The impact of drug samples on prescribing to the uninsured

To determine whether drug samples are associated with physicians prescribing fewer generic, less costly medications.

We conducted a retrospective study at a large university-affiliated internal medicine practice containing over 70 physicians. Using a pharmacy database, we identified all prescriptions written to uninsured or Medicaid patients that belonged to one of four classes of chronic medications. For the 9 months before and after the clinic closed its drug sample closet, we calculated the percentage of medications prescribed as generics and the mean cost of a 30-day supply of a prescription.

Of 8911 prescriptions, 1973 met inclusion criteria. For uninsured patients, the percentage of medications prescribed as generics rose from 12% to 30% after the clinic closed its drug sample closet (P = 0.004). By consecutive three month periods, the percentage of prescribed generic medications rose steadily to a maximum of 40% (P < 0.001). For Medicaid patients, there was no significant change in generic prescribing (63% generic with samples versus 65% generic without samples, P = 0.42). Two factors were associated with generic prescribing in logistic regression: the absence of drug samples (OR 4.54, 95% CI 1.37-15.0) and the prescriber being an attending physician (OR 5.26, 95% CI 2.24-12.4). There was no statistically significant change in cost for either group.

Physicians were three times more likely to prescribe generic medications to uninsured patients after drug samples were removed from the office. Drug samples may paradoxically lead to higher costs if physicians with access to samples prescribe more brand-name only drugs.