Clinical trial investigators and their prescribing patterns: another dimension to the relationship between physician investigators and the pharmaceutical industry

drugs.jpgThe following editorial and article appear in the June 21 issue of JAMA:[full text by subscription]

Read the MedPage Today commentary on How conducting a clinical trial affects physicians' guideline adherence and drug preferences

Psaty BM, Rennie D. Clinical trial investigators and their prescribing patterns: another dimension to the relationship between physician investigators and the pharmaceutical industry [editorial]. JAMA 2006; 295(23):2787-2790.

Extract: Large long-term clinical trials have helped to define first-line drug therapies for conditions such as high blood pressure. Physician adherence to evidence-based guidelines, however, has been modest at best, and the causes remain unclear. In a study of antihypertensive drug use in 10 countries, Fretheim and Oxman characterized the international variation in prescribing patterns. The prescription of thiazides, for instance, was 4-fold higher in the United Kingdom than in Norway, and conversely, the prescription of -blockers was 4-fold higher in Norway than in the United Kingdom. The authors hypothesized that these international differences were related in part to the promotion of more expensive drugs in Norway through "seeding trials," which have been described as "thinly veiled attempts to entice doctors to prescribe a new drug being marketed by the company."
 

Andersen M, Kragstrup J, Sondergaard J. How conducting a clinical trial affects physicians' guideline adherence and drug preferences. JAMA 2006; 295(23):2759-2764.

Context: General practitioners are frequently involved in clinical trials sponsored by pharmaceutical companies but the effects of participation on their prescribing patterns have not been evaluated.
Objective: To determine how conducting a company-sponsored clinical trial influenced physicians' adherence to international treatment recommendations and their prescribing of the pharmaceutical company's drugs.
Design, Setting, and Patients: Observational cohort study in Funen County, Denmark, comparing 10 practices that were conducting a trial on asthma medicine with 165 control (non-trial-conducting) practices. The study population included 5439 patients treated with asthma drugs from the trial-conducting practices and 59 574 patients from the control practices. Practices conducted the trial between April 26, 2001, and October 7, 2002.
Main Outcome Measures: Adherence to guidelines measured as use of inhaled corticosteroids among asthma patients. Prevalence of use of the company's drugs and the trial sponsor's share of the total volume of asthma drugs prescribed. Results The baseline proportion of asthma patients using inhaled corticosteroids was 68.5% in trial-conducting and 69.1% in control practices. Conducting the trial did not influence guideline adherence (odds ratio [OR] after 2 years, 1.00; 95% confidence interval [CI], 0.84-1.19). In trial-conducting practices, the sponsoring company's share of the total prescribed volume of asthma drugs increased compared with control practices (6.7%; 95% CI, 3.0%-11.7%). This could be attributed to a significantly higher preference for the company's inhaled corticosteroids (OR, 1.26; 95% CI, 1.04-1.54) and trends toward increased prescribing of the company's other asthma drugs.
Conclusion: Conducting a trial sponsored by a pharmaceutical company had no significant impact on physicians' adherence to international treatment recommendations but increased their use of the trial sponsor's drugs.
 

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