title: Printed educational messages fail to increase use of thiazides as first-line medication for hypertension in primary care: a cluster randomized controlled trial [ISRCTN72772651].
abstract: Evidence on the effectiveness of printed educational messages in contributing to increasing evidence-based clinical practice is contradictory. Nonetheless, these messages flood physician offices, in an attempt to promote treatments that can reduce costs while improving patient outcomes. This study evaluated the ability of printed educational messages to promote the choice of thiazides as the first-line treatment for individuals newly diagnosed with hypertension, a practice supported by good evidence and included in guidelines, and one which could reduce costs to the health care system.
  
  
  
  The study uses a pragmatic, cluster randomized controlled trial (randomized by physician practice group).
  
  
  
  The setting involves all Ontario general/family practice physicians. Messages advising the use of thiazides as the first-line treatment of hypertension were mailed to each physician in conjunction with a widely read professional newsletter. Physicians were randomized to receive differing versions of printed educational messages: an "insert" (two-page evidence-based article) and/or one of two different versions of an "outsert" (short, directive message stapled to the outside of the newsletter). One outsert was developed without an explicit theory and one with messages developed targeting factors from the theory of planned behaviour or neither (newsletter only, with no mention of thiazides). The percentage of patients aged over 65 and newly diagnosed with hypertension who were prescribed a thiazide as the sole initial prescription medication. The effect of the intervention was estimated using a logistic regression model estimated using generalized estimating equation methods to account for the clustering of patients within physician practices.
  
  
  
  Four thousand five hundred four physicians (with 23,508 patients) were randomized, providing 97 % power to detect a 5 % absolute increase in prescription of thiazides. No intervention effect was detected. Thiazides were prescribed to 27.6 % of the patients who saw control physicians, 27.4 % for the insert, 26.8 % for the outsert and 28.3 % of the patients who saw insert + outsert physicians, p = 0.54.
  
  
  
  The study conclusively failed to demonstrate any impact of the printed educational messages on increasing prescribing of thiazide diuretics for first-line management of hypertension.
  
  
  
  ISRCTN72772651.
authors.affiliation: Centre for Studies in Family Medicine, Department of Family Medicine, Schulich School of Medicine and Dentistry, Western University, 1465 Richmond Street, London, Ontario, N6A 3K7, Canada. merrick.zwarenstein@ices.on.ca.|Institute for Clinical Evaluative Sciences, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada. merrick.zwarenstein@ices.on.ca.
authors.forename: Merrick
authors.initials: M
authors.lastname: Zwarenstein
authors.affiliation: Ottawa Hospital Research Institute, The Ottawa Hospital-General Campus, 501 Smyth Road, Box 711, Ottawa, Ontario, K1H 8L6, Canada.|Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, K1H 8M5, Canada.
authors.forename: Jeremy M
authors.initials: JM
authors.lastname: Grimshaw
authors.affiliation: Ottawa Hospital Research Institute, The Ottawa Hospital-General Campus, 501 Smyth Road, Box 711, Ottawa, Ontario, K1H 8L6, Canada.|School of Epidemiology, Public Health and Preventive Medicine, 451 Smyth Road, Ottawa, Ontario, K1H 8M5, Canada.
authors.forename: Justin
authors.initials: J
authors.lastname: Presseau
authors.affiliation: School of Health Sciences, City University London, Northampton Square, London, EC1V 0HB, UK.
authors.forename: Jill J
authors.initials: JJ
authors.lastname: Francis
authors.affiliation: Faculty of Nursing, Laval University, Pavillon Ferdinand-Vandry, 1050 Avenue de la Medicine, Room 1445, Quebec City, Quebec, G1V 0A6, Canada.
authors.forename: Gaston
authors.initials: G
authors.lastname: Godin
authors.affiliation: Institute of Applied Health Sciences, College of Life Sciences and Medicine, University of Aberdeen, 2nd floor, Health Sciences Building, Foresterhill, Aberdeen, AB25 2ZD, UK.
authors.forename: Marie
authors.initials: M
authors.lastname: Johnston
authors.affiliation: Institute of Health and Society, Newcastle University, Baddiley-Clark Building, Richardson Road, Newcastle Upon Tyne, NE2 4AX, UK.
authors.forename: Martin P
authors.initials: MP
authors.lastname: Eccles
authors.affiliation: Retired, Ottawa, Canada.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Tetroe
authors.affiliation: Institute for Clinical Evaluative Sciences, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada.
authors.forename: Susan K
authors.initials: SK
authors.lastname: Shiller
authors.affiliation: Institute for Clinical Evaluative Sciences, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada.
authors.forename: Ruth
authors.initials: R
authors.lastname: Croxford
authors.affiliation: Canadian Medical Association Journal, 1867 Alta Vista Drive, Ottawa, Ontario, K1G 5W8, Canada.
authors.forename: Diane
authors.initials: D
authors.lastname: Kelsall
authors.affiliation: Institute for Clinical Evaluative Sciences, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada.|Institute of Health Policy, Management and Evaluation, University of Toronto, Health Sciences Building, 155 College Street, Suite 425, Toronto, Ontario, M5T 3M6, Canada.
authors.forename: J Michael
authors.initials: JM
authors.lastname: Paterson
authors.affiliation: Institute for Clinical Evaluative Sciences, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada.|Institute of Health Policy, Management and Evaluation, University of Toronto, Health Sciences Building, 155 College Street, Suite 425, Toronto, Ontario, M5T 3M6, Canada.
authors.forename: Peter C
authors.initials: PC
authors.lastname: Austin
authors.affiliation: Institute for Clinical Evaluative Sciences, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada.|Faculty of Medicine, University of Toronto, 1 King's College Circle, Medical Sciences Building, Toronto, Ontario, M5S 1A8, Canada.
authors.forename: Karen
authors.initials: K
authors.lastname: Tu
authors.affiliation: Institute for Clinical Evaluative Sciences, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada.
authors.forename: Lingsong
authors.initials: L
authors.lastname: Yun
authors.affiliation: Institute for Clinical Evaluative Sciences, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada.|Institute of Health Policy, Management and Evaluation, University of Toronto, Health Sciences Building, 155 College Street, Suite 425, Toronto, Ontario, M5T 3M6, Canada.|Canadian Diabetes Association, 522 University Ave, Toronto, Ontario, M5G 2A2, Canada.
authors.forename: Janet E
authors.initials: JE
authors.lastname: Hux
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000959:Antihypertensive Agents / Q000627:therapeutic use; D016000:Cluster Analysis; D004363:Drug Utilization / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy*; D008297:Male; D009864:Ontario; D010174:Pamphlets; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data*; D011320:Primary Health Care / Q000379:methods / Q000706:statistics & numerical data*; D049993:Sodium Chloride Symporter Inhibitors / Q000627:therapeutic use*
chemical_list: D000959:Antihypertensive Agents; D049993:Sodium Chloride Symporter Inhibitors