CHICAGO – Free-text searches of electronic medical records could be better at identifying patients’ postoperative complications than the currently used billing codes, finds a new study.
According to the study, which was published in the August 24/31 issue of JAMA, in order to improve on identifying patient safety concerns, the Agency for Healthcare Research and Quality developed a set of 20 measures, known as the patient safety indicators, which use administrative data to screen for potential adverse events that occur during hospitalization.
[See also: EMRs critical to research of drug-related adverse events]"Currently most automated methods to identify patient safety occurrences rely on administrative data codes; however, free-text searches of electronic medical records could represent an additional surveillance approach," the authors note.
"The development of automated approaches, such as natural language processing, that extract specific medical concepts from textual medical documents that do not rely on discharge codes offers a powerful alternative to either unreliable administrative data or labor-intensive, expensive manual chart reviews. Nevertheless, there have been few studies investigating natural language processing tools for the detection of adverse events. It is not known whether a surveillance approach based on language processing searches of free-text documents will perform better than currently used tools based on administrative data," authors wrote.
Harvey J. Murff, MD, of the Veterans Affairs Medical Center and Vanderbilt University, and colleagues conducted a study to evaluate a language processing-based approach to identify postoperative complications within a multi-hospital healthcare network using the same EMR.
[See also: Doctors stress importance of reporting EHR problems]The study included 2,974 patients (median [midpoint] age, 64.5 years; 95 percent men) undergoing inpatient surgical procedures at six Veterans Health Administration (VHA) medical centers from 1999 to 2006. Among the outcomes measured were postoperative occurrences of acute renal failure requiring dialysis, deep vein thrombosis, pulmonary embolism, sepsis, pneumonia, or heart attack identified through medical record review as part of the VA Surgical Quality Improvement Program. The researchers determined the sensitivity and specificity of the natural language processing approach to identify these complications and compared its performance with patient safety indicators that use discharge coding information.
Within each analytic sample the percentage of postoperative acute renal failure requiring dialysis was two percent (39 of 1,924); for pulmonary embolism, 0.7 percent (18 of 2,327); for deep vein thrombosis, one percent (29 of 2,327); for sepsis, seven percent (61 of 866); for pneumonia, 16 percent (222 of 1,405), and for heart attack, two percent (35 of 1,822).
The researchers found that in general, using a natural language processing-based approach had higher sensitivities and lower specificities than did the patient safety indicator.
"The increase in sensitivity of the natural language processing-based approach compared with the patient safety indicator was more than two-fold for acute renal failure and sepsis and over 12-fold for pneumonia. Specificities were four percent to seven percent higher with the patient safety indicator method than the natural language processing approach," authors wrote.
"Natural language processing correctly identified 82 percent of acute renal failure cases compared with 38 percent for patient safety indicators. Similar results were obtained for venous thromboembolism (59 percent vs. 46 percent), pneumonia (64 percent vs. five percent), sepsis (89 percent vs. 34 percent), and postoperative myocardial infarction (91 percent vs. 89 percent). Both natural language processing and patient safety indicators were highly specific for these diagnoses," authors concluded.
The authors suggest that a natural language processing-based approach offers several potential advantages over administrative-code based strategies to identify healthcare quality concerns.
"First is the flexibility of the approach to meet the individual institutional needs. Once documents have been processed, different approaches and query strategies to identify a specific outcome can be implemented at a relatively low programming effort using standard database query applications. Second, as opposed to administrative codes, search strategies using daily progress notes, microbiology reports, or imaging reports could be monitored on a prospective basis. Thus, this approach could potentially identify complications while a patient is still in the hospital, which could greatly facilitate real-time quality assurance processes… Finally, in systems with highly integrated EMRs, prospective surveillance could be extended to the outpatient setting for individuals remaining with the health care system."
