Auditing hospital drug utilisation by means of defined daily doses per bed-day.  A methodological study. 
The utilisation of hypnotics, sedatives, and minor tranquillisers (HSmT) was studied by means of drug-delivery and hospital occupancy statistics for 1975-1977 in a Swedish university hospital.  A total of 0.53 so-called defined daily doses (DDD)/bed-day were delivered in 1975, implying that every second patient might have regularly been prescribed HSmT. The benzodiazepines were predominant with 71% of the deliveries.  Five major drugs accounted for 88%.  The drug pattern and the range of DDD/day-bed (0.09-1.18) differed considerably between the departments.  Drugs not recommended by the hospital's Pharmacy and Therapeutics Committe accounted only for 3% of deliveries.  In a drug surveillance study performed in two medical wards, HSmT were prescribed for 43% of 274 patients.  Drug delivery and prescription data were in broad agreement.  Drug information activities in the hospital had a clearly discernable influence on the delivered DDD/bed-day.  This measure is an inexpensive indicator of drug utilisation in a hospital and a suitable basis for therapeutic audit.