E-mail invitations to general practitioners were as effective as postal invitations and were more efficient.
OBJECTIVE
To evaluate which of two invitation methods, e-mail or post, was most effective at recruiting general practitioners (GPs) to an online trial.


METHODS
Randomized controlled trial. Participants were GPs in Scotland, United Kingdom.


RESULTS
Two hundred and seventy GPs were recruited. Using e-mail did not improve recruitment (risk difference=0.7% [95% confidence interval -2.7% to 4.1%]). E-mail was, however, simpler to use and cheaper, costing £3.20 per recruit compared with £15.69 for postal invitations. Reminders increased recruitment by around 4% for each reminder sent for both invitation methods.


CONCLUSIONS
In the Scottish context, inviting GPs to take part in an online trial by e-mail does not adversely affect recruitment and is logistically easier and cheaper than using postal invitations.
Population Health Sciences, University of Dundee, Kirsty Semple Way, Dundee DD2 4BF, UK. streweek@mac.com
Shaun
S
Treweek
Karen
K
Barnett
Graeme
G
Maclennan
Debbie
D
Bonetti
Martin P
MP
Eccles
Jill J
JJ
Francis
Claire
C
Jones
Nigel B
NB
Pitts
Ian W
IW
Ricketts
Mark
M
Weal
Frank
F
Sullivan
D000328:Adult; D000465:Algorithms; D016001:Confidence Intervals; D034742:Electronic Mail / Q000191:economics / Q000706:statistics & numerical data*; D005260:Female; D005500:Follow-Up Studies; D058005:General Practitioners / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D018579:Patient Selection; D011177:Postal Service / Q000191:economics / Q000706:statistics & numerical data*; D016032:Randomized Controlled Trials as Topic; D017010:Reminder Systems / Q000706:statistics & numerical data*; D012494:Sampling Studies; D012606:Scotland / Q000453:epidemiology; D011795:Surveys and Questionnaires