A Taiwan nationwide population-based study of socio-demographic factors and comorbid conditions associated with non-arteritic anterior ischemic optic neuropathy

Aims: To investigate the socio-demographic factors and systemic conditions associated with non-arteritic anterior ischaemic optic neuropathy (NAION).
Methods: This was a nationwide population-based retrospective case-controlled study that recruited 9,261 NAION patients selected from the Taiwan National Health Insurance Research Database. The control group consisted of 9,261 age-, sex-, and index date-matched non-NAION patients recruited from the Taiwan Longitudinal Health Insurance Database, 2000. NAION was designated in the database by the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) as “code 377.41: ischaemic optic neuropathy without ICD-9-CM code 446.5: giant cell arteritis”. Associated socio-demographic factors and systemic medical conditions were analysed using the McNemar’s test, and continuous variables were analysed using the paired t-test. The odds ratio (OR) and adjusted OR of developing NAION were compared using univariate logistic regression and multivariable logistic regression analyses, respectively.
Results: Patients with systemic conditions such as diabetes mellitus, hypertension, hyperlipidaemia, chronic kidney disease, and hypotension were more likely to develop NAION than controls (adjusted OR=1.81, 95% CI=1.67–1.97, p<0.0001; adjusted OR=1.46, 95% CI=1.36–1.57, p<0.0001; adjusted OR=1.44, 95% CI=1.33–1.57, p<0.0001; adjusted OR=3.26, 95% CI=2.65–4.01, p<0.0001; adjusted OR=2.32, 95% CI=1.31–4.10, p=0.0039, respectively). Patients residing in Eastern Taiwan or in a metropolitan city had higher odds of developing NAION. Patients with a monthly income between NT$ 30,000 and NT$ 90,000 and those whose jobs were others also had significantly higher ORs of developing NAION. 
Conclusions: NAION is strongly associated with diabetes mellitus, hypertension, hyperlipidaemia, chronic kidney disease, and hypotension.
