TABLE 7-1 Structure of Study Centers for a Government-Sponsored Randomized Controlled Trial (Diabetes Prevention Program [DPP]) and an Industry-Sponsored Randomized Controlled Trial (A Diabetes Progression Outcomes Trial [ADOPT])

 

DPP

ADOPT

No. of Countries

1

(USA)

17

(USA, Canada, Europe)

No. of Centers

27

488

No. of Subjects

3,819

4,360

Subjects per Center

62–193

(Nat. American: 20–80)

1–48

Caucasian

55%

88%

Reimbursement

FTE based

Visit based

NOTE: FTE = full-time equivalent.

SOURCE: Kahn, 2009.

difference between the best drug (rosiglitazone) and the worst drug (glyburide) in the study was not attributable to bias and therefore still reliable. However, bias could not be ruled out as the cause of the observed difference between the best (rosiglitazone) and intermediate (metformin) drugs. In the DPP trial, the designation of specific staff and budgeting of resources for retaining participants were successful in achieving a 97 percent retention rate, thus avoiding bias in the study results.

The DPP was likely more expensive than ADOPT in terms of cost per patient, according to Kahn. However, the 97 percent patient retention rate in the DPP was perhaps worth the additional cost given that large dropout rates can call into question the legitimacy of the results of any trial. The DPP could have been completed and found the same reduction in the risk of developing type 2 diabetes with a less intensive, less costly level of lifestyle intervention. In general, however, the results of NIH-sponsored, long-term studies such as the DPP, which have high rates of participant follow up, are often more valuable than those of industry-sponsored studies conducted over a short period of time and with dropout rates in the range of 20–25 percent.

OVERCOMING REGULATORY CHALLENGES

In addition to the challenges discussed in Chapter 3, Carla Greenbaum, Director of the Benaroya Research Institute Diabetes Program and Clinical Research Center, reflected on her experience conducting clinical trials



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement