title: A randomised controlled trial of three very brief interventions for physical activity in primary care.
abstract: Very brief interventions (VBIs) for physical activity are promising, but there is uncertainty about their potential effectiveness and cost. We assessed potential efficacy, feasibility, acceptability, and cost of three VBIs in primary care, in order to select the most promising intervention for evaluation in a subsequent large-scale RCT.
  
  
  
  Three hundred and ninety four adults aged 40-74 years were randomised to a Motivational (n = 83), Pedometer (n = 74), or Combined (n = 80) intervention, delivered immediately after a preventative health check in primary care, or control (Health Check only; n = 157). Potential efficacy was measured as the probability of a positive difference between an intervention arm and the control arm in mean physical activity, measured by accelerometry at 4 weeks.
  
  
  
  For the primary outcome the estimated effect sizes (95 % CI) relative to the Control arm for the Motivational, Pedometer and Combined arms were respectively: +20.3 (-45.0, +85.7), +23.5 (-51.3, +98.3), and -3.1 (-69.3, +63.1) counts per minute. There was a73% probability of a positive effect on physical activity for each of the Motivational and Pedometer VBIs relative to control, but only 46 % for the Combined VBI. Only the Pedometer VBI was deliverable within 5 min. All VBIs were acceptable and low cost.
  
  
  
  Based on the four criteria, the Pedometer VBI was selected for evaluation in a large-scale trial.
  
  
  
  Current Controlled Trials ISRCTN02863077 . Retrospectively registered 05/10/2012.
authors.affiliation: Behavioural Science Group, Institute of Public Health, University of Cambridge, CB2 0SR, Cambridge, UK.|Department of Public Health and Primary Care, University of Cambridge, CB2 0SR, Cambridge, UK.
authors.forename: Sally
authors.initials: S
authors.lastname: Pears
authors.affiliation: Behavioural Science Group, Institute of Public Health, University of Cambridge, CB2 0SR, Cambridge, UK.
authors.forename: Maaike
authors.initials: M
authors.lastname: Bijker
authors.affiliation: Behavioural Science Group, Institute of Public Health, University of Cambridge, CB2 0SR, Cambridge, UK.|PUKCRC Centre for Diet and Activity Research (CEDAR), MRC Epidemiology Unit, University of Cambridge, CB2 0QQ, Cambridge, UK.
authors.forename: Katie
authors.initials: K
authors.lastname: Morton
authors.affiliation: Imperial Clinical Trials Unit, Imperial College London, Stadium House, Wood Lane, W12 7RH, London, UK.
authors.forename: Joana
authors.initials: J
authors.lastname: Vasconcelos
authors.affiliation: Health Services Research Unit, Centre for Population Health Sciences, University of Edinburgh, Teviot Place, EH8 9AG, Edinburgh, UK.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Parker
authors.affiliation: MRC Epidemiology Unit, University of Cambridge, CB2 0QQ, Cambridge, UK.
authors.forename: Kate
authors.initials: K
authors.lastname: Westgate
authors.affiliation: MRC Epidemiology Unit, University of Cambridge, CB2 0QQ, Cambridge, UK.
authors.forename: Soren
authors.initials: S
authors.lastname: Brage
authors.affiliation: Cambridge Centre for Health Services Research, University of Cambridge, CB2 0SR, Cambridge, UK.|Department of Public Health and Primary Care, University of Cambridge, CB2 0SR, Cambridge, UK.
authors.forename: Ed
authors.initials: E
authors.lastname: Wilson
authors.affiliation: Imperial Clinical Trials Unit, Imperial College London, Stadium House, Wood Lane, W12 7RH, London, UK.|Department of Public Health and Primary Care, University of Cambridge, CB2 0SR, Cambridge, UK.
authors.forename: A Toby
authors.initials: AT
authors.lastname: Prevost
authors.affiliation: PUKCRC Centre for Diet and Activity Research (CEDAR), MRC Epidemiology Unit, University of Cambridge, CB2 0QQ, Cambridge, UK.|Department of Public Health and Primary Care, University of Cambridge, CB2 0SR, Cambridge, UK.
authors.forename: Ann-Louise
authors.initials: AL
authors.lastname: Kinmonth
authors.affiliation: PUKCRC Centre for Diet and Activity Research (CEDAR), MRC Epidemiology Unit, University of Cambridge, CB2 0QQ, Cambridge, UK.|Department of Public Health and Primary Care, University of Cambridge, CB2 0SR, Cambridge, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Griffin
authors.affiliation: Behavioural Science Group, Institute of Public Health, University of Cambridge, CB2 0SR, Cambridge, UK.|Department of Public Health and Primary Care, University of Cambridge, CB2 0SR, Cambridge, UK.
authors.forename: Stephen
authors.initials: S
authors.lastname: Sutton
authors.affiliation: Behavioural Science Group, Institute of Public Health, University of Cambridge, CB2 0SR, Cambridge, UK. W.Hardeman@uea.ac.uk.|Department of Public Health and Primary Care, University of Cambridge, CB2 0SR, Cambridge, UK. W.Hardeman@uea.ac.uk.|School of Health Sciences, University of East Anglia, Norwich Research Park, NR4 7TJ, Norwich, UK. W.Hardeman@uea.ac.uk.
authors.forename: Wendy
authors.identifier: 0000-0002-6498-9407
authors.initials: W
authors.lastname: Hardeman
mesh_terms: D056044:Actigraphy; D000328:Adult; D015444:Exercise; D005240:Feasibility Studies; D005260:Female; D015438:Health Behavior; D006293:Health Promotion / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009042:Motivation; D011320:Primary Health Care; D016896:Treatment Outcome
keywords: Behaviour change techniques; Health promotion; Physical activity; Primary care; Public health; Very brief interventions