Delirium common but poorly understood in older chemotherapy patients

Delirium appears to be relatively common among older cancer patients receiving chemotherapy, developing in around 10 percent of this population, a recent meta-analysis has found. However, due to gaps in the literature, potential risk factors and interventions remain unestablished.

A systematic search of the databases of Medline, Embase, PsycINFO, CINAHL Plus, and Cochrane Central yielded 1,272 full-text articles for review. Of these, 19 used an acceptable diagnostic standard for delirium and were included in the present analysis.

The cumulative sample included 1,280 patients with mean or median ages ranging from 45 to 68.4 years. Quality assessment on 18 cohort studies using the Newcastle-Ottawa Scale resulted in mean score of 4.11 out of 9 points, suggesting that there were significant limitations to the design; the remaining clinical trial had a high risk of performance and detection bias.

Delirium incidence in the studies ranged from 0 percent to 51 percent, with an average rate of 9 percent. Heterogeneity of evidence was substantial, but none of the subgroup analyses conducted were able to isolate potential sources.

The low number of studies may have contributed to this ambiguity. For example, only two studies constructed multivariable models to assess the interaction of age and delirium. On the other hand, while five studies looked at potential risk factors, only nine such factors were examined in at least two studies. Nevertheless, pooled analysis revealed that dehydration, metabolic abnormalities, and chemotherapy that crosses the blood-brain barrier all possibly contributed to delirium in this population.

There were no identified studies that examined interventions, preventions, and treatments for delirium in older chemotherapy patients.