Factors explaining the use of psychiatric services by general practices

Background. Referral rates from general practitioners to hospital services vary up to 25-fold, and several studies have sought reasons for this appare nt inconsistency in clinical practice. However, few studies have concentrat ed on, or indeed included, psychiatric patients or psychiatric referral rat es. Aim. To determine the effect of population, general practice, and mental he alth service factors on use of specialist mental health services by general practices. Method. Cross-sectional data from computerized records used in managing cli nical care on all patients aged 16 to 64 years who had been in contact with any mental health service staff over a two-year period. Twenty-three pract ices in Huntingdon Health District were studied, with a list population of 87 643 patients aged 16 to 64 years, served by one inpatient ward and three community mental health teams. The main outcome measures were the relation between age-standardized utilization ratio and markers of morbidity, depri vation, community mental health provision, and practice prescribing. Results. Variation between practices in the use of mental health services w as relatively limited, especially compared with the use of other secondary medical and surgical services. Three factors together explained 60.8% of th e variance in use between practices: a census-based index of long-term limi ting illness in females registered with the practice, use of one of the thr ee community mental health teams, and average quarterly defined daily doses of hypnotics prescribed per practice population. Relatively high prescribi ng of hypnotics was associated with lower service use. Conclusion. Population morbidity and factors in the mental health service e xplain a substantial part of the variation in the use of mental health serv ices between practices. Further work is needed to replicate these findings and explore why team factors and prescribing patterns influence utilization ratios. This study underlines the importance of examining population, prac tice, and specialist service factors in explaining variation in the use of secondary care by general practices.