This is the first study to explore the association between preoperative cognitive frailty and adverse outcomes in elderly patients undergoing surgery under general anesthesia. Our prospective study has found that cognitive frailty is an independent risk factor for adverse postoperative outcomes in elderly patients undergoing general anesthesia. Besides, elderly patients with preoperative cognitive frailty have poor postoperative recovery, which includes a high incidence of postoperative complications, mobility disability and prolonged hospital stay.
In our study, the prevalence of preoperative cognitive frailty in elderly patients undergoing elective orthopedic or abdominal general anesthesia surgery was 17.79%, which was higher than the results of Ma[25], Brigola[26], and Yu[27] in the community elderly (2.9%, 10.9%, 8.7%). This may be due to the lack of uniform diagnostic criteria and assessment methods for cognitive frailty, as well as significant differences in the different study designs. In addition, some scholars have found that the prevalence of cognitive frailty in clinical settings can be as high as 37.40%-50.9%[28, 29]. It may be attributed to the impact of the disease on elderly patients undergoing elective general anesthesia surgery, resulting in a decrease in physiological reserve, low immunity and stress response ability, which increases the incidence of cognitive frailty.
We found that cognitive frailty was an independent risk factor for postoperative complications in elderly patients undergoing general anesthesia. Multivariate logistic regression analysis showed that the elderly in the preoperative cognitive frailty group were more likely to have postoperative complications and CD3 complications than those in the only frailty group or the only cognitive impairment group. A review has shown that physical frailty and cognitive dysfunction have similar pathophysiological mechanisms, such as mitochondrial dysfunction and oxidative stress, inflammatory response, and endocrine disorders[30]. Frailty is a geriatric syndrome resulting from age-related cumulative decline across multiple physiologic systems, impaired homeostatic reserve, and reduced capacity to resist stress[31]. Prior work has shown that frail is an important factor in risk stratification and outcome prediction[32, 33], and it was associated with an increased risk for postoperative complications, length of stay health care burdens, and other survival outcomes[34–36]. Cognitive dysfunction refers to different degrees of cognitive impairment stemming from various causes, and it is also known to be associated with increased risk of adverse events post operative, complications of coexisting medical conditions, decreased mobility, increased healthcare utilization, and substantial caregiver burden[37, 38]. Cognitive frailty is the superposition of the above two. The coexistence of the two can accelerate the decline of physical and cognitive functions and form a vicious cycle, bringing more serious cumulative effects on the body[39, 40]. This is consistent with the results of the analysis in this study, showing that the elderly with cognitive frailty had the highest risk of adverse postoperative outcomes compared with the purely frailty or purely cognitive impairment group.
Different from previous research[38, 41, 42], multivariate logistic regression analysis in our study revealed no significant association between frailty and cognitive impairment with postoperative mobility disability or prolonged hospital stay. This could be attributed to the categorization of different states of frailty and cognitive impairment into four distinct groups, where patients with cognitive frailty were no longer classified into the frailty or cognitive impairment groups, resulting in a relatively lower incidence rate of frail. Additionally, it may also be influenced by the use of different assessment scales for frailty and cognitive impairment.
A substantial amount of research has found that association between cognitive frailty in community-dwelling older adults and various adverse outcomes[43–45]. Many communities have incorporated cognitive frailty into their assessments. However, due to the unclear impact of preoperative cognitive frailty on postoperative recovery in the elderly, many countries have not yet included it in clinical practice assessments. Our study indicates that preoperative cognitive frailty is associated with adverse postoperative outcomes in elderly patients. It suggests that healthcare professionals need to pay more attention to cognitive frailty in elderly patients. Besides, it also provides clinical evidence for early screening and intervention for cognitive frailty.
One strength of this study is that the research object was elderly patients undergoing general anesthesia surgery. This is the first study to investigate the relationship between preoperative cognitive frailty and adverse outcomes in elderly patients undergoing elective orthopedic or abdominal general anesthesia surgery. Previous studies on cognitive frailty have mainly focused on the community, and there are few studies on the elderly hospitalized, especially the elderly undergoing surgery. The elderly are more vulnerable to stressors due to their reduced physiological reserves and decreased ability to maintain balance in the body, and surgery as a major physical and psychological blow will deplete the elderly 's limited reserves and lead to decompensation[46]. In addition, the type of the surgery included in this study focused on the high-risk surgery group rather than extensively assessing the risk of different procedures. Due to orthopedic and abdominal general anesthesia surgery as the most common surgical procedures in the elderly. So, this study selected the higher-risk surgical methods in these two types of surgery to explore the impact of cognitive frailty on elderly patients undergoing general anesthesia surgery.
There are some limitations to our study. First, this is a single-center study, which limits the generalizability of its conclusions. Second, unmeasured confounders may exist because of the observational nature of this research. Third, some of the self-reported parameters are subjective in nature and may introduce informational bias. Fourth, although the cognitive frailty group had a higher risk of CD3 complications (15.6% vs. 0%) than the fit group, the small number of patients in each group and low incidence rate of adverse outcomes may limit the statistical power in detecting the significance of the in-group differences in this study. Finally, the long term effects of cognitive frailty on postoperative recovery in elderly patients were not observed. Hence, further multi-centre, large sample trials are needed to investigate the long-term impacts of cognitive frailty on postoperative recovery in elderly patients and explore the effective treatment for cognitive frailty.