Hospitalisation and surgery: are there hidden cognitive consequences? Evidence from The Irish Longitudinal study on Ageing (TILDA).

ABSTRACT

Background: the dramatic shift in the global population demographic has led to increasing numbers of older people undergoing hospitalisation and surgical procedures. Objectives: to determine whether hospitalisation or hospitalisation with surgery under general anaesthesia is associated with poorer cognitive performance in adults over the age of 50. Methods: cognitive function in the domains of global cognition, memory and executive function was assessed in 8,023 individuals at waves 1 and 2 of The Irish Longitudinal Study on Ageing (TILDA), 2 years apart. Mixed-effects models were used to investigate the hypothesis after adjustment for risk factors for cognitive decline and potential confounders. Results: during the 12 months preceding wave 1, 472 participants were hospitalised (mean age 67.0, 54.9% female) and a further 560 participants (mean age 64.6, 52.1% female) were hospitalised and underwent surgery with general anaesthesia; 6,938 (mean age 63.5, 54.5% female) were not hospitalised. There was a 14% higher error rate (IRR[95% CI] = 1.14[1.06, 1.22]) in the MMSE in the hospitalisation group and a 6% higher error rate (IRR[95% CI] = 1.06[0.99, 1.13]) in the surgery group compared to those with no hospitalisation. Poorer cognitive performance in the memory tasks was evident in both hospitalisation and hospitalisation with surgery groups (immediate recall [95% CI] = -0.13 words[-0.22,-0.04] versus -0.13 words[-0.21,-0.04] and delayed recall -0.20 words[-0.33,-0.06] versus -0.20[-0.32, -0.07]) compared to those with no hospitalisation. Increased error in the time-based prospective memory task was observed in the hospitalisation group and the surgery group (OR[95% CI] = 1.32[1.08, 1.60] versus 1.29[1.07, 1.55]). Conclusion: hospitalisation and hospitalisation with surgery and general anaesthesia are associated with poorer global and domain specific cognitive performance.