Title:	Randomised controlled trial of efficacy of a family based programme to increase physical activity among individuals at high risk of diabetes: ProActive Follow-up Study
Principal research question:	What is the long-term efficacy of an intervention to promote physical activity using an objective measure of activity, factors associated with successful maintenance, and consequences (including self rated health and objectively measured future disease risk)? What are the psychological predictors of behaviour change and maintenance. How can self-rated health inform the targets for future intervention?
Methodology description:	We plan to contact, where possible, all 365 participants to invite them to attend for a health assessment five years post-randomisation. Original recruitment and retention of trial volunteers was very high, with 74% of those approached agreeing to take part, and 88% of participants completing the follow-up assessment at one year, and we hope to maintain this high level of participant involvement. The follow-up study will allow a trial analysis of long term effects of the intervention on behaviour and self-reported health and objectively measured risk factors, but also allow tracking of physical activity levels over time in a well-characterised cohort who are at risk of the consequences of a sedentary lifestyle.A qualitative aspect to the study will consist of two sets of interviews, conducted with respondents sampled according to their physical activity responses in the original trial. The initial structured interview, conducted when they come to Addenbrooke’s Hospital, is intended to explore what participants mean when they complete some of the questionnaire items used in the study; in particular those questions that ask them to evaluate their health status and well-being. In contrast, the later second semi- interview will be less structured, and conducted in the homes of participants. It is designed to explore a range of themes in depth, including personal factors that people regard as relevant to their levels of activity, their understanding of being identified as at risk of developing diabetes, and their reflections on participating in the study itself. All interviews will be recorded, transcribed and imported into NVivo, which will incorporate a limited dataset from the main study. Emerging themes will then be compared across the sample cohorts.
Sample group description:	Participants randomised into the original ProActive trial between 2001 and 2003, then aged 30-50 years, with a sedentary lifestyle and parental history of type 2 diabetes.
Outcome measure description:	The primary outcome will be physical activity energy expenditure (PAEE) using heart rate monitoring with individual calibration for the heart rate-energy expenditure relationship. Oxygen uptake (ml O2/kg/body weight) will be measured by indirect calorimetry during a sub-maximal graded treadmill exercise test. Maximal cardio-respiratory fitness (VO2max) will be estimated using predicted maximal heart rate (i.e. 220 minus age). PAEE will be individually calculated from heart rate monitoring as average energy expenditure minus resting energy expenditure. Time (% of monitored time per day) spent above 1.75 resting heart rate will be individually calculated as an indicator of moderate intensity physical activity. We will also assess activity using an accelerometer (MTI Actigraph). Self-reported physical activity will be measured by the EPAQ2 questionnaire covering work, recreation and domestic activity over the previous month and year.
UK ISRCT Number:	61323766
Project organisation
Start date:	2nd October 2006
End date:	31st December 2009
Contact person:	Dr Kate Williams
Contact Details:	Primary Care Research Unit Institute of Public Health University Forvie Site, Robinson Way Cambridge Cambs CB2 0SR UK Telephone: (01223) 330332 Fax: 01223 762515 E-mail: kmw36@medschl.cam.ac.uk
Funding information
Funding Organisation:	NIHR School for Primary Care Research
Funding Reference:	12
Funding Amount:	£366,410
References and Publications