Table 1. Summary of included studies.
| Author, year of publication | Country | Study design | Type of Hospital (unit) | Mean Age (SD)a | Summary of study aims | Summary of study selection criteria |
|---|---|---|---|---|---|---|
| Alhaidari 2018 | New Zealand | Retrospective review of medical records | Tertiary teaching hospital (general medicine) | N/A | To assess and potentially improve a hospital-wide delirium program. | Latest 100 general medicine patients discharged prior to 14 September 2014 with a minimal LOS of three days. |
| Bellelli 2015 | Italy | Prospective cohort multicentre study | Acute hospitals (medical wards) | 79.1 (7.3) | To describe the prevalence and impact on in-hospital mortality of delirium identified through ICD-9 codes. | Adults aged ≥65 years who underwent SBT assessment within 72 hours of admission. |
| Bui 2017 | United States | Retrospective cohort study | Tertiary academic medical centre (surgical ICU) | 61.0 (16.0) | To compare the proportions of surgical ICU patients with delirium detected using CAM-ICU who received administrative delirium documentation. | Adults aged ≥18 years admitted to surgical ICU from 1 June 2012 to 31 May 2013. |
| Non-African American: 75.3 (7.4) | ||||||
| Casey 2019 | Australia | Cross-sectional point prevalence survey | Australian metropolitan public health service consisting of 5 hospitals | 73.0 (16.4) | To determine the extent to which ICD codes represent delirium occurrence. | Adults aged ≥18 years admitted as overnight stay on medical, surgical, specialist medicine, rehabilitation, or palliative care wards. |
| Chuen 2021 | Canada | Retrospective chart review | Academic tertiary acute care Hospital (medical and surgical) | 79.6 (8.4) | To determine the frequency and quality of delirium documentation in DS. | Adults aged ≥65 years admitted to any one of 3 academic tertiary acute care hospitals by a medical or surgical service between 1 April and 30 June 2016. |
| Detweiler 2014 | United States | Retrospective review of medical records | Veterans medical centre (ED, medicine, surgery, psychiatry and consult liaison) | 70.0 (12.9) | To assess the prevalence of missed delirium in acute care veterans coded as not having a diagnosis of delirium. | Inpatient cases of veterans that had not been coded at admission and/or discharge as having delirium |
| Glick 1996 | United States | Retrospective chart review | General hospital (N/A) | 63.8 (N/A) | To determine whether diagnosis and treatment of delirium in IABP-treated patients correlates with delirium recording at discharge. | IABP placement at the Massachusetts General Hospital in 1988. |
| Heriot 2017 | Australia | Retrospective study | Large metropolitan private hospital (CICM) | N/A | To compare incidences of delirium in elderly intensive care patients. | Participants drawn from a larger 24 month QoL follow-up study in patients aged?80 years following ICU admission. |
| Undocumented delirium: 71.0 (12.2) | ||||||
| Inouye 2005 | United States | Prospective validation study | Urban teaching hospital (general medicine) | 80.0 (6.5) | To validate a chart-based method for identification of delirium and compare it with direct interviewer assessment. | Patients aged ≥70 years with no delirium on admission, but at least intermediate risk for delirium at baseline. |
| Johnson 1992 | United States | Prospective observational design and retrospective record review | University hospital (non-critical care medical unit) | N/A | To determine the sensitivity of using alternative retrospective approaches for diagnosing delirium. | Medically ill patients aged >70 years admitted between Sunday afternoons and Friday evenings who were not patient transfers, terminally ill, not admitted on weekends or for short-stays. |
| Kales 2003 | United States | Retrospective study | VA medical facility | 72.0 (7.4) | To determine the rate of recorded delirium. | Veterans aged ≥60 years at discharge with ICD-9CM code from VA. |
| Katznelson 2010 | Canada | Prospective and retrospective study | General hospital (ICU) | 63.0 (13.0) | To determine the incidence of delirium after cardiac surgery. | Cardiac surgical patients. |
| Kelly 2012 | United States | Retrospective chart review | Tertiary referral hospital (surgery, oncology, neurology, PICU, general paediatrics, haematology, cardiology and pulmonology) | N/A | To identify the frequency of recognised and documented delirium at discharge. | Discharged patients between January 2003 and January 2011 |
| McCoy 2017 | United States | N/A | Academic medical centres | 57.0 (18.7) | To characterise incidence of recorded delirium across 2 major health centres. | Inpatients aged ≥18 years with documented discharge from non-obstetrical care between 2005 and 2013. |
| Pendlebury 2020 | United Kingdom | Prospective observational study | General hospital (acute general medicine) | 70.0 (19.2) | To determine the impact of the multicomponent intervention on hospital administrative coding for delirium. | Consecutive unselected admissions to one acute medicine team over five 8-week cycles. |
| Ruangratsamee 2016 | Thailand | Prospective and retrospective patient evaluation | Tertiary referral hospital (geriatric medicine) | 78.6 (5.9) | To investigate the rate of under-recognised delirium and explore the effect of unrecognised delirium on patient mortality. | Adults aged ≥70 years admitted to general medicine between January and March 2009. |
| Sanchez 2013 | Colombia | Cross-sectional study | Tertiary hospital (acute medicine) | N/A | To clarify the state of delirium diagnosis and records in a tertiary level public hospital in the city of Pereira. | Hospitalised adults aged >60 years. |
| Smulter 2019 | Sweden | Retrospective observational analysis | University hospital (cardiothoracic surgery) | N/A | To analyse POD in clinical practice after cardiac surgery. | Adults aged ≥70 years scheduled for routine cardiac surgery with the use of cardiopulmonary bypass. |
| van Zyl 2003 | Canada | Chart review | General teaching hospital (psychiatry) | 73.3 (13.8) | To investigate prevalence of delirium reporting in DS. | Referrals to a consultation-liaison psychiatry service in a university teaching general hospital between July 2000 and September 2001. |
| Welch 2018 | United Kingdom | Prospective cohort study | Tertiary university teaching hospital (acute admissions) | 84.4 (N/A) | To assess if ongoing delirium research activity within an acute admissions unit impacts on prevalent delirium recognition. | Patients aged ≥70 years diagnosed with delirium. |
| Welch 2019 | United Kingdom | Prospective observational study | Acute care trusts (acute medicine, geriatric medicine, other medicine, stroke, general, orthopaedic surgery and other surgery) | 80.0 (8.3) | To ascertain the point prevalence of delirium across UK hospitals and the relationship to adverse outcomes. | Hospitalised adults aged ≥65 years, admitted between 12 March 2018 and 14th March 2018. |
| Zalon 2017 | United States | Retrospective chart review | Community hospital | N/A | To analyse delirium documentation for hospitalised older adults. | Hospitalised patients aged ≥71 years, with known delirium who were enrolled in HELP at a community hospital. |
a
Mean age is provided where reported. SD = standard deviation.
Table abbreviations - CAM-ICU: Confusion Assessment Method (Intensive Care Unit), CICM: College of Intensive Care Medicine, ED: Emergency Department, EHR: Electronic Health Record, HELP: Hospital Elder Life Program, IABP: Intra-Aortic Balloon Pump, ICD-(9, 9CM): International Classification of Diseases (9th Revision, 9th Revision Clinical Modification), ICU: Intensive Care Unit, LOS: Length of Stay, PICU: Paediatric Intensive Care Unit, POD: Post-Operative Delirium, RCT: Randomised Controlled Trial, UK: United Kingdom, VA: Veterans Affairs.