Scale, Skill-Mix, and Access Implications of the Production of Appointments by Primary Care Practices in England.

Primary medical care has traditionally been provided by small organisations. Recent policy developments in many countries have encouraged larger practices in the hope of benefiting from increasing returns to scale, but there is little research evidence to support this. Using monthly data from 6149 primary care practices in England between August 2022 and July 2024, we applied a Generalized Linear Model with a logarithmic link and Poisson distribution to examine the relationship between staffing levels and appointment volumes. At the median level of administrative staffing, the estimated marginal productivity of doctors and other clinical staff on total appointments are 223 and 152 per month, respectively. The marginal effects of all types of staff on appointment volumes increase with staffing levels. We plot the isoquant and isocost curves at the median level of production and examine the implications of our findings for skill-mix and patient access. The current ratios of doctors to other clinical staff and nurses to Direct Patient Care (DPC) staff are lower than cost optimal, though this is less of an issue for larger practices who benefit more from DPC roles. Additional clinical staff improve patient access more when employed in larger practices.