Correlation of Preoperative Global Olfactory Function With Frailty, Perioperative Neurocognitive Disorders and Mortality

Correlation of Preoperative Global Olfactory Function With Frailty, Perioperative Neurocognitive Disorders and Mortality

Correlation of Preoperative Global Olfactory Function With Frailty, Preoperative Cognitive Status, Postoperative Neurocognitive Disorders and Mortality Following Elective Surgery

The aims of this research project are to evaluate whether global olfactory impairment is a reliable indicator of preoperative frailty and cognitive impairment, and whether it may predict postoperative neurocognitive disorders, morbidity and mortality in a population of older patients scheduled for elective intermediate- to high-risk elective surgery. We will measure preoperative global olfactory function (threshold, discrimination, identification) and evaluate whether olfactory impairment predicts preoperative frailty (using the Edmonton Frail Scale, the Clinical Frailty Scale and handgrip strength) and postoperative complications and mortality. We will address the question whether preoperative olfactory impairment may be associated with a preoperative cognitive impairment (through a neuropsychological test battery) and whether it may predict a decrease in postoperative neurocognitive function.

Olfactory impairment increases with age, affecting more than 50% of the population aged between 65 and 80 years old. Recently, many studies have demonstrated a strong association between olfactory impairment and overall mortality risk. At the moment, the underlying physiopathology linking olfactory impairment to mortality remains unknown and only putative mechanisms are suggested. Among them, accelerated physiological brain aging seems to be involved, making olfactory decline a possible marker of frailty. To date, only a few studies (mostly using subjective olfactory assessment) investigated the potential relationship between olfactory impairment and frailty. Moreover, neurodegenerative diseases, through cognitive dysfunction, seem likely to represent a second mechanism potentially underlying the link between olfactory impairment and mortality. Surgery, and more broadly the perioperative period, remains a major source of morbidity and mortality. Meanwhile, the average age of the surgical population continues to rise, making preoperative risk assessment an essential step in order to detect the most vulnerable patients. Yet, it is well-known that frailty is predictive of complications and mortality and that preoperative cognitive impairment is associated with postoperative neurocognitive disorders. The first objective of this research project is thus to evaluate global olfactory function of preoperative older surgical patients in light of an assessment of their frailty and cognitive status. Frailty will be tested with the Edmonton Frail Scale, the Clinical Frailty Scale and handgrip strength. Cognitive function will be tested through a neuropsychological test battery preoperatively and postoperatively. The second and third objectives are to correlate preoperative olfactory function with, on the one hand, postoperative neurocognitive disorders, and on the other hand, postoperative morbidity and mortality.

Frailty, Perioperative/Postoperative Complications, Olfactory Disorder, Neurocognitive Disorders, Postoperative Cognitive Dysfunction

Olfactory function will be evaluated through the Burghart Sniffin' Sticks test which is a validated psychophysical testing method. Sniffin' Sticks test is based on pen-like odor dispensing devices that will be presented to the patients. The extended version of this test will be used and consist of three tests of olfactory function, namely tests for odor threshold, odor discrimination and odor identification.

The Edmonton Frail Scale (EFS) involves nine domains of frailty : functional performance, cognitive function, general health, functional independence, social support, used medications, nutrition, mood and continence. It has been validated with respect to comprehensive geriatric assessment and to other screening tools related to frail state. EFS test is considered most appropriate for use in routine preoperative screening and only requires 5 minutes.

The Clinical Frailty Scale (CFS) uses clinicians' judgement to evaluate frailty. It comprises assessment of specific domains including comorbidity, function, and cognition. Score ranges from 1 (very fit) to 9 (terminally ill).

Patients will undergo a neuropsychological test battery preoperatively and postoperatively. This test consists of a battery of psychometric assessments with the ability to objectively assess specific cognitive domains such as attention, executive function, learning and memory, language, perceptual-motor, or social cognition.

Analysis of the prevalence of frailty assessed by the Edmonton Frail Scale according to preoperative olfactory function (Burghart Sniffin' Sticks extended test).

Analysis of the prevalence of frailty assessed by the Clinical Frailty Scale according to preoperative olfactory function (Burghart Sniffin' Sticks extended test).

Analysis of the incidence of postoperative complications according to preoperative olfactory function (Burghart Sniffin' Sticks extended test).

Analysis of the incidence of mortality according to preoperative olfactory function (Burghart Sniffin' Sticks extended test).

Analysis of the prevalence of neurocognitive disorder (assessed through a neuropsychological test battery) according to preoperative olfactory function.

Analysis of the incidence of postoperative neurocognitive disorder (assessed through a neuropsychological test battery) according to preoperative olfactory function.

Comparison of preoperative and postoperative global olfactory function (both assessed through Burghart Sniffin' Sticks extended test)

Inclusion Criteria: Scheduled for elective surgery (covering orthopedic, spine and cardiovascular surgery) Exclusion Criteria: History of neurological or psychiatric disorder History of severe head trauma History of olfactory trouble or chronic rhinosinusitis or sinus surgery

Pinto JM, Wroblewski KE, Kern DW, Schumm LP, McClintock MK. Olfactory dysfunction predicts 5-year mortality in older adults. PLoS One. 2014 Oct 1;9(10):e107541. doi: 10.1371/journal.pone.0107541. eCollection 2014.

Schubert CR, Fischer ME, Pinto AA, Klein BEK, Klein R, Tweed TS, Cruickshanks KJ. Sensory Impairments and Risk of Mortality in Older Adults. J Gerontol A Biol Sci Med Sci. 2017 May 1;72(5):710-715. doi: 10.1093/gerona/glw036.

Van Regemorter V, Hummel T, Rosenzweig F, Mouraux A, Rombaux P, Huart C. Mechanisms Linking Olfactory Impairment and Risk of Mortality. Front Neurosci. 2020 Feb 21;14:140. doi: 10.3389/fnins.2020.00140. eCollection 2020.

Somekawa S, Mine T, Ono K, Hayashi N, Obuchi S, Yoshida H, Kawai H, Fujiwara Y, Hirano H, Kojima M, Ihara K, Kim H. Relationship between Sensory Perception and Frailty in a Community-Dwelling Elderly Population. J Nutr Health Aging. 2017;21(6):710-714. doi: 10.1007/s12603-016-0836-5.

Laudisio A, Navarini L, Margiotta DPE, Fontana DO, Chiarella I, Spitaleri D, Bandinelli S, Gemma A, Ferrucci L, Incalzi RA. The Association of Olfactory Dysfunction, Frailty, and Mortality Is Mediated by Inflammation: Results from the InCHIANTI Study. J Immunol Res. 2019 Feb 20;2019:3128231. doi: 10.1155/2019/3128231. eCollection 2019.

Harita M, Miwa T, Shiga H, Yamada K, Sugiyama E, Okabe Y, Miyake Y, Okuno T, Iritani O, Morimoto S. Association of olfactory impairment with indexes of sarcopenia and frailty in community-dwelling older adults. Geriatr Gerontol Int. 2019 May;19(5):384-391. doi: 10.1111/ggi.13621. Epub 2019 Apr 9.