conducted on 21 February 2011 using the following keywords: (telephone OR phone OR mobile OR cellphone) AND (outpatient OR out-patient) AND (attendance OR appointment OR reminder) Only papers published in 2000 or later, in English or any of the Scandinavian languages (Danish, Swedish or Norwegian) were included. In addition we examined the reference lists of the papers selected for review. Duplicates were then eliminated. These were screened for relevance, i.e. to conﬁrm that they reported reminders using phones or SMS, leaving papers for full-text eligibility assessment. Papers were eliminated from the study if they provided insufﬁcient data about change in attendance or did not describe reminders for a particular appointment, but general adherence to long-term programmes. Data analysis All papers were analysed by both authors independently. Any disagreements in interpretation were resolved by consensus. Four of the selected papers described multi-arm studies in which reminders were sent both by phone and by SMS, or by phone and by automated phone calls to separate groups. In these cases we used data from both arms of the study as though they were independent studies. The outcome variable of interest was the Did Not Attend (DNA) rate. When a paper reported that a reminder was sent ‘within a week before the appointment’ the reminder time was assumed to be 3.5 days. Study quality A compound quality indicator was created for weighting the results according to the following indices: (1) Study size (0 ¼ not stated; 1 ¼ 1 – 100; 2 ¼ 101 – 1000; 3 ¼ 1001 – 10000; 4 ¼ .10000); (2) Duration of intervention (0 ¼ duration not stated; 1 ¼ 1 – 3 months; 2 ¼ 4 – 12 months; 3 ¼ .12 months); (3) Study design (0 ¼ not stated; 1 ¼ retrospective controls; 2 ¼ before and after, or non-randomized control study; 3 ¼ RCT). Note that in a retrospective trial, the baseline may have been measured in the year before the intervention, i.e. there would have been an interval before the intervention started. In a before and after study, the intervention starts immediately after the baseline has been measured; (4) Cost of intervention (0 ¼ not stated; 1 ¼ estimate of costs; 2 ¼ measurements of costs according to current guidelines for economic evaluation in health care32); (5) Savings from intervention (0 ¼ not stated; 1 ¼ estimate of savings; 2 ¼ measurements of savings according to current guidelines32). Journal of Telemedicine and Telecare Volume 17 Number 7 2011 P E Hasvold and R Wootton Telephone and SMS reminders This gave a possible score for study quality from zero to 14. Similar quality indicators have been used previously by others.33,34 Effect size Two effects were examined: the absolute and the relative change in DNA rate. The absolute change in the DNA rate was calculated as the percentage of DNA in the control group minus the percentage of DNA in the intervention group. The relative change in the DNA rate was calculated by dividing the absolute change by the percentage of DNA in the control group. Pooled estimate of effect size Weighted mean values were calculated using the quality scores as weights. Data extraction In papers reporting the DNA rates only, we did not attempt to contact the authors for clariﬁcation or additional information about their data. We checked the numbers of patients involved and recalculated the rates to four signiﬁcant ﬁgures based on an integer number of patients. We analysed the data on an ‘intention to treat’ basis. We categorised the interventions as manual or automated. Manual reminders were telephone calls made by members of staff. Automated calls were either computer driven voice messages or computer driven SMS text messages. We categorised the ages of the patients as child (neonatal/ paediatric/adolescent) (0 – 17 years), adult (18 – 60 years) or geriatric (.60 years). In some cases the age of the patients was unclear and we assumed it to be adult. Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The search returned 321 records. The reference lists of relevant papers (see below) produced another 99 records. After duplicates were eliminated there were 269 records. These were screened for relevance and the screening eliminated 232 papers, leaving 37 papers for full-text eligibility assessment. Of these, eight papers were eliminated from the study, which left 29 papers for full analysis, see Table 1.3 – 31 Figure 1 shows the PRISMA ﬂowchart of the selection process. Analysis The analysis below is based on data from 29 studies reporting a total of 33 estimates. Eighteen of the interventions were based on manual reminders (i.e. phone calls made by health staff ) and 15 were based on automated 359