Table 3

Summary of quality assessments—controlled trials*

StudyDescribed as RCTAdequate randomisationAllocation concealmentDouble-blind group assignmentBlind outcome assessmentGroups balanced on characteristicsDropout ≤20%Differential dropout ≤15%High protocol adherenceOther interventions avoidedOutcomes: valid, reliable and consistentSufficient sample sizeOutcomes and subgroups prespecifiedIntention to treatQuality rating—quantitative outcomes†
Cook et al, 201041 NNANAN?YYY??Y??YPOOR
Donovan et al, 200349 YYYN??YYYYYYYYGOOD
Eccles et al, 201334 YYYNN?YYYYYNYYFAIR
Ford et al, 200451 Y??NN?N??YYYYNFAIR
  • *Quality assessment checklists adapted from Study Quality Assessment Tools: National Heart, Lung, and Blood Institute (available from:

  • †Quality rated as good, fair or poor with respect to the quantitative recruitment-related outcomes of interest in this systematic review.

  • ?, not reported/unable to determine; N, no; NA, not applicable; RCT, randomised controlled trial; Y, yes.