Variations in antidepressant prescribing practice: clinical need or market influences?

To assess the antidepressant prescribing patterns of community psychiatrists, and the prescriptions issued by general practitioners and private physicians during 1999 in order to analyse and discuss the intensity and sources of variations between doctors.

All reimbursed prescriptions for antidepressants written in 1999 by community psychiatrists and general practitioners working for the Canary Islands Health Service at Santa Cruz de Tenerife were collected from official sources. Prescriptions were available individualized for each psychiatrist but were collected globally for the others. Drugs were classified according to the Anatomic Therapeutic Chemical (ATC-1999 edition) System and use was quantified in terms of defined daily doses (DDDs). As an indicator of the quality of drug prescribing, the DU90% was used.

The total use of antidepressant in Tenerife was 21.4 DDD/1000 inhabitants/day. The most frequently prescribed substances were fluoxetine, paroxetine and sertraline, which accounted for 58% of all prescriptions. Each psychiatrist used between 10 and 20 different substances and between 15 and 26 different trade names. Prescribing by general practitioners mirrored that of psychiatrist, and private doctors (mainly psychiatrist) were found to have a different pattern of prescribing with higher use of new and uncommon antidepressants. Psychiatrists acknowledge the pressures of promotion by the pharmaceutical industry and half of them recognize a personal relationship with some 'company representatives'.

There is a remarkable degree of variation in antidepressant prescribing by psychiatrists and general practitioners, this is due to economic and social factors as much as to morbidity differences.