Table 1 Inclusion criteria details

Population

UK adults. Operationally defined as where at least 50% of participants were aged 18 or over during exposure to peer pressure, and where at least 50% of participants were situated within the UK during exposure to peer pressure.

Exposure

Studies which ‘substantially’ explored the effect of peer pressure. Studies were eligible for inclusion if they stated either a specific research question on the role of peer pressure, or provided a specific conclusion on the role of peer pressure. We adopted the definition of peer pressure by Sim & Koh (2003) ‘Peer pressure is broadly defined as any attempt by one or more peers to compel an individual to follow in the decisions or behaviours favoured by the pressuring individual or group.’

Outcome

Alcohol consumption, drinking related behaviours (e.g. drink-driving, drinking games, pre-partying, purchasing alcohol), values or perceptions towards drinking.

Study type

Any primary study using a qualitative study design. Mixed method primary studies were eligible for inclusion as long as findings from qualitative methodology could be extracted separately.