Table 2

Characteristics of included communication trials

TrialNumber randomisedDisease/conditionParticipantsSettingIntervention(s)ControlOutcome retention trialTime point used in analysis
Enhanced letter vs standard letter
Renfroe 2002 (c)664Treatment of ventricular tachycardia (VT) ventricular fibrillation (VF)Adults cardioverted from VT or resuscitated from VFUS hospitalCover letter signed by physicianCover letter signed by coordinatorPostal questionnaire responseOverall response
Marson 20071815Treatment of epilepsyAdults with epilepsyUK hospital outpatient departmentsLetter explaining the approximate time needed to complete the questionnaireStandard letterPostal questionnaire responseOverall response
Total design postal method for postal questionnaires vs customary method
Sutherland 1996226Prevention of breast cancerWomen with 50% breast volume dysplasiaCanada hospital clinicTotal design method for postal follow-upCustomary method for postal follow-upPostal questionnaire responseResponse at day 70
Priority vs regular post
Renfroe 2002 (b)664Treatment of ventricular tachycardia (VT) ventricular fibrillation (VF)Adults cardioverted from VT or resuscitated from VFUS hospitalOvernight questionnaire deliveryStandard questionnaire deliveryPostal questionnaire responseOverall response number of questionnaires returned
Sharp 2006 (e)233Screening of cervical cancerWomen with low-grade abnormal cervical smearUK primary careFirst class outward postSecond class outward postPostal questionnaire responseOverall response
Sharp 2006 (f)231Screening of cervical cancerWomen with low-grade abnormal cervical smearUK primary careFirst class outward postSecond class outward postPostal questionnaire responseOverall response
Sharp 2006 (g)240Screening of cervical cancerWomen with low-grade abnormal cervical smearUK primary careStamped reply envelopeBusiness reply envelopePostal questionnaire responseOverall response
Sharp 2006 (h)223Screening of cervical cancerWomen with low-grade abnormal cervical smearUK primary careStamped reply envelopeBusiness reply envelopePostal questionnaire responseOverall response
Kenton 2007 (c)149Screening of postnatal depressionWomen postpartum at high risk of postnatal depressionCanada communityPriority outward mailRegular outward mailPostal questionnaire responseOverall response
Kenton 2007 (d)148Screening of postnatal depressionWomen postpartum at high risk of postnatal depressionCanada communityPriority outward mailRegular outward mailPostal questionnaire responseOverall response
Additional reminder vs usual follow-up procedures
Ashby 2011148Prevention of migraineAdults with a history of two migraine attacksUK communityElectronic reminder (email and/or SMS text)No electronic reminderPostal questionnaire responseResponse at 40 days
Maclennan unpublished753Prevention of fractureAdults with a history of osteoporotic fractureUK hospitalTelephone reminder (before receiving first reminder)No telephone reminderPostal questionnaire responseOverall response response rate
Nakash unpublished298Treatment of ankle injuryAdults with acute severe ankle sprainUK accident and emergency departmentsTrial calendar with questionnaire due datesNo calendarPostal questionnaire response at 4, 12 weeks, and 9 monthsResponse at 4 weeks
Severi 2011 (1)1950Treatment of smoking dependenceAdult smokers willing to quit in Txt2stopUK communityText message and fridge magnet emphasising social benefits of study participationText message 3 days after questionnaire sent reminding questionnaire is duePostal questionnaire responseResponse at 30 weeks from randomisation
Severi 2011 (2)127Treatment of smoking dependenceAdult smokers willing to quit in Txt2stopUK communityTelephone reminder from principal investigator that participant is 6 weeks overdue returning their specimenStandard text and no phone call from principle investigatorReturn of cotinine samplesCompleted cotinine sample follow-up for Txt2stop at end of May 2009
Man 2011125Treatment of back painAdults with back painUK primary careSMS text reminder message as follow-up questionnaire sent outNo SMS text messagePostal questionnaire responseOverall response rate
Monthly reminder of upcoming assessment to site vs usual reminders
Land 2007429Treatment of breast cancerWomen with ductal carcinoma in situHospital sites USA, Canada, Puerto RicoProspective monthly reminder of upcoming assessments to sitesNo extra reminders to sitesPostal questionnaire responseOverall response rate
Early vs late administartion of questionnaire
Renfroe 2002 (d)664Treatment of ventricular tachycardia (VT) ventricular fibrillation (VF)Adults cardioverted from VT or resuscitated from VFUS hospitalQuestionnaire sent 2–3 weeks after last AVID follow-up visitQuestionnaire sent 1-4 months after last AVID follow-up visitPostal questionnaire responseOverall response number of questionnaires returned
Recorded delivery vs telephone reminder
Tai 1997192Clinical management of asthma and diabetesAdults with asthma or diabetesUK primary careRecorded delivery reminderTelephone reminderPostal questionnaire responseOverall response number of questionnaires returned
Telephone interview vs questionnaire and monetary incentive
Couper 2007700Weight managementAdults with BMI >25US community web basedTelephone interview by trained interviewerPostal questionnaires with $5 billPost and telephone questionnaire responseResponse at 6 months