The Cost-Effectiveness of Sildenafil (Viagra)

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 Sildenafil." It is in the 20 June 2000 issue of Annals of Internal Medicine (volume 132, pages 933-937). The authors are K.J. Smith and M.S. Roberts.

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

Sildenafil, a drug commonly known by the brand name Viagra, is a treatment for male impotence. Many patients want Viagra, which costs about $5 to $10 per pill, but many insurance companies do not cover the its cost. Cost-effectiveness analysis is a method for determining how much a health treatment costs for a given amount of benefit. The benefit is usually measured in units called quality-adjusted life-years (QALYs). This measure takes into consideration not only how long a person lives but also the quality of their life during that time.

Why did the researchers do this particular study?

To find out how the cost-effectiveness of Viagra compares with that of other health treatments.

Who was studied?

The researchers did not study actual patients. Instead, they created a computer simulation to study a group of virtual 60-year-old men with impotence who took or did not take Viagra.

How was the study done?

The computer model included information about how many men would have improvements in impotence if they took Viagra, the side effects of Viagra (including heart attacks and death), and the costs of treatment and its complications. It also considered quality of life among men with and without impotence by incorporating ratings assigned by actual men with the condition. By estimating the number of QALYs gained with a medical treatment, treatment strategies that save the same number of years get more "credit" if they gain years of high-quality life than if they gain years of low-quality life.

What did the researchers find?

The researchers calculated that Viagra costs about $11,290 per QALY that it produces. This amount is less than many other accepted health treatments. Most accepted health treatments cost less than $50,000 to $100,000 per QALY. The researchers also found that Viagra costs less than $50,000 per QALY if 1) fewer than 0.8% of the men who take the drug have a major treatment-related side effect, 2) fewer than 0.55% of the men die as a result of taking Viagra, 3) Viagra costs less than $244 dollars per month, or 4) successful treatment of impotence improves quality of life by at least.05 on a scale of 0 to 1.

What were the limitations of the study?

The computer model did not consider other treatments for impotence, such as pumps, surgical implants, or other medicines. The model depends on the accuracy of the numbers on effectiveness, side effects, costs, and benefits of treatment that the researchers entered; some of the numbers were based on more convincing data than others.

What are the implications of the study?

The cost-effectiveness of Viagra appears to compare favorably with other accepted medical therapies. There may, however, be many reasons other than cost-effectiveness (such as ethics or total costs) to explain why insurance companies choose not to cover the cost of Viagra.