How widespread is working at scale in English general practice?

Background Over the last five years, national policy has encouraged practices to serve populations of >30,000 people (called ‘working at scale’), by collaborating with other practices.
Aim To describe the number of English general practices working at scale, and their patient populations.
Design and setting Observational study of general practices in England
Methods We supplemented data published by the National Health Service on practices’ self-reports of working in groups with data from reports by various organisations and websites of practice groups. We categorised practices by the extent to which they were working at scale, and examined age distribution of practice population, level of socioeconomic deprivation, rurality and prevalence of longstanding illness by these categories.
Results About 55% English practices (serving 33 million patients) were working at scale, individually or collectively serving populations of >30,000 people. Organisational models representing close collaboration for the purposes of core general practice services were identifiable for ~5% of practices; these were: large practices; superpartnerships; and multisite organisations. About 50% of practices were working in looser forms of collaboration focusing on services beyond core general practice, e.g. primary care in the evenings and weekends. Data on organisational models and purpose of the collaboration were very limited for this group.
Conclusions In early 2018, <5% of general practices were working closely at scale; about half of practices were working more loosely at scale. Data were, however, incomplete. Understanding what is happening at practice level is needed so that we can evaluate benefits and harms.