Frailty index and peri-operative outcome

Abstract

As the population ages, increasing numbers of older adults are undergoing surgery. Frailty is prevalent in older adults and may be a better predictor of post-operative morbidity and mortality than chronological age. This thesis opens with a systematic review of the current literature on frailty and post-operative outcomes in older surgical patients (chapter two). Electronic databases from 2010 to 2015 were searched to identify articles which evaluated the relationship between frailty and post-operative outcomes in surgical patients with a mean age of 75 and older. Demographic data, type of surgery performed, frailty measure and impact of frailty on adverse outcomes were extracted from the selected studies. Quality of the studies and risk of bias was assessed by the Epidemiological Appraisal Instrument. Altogether 60 articles investigated the association between frailty and post-operative outcomes, 37 of them had patients with a mean age under 75 years old. The remaining 23 articles included in the review were assessed as medium to high quality. Participants ranged in age from 75 to 87 years, and included patients undergoing cardiac, oncological, general, vascular and hip fracture surgeries. There were 21 different instruments used to measure frailty. Regardless of how frailty was measured, the strongest evidence in terms of numbers of studies, consistency of results and study quality was for associations between frailty and increased mortality at 30 days, 90 days and one year follow-up, post-operative complications and length of stay. A small number of studies reported on discharge to institutional care, functional decline and lower quality of life after surgery, and also found a significant association with frailty.Though many studies have confirmed that frailty is associated with increased adverse outcome in the surgical population, the time point when frailty was assessed in the current literature was unclear. Whether baseline frailty or inpatient frailty predicts adverse outcome in surgical patients has not been investigated previously. The third chapter of the thesis aimed to derive a baseline and an inpatient frailty index (FI) and examine whether each was associated with adverse outcomes in the surgical population. A retrospective analysis was undertaken which derived baseline and inpatient FI from comprehensive geriatric assessment of 208 general surgical and orthopaedic patients aged 70 and over admitted to four acute hospitals in Queensland, Australia. The association of the FIs with adverse outcomes was examined in logistic regression. The mean (SD) baseline FI was 0.19 (0.09) compared to 0.26 (0.12) on admission, with a predominant increase in domains related to functional status. Both baseline and inpatient FIs were significant predictors of one year mortality, inpatient delirium, and a composite adverse outcome, after adjusting for age, sex and acuity of surgery. Baseline frailty and inpatient frailty, though distinct, are both predictive of adverse outcomes in surgical older patients. Frailty assessed at either time point is valid and useful in predicting adverse outcomes.In the fourth chapter of the thesis, a prospective study evaluated the feasibility of FI-CGA (frailty index based on comprehensive geriatric assessment) in 246 surgical patients aged 70 years and over undergoing intermediate to high risk surgery in a tertiary hospital in Queensland, Australia. Frailty was assessed using a 57-item FI-CGA form, with fit, intermediate and frail patients defined as FI l0.25, g0.25-0.4, and g0.4 respectively. nLogistic regression models assessed the relationship between FI and adverse outcomes, adjusting for age, gender and acuity of surgery. Adverse outcomes of interest were complications, prolonged length of stay, new discharge to residential aged care facility, deaths and unplanned hospital readmissions, ascertained intraoperatively, at 30 days and 12 months post-surgery. Mean age of the participants was 79 (SD 6.5), 52% were female, 91% were admitted from community, 65% underwent orthopaedic operations, and 43% underwent acute surgery. FI-CGA was a feasible tool which took on average 12 minutes to complete at the bedside. There were no statistically significant differences between fit, intermediate and frail groups in peri-operative (17.4%, 23.3%, 19.1% for fit, intermediate frail and frail patients p=0.577) and 30 day post-operative complications (35.8%, 47.8%, 46.8% p=0.183), which may have been a reflection of insufficient sample size. However, greater frailty was associated with increased 12 month mortality (6.4%, 15.6% and 23% for fit, intermediate frail and frail patients, p=0.01) and 12 month hospital readmissions (33.9%, 48.9%, 60%, p=0.004). Using FI-CGA peri-operatively may identify patients at high risk of poor long term outcome.In conclusion, there is strong evidence in the current literature that frailty is a predictor of adverse outcomes in surgical older adults. Frailty both at baseline and during an acute illness is predictive of adverse outcomes. FI-CGA is a potentially useful tool for incorporating into routine pre-operative assessment to help with decision making and to identify vulnerable surgical patients who are at higher risk of adverse outcomes.