Establishing thresholds for adverse patient outcomes

Objective: To establish thresholds for adverse patient outcomes in the absence of knowledge of patient illness severity indices. Outcomes: Pulmonary embolism, unplanned return to operating rooms, unplanned readmissions, clean and contaminated wound infections, and hospital-acquired bacteraemia. Design: Analysis of results of surveys of hospitals in Australia by the Australian Council on Healthcare Standards following the introduction of clinical performance measures into the Accreditation process. Setting: Acute care hospitals in Australia undergoing Accreditation surveys in 1993 and 1994. Methods: Stratification of hospitals into small (1-99 beds), medium (100-199 beds), and large (greater than or equal to 200 beds), calculation of mean rates for the above outcomes in each group, and establishment of thresholds based on two standard errors from the mean. Results: The mean rate of occurrence of incidents was higher for larger hospitals, Thresholds were generally lower for smaller and higher for larger hospitals. Conclusions: Bed-size is a useful index for ''flagging'' peer group variation, The methodological issues in establishing thresholds and their implications in monitoring the quality of care in hospitals are discussed. Copyright (C) 1996 Elsevier Science Ltd.