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

• Published in: Ophthalmic epidemiology Vol. 25; no. 2; pp. 162 - 168
• Main Authors: Biggerstaff, K. S., Frankfort, B. J., Orengo-Nania, S., Garcia, J., Chiao, E., Kramer, J. R., White, D.
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis 04.03.2018
• Subjects: administrative database; Aged; Algorithms; Databases, Factual; Electronic Health Records - statistics & numerical data; Female; Glaucoma; Glaucoma, Open-Angle - diagnosis; Humans; Male; Middle Aged; Reproducibility of Results; Retrospective Studies; ROC Curve; United States; United States Department of Veterans Affairs - statistics & numerical data; validation; veterans; Veterans - statistics & numerical data; United States; Glaucoma; veterans; administrative database; validation
• ISSN: 0928-6586; 1744-5086; 1744-5086
• DOI: 10.1080/09286586.2017.1378688

Purpose: The validity of the International Classification of Diseases, 9th revision, Clinical Modification (ICD-9) code for primary open angle glaucoma (POAG) in the Department of Veterans Affairs (VA) electronic medical record has not been examined. We determined the accuracy of the ICD-9 code for POAG and developed diagnostic algorithms for the detection of POAG. Methods: We conducted a retrospective study of abstracted data from the Michael E. DeBakey VA Medical Center's medical records of 334 unique patients with at least one visit to the Eye Clinic between 1999 and 2013. Algorithms were developed to validly identify POAG using ICD-9 codes and pharmacy data. The positive predictive value (PPV), negative predictive value (NPV), sensitivity, specificity and percent agreement of the various algorithms were calculated. Results: For the ICD-9 code 365.1x, the PPV was 65.9%, NPV was 95.2%, sensitivity was 100%, specificity was 82.6%, and percent agreement was 87.8%. The algorithm with the highest PPV was 76.3%, using pharmacy data in conjunction with two or more ICD-9 codes for POAG, but this algorithm also had the lowest NPV at 88.2%. Conclusions: Various algorithms for identifying POAG in the VA administrative databases have variable validity. Depending on the type of research being done, the ICD-9 code 365.1x can be used for epidemiologic or health services database research.