Appropriateness of laboratory tests: requests for atypical pneumonia serology in a teaching hospital.

The cost of providing medical care is ever-increasing but the resources available are at best static. Major savings can be made by reducing inappropriate investigations. Using serological testing for organisms causing atypical pneumonia as an example, we examined the appropriateness of requests and also physicians' understanding of the test. Of 119 patients tested, only 3 had titres indicative of acute infection. Most patients were tested within 2 days of hospital admission, before receipt of results excluding more likely diagnoses. Forty-five patients had no current or recent respiratory symptoms, in whom infection was highly unlikely. Titres were most often requested by the least experienced members of the clinical team. Of 70 patients with an acute illness in whom a definitive diagnosis, bacteriological or otherwise, was not made, in only 9 was a convalescent specimen sent for follow-up titres. Most requests for serology for organisms causing atypical pneumonia were inappropriate. Furthermore, in the majority of cases the test was incorrectly used.