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.
Campbell 2014 United States Secondary data analysis from an RCT Public hospital (general medical ward) Overall: N/A

African American: 78.6 (8.3)

Non-African American: 75.3 (7.4)
To evaluate the influence of race in the screening and documentation of delirium. Adults aged ≥65 years admitted to a general medical ward of Eskenazi Hospital who spoke English.
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.
Hope 2014 United States Stimulated reporting design and chart review VA medical facility (acute medicine, surgery, neurology and ICU) Documented delirium: 68.4 (12.0)

Undocumented delirium: 71.0 (12.2)
To assess how confirmed cases of delirium are documented in EHR. Admitted patients with bedside diagnosis of delirium between 1 December 2009 and 31 May 2010.
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.