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Open Access Research article

Determinants of generic drug substitution in Switzerland

Anne Decollogny1*, Yves Eggli1, Patricia Halfon2 and Thomas M Lufkin3

Author Affiliations

1 Institute of Health Economics and Management, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Route de Chavannes 31, 1015 Lausanne, Switzerland

2 Institute of Social and Preventive Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Rue du Bugnon 17, 1005 Lausanne, Switzerland

3 Institute of Health Economics and Management, Faculty of Business and Economics, University of Lausanne, Route de Chavannes 31, 1015 Lausanne, Switzerland

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BMC Health Services Research 2011, 11:17  doi:10.1186/1472-6963-11-17

Published: 26 January 2011

Abstract

Background

Since generic drugs have the same therapeutic effect as the original formulation but at generally lower costs, their use should be more heavily promoted. However, a considerable number of barriers to their wider use have been observed in many countries. The present study examines the influence of patients, physicians and certain characteristics of the generics' market on generic substitution in Switzerland.

Methods

We used reimbursement claims' data submitted to a large health insurer by insured individuals living in one of Switzerland's three linguistic regions during 2003. All dispensed drugs studied here were substitutable. The outcome (use of a generic or not) was modelled by logistic regression, adjusted for patients' characteristics (gender, age, treatment complexity, substitution groups) and with several variables describing reimbursement incentives (deductible, co-payments) and the generics' market (prices, packaging, co-branded original, number of available generics, etc.).

Results

The overall generics' substitution rate for 173,212 dispensed prescriptions was 31%, though this varied considerably across cantons. Poor health status (older patients, complex treatments) was associated with lower generic use. Higher rates were associated with higher out-of-pocket costs, greater price differences between the original and the generic, and with the number of generics on the market, while reformulation and repackaging were associated with lower rates. The substitution rate was 13% lower among hospital physicians. The adoption of the prescribing practices of the canton with the highest substitution rate would increase substitution in other cantons to as much as 26%.

Conclusions

Patient health status explained a part of the reluctance to substitute an original formulation by a generic. Economic incentives were efficient, but with a moderate global effect. The huge interregional differences indicated that prescribing behaviours and beliefs are probably the main determinant of generic substitution.