E-mail invitations to general practitioners were as effective as postal invitations and were more efficient.

Posted: Jan 17, 2013
J Clin Epidemiol. 65. 7. 793-7.
KEYWORDS: Incentives, International, Non-Cancer


E-mail recruitment of general practitioners is easy and inexpensive.

Why this item may be useful

This study compared cost and effectiveness of recruiting general practitioners (GPs) to an online trial by e-mail compared with postal invitations. Use of e-mail did not improve recruitment, but it also did not adversely affect accrual. It was also logistically easier than mailing and lowered costs. Reminders using both methods resulted in a 4 percent increase in accrual.


  • Two hundred seventy GPs in Scotland were recruited to participate in an online trial designed to improve antibiotic prescribing for upper respiratory infections in primary care.  Embedded in this study, was a a trial evaluating which of two invitation methods, email or post,  was more effective at recruiting GP's to the study.
  • E-mail recruitment in this study had a per-patient cost of £3.20 (~$5), compared with £15.69  (~$25) using postal invitations.
  • All GP's were offered a £20 gift voucher from outlets such as Amazon, iTunes, and Starbucks as an incentive to participate regardless of how they were contacted.  GP's could also opt to receive no voucher.  98% of GP's opted to receive a voucher, 46% of them opted for Amazon.