Table 2.

A summary of the anti-NMDAR autoAb tests done with our optimized approach for patients suspected of anti-NMDAR-related autoimmune encephalopathy.

Blood anti-NMDAR test results	Number of blood samples tested*	Number of CSF samples tested*	Number of CSF results matched to blood results#	%CSF-blood result matches	Number of double-stain tests performed
Positive**	37	20	17	85% (17/20)	5
initial titer 1:10	17	9	8	89% (8/9)	1
initial titer 1:32	13	4	3	75% (3/4)	1
initial titer 1:100	4	4	3	75% (3/4)	1
initial titer 1:320	3	3	3	100% (3/3)	2
Negative	39	8	8	100% (8/8)	2

^*All patients suspected of anti-NMDAR encephalitis or referred by other hospitals were first tested with blood samples using our modified protocol based on EUROIMMUN IIFT (as outlined in Figure 7). Suspected patients presenting milder symptoms (e.g., predominantly psychiatric presentation) did not usually provide CSF samples, unless their blood test results later suggested a likelihood for the disease. So the number of CSF testing was lower than that of blood testing for the negative and lower titer groups.

^**The initial titer was generally determined with the blood sample retrieved when a patient was first suspected of anti-NMDAR encephalitis or referred by other hospitals. We only provide positive or negative findings for CSF samples.

^#The three cases that show discordance between blood and CSF test results were all due to negative CSF findings but positive blood findings.