|The cost-effectiveness of different management strategies for type I diabetes: a Swiss perspective
|Palmer A J, Weiss C, Sendi P P, Neeser K, Brandt A, Singh G, Wenzel H, Spinas G A
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.
Management strategies for Type I diabetes.
Type of intervention
Prevention and treatment.
Economic study type
A hypothetical cohort of newly diagnosed 19 year old patients with Type I diabetes, with no baseline complications.
A hospital setting. The study was set in Switzerland.
Dates to which data relate
Effectiveness data were collected from studies published between 1981 and 1996. Resource use data were collected from a study published in 1995. Cost data were collected from studies published between 1994 and 1997. The price year was 1996.
Source of effectiveness data
Effectiveness data were derived from a review of the literature.
A decision analytic Markov model was used to determine the cost-effectiveness of the different management strategies.
Outcomes assessed in the review
The review assessed the probabilities of seven diabetes complications: renal disease, retinopathy, amputation, myocardial infarction, stroke, major hypoglycaemic events, and ketoacidosis.
Study designs and other criteria for inclusion in the review
The study designs and other criteria for inclusion were not reported.
Sources searched to identify primary studies
The sources searched to identify primary studies were not reported.
Criteria used to ensure the validity of primary studies
The criteria used to ensure the validity of primary studies were not reported.
Methods used to judge relevance and validity, and for extracting data
Summary statistics from individual studies were used.
Number of primary studies included
At least 12 studies were included in the review.
Methods of combining primary studies
Investigation of differences between primary studies
An investigation of differences between the primary studies was not reported.
Results of the review
Intensive insulin therapy resulted in a reduction of all macrovascular events combined by 41%. The annual increase in urinary albumin excretion (UAE) rate was 20%. The reduction in the rate of annual increase in UAE with ACE use was 55%. The reduction in the probability of progression to end-stage renal disease (ESRD) with ACE was 50%. The reduction in incidence of background retinopathy (BR) with intensive therapy was 76%. The reduction in progression from BR to proliferative retinopathy (PR) with intensive therapy was 47%. The progression from PR to Blind without laser therapy was 0.1. The reduction in the rate of progression from PR to Blind with laser therapy was 90%. The probability of a major hypoglycaemic event with conventional therapy was 0.270 if aged under 18, and 0.185 if aged over 18. The probability of a major hypoglycaemic event with intensive therapy was 0.857 if aged under 18, and 0.569 if aged over 18. There was a 2.8-fold increase in risk of severe hypoglycaemic event with ACE-I. Case fatality of severe hypoglycaemic event was 0.01%. The probability of ketoacidosis conventional therapy was 0.048 if aged over 18, and 0.013 if aged under 18. The probability of ketoacidosis with intensive therapy was 0.028 (under 18 years old), and 0.018 (over 18). The case fatality of ketoacidosis was 5%.
Measure of benefits used in the economic analysis
The number of life years gained was used as the measure of benefits. Due to controversy over which discount rates to use, benefits (and costs) were discounted at an annual rate of 0%, 3%, 5%, and 6%.
Direct costs were discounted at an annual rate of 0%, 3%, 5%, and 6%. Quantities and costs were reported separately. Direct costs reflected costs for each of the management strategies and included costs for equipment, investigations, procedures, medications, hospitalisation, and complications. The quantity/cost boundary adopted was that of the Swiss third party-payer. The estimation of quantities and costs was based on actual data. Cost data were taken from published Swiss and American sources. The price year was 1996.
Statistical analysis of costs
There was no analysis of costs.
Indirect costs were not included.
One-way sensitivity analyses were conducted on the effect of intensive therapy on the incidence of stroke and AMI, costs, and life expectancy (+/- 10%). Threshold analysis was conducted on annual costs of insulin therapy.
Estimated benefits used in the economic analysis
Using a discount rate of 3%, the number of life years gained compared with conventional therapy alone varied between 0 for C+EYE and 2.24 for E+ACE and I+EYE+ACE. Using a discount rate of 6%, the number of life years gained compared with conventional therapy alone varied between 0 for C+EYE and 0.62 for E+ACE and I+EYE+ACE. The combination of intensive and ACE therapy showed the maximal effect on survival function. The combination of intensive and ACE therapy almost eliminated the development of ESRD. The combination of intensive therapy plus screening and laser therapy will have the optimal effect by reducing cumulative incidence of blindness at age 50 years to less than 2%. The cumulative incidence of first amputation is reduced from 30% with conventional therapy to 22% with intensive insulin therapy alone. Reduction in diabetes-attributed risk of AMI and reduction in incidence and progression of MAU with intensive insulin therapy had the greatest impacts on life expectancy.
Assuming a reduction in attributed risk of myocardial infarction and stroke due to diabetes of 41% with intensive therapy, total non-discounted lifetime costs (and discounted at 6%) for the different strategies were as follows:
SFr314,643 (71,176) for C,
SFr309,215 (72,472) for C+EYE,
SFr279,593 (67,427) for C+ACE,
SFr272,249 (68,594) for C+EYE+ACE,
SFr407,785 (107,690) for I,
SFr413,287 (110,755) for I+EYE,
SFr416,381 (116,617) for I+ACE
and SFr421,641 (119,676) for I+EYE+ACE.
The annual cost of intensive therapy had the greatest impact on the total lifetime costs in patients treated with a combination of intensive insulin therapy, eye and MAU screening and treatment.
Synthesis of costs and benefits
The following strategies were dominated: C+EYE, C+ACE, C+EYE+ACE. Assuming a reduction in attributed risk of myocardial infarction and stroke due to diabetes of 41% with intensive therapy, the incremental cost-effectiveness (non-discounted) was SFr12,536 for I, SFr13,276 for I+EYE, SFr10,277 for I+ACE and SFr10,808 for I+EYE+ACE. Assuming no effect of intensive therapy on myocardial infarction and stroke incidence, the incremental cost-effectiveness (non-discounted) was SFr13,342 for I, SFr14,218 for I+EYE, SFr10,886 for I+ACE and SFr11,507 for I+EYE+ACE.
Optimal management of Type I diabetic patients, including secondary and tertiary prevention, leads to reduced complications and improved life expectancy, with the increased costs of prevention offset to varying degrees by cost savings because of complications avoided.
CRD COMMENTARY - Selection of comparators
A justification was given for the comparators used, namely currently available prevention and treatment strategies. You, as a user of the database, should decide if these health technologies are relevant to your setting.
Validity of estimate of measure of benefit
The authors did not state that a systematic review of the literature had been undertaken. More details could have been provided about the design and conduct of the review. Effectiveness estimates were combined using narrative methods. Effectiveness estimates were derived credibly from primary studies. The estimation of benefits was obtained directly from the effectiveness analysis.
Validity of estimate of costs
All categories of costs relevant to the perspective adopted were included in the analysis. Quantities and costs were reported separately. A sensitivity analysis was conducted on prices, but not on quantities. Charges were not used to proxy prices. The price year was reported.
The authors made appropriate comparisons of their findings with those from other studies. The issue of generalisability to other settings was not addressed. The authors did not present their results selectively. The study examined Type I diabetic patients and this was reflected in the authors' conclusions. The effect of intensive therapy was possibly under-estimated because it was assumed it would have no effect on progression from proteinuria to renal failure. The authors did not consider quality-adjusted life expectancy. Hence, the analysis possibly underestimates the effect of intensive insulin therapy. The population used in this study was highly motivated, highly intelligent, well-educated, and is possibly not representative of the overall Type I diabetic population. Possible effects of ACE inhibitors and survival post-AMI were not considered.
Implications of the study
Future research needs to examine the effects of insulin therapy in more detail.
Source of funding
Partially funded by research grants from Roche Diagnostics Schweiz AG and Roche Diagnostics Boehringer Mannheim GmbH.
Palmer A J, Weiss C, Sendi P P, Neeser K, Brandt A, Singh G, Wenzel H, Spinas G A. The cost-effectiveness of different management strategies for type I diabetes: a Swiss perspective. Diabetologia 2000; 43(1): 13-26
Subject indexing assigned by NLM
Albuminuria; Cost-Benefit Analysis; Diabetes Mellitus, Type 1 /economics /physiopathology /therapy; Diabetic Angiopathies /prevention & Diabetic Nephropathies /epidemiology /prevention & Diabetic Retinopathy /epidemiology /prevention & Humans; Incidence; Insulin /economics /therapeutic use; Kidney Failure, Chronic /prevention & Life Expectancy; Markov Chains; Mass Screening; Models, Statistical; Switzerland; control; control; control; control
Date bibliographic record published
Date abstract record published