Errors, mistakes, blunders, outliers, or unacceptable results: how many?

We have studied 219353 individual clinical chemistry results obtained in methods comparison studies. Each result was prospectively compared with its replicate, comparative, or repeat value to identify differences from expected values. Unacceptable results were defined as differing from the expected values by < or = 7 SDs or CVs. We believe these differences represent special-cause variation and should be expressed as unacceptable rates per million results (ppm). We observed 447 ppm unacceptables: 196 ppm in control samples and 251 ppm in patients' samples. Results judged likely to alter patient care occurred at a rate of 41 ppm. To better understand the magnitude of these rates, we compared these results with reports of error rates in HIV testing and the airline industry. The measurements reported were made for the purpose of quality improvement, not judgment or discovery. The significance of these findings for laboratorians, manufacturers, and regulators is discussed.

Comparison of intra-articular morphine and bupivacaine following knee arthroscopy.

A prospective study was conducted to investigate and compare the analgesic effect of morphine and bupivacaine injected intra-articularly following elective knee arthroscopy performed under general anesthesia without the use of a tourniquet. Cost-effectiveness of these agents was also evaluated. Patients in Group 1 (n = 41) received 30 cc of 0.25% bupivacaine with 1:200,000 epinephrine; while Group 2 (n = 40) received 2 mg morphine (1 mg/cc) in 28 cc normal saline (total volume 30 cc). Postoperative pain scores and the amount of supplemental analgesic agents used in a 24-hour period were recorded. Results showed that patients in Group 2 reported significantly less pain overall (P < .006) and significantly lower analgesic requirements (P < .0004) at a lower average patient cost than Group 1. We conclude that intra-articular morphine reduces postoperative pain and analgesic requirements more effectively and at a lower average patient cost than bupivacaine.