Ocular sarcoidosis diagnosis can be challenging in children. The correct interpretation of serum ACE levels is essential to guide the diagnostic approach and the need for complementary tests that could be invasive and have a low rentability in children. The aim of the study was to evaluate the diagnostic value of serum ACE for the diagnosis of paediatric sarcoid uveitis.
Observational, retrospective, multicentre study of patients under the age of 18 with chronic or severe uveitis between 2013 and 2019. ACE higher than 112 U/L was considered elevated. Sensitivity (Se), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (+LR) and negative likelihood ratio (-LR) were calculated.
Serum ACE value was available in 105 children out of the 150 patients included in the study. Ocular sarcoidosis was diagnosed in nine patients. Among them only two patients had elevated serum ACE levels. Among the 96 patients with non-sarcoid uveitis, 12 had elevated serum ACE levels. Diagnostic values were as follows: Se = 22.2%, Sp = 87.5%, PPV = 14.3%, NPV = 92.3%, +LR = 1.8, -LR = 0.9.
False positives were frequent. That could be explained by the physiological elevation of serum ACE levels in children. NPV was higher than 90%. However, seven children with confirmed sarcoid uveitis had normal ACE levels, showing a NPV of low clinical interest. Likelihood ratios, which are independent of disease prevalence, were low in our cohort. This confirmed the high risk of incorrectly concluding that there was no ocular sarcoidosis when ACE levels were within normal limits. Serum ACE has poor diagnostic value for the diagnosis of paediatric sarcoid uveitis. Its interest in the aetiological assessment of paediatric uveitis must be questioned.