Detecting accidental punctures and lacerations during cholecystectomy in large datasets: Two methods of analysis

Background: After the Institute of Medicine (IOM) report To Err Is Human highlighted the impact of medical errors, the Agency for Healthcare Research and Quality (AHRQ) developed Patient-Safety Indicators (PSI) to improve quality by identifying potential inpatient safety problems. PSI-15 was created to study accidental punctures and lacerations (APL), but PSI-15 may underestimate APLs in populations of patients. This study compares PSI-15 with a more inclusive approach using a novel composite of secondary diagnostic and procedural codes. Methods: We used Nationwide Inpatient Sample (NIS) data (2000–2012) from AHRQ's Healthcare Cost and Utilization Project (H-CUP). We analyzed PSI-15-positive and -negative cholecystectomies. Cross tabulations identified codes that were significantly more frequent among PSI-15-positive cases; these secondary diagnostic and procedural codes were selected as candidate members of a composite marker (CM) of APL. We chose cholecystectomy patients for study because this is one of the most common general operations, and the large size of NIS allows for meaningful analysis of infrequent occurrences such as APL rates. Results: CM identified 1.13 times more APLs than did PSI-15. Patients with CM-detected APLs were significantly older and had worse mortality, comorbidities, lengths of stay, and charges than those detected with PSI-15. Further comparison of these two approaches revealed that time-series analysis for both APL markers revealed parallel trends, with inflections in 2007, and lowest APL rates in July. Conclusions: Although CM may yield more false positives, it appears more inclusive, identifying more clinically significant APLs, than PSI-15. Both measures presented similar trends over time, arguing against inflation in PSI-15 reporting. While arguably less specific, CM may increase sensitivity for detecting APL events during cholecystectomies. These results may inform the interpretation of other large population studies of APLs following abdominal operations.