Association between Pre-operative frailty and Post-Operative Delirium and Cognitive dysfunction in elderly patients undergoing spinal surgery under general anaesthesia : A Prospective Observational Study.

INTRODUCTION

With advances in medical care and technology, the world is currently facing a growth in the aging population of above 60 years of age seen as a 56% rise from 901 million to a projected 1.4 billion between 2015 and 2030 (1), which is in turn associated with a rise in the comorbidities associated with the same. In India, compared to 1951 national survey when elderly population was 5.4%, there has been an increase up to 7.4% in the 2001 national survey. This rising trend seen in the average life span of the population is inadvertently associated with increase in incidence of pathologies and hence, demand for surgical procedures to manage them which in turn pushes health care system to deal with expectant comorbidities of old age to begin with in all these cases(2).

One of the most common pathologies seen in the aforementioned population is the presence of spinal conditions associated with both degenerative and traumatic pathologies. It has been observed from studies that there is a rise in the prevalence of degenerative spinal conditions with increasing age and that this is expected to rise with increase in population and life expectancy (3).

As we talk about the different comorbidities, elderly population is associated with risk of frailty and sarcopenia. Frailty is a geriatric syndrome rendering the patient more vulnerable to any kind of stressors and poor homeostatic reserve (4). Due to increased vulnerability to stress, physical frailty describes the impact of medical comorbidities on a patient’s overall state of health. In 2001, Fried et al defined frailty by the presence of three or more of the following criteria: unintentional weight loss, weakness as measured by grip strength, self-reported exhaustion, slow walking speed and low physical activity level. Sarcopenia is defined as loss of skeletal muscle and strength which causes age-related functional and physical impairment.

It is featured by a poor hand grip strength and slow walking pace. The similarity in the features associated with both frailty and sarcopenia reflects in their similar association with poor outcomes post-surgery like increased length of hospital stay, higher 30-day readmission rates and mortality(5).

Of the various morbidities noticed in elderly individuals after surgery, delirium, defined as disturbance in attention and awareness that develops over a short period of time, typically evolves within 72 hours following surgery(6,7,8). Makary et al. showed that preoperative frailty using the Fried criteria was associated with increased risk for postoperative complications for patients undergoing cardiac surgery like a higher risk of postoperative delirium (POD). POD is the most common postsurgical complication in older adults and occurs in 14%–60% of older surgical patients (9) with an incidence ranging from 5 to 51% in major surgeries(10). The incidence of POD in elderly patients after total joint arthroplasty differs significantly among reports, ranging from 10% to 70% (11,12).

In about 30-50% cases, even after delirium is resolved, elderly patients are additionally affected by post-operative cognitive dysfunction (POCD) (13). Other than as sequelae to post-operative delirium, it can independently occur after surgeries up to 3 months. POCD refers to deterioration in cognition temporally associated with surgery as quantified by

neurophysiological tests. Its incidence among patients older than 65 years is about 25.8% at ne week and 9.9% at three months following surgery (14).

Although aetiology of both these are not completely understood, a multicausal association of neuroinflammation, brain network dysfunction, endocrine stress response and neurotransmitter imbalance is described in literature (15). Frailty has been found to have strong association with post-operative delirium (POD), and to a lesser extent with cognitive dysfunction (POCD)(16). However there is no established data regarding the same in non-cardiac surgery in Indian population.

This study aims at observing a correlation between presence of frailty in pre-operative period in the elderly Indian population undergoing orthopaedic surgeries with the occurrence of delirium and cognitive dysfunction in the post-operative period. We also try to determine if the presence of frailty and sarcopenia is associated with increased incidence of postoperative morbidity such as cardiac, pulmonary, renal complications, deep vein thrombosis, surgical site infection, length of hospital stay, length of ICU stay, readmission rates and mortality rates.

HYPOTHESIS: Frailty in elderly population is associated with post-operative delirium and cognitive dysfunction.

PRIMARY OBJECTIVE :

To determine the association between pre-operative frailty in elderly patients undergoing spinal surgery under general anaesthesia with post-operative delirium.

SECONDARY OBJECTIVES:

1)To determine the association between pre-operative frailty in elderly patients undergoing spinal surgery under general anaesthesia with post-operative cognitive dysfunction.

2)To determine the association between sarcopenia in elderly patients undergoing spinal surgery under general anaesthesia with post-operative delirium.

3)To determine the association between sarcopenia in elderly patients undergoing spinal surgery under general anaesthesia with post-operative cognitive dysfunction.

4)To determine the correlation between sarcopenia and post-operative morbidity and mortality.

5)To compare the discriminative ability of modified frailty index and ASA classification to predict morbidity and mortality.