Proton pump inhibitors prescribing following the introduction of generic drugs

Abstract

Background: In many countries, the introduction of generic proton pump inhibitors (PPIs) onto the pharmaceutical market increased the phenomenon of therapeutic substitution in acid-related disorders (ARDs).

Aim: To investigate the treatment of ARDs in an Italian primary care setting from 2005 to 2008 by verifying: (i) dynamics of PPI prescribing; (ii) predictors of PPI switching; and (iii) healthcare resource consumption costs.

Methods: This was a retrospective cohort study of 102 general practitioners (GPs) who managed an average of 150000 inhabitants in Naples. Multilevel logistic regression was used to assess the potential predictors of both PPI switching and termination. Primary care costs were expressed as the cost of ARD management per PPI user year.

Results: The percentage of PPI users with ARD increased from 5·5% (2005) to 7·0% (2008) (P<0·0001), especially for dyspepsia (from 9·5% to 13·7%; P<0·0001) and chronic treatments (from 23·4% to 29·4%; P<0·0001). PPI switching rose from 13·0% to 16·7% during the period observed (P<0·0001). Calendar years, long-term treatments and gastroesophageal reflux disease were positive predictors of PPI switching. Primary care costs relating to PPI switchers increased by 61·14€ compared with nonswitchers (P<0·0001).

Conclusions: The introduction of generic PPIs onto the Italian market was associated with an increasing amount of PPI prescribing related to chronic treatments, unlicensed indications (e.g. dyspespsia) and therapeutic substitutions. Growing overall costs linked to the phenomenon of PPI switching was also found. Our data support the need to assess the effects of the introduction of generic drugs on both clinical outcomes and the cost management of ARDs.