Autoimmune encephalitis screening cost-effective for those with first-episode psychosis

Routine screening for autoimmune encephalitis among patients with first-episode psychosis appeared cost-effective in the United States, according to study results published in Journal of Clinical Psychiatry.

“There are few guidelines and limited published evidence to help psychiatrists decide what tests to order to identify medical causes of first-episode psychosis,” Eric L. Ross, MD, of the department of psychiatry at McLean Hospital in Massachusetts, told Healio Psychiatry. “Deciding when to test for autoimmune encephalitis can be particularly challenging, as the autoantibody panels used to test for the condition are quite expensive and identifying the patients who are at highest risk can be difficult. To address this challenge, we aimed to determine if it would be cost-effective to routinely test for autoimmune encephalitis in all patients with first-episode psychosis.”

Ross and colleagues drew model parameters from prior published literature, and these included the prevalence of neuronal autoantibodies in first-episode psychosis, serum autoantibody panel cost, remission probability with antipsychotics and remission probability with immunotherapy for individuals diagnosed with autoimmune encephalitis. Quality-adjusted life years (QALYs), costs and incremental cost-effectiveness ratios served as outcomes. The researchers defined cost-effectiveness using incremental cost-effectiveness ratio thresholds of $50,000/QALY to $150,000/QALY.

Eric L. Ross

Results showed mean QALY gains linked to routine screening of 0.008 among all patients and 0.174 among those with neuronal autoantibodies. Ross and colleagues noted mean cost increases of $780 from a societal perspective and $1,150 from a health care sector perspective, which resulted in incremental cost-effectiveness ratios of $99,330/QALY and $147,460/QALY, respectively. Upon incorporation of joint input data uncertainty, the likelihood routine screening had an incremental cost-effectiveness ratio of $150,000/QALY or less was 55% from a societal perspective and 37% from a health care sector perspective. The effectiveness of immunotherapy relative to antipsychotics was the model parameter that contributed most greatly to overall uncertainty.

“Overall, our findings suggest that testing for autoimmune encephalitis in every patient with first-episode psychosis would be reasonable from a cost-effectiveness perspective,” Ross said. “However, there was a lot of uncertainty in the results of our analysis, and because of this we can’t say definitively that routine testing is cost-effective. Based on these results, I’ve been telling my colleagues the following: it’s not wrong to test for autoimmune encephalitis in any patient with first-episode psychosis, but there’s not enough evidence yet for me to say that it’s imperative to test.”