Lack of Standardized Coding Limits Accuracy of Electronic Clinical Quality Measure for Pulmonary Embolism Diagnosis
Authors: Baumann Kreuziger Lisa , Keenan Megan , Dykhoff Hayley , Hall Marie , Campbell Kyle , Cahill Emily , Hanson Ryan , McEvoy Dustin , He Wei , Dutta Sayon , Rosovsky Rachel P. , Houghton Damon E. 
Published: February 2025

Guidelines for diagnosing pulmonary embolism (PE) start with a risk assessment using a pretest probability (PTP) tool, followed by D-dimer testing or computed tomography pulmonary angiography (CTPA) depending on risk. The project aimed to develop an electronic clinical quality measure (eCQM) to encourage broader use of a validated PTP scoring tool in emergency departments (EDs) to more accurately diagnose PE and to reduce unnecessary CTPAs. To identify a value set to accurately identify CTPA and abnormal D-dimer tests using standard classification systems and clinical vocabularies (ie, Current Procedural Terminology [CPT], Logical Observation Identifiers Names and Codes [LOINC], systematized nomenclature of medicine clinical terms [SNOMED CT]) across 3 academic United States health care systems. A comprehensive value set to identify CTPAs was selected, which contained 31 codes. Additionally, each health care system had unique, site-specific codes to more granularly identify CTPAs. Three health care systems representing 38 EDs from across the country submitted data from all ED encounters between September 12, 2022, and January 11, 2023. Imaging types were reviewed from each of the CPT codes and LOINC. The project evaluated whether a D-dimer was obtained using CPT and LOINC and whether the D-dimer result was elevated using SNOMED CT. The number of ED encounters, PTP use, and diagnosis of PE using different codes were determined. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value for selected codes were calculated. Over a 4-month study period, 270,214 encounters were included from 38 EDs. 11,794 ED encounters with CTPAs during the study period, using the site-specific codes were identified. The comprehensive value set had a PPV of 63.4%. Restricting the CTPA value set to CPT code 71275 or LOINC 88322-3 improved the PPV to 82% with 100% sensitivity and 99% specificity. The restricted value set captured the highest proportion of relevant site-specific codes. D-dimer values were identified using LOINC codes 48065-7 and 91556-1 at Site 1 and 48067-3 at Site 2. SNOMED CT codes were not used at any site to identify elevated D-dimer results. Different D-dimer tests with different normal ranges were used at each site, and only one site provided an abnormal flag for D-dimer results. Heterogeneity in the use of nationally standardized codes for labs and imaging tests limits the ability to measure and compare quality across health care organizations for CTPA and D-dimer results. Restricting the identification of CTPA to CPT Code 71275 or LOINC 88322-3 resulted in high sensitivity and specificity, but false positives remain. Additionally, coding for an abnormal D-dimer test result is not standardized across institutions. Therefore, the currently available value sets cannot be used to develop eCQMs whose aim is to evaluate whether CTPA is ordered appropriately based on the PTP risk level and laboratory testing.