Drug alerts have variable impact on prescribing habits

By Joanna Lyford, Senior medwireNews Reporter

Direct communication with healthcare professionals, in the form of so-called "Dear doctor" letters, can be effective in reducing inappropriate and unsafe use of medicines, Dutch scientists believe.

In a study published this month, they identify features of risk communications that correlate with likelihood of having the desired impact on physicians' behavior and prescribing habits.

Peter Mol (University Medical Center Groningen, the Netherlands) and colleagues analyzed 59 Direct Health-Care Professional Communications (DHPCs) issued by the Dutch drugs regulator between 2001 and 2008. The letters concerned 46 drugs that were dispensed in ambulatory care.

For each drug, the researchers compared the rate of new prescriptions before versus after the relevant DHPC, and then used regression analysis to identify factors that predicted the impact of the alert.

Reporting their findings in Clinical Pharmacology & Therapeutics, Mol et al say that the median number of new drug users per month in the year before issuing the DHPC ranged from seven (sirolimus) to 53,596 (salbutamol).

The mean relative change in new drug use among all the DHPCs analyzed was -9% and ranged from -67.4% for strontium ranelate to +71.7% for sirolimus.

On average, drugs had been approved 6.8 years before the DHPC was issued, and 80% of the DHPCs were issued for drugs that had been licensed for more than 3 years. Similar numbers of DHPCs were issued for all drugs independent of their degree of innovation, while 59% of DHPCs concerned specialist drugs.

In the linear regression analysis, four factors were significantly associated with a greater impact on new drug use. These were DHPCs for specialist rather than nonspecialist drugs; DHPCs for drugs that were already declining in use before the communication; DHPCs whose structure and layout followed a standardized template; and DHPCs that communicated serious safety issues potentially causing death or disability.

Mol et al note that the new European pharmacovigilance legislation makes it mandatory to monitor the impact of risk-minimization measures such as DHPCs.

"This study provides a first exploration of determinants that influence the impact of DHPCs on drug use," they conclude.

"With the results of this study, it will be possible to anticipate, and possibly enhance, the impact of future DHPCs on drug use by tailoring risk communication about safety issues of drugs more specifically."

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