[The computerised prescription in Primary Care and its impact on drug spending using time series analysis].

OBJECTIVES: To describe the monthly costs of drugs per standardized patient in the Doctor Peset health department in Valencia, Spain and to correlate them with the computerization of prescription in primary care clinics using time series analysis. Other objectives were to identify internal causes that could explain the variations observed, and to evaluate the drug costs associated with these variations.
MATERIAL AND METHODS: Observational and retrospective study to analyse the variables: a) monthly costs of drugs by standardized patient and b) number of defined daily doses (DDD) per 1000 inhabitants and per day of drugs used to prevent cardiovascular risk prescribed by the Primary Care doctors of the Doctor Peset health department in Valencia, between January 2001 and August 2009. Time series were adjusted using ARIMA models. The impact of computerization was assessed using an intervention analysis on time series.
RESULTS: ARIMA models for the monthly costs of drugs by standardized patient shows that this indicator was increased by 4.9% in August 2007. The modelling of daily DDD per 1000 inhabitants showed an increase of 8.5% on the same date. Both increases occurred together with the introduction of the computerized prescription in Primary Care clinics. The pharmacoeconomic study estimated that drug costs associated with the trend changes increased by 11,365,409 euros within the period September 2007 to August 2009.
CONCLUSIONS: The computerization of prescription in Primary Care clinics can be correlated with an increase in the monthly costs of drugs per standardized patient and with the number of daily DDD per 1000 inhabitants of drugs to reduce the cardiovascular risk by 4.5% and 8.5%, respectively.