Social norms interventions to change clinical behaviour in health workers: a systematic review and meta-analysis
Authors: Cotterill Sarah , Tang Mei Yee , Powell Rachael , Howarth Elizabeth , McGowan Laura , Roberts Jane , Brown Benjamin , Rhodes Sarah 
Published: November 2020

Background
A social norms intervention seeks to change the clinical behaviour of a target health worker by exposing them to the values, beliefs, attitudes or behaviours of a reference group or person. These low-cost interventions can be used to encourage health workers to follow recommended professional practice.

Objective
To summarise evidence on whether or not social norms interventions are effective in encouraging health worker behaviour change, and to identify the most effective social norms interventions.

Design
A systematic review and meta-analysis of randomised controlled trials.

Data sources
The following databases were searched on 24 July 2018: Ovid MEDLINE (1946 to week 2 July 2018), EMBASE (1974 to 3 July 2018), Cumulative Index to Nursing and Allied Health Literature (1937 to July 2018), British Nursing Index (2008 to July 2018), ISI Web of Science (1900 to present), PsycINFO (1806 to week 3 July 2018) and Cochrane trials (up to July 2018).

Participants
Health workers took part in the study.

Interventions
Behaviour change interventions based on social norms.

Outcome measures
Health worker clinical behaviour, for example prescribing (primary outcome), and patient health outcomes, for example blood test results (secondary), converted into a standardised mean difference.

Methods
Titles and abstracts were reviewed against the inclusion criteria to exclude any that were clearly ineligible. Two reviewers independently screened the remaining full texts to identify relevant papers. Two reviewers extracted data independently, coded for behaviour change techniques and assessed quality using the Cochrane risk-of-bias tool. We performed a meta-analysis and presented forest plots, stratified by behaviour change technique. Sources of variation were explored using metaregression and network meta-analysis.

Results
A total of 4428 abstracts were screened, 477 full texts were screened and findings were based on 106 studies. Most studies were in primary care or hospitals, targeting prescribing, ordering of tests and communication with patients. The interventions included social comparison (in which information is given on how peers behave) and credible source (which refers to communication from a well-respected person in support of the behaviour). Combined data suggested that interventions that included social norms components were associated with an improvement in health worker behaviour of 0.08 standardised mean differences (95% confidence interval 0.07 to 0.10 standardised mean differences) (n = 100 comparisons), and an improvement in patient outcomes of 0.17 standardised mean differences (95% confidence interval 0.14 to 0.20) (n = 14), on average. Heterogeneity was high, with an overall I
2 of 85.4% (primary) and 91.5% (secondary). Network meta-analysis suggested that three types of social norms intervention were most effective, on average, compared with control: credible source (0.30 standardised mean differences, 95% confidence interval 0.13 to 0.47); social comparison combined with social reward (0.39 standardised mean differences, 95% confidence interval 0.15 to 0.64); and social comparison combined with prompts and cues (0.33 standardised mean differences, 95% confidence interval 0.22 to 0.44).

Limitations
The large number of studies prevented us from requesting additional information from authors. The trials varied in design, context and setting, and we combined different types of outcome to provide an overall summary of evidence, resulting in a very heterogeneous review.

Conclusions
Social norms interventions are an effective method of changing clinical behaviour in a variety of health service contexts. Although the overall result was modest and very variable, there is the potential for social norms interventions to be scaled up to target the behaviour of a large population of health workers and resulting patient outcomes.

Future work
Development of optimised credible source and social comparison behaviour change interventions, including qualitative research on acceptability and feasibility.

Study registration
This study is registered as PROSPERO CRD42016045718.

Funding
This project was funded by the National Institute for Health Research (NIHR) Health Services and Delivery Research programme and will be published in full in Health Services and Delivery Research; Vol. 8, No. 41. See the NIHR Journals Library website for further project information.