The effect of pharmaceutical marketing on the prescription of rofecoxib in Dutch general practice.

Background: In 2000 the new painkiller rofecoxib was introduced in the Netherlands as an alternative for NSAIDs. It was extensively marketed by the pharmaceutical industry stressing its gastro protective qualities and significant pain reduction. Rofecoxib vastly obtained a significant market share. However, GPs differed considerably in the adoption of this new drug. Aim: To study the effect of the use of information of the pharmaceutical industry on the prescription of the new drug rofecoxib in Dutch general practice. Methods: Data from the Second Dutch National Survey of General Practice (DNSGP-2) were used.During this representative survey of morbidity in 104 Dutch general practices (comprising of 195 GP’s who served 385.461 patients) in 2001 all contacts with patients were registered. Additional data were collected on all GP’s of DNSGP-2, they filled in a detailed questionnaire. GP questionnaire were linked to prescription data from the GP’s registrations. Data were analysed using multilevel analysis to take into account the clustering of rofecoxib prescriptions within GP’s. Outcome variables were number of rofecoxib prescriptions and number of NSAID prescriptions within the year of registration. Results: Preliminary analyses show that prescriptions of rofecoxib rapidly increased in the first year of introduction in 2000. After the first year of introduction rofecoxib prescriptions still increases but more steadily. Both patient and GP characteristics influence the volume of the prescription of rofecoxib. The most influencing factor at the GP level is the number of visits of drug representatives the GP had: the more visits the more rofecoxib the GP prescribed. Moreover, the more written information the GP used (such as information of the pharmaceutical industry), the more rofecoxib was prescribed. GPs who used national or regional professional guidelines more often, prescribed less rofecoxib. Conclusions: Information of the pharmaceutical industry is an important factor in stimulating the prescription of the new drug rofecoxib. Implications of this finding will be discussed at the conference.