibliographic record published 31/10/2003 Date abstract record published 31/10/2003 |
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