Generic dispensing rates for substitutable drugs prescribed by general practitioners compared with other private ambulatory specialists: A study based on a French national reimbursement database.

Background: The use of generic drugs is a way for healthcare systems to reduce costs, particularly in ambulatory care. Several studies suggest that the prescriber's speciality is associated with the use of generic drugs, and that substitutable drugs prescribed by General Practitioners (GPs) are more often generic, but this association has never been studied in France. In the French legislative context, except in rare situations, all substitutable drugs prescribed should be dispensed in generic form.

Objectives: Compare the generic drugs dispensing rate among substitutable drugs dispensed in community pharmacies prescribed by French private GPs with that of other private specialists, all other specialities combined (first objective) or each other speciality taken individually (second objective).

Methods: We used a sample of an open available semi-aggregated database from the 2019 French health insurance system database. We compared with logistic regression models GPs to all other specialities combined, then GPs to the 19 other specialties taken individually, only on the substitutable drugs they prescribe in common.

Results: In 2019, 53.4% of the drugs prescribed by French private ambulatory physicians were substitutable drugs, and 81.5% of them were dispensed in generic form. After adjustment, the generic dispensing rate for substitutable drugs was significantly higher for GPs than for other specialties (ORa 0.74 [IC95% 0.72-0.76]). Thirteen of the nineteen other specialities taken individually, such as endocrinologists (ORa 0.64 [IC95% 0.57-0.72]) and cardiologists (ORa 0.60 [0.56-0.63]) had significantly lower generic dispensing rates than GPs. No other speciality had a rate significantly higher than GPs.

Conclusions: Substitutable drugs prescribed by French private GPs are more often dispensed in generic form than those from other private ambulatory specialties. To understand this result and optimise the use of generic drugs in outpatient settings, we need to study the different stages of drug use, from prescription by the physician to dispensing by the pharmacist and acceptance by the patient.