Initial serum thyroid peroxidase antibodies and long-term outcomes in SREAT

To quantify clinical outcome in patients with steroid-responsive encephalopathy and associated autoimmune thyroiditis (SREAT) after the acute phase and explore potential associations of initial serum thyroid peroxidase antibody titers (TPO-Abs) with outcome.

Retrospective chart review of patients diagnosed with SREAT between 01/2005 and 05/2014 in a tertiary care center and followed in an affiliated autoimmune outpatient clinic. Outcome was quantified using the extended Glasgow Outcome Scale (GOS-E). We calculated Pearson's correlation coefficients to quantify associations with clinical outcome at follow-up.

Among 134 patients with encephalopathy of unknown etiology, we identified 13 patients diagnosed with SREAT. In two patients, the diagnosis was revised at subsequent hospitalization (NMDA-R encephalitis and adult-onset Still's disease). The median follow-up time was 11 months, and the median GOS-E was 6 (range 3-8). Higher serum TPO-Ab-titers correlated with more favorable outcomes (Pearson coefficient 0.65, P = 0.03).

A correlation between TPO-Ab-titers and outcome has not been reported previously and challenges the notion of a mere bystander role of TPO-Abs in SREAT.