The Patient Safety Indicator postoperative respiratory failure (PRF) flags cases using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes for acute respiratory failure or mechanical ventilation/intubation. The authors examined how frequently PRF missed events and ways to improve event identification. A total of 125 high-risk unflagged cases were selected based on predicted probability and presence of clinically relevant codes. False-negative (FN) proportion and associated reasons were determined through chart review, and likelihood ratios (LRs) of associated codes were calculated. In all, 27% of elective cases were FNs; 55% of FNs lacked ventilation/intubation codes. "Respiratory arrest," 799.1, had the highest LR (5.4) but occurred in only 8% of FNs. All other individual diagnostic or procedure codes had relatively low LRs (≤ 3.1), despite occurring in up to 36% of FNs. Among high-risk cases, the PRF algorithm often missed events. Improved ventilation/intubation coding will have more of an impact on case identification than adding ICD-9-CM codes to the algorithm.
Keywords: adverse events; patient safety; postoperative respiratory failure; quality indicators; quality of care.