Participants (n = 59) were free of clinical
dementia, age ≥ 70 years, and scheduled for elective total knee or hip
arthroplasties. Cerebrospinal fluid (CSF) was collected at the time of induction for
spinal anesthesia. CSF AD
biomarkers were measured by
enzyme-linked
immunosorbent assay (ELISA) (ADX/Euroimmun); cut points for
amyloid, tau, and neurodegeneration (ATN)
biomarker status were A = amyloid beta (Aβ)42 <175 pg/mL or Aβ42/40 ratio <0.07; T = p-tau >80 pg/mL; and N = t-tau >700 pg/mL.
Confusion Assessment Method (CAM) and CAM-Severity (CAM-S) were rated daily post-operatively for
delirium and
delirium severity, respectively.
RESULTS: Aβ42, tau, and p-tau mean pg/mL (SD) were 361.5 (326.1), 618.3 (237.1), and 97.1 (66.1), respectively, for those with
delirium, and 550.4 (291.6), 518.3 (213.5), and 54.6 (34.5), respectively, for those without
delirium. Thirteen participants (22%) were ATN positive.
Delirium severity by peak CAM-S [mean difference (95% confidence interval)] was 1.48 points higher (0.29-2.67), P = 0.02 among the ATN positive.
Delirium in the ATN-positive group trended toward but did not reach statistical significance (23% vs. 7%, p = 0.10). Peak CAM-S [mean (SD)] in the
delirium group was 7 (2.8) compared to no
delirium group 2.5 (1.3), but when groups were further classified by ATN status, an incremental effect on
delirium severity was observed, such that patients who were both ATN and
delirium negative had the lowest mean (SD) peak CAM-S scores of 2.5 (1.3) points, whereas those who were ATN and
delirium positive had CAM-S scores of 8.7 (2.3) points; other groups (either ATN or
delirium positive) had intermediate CAM-S scores.
DISCUSSION: The presence of AD
biomarkers adds important information in predicting
delirium severity. Future studies are needed to confirm this relationship and to better understand the role of AD
biomarkers, even in pre-clinical phase, in
delirium.