# Strabismus and Strabismus Surgery in the U.S. Veterans Health Administration: Foundational Analyses of Electronic Health Record Data from 2000 to 2022

## TL;DR

This study analyzes strabismus in U.S. Veterans using EHR data from 2000 to 2022, finding demographic patterns and surgical trends.

## Contribution

The study provides foundational insights into strabismus prevalence and surgery among U.S. Veterans using a large EHR dataset.

## Key findings

- Strabismus prevalence peaked at 2.29% in 2022 with notable demographic differences.
- African American Veterans had a higher surgery rate despite lower strabismus prevalence.
- ICD and CPT code inconsistencies suggest potential underestimation of strabismus cases.

## Abstract

Background/Objectives: Strabismus, or eye misalignment, has not been well-described in U.S. military Veterans. This study was undertaken to characterize Veterans with a strabismus diagnosis as well as those who underwent strabismus surgery. Methods: A retrospective analysis of electronic health records (EHR) from the Veterans Health Administration (VHA) was conducted using patient data from 2000 to 2022. VHA-enrolled Veterans ≥ 18 years with strabismus-related International Classification of Diseases (ICD) codes and/or Current Procedural Terminology (CPT) codes were identified. Total and demographic (age group, sex, race, and ethnicity) stratified prevalence and incidence rates were calculated, as well as sex-stratified residual lifetime risk. Results: A total of 321,639 patients had a strabismus diagnosis, with most (320,107) identified by ICD code (CPT code only = 1532). The peak prevalence was 2.29% in the 2022 VHA fiscal year (1 October 2021 to 30 September 2022) with a median annual age-adjusted incidence rate of 168.9/100 000 enrollees. Age-adjusted lifetime risk was 10.19% for males and 11.03% for females. Significant differences by age group, sex, race, and ethnicity were identified for strabismus prevalence (p < 0.001), strabismus diagnosis types (p < 0.001), and between patients with strabismus who either did or did not have surgery (sex p < 0.05, all others p < 0.001). Compared with other U.S. adult populations, VHA Veterans have similar or higher prevalence, annual incidence rates, and lifetime risk of a strabismus diagnosis, with demographic factors significantly affecting the rates and types of strabismus. Notably, despite lower prevalence and incidence than other racial groups, a higher percentage of African American patients with strabismus underwent surgery, contrasting with published Medicare data. Inconsistencies between ICD and CPT codes highlight potential miscoding and/or missing codes, with reliance on ICD code diagnoses potentially underestimating strabismus prevalence. Conclusions: Further characterization of factors affecting strabismus risk among these patients may help improve strabismus diagnosis and management for many US Veterans. This foundational study serves as a platform for detailed predictive analyses in determining risk outcomes for individuals. This includes better identification of at-risk individuals, informing effective resource allocation for treatment.