Singaporeans are rapidly ageing. One in every 4 Singaporeans will be aged 65 years and older in 2030, double the rate of that in 2015. Elderly patients have more chronic diseases and have a poorer recovery profile after illness or surgery. More recently, it has been reported that Singaporeans spend 10 years of their lives in poor health. Elderly patients are over-represented in patients coming for surgery, particularly for major cardiac and non-cardiac surgeries. While surgery is wonderful and lifesaving, the truth is that many elderly patients do not do well after major surgery. This was eloquently reported in the New York Times recently in an article titled "The Elderly Are Getting Complex Surgeries. Often It Doesn't End Well." Elderly patients value quality of life over quantity of life, but many are not aware of the long-term debilitation, organ dysfunction, pain, depression, economic burden and social strain that frequently accompanies major surgery. Elderly patients are more likely to lose independence after surgery, both physically and cognitively, and may never recover fully. There is clearly a disconnect between the elderly patient's (and their loved ones') expectations and reality. There is therefore a need to look closely at the operative journey of the elderly patient undergoing major surgery. Currently, clinical care is primarily concerned about achieving a technically successful surgery and recovery in the immediate postoperative phase, but there is much less oversight once the patient leaves the hospital system to community care. However, perioperative management significantly impacts the quality of life and activities of daily living for years after surgery. At NUHS, the MILES (Management and Innovation for Longevity in Elderly Surgical patients) programme has successfully reduced hospital length of stay of elderly patients undergoing abdominal surgery by addressing frailty and performing prehabilitation in selected patients. In this study, the study team intend to expand on this clinical programme to look at 3 primary concerns, namely postoperative delirium, trajectory of ageing, and myocardial injury, and the long-term implications of these concerns. Second, the team will incorporate biomarkers and other investigations to better risk profile patients, elucidate mechanistic processes, and provide better diagnostic and prognostic tools to clinicians. Third, the team will investigate the complimentary and detrimental roles of common systemic pathologies such as diabetes, anemia, renal dysfunction, malignancy, pain, and poor sleep on these outcomes. Therefore, the team intends to do a longitudinal study starting from the preoperative period up to 5 years after surgery in patients aged 65 years and above undergoing elective non-cardiac major surgery, defined as a surgery lasting at least 2 hours and requiring at least one day stay in hospital after surgery. It is envisioned that by using the data gained from this study, the investigators will be able to identify risk factors, trajectories of outcomes and gaps in their clinical care, and from there, formulate clinical strategies to address these gaps and mitigate the risk factors.