Objectives: To examine and explain variations in prescribing costs associated with nursing home patients and patients matched by age and sex living in the community.
Design: A 12-month case control study.
Subjects: All nursing home residents over 65-years-old registered with nine general practices and patients matched with them for age and sex living in the community.
Method: Multivariate regression analysis of variations in monthly GP prescribing costs.
Results: Multivariate regression models explaining cost variations in terms of the GP practice delivering care and patients' age and sex had little explanatory power (R(2)=0.07 for nursing home patients, R(2)=0.03 for matched pairs). A fuller model for nursing home patients only, incorporating the patient's Barthel score and initial diagnosis as additional explanatory variables, added little to the explanatory power of the model (R(2)=0.16).
Conclusion: The ability of the multivariate models used here to explain variations in prescribing costs among a group of elderly patients is poor. Adjusting weighted capitation formulae with respect to older patients to take account of such information or referring to it in negotiations on prescribing budgets would not appear to be warranted.