Clinical drug trials in general practice: a 10-year overview of protocols

Drugs predominantly prescribed in general practice should ideally be tested in that setting; however, little is known about drug trials in general practice. Our aim was to describe drug trials in Norwegian general practice over the period of a decade.

The present work concerns a 10-year retrospective study of protocols submitted to the Norwegian national medicines agency (1998 to 2007) identifying all studies involving general practitioners (GPs) as clinical investigator(s). We analyzed the number of trials, drug company involvement, patients, participating doctors, payment, medications tested and main diagnostic criteria for inclusion. We also analyzed one trial in greater detail.

Out of 2,054 clinical drug trials, 196 (9.5%) were undertaken in general practice; 93% were multinational, 96% were industry funded and 77% included patients both from general practice and specialist care. The trials were planned to be completed in the period 1998 to 2012. A total of 23,000 patients in Norway and 340,000 patients internationally were planned to be included in the 196 trials. A median of 5 GPs participated in each trial (range 1 to 402). Only 0.7% of 831 GP investigators had general practice university affiliations. Median payment for participating investigators was €1,900 (range €0 to 13,500) per patient completing the trial. A total of 30 pharmaceutical companies were involved. The drugs most commonly studied were antidiabetics (21%), obstructive airway disease medications (12%), agents acting on the renin-angiotensin system (10%), and lipid modifying agents (10%). One trial, presented in more detail, had several characteristics of a seeding or marketing trial.

Only one in four drug trials involving general practice were solely general practice trials and almost all were industry initiated without input from academic general practice. There was a large variation in the number of patients, participating doctors, and economic compensation for trial investigators, with some investigators receiving substantial payments.