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We thank Dr. Tsai for his interest in our paper. 1 Park S.J. Yang H.K. Byun S.J. Park K.H. Hwang J.M. Risk of stroke after nonarteritic anterior ischemic optic neuropathy. Am J Ophthalmol. 2019; 200: 123-129 Abstract Full Text Full Text PDF PubMed Scopus (12) Google Scholar Dr. Tsai and associates already published a study which showed that nonarteritic anterior ischemic optic neuropathy (NAION) is a risk factor for subsequent ischemic stroke but not for hemorrhagic stroke. 2 Lee Y.C. Wang J.H. Huang T.L. Tsai R.K. Increased risk of stroke in patients with nonarteritic anterior ischemic optic neuropathy: a nationwide retrospective cohort study. Am J Ophthalmol. 2016; 170: 183-189 Abstract Full Text Full Text PDF PubMed Scopus (30) Google Scholar They suggested that we should separate hemorrhagic stroke from ischemic stroke in the investigation of risk of stroke after NAION. We deeply appreciate Dr. Tsai and associates for pointing out that we should take another opportunity to further analyze our data and clarify the risk of ischemic and hemorrhagic stroke separately after NAION. Based on their suggestion, we divided the outcome according to the type of stroke, ischemic and hemorrhagic stroke, which was defined as the time to first hospital admission with diagnostic codes of ischemic stroke (I60–I62) and hemorrhagic stroke (I63) after entering the cohort, respectively. For each of the types of stroke, we performed the same set of analyses using the 3 time-varying covariate Cox regression models, as we did in our previous article. 1 Park S.J. Yang H.K. Byun S.J. Park K.H. Hwang J.M. Risk of stroke after nonarteritic anterior ischemic optic neuropathy. Am J Ophthalmol. 2019; 200: 123-129 Abstract Full Text Full Text PDF PubMed Scopus (12) Google Scholar The results of all three models showed that incident NAION was not associated with an increased risk of subsequent ischemic stroke (hazard ratio [HR] = 1.16; 95% confidence interval [CI], 0.52–2.59 in model 1; HR = 1.10; 95% CI, 0.49–2.45 in model 2; and HR = 1.05; 95% CI, 0.47–2.34 in model 3) and hemorrhagic stroke (HR = 1.44; 95% CI, 0.96–2.17 in model 1; HR = 1.30; 95% CI, 0.86–1.95 in model 2; and HR = 1.19; 95% CI, 0.79–1.80 in model 3). In addition, we performed a sensitivity analysis by using propensity score-based matching in the defined cohort in the same way as previously mentioned. We matched 10 controls to each NAION patient, and details regarding the estimation and assessment of propensity scores are described in our previous article. 1 Park S.J. Yang H.K. Byun S.J. Park K.H. Hwang J.M. Risk of stroke after nonarteritic anterior ischemic optic neuropathy. Am J Ophthalmol. 2019; 200: 123-129 Abstract Full Text Full Text PDF PubMed Scopus (12) Google Scholar The demographics, comorbidities, and use of comedications were comparable between subjects with NAION and their matched controls when they entered the cohort. The results of sensitivity analyses also showed that incident NAION was not associated with an increased risk of ischemic stroke (HR = 1.10; 95% CI, 0.48–2.53 in model 1; HR = 1.06; 95% CI, 0.46–2.42 in model 2; and HR = 1.03; 95% CI, 0.45–2.35 in model 3) and hemorrhagic stroke (HR = 1.40; 95% CI, 0.91–2.14 in model 1; HR = 1.31; 95% CI, 0.85–2.00 in model 2; and HR = 1.27; 95% CI, 0.83–1.95 in model 3). We used SAS software version 9.3 (SAS Inc., Cary, North Carolina) and R programming version 3.1.0 (R Foundation, Vienna, Austria) for all analyses. In conclusion, NAION is not associated with a subsequent risk of both hemorrhagic and ischemic stroke in the general population of South Korea. Risk of Stroke After Nonarteritic Anterior Ischemic Optic NeuropathyAmerican Journal of OphthalmologyVol. 203PreviewWe are interested to read the study led by Park and associates1 about the risk of stroke in patients with nonarteritic anterior ischemic optic neuropathy (NAION). According to this retrospective cohort study, 1125 NAION patients were identified from January 1, 2004 to December 31, 2013, based on the Korean National Health Insurance Service (NHIS)–National Sample Cohort (NSC) database. The occurrence of incident NAION was associated with an increased risk of subsequent stroke in model 1 (crude analysis; hazard ratio [HR] = 1.31; 95% confidence interval [CI], 0.89–1.92), model 2 (adjusted analysis for demographics; HR = 1.19; 95% CI, 0.81–1.75), and model 3 (adjusted analysis for demographics, comorbidity, co-medication, and the Charlson index score; HR = 1.10; 95% CI, 0.75–1.62), respectively. Full-Text PDF