The advancement of science requires the cooperation of clinical investigators. Recent discourse, which attempts to relate pharmaceutical company grant payments to clinical investigators to subsequent preferential prescribing behavior, erodes the physician/patient relationship and may lead to an inadequate number of investigators. This study was designed to determine why the level of grant payments to Phase 3 clinical investigators differs for comparable levels of work and whether these differences are related to subsequent prescribing behavior of either the study drug or other drugs from the same sponsoring company. From a database of 100,000 investigator contracts, 2,108 U.S. physicians participating in Phase 3 trials at 2,897 clinical sites for new drugs launched in 1999-2000 were randomly selected in 10 outpatient indications. The relative grant amounts (RGAs) paid to the investigators were compared with their subsequent prescribing of the study drug and other sponsor company drugs for a period of six months after study drug introduction. The RGA is the payment percentile represented by the absolute cost per patient grant paid to any specific investigator compared with other similar studies, including such considerations as the number of patient visits, the number and types of medical procedures performed, the investigator's geographic location, and whether the study was conducted at the investigator's office or hospital. Linear regression correlations were calculated between study, investigator, and drug characteristics with the RGA, and the correlation between the RGA and subsequent prescribing behavior of the study drug and other drugs from the sponsor company at three and six months after study drug product launch. Five variables were statistically significantly related to the RGA received by an investigator: compound therapeutic novelty, the number of similar studies being conducted at same time, investigator clinical research experience, and the inverse of drug class prescription volume. Most significantly, investigators' post-study prescribing behavior was not related to RGA. Drug development and market forces explain the RGA, but RGA is not related to subsequent sponsor or study drug prescribing.

This study examines the demographic and prescribing characteristics of Phase IV clinical investigators who subsequently increase their prescribing level of the study drug.

Since 2007, the US federal government has required that organizations sponsoring clinical trials with a least one site in the United States submit information on these clinical trials to an existing database: ClinicalTrials.gov . Over time, the number of mandatory variables has grown and will probably continue to grow. The database now represents an important source of descriptive information about the landscape for clinical trials. In addition, it constitutes a rich pool of data to test hypotheses-for instance, what variables are associated with an organization's ability to correctly estimate study completion times or complete those studies in as short a time frame as possible. This paper concludes that for mandated variables that the authors have labeled study identification, protocol and study design, and study execution, the data set constitutes a potentially very valuable research resource. With the exception of some site-related information, incomplete data did not exceed 3%. The incomplete site data are concentrated in several companies, so it is not unreasonable to assume that those data will also become more complete.

Background:Clinical investigator physicians who take part in clinical trials influence how other doctors adopt new drugs; however, not much is known about the attributes of these investigators (usually with office-based practices and a smaller number working in hospitals or academic medical centres) who tend to prescribe more of the study drug once it gets to the market. Aim: To examine the descriptive factors associated with higher study drug prescribing volumes among clinical investigators who participated in phase III clinical trials of that study drug. Method: The post-launch prescribing behaviour of a random sample of 2187 clinical investigator physicians was followed for 18 months. These investigator physicians had participated in phase III clinical trials for any one of 38 new drugs between 1997-2000. Investigators were matched, on a number of descriptive and prescribing variables, with a control set of physicians who had not participated in clinical trials of any sort. Results: Sponsor company marketing support in general, along with pre-launch investigator prescribing patterns, and to a lesser extent investigator clinical trial experience, are important in understanding an investigator's willingness to prescribe the study drug after it comes to market. Conclusions: Clinical investigators play an important role in the adoption of a new drug, not only in prescribing the drug themselves but also in influencing the prescribing behaviour of their peers. ORIGINAL RESEARCH ARTICLEInt J Pharm Med 2005; 19 (2): 97-104 1364-9027/05/0002-0097/$34.95/0

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