Is drug choice by general practitioners influenced by exposure to specialists? Record-linkage study in Italy

To investigate whether previous drug prescriptions by, or exposure to, specialists influence general practitioners' prescribing (using the example of inhibitors of the renin-angiotensin system).

Drug prescriptions in GP and specialist care, hospital records and outpatient visits in the Emilia-Romagna region (northern Italy) were linked to assess, among patients who in 2013 had been prescribed Angiotensin Converting Enzyme (ACE)-inhibitors or Angiotensin Receptor Blocker (ARBs) in general practice for the first time, whether those who had been previously prescribed these drugs by specialists (or have been recently exposed to cardiovascular, diabetes or nephrology specialists) were more likely to be prescribed an ARB or a patented ACE-inhibitor/ARB.

A cohort of 88,926 patients was identified of whom 52,666 had not been exposed to specialists. Of these patients, 77.6% were initially prescribed ACE-inhibitors and 87.2% a non-patented drug. Higher prescription of ACE-inhibitors (82.0%) and of non-patented drugs (95.8%) in general practice were observed in the 10,243 the patients who had already been prescribed these drugs by a specialist compared to unexposed patients (p < 0.001 in both cases) and in the 14,648 patients exposed to specialists in the 90 days preceding the first prescription in general practice (79.0% and 89.6%, respectively, p < 0.001 in both cases).

Exposure to specialists was not associated with higher prescription of ARBs and of patented drugs in this Region of Italy. The hypothesis of prescribing induction by specialists is not supported by these data. This kind of analysis can provide help inform local prescribing agreements.