Cost but not use of clopidogrel increased after direct-to-consumer advertising

Clopidogrel use did not increase after initiation of direct-to-consumer advertising for the drug in 2001; however, according to recent data, the drug cost per unit increased after direct-to-consumer advertising began, thereby increasing Medicaid pharmacy expenditures.

Researchers examined pharmacy data from 27 Medicaid programs from 1999 to 2005 and used interrupted time series analyses to evaluate number of units dispensed, costs per unit and total pharmacy expenditures after direct-to-consumer advertising for clopidogrel began in 2001. From 2001 to 2005, direct-to-consumer advertising for clopidogrel exceeded $350 million, an average of $70 million per year.

Before the initiation of direct-to-consumer advertising, the researchers reported that clopidogrel use was increasing at a constant 27.43 additional units per 1,000 enrollees per quarter (P<.001). This trend did not change after initiation of direct-to-consumer advertising (P=.10). After controlling for the pre-direct-to-consumer advertising trends, the immediate change in level of units dispensed per 1,000 enrollees was –22.64 (P=.18).

Despite no change in the number of units dispensed, the researchers found that the cost per unit increased by $0.40 after 2001 (P<.001) — an immediate 12% increase in the cost per unit dispensed after direct-to-consumer advertising began. This increase drove up the total rate of pharmacy expenditures for clopidogrel by $40.58 per 1,000 enrollees per quarter (P<.001).

“The net result confirmed our hypothesis: There was an overall increase in drug expenditures associated with the start of a direct-to-consumer advertising campaign that amounted to an additional $207 million for 27 state Medicaid programs,” the researchers wrote. “These results may have implications for other heavily marketed drugs and for other public or private drug reimbursement programs.”

Law MR. Arch Intern Med. 2009;169:1969-1974.