Life-expectancy gains from pharmaceutical drugs: a critical appraisal of the literature

Abstract

Objectives: Several studies suggest that, on the basis of life-expectancy regressions, pharmaceutical drugs are responsible for much of the marked gains in life expectancy observed over the last 50 years. In this article, we critically appraise these studies. Methods: We point out several modeling issues: identification of the contribution of new drugs from advances in disease management, changes in the distribution of healthcare and other confounding factors. Results: We suggest that some models produce estimates of pharmaceutical productivity that are implausibly high. Other models have very large forecast errors. Finally, the models that we replicated were found to be sensitive to seemingly innocuous changes in specification. Conclusion: It is difficult to estimate the biomedical determinants of life expectancy using aggregate data. Analyses using individual level data or perhaps disease-specific data will probably produce more compelling results.

Keywords::

• aggregate data
• health outcome
• infant mortality
• life expectancy
• pharmaceutical expenditure
• sensitivity analysis

Financial & competing interests disclosure

Paul Grootendorst acknowledges support from the Premier’s Research Excellence Award and the research program into the Social and Economic Dimensions of an Aging Population centered at McMaster University that is primarily funded by the Social Sciences and Humanities Research Council of Canada (SSHRC) and which has received additional support from Statistics Canada. Grootendorst thanks Marie Dean and seminar participants at the University of Toronto, University of Waterloo, the Toronto Health Economics Network, the 2006 meeting of the Canadian Association for Health Services and Policy Research, and the 2007 International Health Economics Association meetings for helpful comments on an earlier version of this manuscript. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Ethical conduct of research

The authors state that they have obtained appropriate institutional review board approval or have followed the principles outlined in the Declaration of Helsinki for all human or animal experimental investigations. In addition, for investigations involving human subjects, informed consent has been obtained from the participants involved.

Notes

t-statistics appear in parentheses.

NME: New molecular entities.

Data from [6].