The effect of competing direct-to-consumer advertising campaigns on the use of drugs for benign prostatic hyperplasia: time series analysis.

BACKGROUND

Direct-to-consumer advertising (DTCA) remains a controversial issue, with concerns that it leads to unnecessary and inappropriate prescribing. Whether DTCA shifts prescribing from first-line (guideline-recommended) therapy to second-line drugs has not been studied.

OBJECTIVE

The purpose of this study was to determine the impact of sequential DTCA campaigns for two drugs used to treat benign prostatic hyperplasia (BPH): one newer agent, dutasteride (Avodart(®)), and one older first-line agent, tamsulosin (Flomax(®)).

DESIGN

Interrupted time series analysis was used to assess the impact of each DTCA campaign using data on consumer "response" from Google Trends and dispensed prescriptions from IMS Health.

PARTICIPANTS

We analyzed data for the United States from January 2003 to December 2007.

INTERVENTION

DTCA for dutasteride and tamsulosin commenced on July, 2005 and April, 2006, respectively.

MAIN MEASURES

Monthly Internet search volume (scaled from 0 to 100) for the advertised trade name of each drug and monthly U.S. prescription rates per 1,000 population were analyzed.

KEY RESULTS

The dutasteride campaign was associated with an increase in Internet searches for both "Avodart" (level change +31.3 %, 95 % CI: 27.2-35.4) and "Flomax" (level change +8.3 %, 95 % CI: 0.9-15.7), whereas the tamsulosin campaign was associated with increased "Flomax" searches (level change +25.3 %, 95 % CI: 18.7-31.8). The dutasteride campaign was associated with an increase in the prescription of dutasteride (trend = 0.45/month, 95 % CI: 0.33-0.56), but a larger impact was observed with tamsulosin prescriptions (trend = 0.76/month, 95 % CI: 0.02-1.50). Similarly, the tamsulosin campaign was associated with an immediate fourfold increase in the prescribing of tamsulosin (level change +5.76 units, 95 % CI: 1.79-9.72) compared to dutasteride (level change +1.47 units, 95 % CI: 0.79-2.14).

CONCLUSIONS

DTCA was associated with the utilization of drugs to treat symptomatic BPH. However, both campaigns were associated with greater increases in the use of the guideline-recommended first-line agent. DTCA campaigns may increase the overall levels of guideline-recommended treatments to a greater extent than the specific advertised agents.