Abstract
Purpose:
To characterize a county hospital-based uveitis population and to evaluate the utility of tuberculosis (TB) screening by means of calculated predictive values.
Methods:
In this retrospective study, the charts of 142 patient seen between August 2011 and August 2012 at the uveitis subspecialty clinic at the Los Angeles County + University of Southern California Hospital were reviewed for birthplace, laterality and major manifestation of uveitis, TB-screening test (purified protein derivative and interferon-gamma release assay), chest X-ray, ophthalmic imaging, TB-treatment history and response to treatment, and final diagnosis. Uveitis was presumed TB-related when patients showed favorable response to anti-TB therapy within 2 to 4 months of initiation. Posttest probabilities were determined using numbers derived from our patient population and Bayes’ theorem.
Results:
Tuberculosis-screening test was positive in 30 of 142 patients (21.1% of total population). Six patients (20% of TB-screening positive population) received a final diagnosis of TB-related uveitis: 1 definite TB uveitis by PCR in setting of systemic TB (3.3%), 4 presumed TB uveitis by response to anti-TB therapy (13.3%), and 1 systemic TB with presumed TB uveitis (3.3%). Foreign place of birth was the only risk factor that reached statistical significance yielding an odds ratio of 2.26 (95% confidence interval [CI], 1.00-5.13; P<0.01) if born in Mexico and 4.90 (95%CI, 1.74-13.83; P<0.01) if born in other foreign countries versus 0.12 (95% CI, 0.04-0.38; P<0.01) for U.S.-born patients. Bayesian analysis yielded a posttest probability of 17.2% (all patients) and 30.3% (foreign-born patients) for TB-related uveitis among uveitis patients with positive TB-screening. Negative predictive values of 98.8% (all patients) and 97.5% (foreign-born patients) were calculated for those patients with negative TB-screening.
Conclusions:
Tuberculosis screening plays an important role in high risk groups, such as immigrants from TB endemic regions.
Keywords: 745 uvea •
463 clinical (human) or epidemiologic studies: prevalence/incidence •
464 clinical (human) or epidemiologic studies: risk factor assessment