title: Carbon cost of pragmatic randomised controlled trials: retrospective analysis of sample of trials.
abstract: OBJECTIVE
  To calculate the global warming potential, in carbon dioxide (CO(2)) equivalent emissions, from a sample of pragmatic randomised controlled trials.
  
  
  METHODS
  Retrospective analysis. Data source Internal data held by NIHR Evaluation, Trials and Studies Coordinating Centre. Studies included All eligible pragmatic randomised controlled trials funded by the NIHR Health Technology Assessment programme during 2002 and 2003.
  
  
  METHODS
  CO(2) equivalents for trial activities calculated with standard conversion factors.
  
  
  RESULTS
  12 pragmatic randomised controlled trials involving more than 4800 participants and a wide range of technologies were included. The average CO(2) emission generated by the trials was 78.4 (range 42.1-112.7) tonnes. This is equivalent to that produced in one year by approximately nine people in the United Kingdom. Commuting to work by the trial team generated the most emissions (average 21 (11.5-35.0) tonnes per trial), followed by study centres' fuel use (18 (9.3-32.2) tonnes per trial), trial team related travel (15 (2.0-29.0) tonnes per trial), and participant related travel (13 (0-46.7) tonnes per trial).
  
  
  CONCLUSIONS
  CO(2) emissions from pragmatic randomised controlled trials are generated in areas where steps could be taken to reduce them. A large proportion of the CO(2) emissions come from travel related to various aspects of a trial. The results of this research are likely to underestimate the total CO(2) emissions associated with the trials studied, because of the sources of information available. Further research is needed to explore the additional CO(2) emissions generated by clinical trials, over and above those generated by routine care. The results from this project will feed into NIHR guidelines that will advise researchers on how to reduce CO(2) emissions.
authors.affiliation: NIHR Evaluation, Trials and Studies Coordinating Centre, University of Southampton, Southampton SO16 7NS. k.lyle@southamtpon.ac.uk
authors.forename: Katy
authors.initials: K
authors.lastname: Lyle
authors.forename: Louise
authors.initials: L
authors.lastname: Dent
authors.forename: Sally
authors.initials: S
authors.lastname: Bailey
authors.forename: Lynn
authors.initials: L
authors.lastname: Kerridge
authors.forename: Ian
authors.initials: I
authors.lastname: Roberts
authors.forename: Ruairidh
authors.initials: R
authors.lastname: Milne
mesh_terms: D000393:Air Pollutants / Q000032:analysis; D020811:Biomedical Technology / Q000706:statistics & numerical data; D002245:Carbon Dioxide / Q000032:analysis*; D017752:Greenhouse Effect; D006801:Humans; D007255:Information Services; D016032:Randomized Controlled Trials as Topic / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D014186:Transportation / Q000706:statistics & numerical data; D014195:Travel / Q000706:statistics & numerical data
chemical_list: D000393:Air Pollutants; D002245:Carbon Dioxide