Delirium is a syndrome characterized by an acute disturbance in attention, awareness, arousal, and cognition from baseline and remains the most common postoperative complication in adults 65 years of age and older (BMC Med 2014;12:141; Lancet 2014;383;911-22). The cost of postoperative delirium (POD) and longer-term cognitive decline associated with the condition is enormous from a monetary, individual, and societal perspective. According to Gou et al., following major elective surgery, the total annual cost of POD to the U.S. health care system is $32.9 billion (JAMA Surg 2021;156:430-42). Moreover, POD has been associated with long-term cognitive decline, and a recent qualitative study reported persistent negative impacts on psychological well-being in individuals who experienced POD (JAMA Neurol 2020;77:1373-81; Anesth Analg 2023;136:1174-81).
Since its launch in 2015, the ASA Perioperative Brain Health Initiative (ASA BHI) has been an important patient safety initiative focusing on preserving brain function in adults at risk for cognitive decline following surgery and anesthesia (asamonitor.pub/2UcqKDd). One recommendation from the ASA BHI – which aligns with expert recommendations from the American Geriatric Society and American College of Surgeons, American Delirium Society, and the American Society for Enhanced Recovery and the Perioperative Quality Initiative – is to perform preoperative cognitive screening routinely in older adults prior to surgery and anesthesia (asamonitor.pub/2UcqKDd; Br J Anaesth 2019;123:464-78; J Am Coll Surg 2012;215:453-66; Eur J Anaesthesiol 2017;34:192-14; Anesth Analg 2018;127:1406-13). The ASA BHI has further developed the Perioperative Diagnostic Excellence in the Older Adult: An Educational Initiative, which provides tools for training anesthesia professionals on performing basic cognitive screenings and identifying frail patients (Perioperative Diagnostic Excellence in the Older Adult: An Educational Initiative, 2022). The basis for this screening recommendation is that preexisting cognitive decline is quite common in older adults, occurring in 37% of these patients presenting for elective surgery versus 50% for emergency surgery, and baseline cognitive impairment is one of the strongest predictors for postoperative delirium (J Clin Anesth 2022;76:110574; Anesthesiology 2017;127:765-74; J Am Geriatr Soc 2023;71:227-34).
Furthermore, over the last decade, there has been an increase in the development of bundles of perioperative care designed to mitigate the incidence and severity of POD. These bundles are informed on evidence-based recommendations and preliminary research findings that show some potential benefit (e.g., perioperative dexmedetomidine administration, EEG-guided depth of sedation monitoring) but warrant further investigation (Anaesthesia 2022;77:92-101). The delirium preventative bundles include risk stratification with frailty and cognitive screening and nonpharmacological strategies such as frequent orientation, promotion of sleep hygiene, accessibility to sensory aids such as eyeglasses and hearing aids, early mobilization, and avoidance of potentially inappropriate medications (N Engl J Med 1999;340:669-76; J Am Geriatr Soc 2001;49:516-22; J Am Geriatr Soc 2009;57:2029-36; Am J Crit Care 2016;25:535-44). Interestingly, nonpharmacological strategies have been demonstrated to significantly reduce the incidence of delirium by up to 40% (JAMA Intern Med 2015;175:512-20). The implementation of strategies to mitigate the incidence and severity of POD is of vital importance, as there is now strong scientific evidence suggesting that the development of POD is associated with long-term cognitive impairment, including a downward cognitive trajectory in patients after severe POD that outpaces individuals diagnosed with dementia (J Alzheimers Dis 2018;61:347-58).
Despite evidence that the delirium mitigation strategies mentioned here are effective, there is also evidence that the implementation of these important patient safety measures has been fraught with significant challenges. For example, a recent study of 245 patients undergoing spine surgery demonstrated that – despite the development of a geriatric cognitive care bundle for older surgical adults, which included rapid restoration of aids to reverse sensory deficits, sleep hygiene, frequent patient orientation with family participation, and order sets to avoid potentially inappropriate medications – 45% of patients didn’t receive delirium preventative orders (J Am Geriatr Soc 2024;72:2133-9). Furthermore, 43% still received potentially inappropriate medications, while sleep orders were absent in nearly half of the patients. At least one element of the delirium preventive interventions was missing in 70% of patients (J Am Geriatr Soc 2024;72:2133-9). Interestingly, in this cohort of spine surgery patients, cognitive screening demonstrated that 40% had preexisting cognitive impairment. Given the significant association between preoperative cognitive impairment and POD, it is imperative that these assessments are performed in older adults and that those who are at high risk are further incorporated into delirium prevention pathways. Understanding what the barriers to implementation are and how to overcome them is still an underdeveloped area.
Additionally, there is evidence that even when preoperative cognitive screening is being routinely performed, there can be inequities in the implementation of this clinical practice (Anesth Analg 2024;139:903-11). Canales et al. recently observed that, although 80% of patients who were assessed in a preoperative clinic underwent cognitive screening, there was a significant difference in who was screened. Whereas 89% of English-speaking patients underwent preoperative Mini-Cog screening, only 58% of patients with a language-other-than-English preference underwent this screening. This despite the observation that the screening had significant risk stratification value in both groups. The odds of having POD in either English-speaking or language-other-than-English patients with a positive cognitive screen were similar: 3.5 and 3.9 times higher, respectively, versus having a negative cognitive screen (Anesth Analg 2024;139:903-11). Again, this highlights the fact that, even when interventions and practices to maintain optimal perioperative brain health are incorporated into clinical practice, problems remain with successful implementation.
Investigators have estimated that there is a 17-year lag for research findings to be translated into clinical practice (Yearb Med Inform 2000:65-70; J R Soc Med 2011;104:510-20). Despite evidence that preventative bundles are effective in decreasing the incidence of POD, considerable challenges remain in incorporating these strategies into perioperative medicine practice (N Engl J Med 1999;340:669-76; J Am Geriatr Soc 2001;49:516-22; J Am Geriatr Soc 2009;57:2029-36; Am J Crit Care 2016;25:535-44; J Am Geriatr Soc 2024;72:2133-9). Over the last several decades, the field of implementation science has rapidly grown to accelerate and optimize the application of research findings and evidence-based practices into clinical settings. Implementation science seeks to move evidence-based innovations into broader clinical practice (Psychiatry Res 2020;283:112376; Urogynecology 2023;29:307-12; Anesthesiol Clin 2018;36:1-15). Furthermore, implemenatation science actively intervenes to adjust the context in which these innovations are employed to facilitate and increase their clinical uptake (Psychiatry Res 2020;283:112376). A review of implementation science frameworks and models is beyond the scope of this article; however, an excellent resource for framing implementation science research questions can be found at the University of Washington Implementation Science Research Pathway and the NIH Implementation Science toolkit websites (Implement Sci 2015;10:53; asamonitor.pub/4hDgn1k; asamonitor.pub/4eydDQt).
There is currently a dearth of implementation science-focused models and frameworks in perioperative brain health research. Given that over the next decade the number of older adults presenting for surgery and anesthesia in the U.S. is expected to rapidly increase – as the number of those 65 years or older is expected to double by 2060 – there will be an increase in patients at risk for delirium and other forms of longer-term postoperative cognitive impairment (Ann Surg 2023;277:87-92; asamonitor.pub/40D1GFB). Therefore, the lack of implementation science-focused research in perioperative brain health represents a significant gap. There is an urgent need for more implementation science methodologies, especially during the design phase of clinical trials; otherwise, much research time, money, and effort will be wasted, and the perioperative safety of older adults further compromised.
We stand at an intersection where there is a need for implementation science-associated frameworks and models that can be pursued to better define the requisite change management principles required to increase the uptake of POD mitigation strategies and perioperative brain health best practices. It is no longer adequate just to evaluate clinical effectiveness in studies. Instead, to “move the needle,” future research in perioperative brain health must engage experts in implementation science to efficiently change clinical practice and policies that can lead to improved perioperative cognitive safety for older adults. The incorporation of a multidisciplinary approach that includes anesthesiologists, geriatricians, and implementation science experts would allow for a perspective that can adapt to the current times. In the next five to 10 years, we expect to see robust advancement in this area as we tackle these problems using a multidisciplinary patient-oriented approach, which will allow us to move the research into successful clinical integration and uptake.