The Costs of Preventing Kidney Failure in People with Diabetes

Summaries for Patients are a service provided by Annals to help patients better understand the complicated and often mystifying language of modern medicine.

Summaries for Patients are presented for informational purposes only. These summaries are not a substitute for advice from your own medical provider. If you have questions about this material, or need medical advice about your own health or situation, please contact your physician. The summaries may be reproduced for not-for-profit educational purposes only. Any other uses must be approved by the American College of Physicians-American Society of Internal Medicine.

The summary below is from the full report titled "The Cost-Effectiveness of Treating All Patients with Type 2 Diabetes with Angiotensin-Converting Enzyme Inhibitors." It is in the 2 November 1999 issue of Annals of Internal Medicine (volume 131, pages 660-667). The authors are L. Golan, J.D. Birkmeyer, and H.G. Welch.

What is the problem and what is known about it so far?

Kidney failure is a late complication of diabetes. Medicines called angiotensin-converting enzyme (ACE) inhibitors delay kidney failure in persons with diabetes. There are two ways to detect early kidney damage: testing urine for a moderate amount of protein (proteinuria) or for a small amount of protein (microalbuminuria). (Proteinuria is easier to test for but detects kidney damage later). Experts therefore recommend testing diabetic patients yearly and starting therapy with ACE inhibitors as soon as microalbuminuria develops. However, many patients with diabetes who might benefit from ACE inhibitors do not get them. More diabetic patients might get ACE inhibitors if all diabetic patients were treated with ACE inhibitors without requiring the additional step of testing for mild kidney damage first. On the other hand, treating everyone with ACE inhibitors is likely to be more expensive because it involves treating all diabetic patients for many years.

Why did the researchers do this particular study?

The researchers wanted to see how much it would cost to provide the potential benefits of treating all diabetic patients with ACE inhibitors, compared with the costs and benefits of giving ACE inhibitors only if tests show early kidney damage.

Who was studied?

Trying to answer this question by using actual patients would need a study involving many patients over many years. Instead, the researchers made use of three studies on the effect of ACE inhibitors in diabetic patients at different stages of disease. The researchers then used computers to combine these trials and to describe what would happen to a "virtual" group of 50-year-old patients recently found to have diabetes and followed them for many years.

How was the study done?

The authors looked to see what would happen to patients over time with each of the following three approaches. 1) Yearly tests for microalbuminuria and therapy with ACE inhibitors only if the test is positive. 2) Yearly tests for proteinuria and therapy with ACE inhibitors only if the test is positive. 3) Therapy with ACE inhibitors begun at the time diabetes is diagnosed, without testing for early kidney damage. The information about what might happen to patients with each approach came from previous studies. The results were expressed as the cost (in dollars) per "quality-adjusted life-year." This measure estimates how much a particular medical care approach would cost for each additional year of life it saves. "Quality adjusted" means that more benefit comes from saving a year of healthy life than from saving a year of life with poor health.

What did the researchers find?

Treating all patients with ACE inhibitors appears to be the most cost-effective strategy. The researchers estimate that treating all new diabetic patients with ACE inhibitors without testing first costs society about $7500 per quality-adjusted life-year gained. Compared with many other health care items that society is willing to pay for, this is a relatively efficient way to spend health care dollars.

What were the limitations of the study?

This study was a computer simulation and cannot tell us for sure that this is what would happen with actual patients. However, the estimates from this simulation can be useful since studies using actual patients are unlikely to be done any time soon. These findings may not apply to patients who are much younger or much older than 50 at the time of diabetes diagnosis.

What are the implications of the study?

Treating all middle-aged diabetic patients with ACE inhibitors is a simple approach that appears to provide benefit at a modest additional cost. Of course, this strategy does not make sense for people with unpleasant or toxic side effects from these medicines. It may also not make sense for people with mild diabetes.