Impact of US Drug Advertising on Canadian Prescribing
Author Information
Author(s): Michael R Law, Sumit R Majumdar, Stephen B Soumerai
Primary Institution: Harvard Medical School and Harvard Pilgrim Health Care
Hypothesis
US direct to consumer advertising campaigns would increase use of marketed drugs in English speaking Canadian provinces.
Conclusion
US direct to consumer advertising transiently influenced Canadian prescribing rates for tegaserod, a drug later withdrawn due to safety concerns.
Supporting Evidence
- US direct to consumer advertising spending ranged from $194m to $314m.
- Tegaserod prescriptions increased by 42% immediately after US advertising.
- Prescription rates for etanercept and mometasone did not increase after advertising.
Takeaway
The study looked at how US drug ads affected Canadian prescriptions. It found that one drug's use went up for a short time after the ads, but then it went back down.
Methodology
Controlled quasi-experimental study using interrupted time series analysis.
Potential Biases
Potential selection bias due to differences in drug characteristics and advertising exposure.
Limitations
Generalizing beyond the three drugs studied is difficult, and there may be confounding factors affecting results.
Participant Demographics
Representative sample of Canadian pharmacies and US Medicaid programmes.
Statistical Information
P-Value
<0.001
Confidence Interval
0.37 to 0.76
Statistical Significance
p<0.001
Digital Object Identifier (DOI)
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