Association between major surgical admissions and the cognitive trajectory: 19 year follow-up of Whitehall II cohort study

Abstract

Objective: To quantify the association between major surgery and the age related cognitive trajectory.

Design: Prospective longitudinal cohort study.

Setting: United Kingdom.

Participants: 7532 adults with as many as five cognitive assessments between 1997 and 2016 in the Whitehall II study, with linkage to hospital episode statistics. Exposures of interest included any major hospital admission, defined as requiring more than one overnight stay during follow-up.

Main outcomes measures: The primary outcome was the global cognitive score established from a battery of cognitive tests encompassing reasoning, memory, and phonemic and semantic fluency. Bayesian linear mixed effects models were used to calculate the change in the age related cognitive trajectory after hospital admission. The odds of substantial cognitive decline induced by surgery defined as more than 1.96 standard deviations from a predicted trajectory (based on the first three cognitive waves of data) was also calculated.

Results: After accounting for the age related cognitive trajectory, major surgery was associated with a small additional cognitive decline, equivalent on average to less than five months of aging (95% credible interval 0.01 to 0.73 years). In comparison, admissions for medical conditions and stroke were associated with 1.4 (1.0 to 1.8) and 13 (9.6 to 16) years of aging, respectively. Substantial cognitive decline occurred in 2.5% of participants with no admissions, 5.5% of surgical admissions, and 12.7% of medical admissions. Compared with participants with no major hospital admissions, those with surgical or medical events were more likely to have substantial decline from their predicted trajectory (surgical admissions odds ratio 2.3, 95% credible interval 1.4 to 3.9; medical admissions 6.2, 3.4 to 11.0).

Conclusions: Major surgery is associated with a small, long term change in the average cognitive trajectory that is less profound than for major medical admissions. The odds of substantial cognitive decline after surgery was about doubled, though lower than for medical admissions. During informed consent, this information should be weighed against the potential health benefits of surgery.

Fig 1

Inclusion of participants from Whitehall II cohort study and hospital episode statistics. Numbers in parentheses refer to participants, not events. *Medical admissions include stroke. Admissions after the final cognitive assessment are not included as cognitive impact cannot be assessed. †Participants with stroke excluded from this analysis

Fig 2

Age and duration of follow-up for surgical operations and medical admissions. (Top panel) Participant age at time of event. (Bottom panel) Cumulative follow-up duration of cognitive assessments after major events. Counts reflect both number of admissions and number of cognitive assessments and therefore each assessment is counted once for each preceding event and there are multiple assessments per participant

Fig 3

Predicted cognitive trajectory before and after admission events. Trajectories represent means and 95% credible intervals for a hypothetical average patient with a surgical or medical admission or stroke occurring at the median age (67.4 years) for first admission (or no admission). Shaded region reflects credible intervals for the impact of surgical admissions, medical admissions, and stroke rather than population variability in baseline and decline, because random effects coefficients and residuals are ignored for these prediction intervals (ie, they reflect the trajectory of a hypothetical average participant rather than the family of trajectories for a hypothetical population)