[Factors determining costs of drug prescriptions in primary health care]

To describe and explain the annual pharmaceutical expenditure generated by the professionals in a Health Area.

An observational crossover study.

Primary Care. Doctors in a Health Area.

99 general practitioners who worked during 1992 in Area 3, Castellón.

We used as a variable reply the pharmaceutical expenditure of each doctor during 1992, the expenditure per inhabitant and the expenditure per inhabitant standardised for the percentage of passives. We gathered as explanatory variables of the same: age, gender, whether the post was provisional or permanent, rural or urban area, MIR (resident) training or not, the model of Primary Care, frequency of attendance, whether the doctors worked there exclusively, the number of pensioners and the number of patients at work registered.

In the bivariant analysis we found a significant association of expenditure with being provisional in the post, the old model of primary care, an urban area, greater age of the doctor, greater frequency of attendance, non-exclusivity and the number of patients registered. These associations varied in line with the variable reply used. In the different models of multiple linear regression obtained, the influence of the number, non-exclusivity, gender and work-place characteristics predominated.

Greater pharmaceutical expenditure appears to be related to the number of patients registered, the absence of exclusivity, doctors being women and the features of the town where they work.