Postoperative Delirium in Elderly Patients Undergoing Major Non-Cardiac Surgery in Singapore
Condition: Postoperative Delirium
MeSH terms: Delirium; Emergence Delirium
Study type: Observational

Summary: 
      The primary aim of this study is to investigate the incidence, risk factors and sequelae of
      postoperative delirium in elderly patients undergoing major non-cardiac surgery in Singapore.
      The secondary aim of this study is to look for EEG markers of POD that may potentially lead
      to the development of a POD monitor.
    

Detailed description: 
      Singapore's population is growing older and increasingly burdened with systemic disease. It
      is estimated that over 320 million people underwent surgery worldwide in 2010, with Asia
      being the fastest growing region. Elderly patients aged >65 years are presenting for surgery
      at an ever-increasing rate. In the United States, studies have estimated that approximately
      53% of all surgical procedures are performed on patients over the age of 65. Projections
      estimate that approximately half of the population over the age of 65 will require surgery
      once in their lives.

      It is recognized that for elderly patients, quality of life after surgery matter more than
      quantity of life. Elderly patients have diminished reserves and poorer recovery potential.
      Therefore, to fully benefit from surgery, it is essential to adopt measures to preserve
      quality of life in addition to survival after surgery in the perioperative period. One
      example is the enhanced recovery after surgery (ERAS) programme where protocolized care
      involving optimal analgesia, less invasive surgeries, early mobilisation and early hospital
      discharge has improved the recovery of patients after surgery. In the best practice
      guidelines for care of elderly surgical patients put forward by the American College of
      Surgeons National Surgical Quality Improvement Program (ACS NSQIP) and the American
      Geriatrics Society (AGS) published in 2012, anaesthesia plays a role in more than half of the
      13 recommendations put forward.

      One of these recommendations is to reduce postoperative delirium (POD). The anaesthetic
      agents we use is toxic to the brain, and deep anaesthesia causes POD, which is linked to
      increased hospital length of stay, unplanned hospital readmissions, increased 30-day
      mortality, and dementia. POD is one of the leading causes of why patients fall at home after
      surgery. Up to 10% will develop long-term neurocognitive deficits, which in turn diminish the
      quality of life and levy a tremendous socio-economic burden on family and care-givers, and
      shortens life. The topic of POD has dominated the anaesthesia literature in the last year,
      with both the US and European societies issuing best practice guidelines such as the Brain
      Health Initiative and the Safe Brain Initiative, as well as harmonization of the definitions
      of postoperative neurological outcomes with that used by neurologists in compliance with
      DSM-5 definitions to allow for collaborative solutions.

      More recently it was reported in the Straits Times that Singaporeans have the longest life
      expectancy in the world. However, 10.7 years of this is spent in poor health, with diminished
      mental health ranking as the second most important cause for this. Because POD is strongly
      linked to the development of dementia and/or alters the trajectory at which age-related
      dementia occurs, it is very important to prevent the development of POD. This is particularly
      so as studies have shown that POD is very common, occurring in as many as 11-50% of patients
      undergoing major non-cardiac surgery, and that up to 40% of POD is preventable.

      Awareness of POD remains poor amongst both doctors and the public. The reason for this is
      that POD requires specialized neurological testing and currently, there are no established
      biomarkers or monitors to detect it. Anecdotally, POD is one of the leading reasons for
      in-hospital (blue letter) psychiatric referrals after surgery in NUHS, as delirious patients
      will refuse to comply with physiotherapy, medications and wound care, leading to delayed
      healing, infection and delayed discharge. Patients are not routinely assessed for POD and can
      be discharged from hospital with it. Patients who are still delirious can end up with poor
      feeding and self-care, and even hurt themselves leading to rehospitalisation. In short, POD
      is a common yet under-diagnosed, and potentially preventable, complication of anaesthesia and
      surgery in the elderly that has significant long-term effects on the independence of patients
      after surgery and their quality of life.

      The current accepted standard for diagnosing POD is to perform twice daily neurocognitive
      assessments daily in the first 5 postoperative days. However, as this is difficult to
      implement due to the significant manpower requirements, delirium in the post-anaesthesia care
      unit (PACU delirium) has been used as a surrogate for POD. PACU delirium is distinct from
      emergence delirium which occurs upon arrival or soon after admission into the PACU and is
      related to residual effects of anaesthesia. Emergence delirium typically is self-limiting and
      has no long-term sequelae. In contrast, PACU delirium occurs after recovery from the effects
      of anaesthesia, presenting at 30-60 minutes after arrival in the PACU. PACU delirium occurs
      in up to 80% of patients who subsequently develop POD in the wards and has been independently
      associated with increased length of hospitalization, unplanned readmission, and increased
      in-hospital mortality.

      Therefore, the primary aim of this study is to investigate the incidence, risk factors and
      sequelae of postoperative delirium in elderly patients undergoing major non-cardiac surgery
      in Singapore. The secondary aim of this study is to look for EEG markers of POD that may
      potentially lead to the development of a POD monitor. This study will provide preliminary
      data to enable the investigators to apply for a national grant for a more definitive and
      adequately powered study. It is envisaged that eventually, the information gathered will
      allow the investigators to form an effective clinical plan to reduce postoperative delirium
      in our elderly patients undergoing non-cardiac surgery, and a basis to apply for national
      grant funding to implement the clinical intervention.
    

Intervention name(s): Neurocognitive tests
Intervention type(s): Other
Intervention description(s): Preoperative: Battery of neurocognitive tests and questionnaires (MoCA, PHQ-9, Falls History, FIFE, STOPBANG, Nutritional Survey) Postoperative in PACU: NuDESC test Postoperative 30 days: 10 minute phone interview
Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Elderly patients aged 65 and above who are planned for major non-cardiac surgery of at
        least 2 hours in duration and requiring at least 1 postoperative stay in hospital.
      
Keywords: Geriatrics; Postoperative Delirium