In an in vitro study, it was found that aspirin might decrease neopterin production and tryptophan degradation. The aim of the present study was to evaluate the possible association between aspirin use and mean neopterin and tryptophan levels in patients with and without a delirium and whether the use of aspirin is associated with a decreased prevalence of delirium. Neopterin and tryptophan levels were determined previously in acutely ill admitted patients aged ≥65 years. The possible influence of aspirin on mean levels of neopterin and tryptophan was investigated with univariate analysis of variance in adjusted models. Eighty-three patients were included; 22 had a delirium. In patients without a delirium (no aspirin (n = 31) versus aspirin (n = 27)), mean neopterin levels were 47.0 nmol/L versus 43.6 nmol/L (p = 0.645) and tryptophan levels were 33.1 µmol/L versus 33.9 µmol/L (p = 0.816). In patients with a delirium (no aspirin (n = 13) versus aspirin (n = 9)), mean neopterin levels were 77.8 nmol/L versus 71.1 nmol/L (p = 0.779) and tryptophan levels were 22.4 µmol/L versus 27.3 µmol/L (p = 0.439). No difference was found in the distribution of aspirin users between patients with and without a delirium. In this study, we found that the use of aspirin had no significant effect on mean levels of neopterin and tryptophan. However, the raw data suggest that there might be a potential influence in patients with a delirium. Aspirin use was not associated with a decreased prevalence of delirium.
Keywords: NSAIDs; aspirin; delirium; neopterin; tryptophan.