Validity of code based algorithms to identify primary open angle glaucoma (POAG) in Veterans Affairs (VA)...

Area of Science:

• Ophthalmology
• Health Informatics
• Medical Coding

Background:

• The accuracy of International Classification of Diseases, 9th revision, Clinical Modification (ICD-9) codes for primary open-angle glaucoma (POAG) in electronic medical records within the Department of Veterans Affairs (VA) has not been previously established.
• Accurate coding is crucial for reliable epidemiological and health services research.

Purpose of the Study:

• To determine the accuracy of the ICD-9 code for primary open-angle glaucoma (POAG).
• To develop and evaluate diagnostic algorithms for identifying POAG in VA electronic medical records.

Main Methods:

• A retrospective study analyzed 334 patient records from the Michael E. DeBakey VA Medical Center (1999-2013).
• Algorithms were developed using ICD-9 codes and pharmacy data to identify POAG cases.
• Key performance metrics including positive predictive value (PPV), negative predictive value (NPV), sensitivity, specificity, and percent agreement were calculated.

Main Results:

• The standalone ICD-9 code 365.1x for POAG demonstrated a PPV of 65.9%, NPV of 95.2%, sensitivity of 100%, specificity of 82.6%, and 87.8% agreement.
• An algorithm combining pharmacy data with two or more POAG ICD-9 codes achieved the highest PPV (76.3%) but had the lowest NPV (88.2%).

Conclusions:

• The validity of algorithms for identifying POAG in VA administrative databases varies.
• The ICD-9 code 365.1x can be utilized for specific research purposes, such as epidemiologic or health services database research, depending on the required level of accuracy.