Uveitis in AS Increases Risk of Stroke, Large Database Analysis Shows
Inflammatory eye condition in patients linked to stroke risk factors
People with ankylosing spondylitis (AS) who experience uveitis, an inflammatory condition of the eye, have a significantly higher risk of stroke than those without this AS symptom, according to a large medical database analysis.
Uveitis in AS also was linked with an increased incidence of known stroke risk factors, including diabetes, high blood pressure, chronic heart failure, and irregular heartbeat — all of which further elevated the patients’ stroke risk.
Researchers suggested that clinicians consider the elevated risk of stroke for people with AS — especially those with co-existing conditions such as uveitis — when treating patients.
“Careful history taking and closely monitoring the neurological signs and symptoms are crucial in these patients for early detection of stroke, appropriate referral and prompt management for all clinicians,” the researchers wrote.
Further studies are still needed to understand the exact mechanisms underlying uveitis and stroke in AS, the team noted.
Uveitis linked to stroke risk in AS
The database study, “Uveitis increases the risk of stroke among patients with ankylosing spondylitis: A nationwide population-based longitudinal study,” was published in the journal Frontiers in Immunology.
AS is a type of arthritis mainly characterized by inflammation of the spine, particularly in the sacroiliac joints, where the base of the spine meets the pelvis.
Elevated levels of pro-inflammatory immune signaling proteins can be found in the bloodstream of AS patients. These proteins also play a role in cardiovascular disease, leading to heart attack and stroke. In fact, AS is associated with a higher risk of heart attack and stroke.
Beyond inflammation of the joints, up to 40% of people with AS experience uveitis — inflammation of the uvea, the middle layer of the eye between the white outer layer and the inner light-sensitive retina.
A team of researchers at the National Defense Medical Center, in Taiwan, recently found that uveitis is a significant risk factor for heart attack in patients with AS.
Now, the researchers investigated the incidence of stroke in AS.
Data were collected from the National Health Insurance Research Database (NHIRD), which contains the medical records of more than 99% of Taiwan’s population. Between 2000 and 2015, 4,140 AS patients were enrolled. Their mean age was 37, and 56.9% were women. Among them, 828 (20%) were diagnosed with uveitis.
Overall, 28.3% of the AS patients were diagnosed with diabetes, 23.2% had high blood pressure, 20.6% lived with asthma, and 17.9% with chronic obstructive pulmonary disease (COPD). Less than 7% had high blood fat, chronic heart failure, coronary heart disease, and arterial fibrillation (irregular heartbeat).
At the study’s start, there were no differences between those with and without uveitis regarding sex, age, and co-existing conditions (comorbidities) related to stroke. This included diabetes, high blood pressure, high blood fat, chronic heart failure, coronary heart disease, arterial fibrillation, asthma, and COPD.
By the study’s end, 137 patients in the uveitis group (16.5%) had a stroke, as did 344 of the 3,312 patients (10.4%) without uveitis. The mean age of those who experienced a stroke was the same, with or without uveitis. All-cause mortality, or death from any cause, occurred in 12.56% of the uveitis group and 9.81% of the non-uveitis group.
Except for high blood fat and coronary heart disease, all other co-existing conditions were significantly higher in AS patients with uveitis than those without by the end of the study.
Co-existing conditions common in AS
Statistical analysis of the data revealed that AS patients with uveitis had a significantly higher risk of stroke than those without uveitis. The risk remained higher regardless of the type of stroke: either ischemic stroke, caused by blood vessel blockage, or hemorrhagic stroke, caused by blood vessel leakage.
Calculations demonstrated that uveitis in AS was associated with an 85% higher relative risk of stroke.
Overall, men had a 56% higher relative stroke risk than women. Between ages 40–59, there was a 52% elevated relative risk of stroke and 89% higher in those 60 and over. Further, stroke risk was significantly higher in AS patients with diabetes, high blood fat, high blood pressure, chronic heart failure, coronary heart disease, arterial fibrillation, asthma, and COPD.
Consistently, the incidence rate of stroke was higher in AS with uveitis than without — 1,755.44 vs. 1,080.79 per 100,000 person-years. Person-years is a measure that accounts for the number of patients in the study and the follow-up duration in each patient.
After adjusting for sex, age, and co-existing conditions, the risk of stroke in the uveitis group remained significantly higher than in the non-uveitis group. Higher stroke risk was also seen across all age groups.
Compared with AS patients without uveitis, those with the inflammatory condition had an even higher stroke risk when combined with diabetes, high blood fat, high blood pressure, chronic heart failure, arterial fibrillation, asthma, and COPD.
Increased stroke risk with uveitis was similar in those with inflammation in the front of the eye (anterior uveitis) or the back of the eye (posterior uveitis).
“Uveitis is an independent risk factor for developing stroke among patients with AS irrespective of the listed clinical variables,” the team concluded. “When encountering uveitis in patients with AS, clinicians should keep in mind the cerebrovascular risk, especially in those with underlying comorbidities.”
“Further prospective [forward in time] studies are still needed to clarify the mechanisms between uveitis and stroke in patients with AS,” the team wrote.