Research article

Is new drug prescribing in primary care specialist induced?

Stefan R Florentinus¹ , Eibert R Heerdink¹ , Liset van Dijk² , AMG Fabiënne Griens⁴ , Peter P Groenewegen^2,3 and Hubert GM Leufkens¹

¹Utrecht University, Department of Pharmacoepidemiology and Pharmacotherapy, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht, The Netherlands

²NIVEL (Netherlands Institute for Health Services Research), Utrecht, The Netherlands

³Utrecht University, Department of Sociology and Department of Human Geography, Utrecht, The Netherlands

⁴SFK (Foundation for Pharmaceutical Statistics), The Hague, The Netherlands

author email corresponding author email

BMC Health Services Research 2009, 9:6doi:10.1186/1472-6963-9-6

Published:	11 January 2009

Abstract

Background

Medical specialists are often seen as the first prescribers of new drugs. However, the extent to which specialists influence new drug prescribing in primary care is largely unknown.

Methods

This study estimates the influence of medical specialists on new drug prescribing in primary care shortly after market introduction. The influence of medical specialists on prescribing of five new drugs was measured in a cohort of 103 GPs, working in 59 practices, over the period 1999 until 2003. The influence of medical specialists on new drug prescribing in primary care was assessed using three outcome measures. Firstly, the proportion of patients receiving their first prescription for a new or reference drug from a specialist. Secondly, the proportion of GPs prescribing new drugs before any specialist prescribes to their patients. Thirdly, we compared the time until the GP's first own prescribing between GPs who waited for prescriptions from specialists and those who did not.

Results

The influence of specialists showed considerable differences among the new drugs studied. The proportion of patients receiving their first prescription from a specialist was greatest for the combination salmeterol/fluticasone (60.2%), and lowest for rofecoxib (23.0%). The proportion of GPs prescribing new drugs before waiting for prescriptions from medical specialists ranged from 21.1% in the case of esomeprazole to 32.9% for rofecoxib. Prescribing new drugs by specialists did not shorten the GP's own time to prescribing.

Conclusion

This study shows that the influence of medical specialists is clearly visible for all new drugs and often greater than for the existing older drugs, but the rapid uptake of new drugs in primary care does not seem specialist induced in all cases. GPs are responsible for a substantial amount of all early prescriptions for new drugs and for a subpopulation specialist endorsement is not a requisite to initiate in new drug prescribing. This contradicts with the idea that the diffusion of newly marketed drugs always follows a two-step model, with medical specialists as the innovators and GPs as the followers.