Study protocol for a national observational cohort investigating frailty, delirium and multimorbidity in older surgical patients: the third Sprint National Anaesthesia Project (SNAP 3)

Background

The proportion of people aged 60 years or more undergoing surgery in England increased from 12.6% in 2000 to 17.8% in 2015.1 This is due to increased longevity; patient expectations of quality and length of life increasing; and advances in perioperative medicine, anaesthetic and surgical techniques.2

Many older people benefit from surgery through an increase in longevity or an improvement in symptoms. Yet, among surgical patients, older age, frailty and multimorbidity are associated with higher rates of postoperative morbidity, mortality and adverse patient-reported outcomes such as quality of life and loss of independence.3–14 Frailty is characterised by physiological decline across multiple organ systems with multidomain loss of reserve, resulting in vulnerability to a range of adverse outcomes following a stressor event.15 Multimorbidity is the presence of two or more coexisting chronic diseases in one individual.16 The relationship between frailty and multimorbidity and their contribution to postoperative outcome in a surgical setting has not been thoroughly explored to date.17

Delirium is a state of acute confusion that is commonly reversible and is characterised by fluctuating levels of attention and awareness; disorientation; memory impairment; disturbances of perception; and disorganised thinking.18 It is one of the most frequently occurring postoperative complications in older adults. It is commonly reversible and is preventable in approximately 40% of cases.19 20 Occurrence of delirium is associated with increased mortality at 12 months, as well as functional and cognitive decline.21 22

Frailty and delirium are geriatric syndromes which commonly coexist in older patients; however, the details of their relationship are not fully understood. Those who are frail are vulnerable to minor stressors, and so might be expected to more commonly suffer with delirium and other poor outcomes.15 23 In a study of older patients recently discharged from hospital, those who were frail were found to be 2.5 times more likely to experience delirium than the corresponding non-frail population.24 Another study of older vascular patients found that frailty was a strong predictor for delirium with an OR of 5.66 (95% CI 1.53 to 21.03).25 Intuitively, the presence of multimorbidity might also be expected to increase a patient’s likelihood of suffering delirium. A study of older patients undergoing elective surgery found a relative risk (RR) of 1.75 for delirium in those suffering multimorbidity compared with those without.26

The influence of frailty on a range of patient outcomes including postoperative quality of life, mortality, morbidity, reoperation, length of stay, readmission and discharge to residential care is widely reported.3 4 6 27–29 A review of older surgical patients by Lin et al demonstrated a significant relationship with 12-month mortality, finding an OR of 1.1–4.97 for those living with frailty, compared with patients who were not frail.3 30 31 Two of the studied papers also reported an association with 2-year mortality (OR 4.01 (95% CI 2.61 to 6.16)31) and 5-year mortality (OR 3.6 (95% CI 2.3 to 5.532). The review also highlighted an association between frailty and length of stay.3 33–36 This association was further demonstrated in a systematic review of acute surgical patients by Leiner et al. In this meta-analysis, those living with frailty experienced an increased length of stay with a weighted mean difference of 4.75 days (95% CI 1.79 to 7.71, p=0.002).28 A further meta-analysis by Panayi et al found that surgical patients living with frailty were more likely to experience postoperative complications (RR of 1.48, 95% CI 1.35 to 1.61, p<0.001), readmission (RR of 1.61, 95% CI 1.44 to 1.80, p<0.001) and discharge to skilled care (risk ratio of 2.15, 95% CI 1.92 to 2.40, p<0.001).29

Routine assessment and management of frailty, multimorbidity and risk of postoperative delirium can reduce the likelihood of adverse outcomes in older patients.2 27 37 In recent years, the specialty of perioperative medicine has brought together physicians, geriatricians, anaesthetists, surgeons, nurses and allied healthcare professionals, to enhance preoperative assessment; management and postoperative care of these patients. However, the provision of this skilled and specialised service differs across the UK with the varying degrees of resource allocation, local enthusiasm and operational priorities. Furthermore, surgical pathways are heterogenous, often combining proactive and reactive services led by different specialities. The criteria for accessing perioperative medicine services are diverse, based on age, clinical need, surgical specialty, surgical procedure and clinician preference.37–40

There is no single metric that defines a ‘good’ outcome following surgery. Length of hospital stay as a metric of outcome has been criticised due to the influence of social and organisational factors. However, these factors are associated with frailty and multimorbidity, and furthermore are important metrics at an organisational and financial level in particular due to an ageing surgical population and resource constraints within healthcare.

In order to support objective decision-making for individual patients, services and national planning, accurate, granular and contemporary data are needed describing the impact and association among frailty, multimorbidity and processes of care with patient and service-level outcomes.

This study is called the Sprint National Anaesthesia Project 3 (SNAP 3). We have designed it to describe the incidence of and relationships among frailty, multimorbidity and postoperative delirium in the older surgical patient. This protocol will be used across participating UK hospitals. Further research using an adapted SNAP 3 protocol is planned in Australia. From our results, we hope to provide suggestions for the future development of perioperative care for the older surgical population.

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