Hospital-based toxicology: patterns of use and abuse

We examined 949 consecutive toxicology requests to determine (a) the identity and relative frequency of the most commonly detected drugs in our hospital population; (b) degree of concordance between clinical impression and laboratory analysis; (c) influence of age and sex upon the numbers and results of toxicologic analyses; (d) temporal pattern of our annual toxicology case-load; (e) temporal and sexual distribution of various common drugs; (f) drugs most often found together; and (g) frequency with which inappropriate toxicology request were received. Laboratory analysis agreed with clinical impression in only 17.4% of cases. Age and sex correlated with the detection of specific drugs. But for benzodiazepines, no consistent temporal pattern was present regarding either type or number of drugs detected. Certain days of the week demonstrated a statistically significant effect upon the number of toxicology requests received, while seasons, holidays, and lunar phases had no influence. Inappropriate requests comprised 9% of the total annual toxicology caseload.