The authors reported that a number of interventions can help improve childhood immunisation rates in developed countries. These included reminding parents and providers of upcoming and overdue immunisations and educating and providing feedback to the vaccination providers. Concerns about study quality, reporting of the review and the synthesis mean that the conclusions may not be sufficiently cautious and reliable.

To evaluate strategies to optimise immunisation uptake within preschool children in developed countries.

MEDLINE, EMBASE, PsycINFO, The Cochrane Library and OpenSIGLE were searched up to June 2010. Search terms were reported. Reference lists of retrieved studies and reviews were consulted and experts were contacted to identify additional studies. Conference papers, dissertations and government guidelines were consulted for further studies. Only studies in English were included.

Experimental studies of interventions to optimise immunisation uptake in children under five years in developed countries were eligible for inclusion. The main outcome of interest was increase in the proportion of the target population who were up to date with standard recommended universal vaccinations.

Study participants were between six weeks and 11 years old and most studies focused on preschool children. Interventions were delivered in various primary care settings. About one in eight studies were conducted in the UK. Where reported, most studies were conducted before 2000.

Two reviewers independently selected studies for inclusion. Disagreements were resolved through discussion or with a third reviewer.

Quality was graded independently by two reviewers using a scale with a maximum of 31 points. The assessment covered reporting quality, internal and external validity.

Data on the main outcome (including p-values and 95% confidence intervals, where reported) were extracted independently by two reviewers.

Results were presented narratively and were stratified by type of intervention.

Forty-six papers were included: 26 randomised controlled trials (RCTs), nine were classed as controlled intervention trials and 11 were before-and-after studies. Quality scores ranged from 17.5 to 29.5 out of 31.

Parental reminders and recall studies (22 studies) showed a statistically significant increase in immunisation rates in 34% of included intervention arms (median 11%, mean 10%, range -11% to 24%). These effects were reported with both generic and specific reminders and with all methods of reminders and recall. There was no significant effect of parental education programmes (two studies) and the use of a parent-held record booklet (one study) on immunisation rates.

Strategies aimed at immunisation providers were shown to improve immunisation rates with a median change in immunisation rates of 7% (mean 10%, range -2% to 33%; five studies) when reminders were used, 8% (mean 10%, range 1% to 25%; four studies) when educational programmes were used and 19% (mean 17%, range 12 to 19%; four studies) when feedback programmes were used.

Three of eight intervention arms of multicomponent programmes reported a statistically significant difference in immunisation rate.

There are a number of interventions that can help improve childhood immunisation rates in developed countries. These include reminding parents and providers of upcoming and overdue immunisations and educating and providing feedback to the vaccination providers.

The review question and selection criteria were broad but clearly stated. Several sources were consulted when conducting the literature searches. Language restrictions were applied. Steps were taken to minimise reviewer error and bias throughout the stages of the review.

Results of the quality assessment were reported and a significant proportion of the studies were not randomised and several were also not controlled. A meta-analysis could not be performed. The choice of a narrative synthesis was based on the diversity of settings, service and intervention delivery and study quality and appeared generally appropriate. Sample sizes were often not reported and this made interpretation of the results difficult. Where reported, only a limited number of studies reported a statistically significant effect in favour of interventions.

Concerns about study quality, reporting of the review and the synthesis mean that the conclusions may not be sufficiently cautious and reliable.

Practice: The authors stated that health planners and professionals must engage actively with parents and the public and invest in process measures that ensure children receive primary prevention.

Research: The authors stated that research was needed to test the cost-effectiveness of reminders for parents, education and feedback to vaccination providers and the impact of interventions on groups with poor immunisation rates or high risks of complications from vaccine-preventable diseases.

National Institute for Health Research, UK; Centre for Patient Safety and Service Quality, Imperial College, UK.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.