# Diagnostic accuracy of the international classification of disease “I26” code to detect acute pulmonary embolism in a surveillance network

## TL;DR

This study evaluates how well the ICD-10 code I26 can detect acute pulmonary embolism in emergency departments using electronic medical records.

## Contribution

The study demonstrates the diagnostic accuracy of the I26 code for real-time surveillance of pulmonary embolism in a large ED network.

## Key findings

- The I26 code had high specificity (99.7%) but modest sensitivity (50.9%) for detecting acute pulmonary embolism.
- The I26 code showed high likelihood ratio positive (191) for detecting pulmonary embolism in emergency departments.
- The I26 code holds promise for low-latency surveillance of venous thromboembolism in the U.S.

## Abstract

Emergency departments (EDs) offer a unique platform for a surveillance network for acute pulmonary embolism (PE) using International Classification of Disease (ICD-10) codes extracted from electronic medical records.

Test the diagnostic accuracy of the I26 "leader" ICD-10 code for the detection of PE in near real-time in a large, ED-based surveillance network.

Standardized structured language queries were deployed at 91 hospitals to extract data, including ICD-10 codes, on a weekly basis from electronic medical records on ED patients with acute respiratory complaints. We used 2 methods for coding computed tomography pulmonary angiogram (CTPA) reports to derive a criterion or gold standard for PE diagnosis: (1) research associates were trained to interpret the CTPA reports, and (2) a validated Regular Expression computer program was used to interpret PE on CTPA reports. These 2 methods were independently adjudicated (PE+ or PE−). The primary outcome was diagnostic accuracy of the I26 leader compared with the final adjudication.

From 6448 valid CTPA scan reports, 442 (6.8%) were adjudicated as PE+. On a weekly basis, the I26 leader had a sensitivity of 50.9% (95% CI, 46.1%-55.6%) and a specificity of 99.7% (95% CI, 99.5%-99.8%), likelihood ratio (LR) negative of 0.49 (95% CI, 0.44-0.54) and LR positive of 191 (95% CI, 116-12). At 1 month, the I26 sensitivity was 57.5% (95% CI, 52.7%-62.1%), and specificity was 99.5% (95% CI, 99.2%-99.6%); LRnegative of 0.43 (95% CI, 0.38-0.47) and LRpositive of 111 (95% CI, 77-159).

For low-latency surveillance of PE diagnosed in EDs, the ICD leader code I26 affords high specificity and high LR(+) for detection of acute PE in the United States but has modest sensitivity.

•No national surveillance system exists for real-time surveillance of venous thromboembolism (VTE).•An existing network designed for surveillance of acute respiratory illness emergency departments.•The International Classification of Disease “I26” code demonstrated high specificity for VTE.•The International Classification of Disease code I26 holds promise as a method for low-latency surveillance of VTE.

No national surveillance system exists for real-time surveillance of venous thromboembolism (VTE).

An existing network designed for surveillance of acute respiratory illness emergency departments.

The International Classification of Disease “I26” code demonstrated high specificity for VTE.

The International Classification of Disease code I26 holds promise as a method for low-latency surveillance of VTE.