Patients with NAION may be more susceptible to ischemic kidney injury

This population-based retrospective study assessed the risk of acute tubular necrosis (ATN) in patients with nonarteritic anterior ischemic optic neuropathy (NAION).

Study design

The authors mined the Korean national health claims database for records entered between 2011 and 2015. They identified 22,498 patients with NAION and 31,475 random controls matched for age and vascular risk factors.

Outcomes

Twenty-six cases of acute tubular necrosis were identified among patients with NAION compared with 11 cases in the control group (adjusted HR 2.55). Half of the acute tubular necrosis cases occurred within 6 months of the NAION diagnosis.

Limitations

The study’s strengths lie in its large size and population-based methodology. However, the main limitation, as with any big data analysis, is the inability to review the individual medical records to confirm the diagnoses of NAION or acute tubular necrosis. The authors limited this bias by requiring 2 separate diagnoses of NAION, and by excluding other optic neuropathies such as optic neuritis or giant cell arteritis, which can mimic NAION. However, the inability to confirm diagnoses remains a potential problem because the study evaluates for an association between 2 rare diseases. Despite the very large sample size, the p-value of the hazard ratio was 0.029; therefore, small errors in diagnoses could abolish the association.

Clinical significance

Though further studies are needed to confirm these findings, the potential association between acute tubular necrosis and NAION is intriguing because both diseases share ischemia as an underlying cause. This study suggests that patients with NAION may be susceptible to ischemic injury of other organs, which warrants systemic evaluation for other medical conditions that stem from ischemia.