The Association Between Sociodemographic Factors, Common Systemic Diseases, and Keratoconus: An Analysis of a Nationwide Heath Care Claims Database

Abstract

Purpose: The purpose of this study was to determine whether an association exists between common systemic diseases, sociodemographic factors, and keratoconus (KCN) among a large, diverse group of insured individuals in the United States.

Design: Retrospective longitudinal cohort study.

Participants: Sixteen thousand fifty-three patients with KCN were matched 1:1 with persons without KCN.

Methods: Persons with KCN were identified using billing codes and matched by age, gender, and overall health with a control group with no record of KCN. Multivariable logistic regression assessed whether sociodemographic factors and certain systemic diseases affected the odds of KCN.

Main outcome measures: Odds ratios (ORs) with 95% confidence intervals (CIs) of receiving a KCN diagnosis.

Results: After adjustment for confounders, black persons had 57% higher odds (adjusted OR, 1.57; 95% CI, 1.38-1.79; P < 0.001) and Latino persons had 43% higher odds (adjusted OR, 1.43; 95% CI, 1.26-1.62; P < 0.001) of being diagnosed with KCN compared with whites. Asians had 39% reduced odds (adjusted OR, 0.61; 95% CI, 0.50-0.75; P < 0.001) of being diagnosed with KCN compared with whites. Patients with uncomplicated diabetes mellitus (DM) had 20% lower odds of KCN (adjusted OR, 0.80; 95% CI, 0.71-0.90; P = 0.002), and patients with DM complicated by end-organ damage had 52% lower odds of having KCN (adjusted OR, 0.48; 95% CI, 0.40-0.58; P < 0.001) compared with those without DM. Persons with collagen vascular disease had 35% lower odds of KCN (adjusted OR, 0.65; 95% CI, 0.47-0.91; P = 0.01). Other conditions found to have increased odds of KCN included sleep apnea (adjusted OR, 1.13; 95% CI, 1.00-1.27; P = 0.05), asthma (adjusted OR, 1.31; 95% CI, 1.17-1.47; P < 0.001), and Down syndrome (adjusted OR, 6.22; 95% CI, 2.08-18.66; P < 0.001). There was no association between KCN and allergic rhinitis, mitral valve disorder, aortic aneurysm, or depression (P > 0.1 for all comparisons).

Conclusions: Clinicians caring for persons with KCN should inquire about breathing or sleeping and, when appropriate, refer patients for evaluation for sleep apnea or asthma. Patients with DM have lower risk of KCN, potentially because of corneal glycosylation.

Figure 1

Selection of beneficiaries for analysis. Abbreviations: ICD-9-CM, International Classification of Diseases, 9^th Revision, Clinical Modification; PK, penetrating keratoplasty; DALK, deep anterior lamellar keratoplasty.