Uveitis increases the risk of stroke among patients with ankylosing spondylitis: A nationwide population-based longitudinal study

Unraveling the connection: Uveitis prevalence and risk factors in psoriasis patients - a population-based study

The association between uveitis and spondyloarthropathy (SpA)-related conditions is well-established. However, evidence describing the link between uveitis and psoriasis, and psoriasis without concomitant SpA-related conditions is scarce and conflicting. This large-scale population-based study sought to describe the prevalence and features of uveitis among psoriasis patients in Israel as well as investigating the risk for uveitis in different subgroups of psoriasis patients compared to the general population. We conducted a retrospective study utilizing the electronic database of the Meuhedet Health Maintenance Organization. The study included all patients diagnosed with psoriasis between 2000 and 2020, each patient was matched with four controls based on age, sex, place of residence, and index date. Logistic regression models were employed to assess the association between psoriasis and uveitis while adjusting for the presence of SpA-related conditions. A total of 61 003 psoriasis patients and 244 012 matched controls were included. The prevalence of uveitis was 1.3% versus 1.1% respectively (OR  1.12; 95% CI 1.10-1.30; p < 0.001). When adjusting to psoriasis severity, concurrent SpA, and psoriasis treatment no significant association was found. The rates of uveitis among psoriasis patients with concurrent SpA-related conditions was 3.2% compared to 1.4% in controls without psoriasis or SpA (OR 2.38; 95% CI 2.00-2.83; p < 0.001), while in psoriasis patients without SpA, the rate of uveitis was 1.0% and was similar to controls. Although crude rates of uveitis were higher in patients with severe psoriasis compared to mild psoriasis (2.1% vs. 1.1%), after adjustment, no significant association compared to controls was found in either group. Our findings suggest that the positive association between psoriasis and uveitis is primarily mediated by the coexistence of other SpA-related conditions. These findings imply the presence of a shared pathogenetic mechanism and set the direction for a phenotypic-targeted screening strategy.

Validation of diagnosis algorithms for ankylosing spondylitis in claim-based database

BACKGROUND

Claims-based algorithms using International Classification of Diseases (ICD) codes have become a common approach for researchers to define ankylosing spondylitis (AS) in studies. To address potential misclassification bias caused by the claim-based algorithms, we conducted the current study to validate whether these algorithms of medical claims could accurately represent AS diagnoses.

METHODS

Patients diagnosed with AS based on ICD codes were retrieved from the electronic medical records database at a Taiwanese medical center (Chung Shan University Hospital, Taiwan). After random sampling and stratification based on age and sex, the medical information of participants was appraised based on the 2009 ASAS guideline to evaluate the actual status of ICD codes claim-based AS patients. Positive predict values (PPV) of different algorithms of ICD codes were also calculated.

RESULTS

Within the 4160 patients with claim-based AS diagnosis, 387 eligible patients were finally included in the study design after random sampling. The PPV of the diagnostic algorithm of having at least 4 outpatient or 1 inpatient ICD record was 72.77 (95% CI, 66.79-78.75), whereas the PPV increased to 85.64 when the diagnoses were restricted to be made by rheumatologists (95% CI, 80.53-90.74).

CONCLUSIONS

While performing database studies, researchers should be aware of the low PPV of specific algorithms when defining AS. Algorithms with higher PPV were recommended to be adopted to avoid misclassification biases.