Impact of vertical integration on patients' use of hospital services in England: an analysis of activity data.

Background: Debate surrounding the organisation and sustainability of primary care in England highlights the desirability of a more integrated approach to patient care across all settings. One such approach is 'vertical integration', where a provider of specialist care, such as a hospital, also runs general practices.

Aim: To quantify the impact of vertical integration on hospital use in England.

Design & setting: Analysis of activity data for NHS hospitals in England between April 2013 and February 2020.

Method: Analysis of NHS England data on hospital activity, which looked at the following seven outcome measures: accident and emergency (A&E) department attendances; outpatient attendances; total inpatient admissions; inpatient admissions for ambulatory care sensitive conditions; emergency admissions; emergency readmissions; and length of stay. Rates of hospital use by patients of vertically integrated practices and controls were compared, before and after the former were vertically integrated.

Results: In the 2 years after a GP practice changes, for the population registered at that practice, compared with controls, vertical integration is associated with modest reductions in rates of A&E attendances (2% reduction [incidence rate ratio {IRR} 0.98, 95% confidence interval {CI} = 0.96 to 0.99, P<0.0001]), outpatient attendances (1% reduction [IRR 0.99, 95% CI = 0.99 to 1.00, P = 0.0061]), emergency inpatient admissions (3% reduction [IRR 0.97, 95% CI = 0.95 to 0.99, P = 0.0062]), and emergency readmissions within 30 days (5% reduction [IRR 0.95, 95% CI = 0.91 to 1.00, P = 0.039]), with no impact on length of stay, overall inpatient admissions, or inpatient admissions for ambulatory care sensitive conditions.

Conclusion: Vertical integration is associated with modest reductions in use of some hospital services and no change in others.