The relationship between C-RP and delirium and its severity
The May International Psychogeriatrics Article of the Month is entitled ‘The association between C-reactive protein and delirium in 710 acute elderly hospital admissions’ by C.W. Ritchie, T.H. Newman, B. Leurent and E.L. Sampson.
Delirium is a common but poorly understood condition that primarily affects elderly patients; it is defined as having an acute onset and fluctuating course with deficits in attention, arousal state and perception and is associated with poor outcomes. The burden delirium places on the healthcare system will only increase as the ageing population grows, which means improvements in prediction, diagnosis and management are necessary. Whilst peripheral inflammation is a recognized precipitant of delirium, and evidence supports a neuroinflammatory basis, the role that the inflammatory marker C-reactive protein (C-RP) plays has not been defined. C-RP is regularly measured and is raised in many conditions which are associated with delirium however studies investigating C-RP’s relationship with delirium show contrasting results.
Our study took a large population of elderly patients who were admitted to hospital after presenting acutely and investigated the relationship between C-RP and delirium. Published in the May edition of International Psychogeriatrics the article describes the finding that C-RP was associated with delirium independent of other risk factors but not with delirium severity. On sub-group analysis this association remained in those patients who suffered musculoskeletal problems such as fractures and traumatic injuries. To our knowledge this was the largest study to date which investigated this relationship in a general elderly population.
These observations suggest that C-RP may represent a major factor in the genesis of delirium secondary to musculoskeletal damage. Additionally C-RP could act as a marker for current or incipient delirium and as such may form part of a risk score to aid recognition of at risk patients. Importantly it must be noted that longitudinal studies are necessary in order to establish a timeline to this relationship.
Furthermore this study adds weight to the neuroinflammatory hypothesis underlying delirium genesis and proposes that whilst C-RP may be important in musculoskeletal cases it is unlikely to be part of a unifying pathway leading to the common end point that is delirium. Future studies should investigate this relationship as well as other inflammatory mediators to further our understanding of delirium.