Bradley JohnstonPhD

Associate Professor

Phone: 9024941659
Fax: 9024941597
Mailing Address: 
Centre for Clinical Research, Room 404, 5790 University Ave, Halifax, Nova Scotia, Canada, B3H 1V7
Research Topics:
  • Health Research Methodology
  • Clinical and Public Health Practice Guidelines
  • Systematic Review and Meta-Analysis
  • Randomized Clinical Trials
  • Minimal Important Difference and Patient Reported Quality of Life Outcomes
  • Food, Diet, Nutrition and Physical Activity
  • Evidence-Based Nutrition


  • Post-Doctorate (McMaster University)
  • Post-Doctorate (University of Oxford)
  • PhD (University of Alberta)
  • BPE (University of New Brunswick)

Research interests

Dr. Johnston’s academic interests include the methodology of patient-reported quality of life outcomes, meta-analyses, randomized trials and practice guidelines. His work involves the application of these methods to a wide range of areas, with a particular interest in evidence-based nutrition. Dr. Johnston is the Director and Co-founder of the NutriRECS research and education program.

Selected publications

1. Goldenberg JZ, Mertz D, Johnston BC. Probiotics to Prevent Clostridium difficile Infection in Patients Receiving Antibiotics. JAMA. 2018 Jul 19. doi: 10.1001/jama.2018.9064. [Epub ahead of print]

2. Johnston BC, Lytvyn L, Lo CK, Allen SJ, Wang D, Szajewska H, Miller M, Ehrhardt S, Sampalis J, Duman DG, Pozzoni P, Colli A, Lönnermark E, Selinger CP, Wong S, Plummer S, Hickson M, Pancheva R, Hirsch S, Klarin B, Goldenberg JZ, Wang L, Mbuagbaw L, Foster G, Maw A, Sadeghirad B, Thabane L, Mertz D. Microbial Preparations (Probiotics) for the Prevention of Clostridium difficile Infection in Adults and Children: An Individual Patient Data Meta-analysis of 6,851 Participants. Infect Control Hosp Epidemiol. 2018 Jul;39(7):771-781.

3. Ebrahim S, Vercammen K, Sivanand A, Guyatt GH, Carrasco-Labra A, Fernandes RM, Crawford MW, Nesrallah G, Johnston BC. Minimally Important Differences in Patient or Proxy-Reported Outcome Studies Relevant to Children. Pediatrics. 2017 Mar;139(3).

4. Erickson J, Sadeghirad B, Lytvyn L, Slavin J, Johnston BC. The Scientific Basis of Guideline Recommendations on Sugar Intake: A Systematic Review. Ann Intern Med. 2017 Feb 21;166(4):257-267.

5. Johnston BC, Goldenberg JZ, Parkin PC. Probiotics and the prevention of antibiotic-associated diarrhea in infants and children. JAMA. 2016 Oct 11;316(14):1484-1485.

6. Sadeghirad B, Duhaney T, Motaghipisheh S, Campbell NR, Johnston BC. Influence of unhealthy food and beverage marketing on children's dietary intake and preference: a systematic review and meta-analysis of randomized trials. Obesity Rev. 2016 Oct;17(10):945-59.

7. Johnston BC, Miller PA, Agarwal A, Mulla S, Khokhar R, De Oliveira K, Hitchcock CL, Sadeghirad B, Mohiuddin M, Sekercioglu N, Seweryn M, Koperny M, Bala MM, Adams-Webber T, Granados A, Hamed A, Crawford MW, van der Ploeg AT, Guyatt GH. Limited responsiveness related to the minimal important difference of patient-reported outcomes in rare diseases. J Clin Epidemiol. 2016 Jul 2. pii: S0895-4356(16)30187-1.

8. Johnston BC, Alonso-Coello P, Friedrich JO, Mustafa RA, Tikkinen KA, Neumann I, Vandvik PO, Akl EA, da Costa BR, Adhikari NK, Dalmau GM, Kosunen E, Mustonen J, Crawford MW, Thabane L, Guyatt GH. Do clinicians understand the size of treatment effects? A randomized survey across 8 countries. CMAJ. 2016 Jan 5;188(1):25-32.

9. Shamseer L, Sampson M, Bukutu C, Schmid CH, Nikles J, Tate R, Johnston BC, Zucker D, Shadish WR, Kravitz R, Altman DG, Moher D, Vohra S; CENT Group. CONSORT extension for reporting N-of-1 trials (CENT) 2015: Explanation and elaboration. BMJ. 2015 May 14;350:h1793.

10. Johnston BC, Kanters S, Bandayrel K, Wu P, Naji F, Siemieniuk RA, Ball GD, Busse JW, Thorlund K, Guyatt G, Jansen JP, Mills EJ. Comparison of weight loss among named diet programs in overweight and obese adults: a network meta-analysis. JAMA. 2014 Sep 3;312(9):923-33. 


  • Associate Professor, Department of Community Health and Epidemiology, Dalhousie University, Halifax, NS (2017 to present)
  • Assistant Professor (status only), Institute of Health Policy, Management and Evaluation, Dalla Lana School of Public Health, University of Toronto, Toronto, ON (2012-2017)
  • Scientist, The Hospital for Sick Children Research Institute, Toronto, ON (2011 to 2017)
  • Clinical Epidemiologist, Department of Anesthesia and Pain Medicine, The Hospital for Sick Children, Toronto, ON (2011 to 2017)

Professional affiliations

  • Associate Professor (status only), Health Research Methodology, Evidence, Impact (formally Clinical Epidemiology and Biostatistics), McMaster University, Hamilton, ON
  • Member, Patient Reported Outcomes Methods Group, Cochrane Collaboration
  • Adjunct Scientist, The Hospital for Sick Children Research Institute, Toronto, ON


  • Methods in Controlled Trials course (CH&E 6024)
  • PhD module in Evidence-Based Practice Guidelines (CH&E 8020)

Service & activities

  • MSc and PhD graduate program member, Department of Community Health & Epidemiology, Dalhousie University.
  • Associate Editor, BMC Medical Research Methodology

Selected awards and honours

  • SickKids Foundation Duncan L. Gordon Fellowship
  • Canadian Institute of Health Research Fellowship
  • Petro-Canada Scholarship Fund, Canadian Olympic Association
  • Royal Bank Academic All-Canadian, Canadian Intercollegiate Athletic Union