Study reveals risk factors for TB uveitis treatment failure
The presence of vitreous haze, snow banking, and choroidal involvement is associated with an increased risk of antitubercular treatment failure in patients with tubercular (TB) uveitis, according to research by the COTS-1* Study Group.
This retrospective study included 801 patients (mean age 40.5 years, 51.6 percent male, 73.6 percent Asian) treated for TB uveitis with antitubercular therapy between 2004 and 2014 from 25 centres worldwide including Tan Tock Seng Hospital and Singapore National Eye Centre, Singapore. Patients were followed up for at least 1 year. About 75 percent of patients had no history of systemic TB.
Almost 59 percent of patients had bilateral involvement, and posterior uveitis was the most common form of uveitis, affecting 36.3 percent (n=452) of 1,249 eyes.
Treatment failure, defined in this study as persistent or recurrent inflammation within 6 months of antitubercular therapy completion, inability to reduce oral or topical corticosteroid therapy to <10 mg/day or <2 drops/day, respectively, and/or recalcitrant inflammation requiring corticosteroid-sparing immunosuppressive therapy, occurred in 12.7 percent of patients (n=102).
Patients with vitreous haze had a significantly higher risk of treatment failure than those without (adjusted hazard ratio [adjHR], 2.98, 95 percent confidence interval [CI], 1.50–5.94; p=0.002). [JAMA Ophthalmol 2017;doi:10.1001/jamaophthalmol.2017.4485]
Other factors that were significantly associated with treatment failure were presence of snow banking (adjHR, 3.71, 95 percent CI, 1.18–11.62; p=0.02) and choroidal involvement (adjHR, 2.88, 95 percent CI, 1.22–6.78; p=0.02).
There were 24 cases with these signs, of which 91.7 percent (n=22) had panuveitis.
“The risk of [treatment failure] increases significantly with the presence of these three clinical features,” said the researchers. “[P]atients with panuveitis having vitreous and choroidal involvement had a higher risk of treatment failure,” they said.
“[O]cular TB often precedes symptomatic evidence of systemic TB,” said the researchers. “[The lack of comprehensive clinical information and diagnosis guidelines may] lead to delayed and even missed diagnoses, resulting in suboptimal clinical outcomes,” said the researchers.
According to Dr Russell N. Van Gelder from the University of Washington School of Medicine in Seattle, Washington, US, TB uveitis is a challenging condition, mainly due to “the lack of a gold standard diagnostic test”.
“[T]his study strongly suggests that most patients in endemic areas with presumed TB uveitis will have their uveitis resolve if treated with antitubercular therapy, with or without concomitant corticosteroids,” he said in a commentary. [JAMA Ophthalmol 2017;doi:10.1001/jamaophthalmol.2017.3514]
“The work ahead is to determine which patients truly have TB uveitis, to determine the optimal regimen for treatment, and to determine the predictors of outcome, particularly in the developing world,” he said, calling for large registry or prospective studies to achieve this goal.
The researchers acknowledged that the retrospective study design and lack of data on drug resistance were limitations, as well as the potential for over- or misdiagnosis as reasons for the poor outcomes in this study.
The lack of standardization in TB treatment regimen may have also impacted the findings, said Van Gelder.