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Table 1 Study design and number of practice groups/number of physicians

From: Printed educational messages fail to increase use of thiazides as first-line medication for hypertension in primary care: a cluster randomized controlled trial [ISRCTN72772651]

  Randomized Included in the analysis
(started at least one patient with uncomplicated hypertension on medication during the follow-up year)
Intervention Number of practice groups Number of physicians Number of practice groups Number of physicians
1. informed only (no PEM) 1057 1330 947 1166
2. informed plus insert 1058 1265 926 1093
3. informed plus outsert     
 a. Atheoretical outsert 529 644 475 565
 b. TPB-based outsert 529 652 476 585
4. informed plus insert and outsert     
 a. Atheoretical outsert 529 648 461 550
 b. TPB-based outsert 529 640 449 545
Total 4231 5179 3734 4504
  1. Physician practices were randomly assigned to one of four intervention groups. The two intervention groups selected to receive an outsert were further randomly divided into two sub-groups, one of which received the outsert developed by the OPEM team (atheoretical outsert), the other receiving the TPB-based outsert. Interventions were included in the July 2005 edition of informed
  2. PEM printed educational message, TPB theory of planned behaviour