Effect of Age and Sex Related Therapeutic Needs on General Practices' Prescribing Cost: The ASSET (Age/Sex Standardised Estimates of Treatment) Research Model

Abstract

The primary objective of this study was to derive cost comparators for the fourteen Anatomical Therapeutic Chemical (ATC) classes of drugs at first level, based on age-sex related weightings. It was hoped to develop an accurate method of analysing prescribing patterns in general practice and to be able to explain individual variations in prescribing cost based on the age/sex distribution of the population and individual clinical needs. Individual cost data were collected for 3,175,691 subjects living in three different regions of Italy (Lombardy, situated in the north, Marche in the centre and Basilicata in the south). The observation period was 12 months (September 2004 - August 2005).The analysis by ATC class showed large variations in prescribing costs for the different age groups in each of the ATC classes for both sexes, and, in some instances, wide differences in prescribing costs by sexes. The largest cost difference between age groups, for both males and females occurred in drugs used for the cardiovascular system. Antibiotics revealed a difference from the general pattern with more prescribing occurring in the youngest age groups compared to other ATC classes. Large differences between the sexes were observed in the older age groups in drugs used for the respiratory system.The ASSET model was a robust proxy of the actual public spending by ATC, while the therapeutic group age/sex related weightings were unable to explain the large individual variations in individual prescribing costs.The ASSET model confirmed the validity of demographic adjusted models to quantify the impact of ageing population in terms of resources needed to satisfy long term population prescribing needs. The ASSET age/sex weightings of total prescribing costs should be used as a guide, not as the ultimate determinant, for an equitable allocation of prescribing resources in conjunction with historic utilisation and cost data.