Abstract
Crestor, an important but controversial cholesterol-lowering drug, is contraindicated for use by senior and Asian patients. In this paper, we exploit this fact along with unique physician-level prescription and detailing data for statin drugs to examine the hypothesis that detailing is informative. Our tests are based on a simple model in which detailing impacts physicians’ expected match utility of Crestor for different types of patients. We find strong evidence for the informative-detailing hypothesis: relative to the other patients, detailing significantly reduces physicians’ likelihood of prescribing Crestor to contraindicated patients. Our results are robust to detailing being correlated with physician-specific unobserved factors and/or differential trends in individual physicians’ attitudes toward Crestor.
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Notes
From The Lancet (2003).
See also Chan and Hamilton (2006) for a similar approach to patient learning in drug trials.
There is only the before period for physicians who had not been detailed by the end of the two years that our data cover.
Zocor lost patent protection in 2006, and its active ingredient simvastatin is now available in generic versions.
Source: https://www.accessdata.fda.gov/drugsatfda_docs/label/2003/21366_crestor_lbl.pdf, page 3, Section “Special Populations”.
Source: https://www.accessdata.fda.gov/drugsatfda_docs/label/2005/21366slr005lbl.pdf, page 3, Section “Special Populations”.
See the warning on patients disposed for myopathy in FDA’s approval package from Aug 2003.
The data are obtained from a pharmaceutical consulting firm, which also provided a similar dataset to a marketing study by Narayanan and Manchanda (2009). The data include more physicians with higher prescription volumes relative to the whole U.S. population of physicians. As will become clear later, the oversampling of high-volume prescribers makes it harder to detect informative detailing.
There are four dosage forms for Crestor: 5mg, 10mg, 20mg and 40mg. 5mg are considered low dosage, 10mg normal dosage and the 20mg and 40mg high dosages.
The overall impact of detailing on the prescription of Crestor to senior and Asian patients is measured by the sum of the coefficients of “After” and “After*Senior” and the sum of the coefficients of “After” and “After*Asian” respectively.
Hawthorne effects may exist simply because the panel of physicians in our data report information on their prescriptions and detailing to our data provider. However, with our focus on the interaction effects of detailing and contraindications (as opposed to the main effect of detailing), the Hawthorne effect seems unlikely to be the driver of our findings. Moreover, pharmaceutical companies regularly observe physicians’ prescriptions through data obtained from ‘Health Information Organizations’. As a result, physicians have always been under observation and, thus, are less likely subject to Hawthorne effects.
Note that we refer to senior patients of Asian descent as “senior Asian patients” in this paper.
We thank one of the referees for pointing out the issue.
The instrumental-variable (IV) approach could also be applied, in principle, to deal with the endogeneity problem here. For example, the one-year lagged competitors’ detailing intensity on the same calendar day could be an IV for the current competitors’ detailing intensity. We, however, cannot take the approach here because it would require data from 2002, which are not included in our data. In addition, it seems also challenging to find an instrument for the variable “After” within our data.
As we noted earlier, our data include more physicians with higher prescription volumes relative to the whole U.S. population of physicians. The findings here also imply that the oversampling of high-volume prescribers makes it harder to detect informative detailing.
Source: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=202.1, part (d) (5) ii in Section 202.1 “Prescription-drug advertisements”.
This may partly explain the industry’s increasing reliance on detailers for promotions.
Related to this argument, Gentzkow and Shapiro (2006) shows that media companies, which care about the reputation of their news quality, are less biased when there is more competition.
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We thank Daniel Sgroi, Brad Shapiro, Michelle Sovinsky and Juanjuan Zhang for comments on previous drafts.
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Huang, G., Shum, M. & Tan, W. Is pharmaceutical detailing informative? Evidence from contraindicated drug prescriptions. Quant Mark Econ 17, 135–160 (2019). https://doi.org/10.1007/s11129-018-9206-4
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DOI: https://doi.org/10.1007/s11129-018-9206-4