Table 1

Characteristics of 49 included studies on 28-day or 30-day unplanned hospital readmission (UHR) predictive models

ReferenceModel nameModel outcomeStudy design/data sourceSample sizeAge group (years)Duration of retrieved data sourceReadmission rate
All-cause UHRs (14)
Escobar et al16
USA
ED 30
Discharge 30 LACE (validation)
30-day all-cause readmissionsRetrospective cohort
21 hospitals
Electronic medical records
A total of 360 036 patients
179 978 derivation set
180 058 validation set
Mean=64.11 June 2010–31 December 2013Derivation: 12.5%; Validation: 12.4%
Yu et al17
USA
Institution-specific prediction model
LACE (validation)
30-day all-cause readmissionRetrospective cohort
3 hospitals
Hospital 1=2441
Hospital 2=26 520
Hospital 3=45 785
≥65Not reportedH1=23%
H2=20%
H3=18%
Baillie et al18
USA
Prediction model30-day all-cause readmissionsRetrospective and prospective cohort
3 hospitals
Retrospective: 120 396 discharges
prospective validation
Not reported—adultAugust 2009–September 2012Retrospective: 14.4%; Prospective: 15.1%
Choudhry et al12
USA
ACC Admission and Discharge model30-day all-cause readmissionsRetrospective cohort

8 hospitals
A total of 126 479 patients
94 859 derivation set
31 619 internal and 6357 external validation
Mean=66.01 (readmission)
57.65 (no readmission)
1 March 2010–31 July 20127.25%
Gildersleeve and Cooper19
USA
Risk of readmission score (RRS)30-day all-cause readmissionRetrospective cohort
1 community hospital
Derivation: 8700 patientsMean=60.6201014.1%
Validation: 8189 patientsMean=65201114.8%
Kruse et al20
USA
Unnamed30-day all-cause readmissionRetrospective cohort
91 hospitals—Health Facts Database
463, 351 Index admissions≥181 October 2008–31 August 20109.7%
Richmond21
USA
Unnamed30-day all-cause readmission for patients≥65 yearsRetrospective cohort
state-level database
4717 patients split into a derivation (80%) and validation sample (20%)Mean=77.27January 2010–December 201214.4%
Shulan et al22
USA
Unnamed30-day all-cause readmissionRetrospective cohort
centralised database
8718 patients
Derivation (50%)
Validation (50%)
Mean=67.04 (UHRs); 66.43 (no UHRs)201116.2%
van Walraven et al23
Canada
LACE+ (extension of a validated index)30-day all-cause readmissionRetrospective cohort
centralised database
499 996 patients/858 410 index hospitalisations>182004–200911.8%
Cotter et al13
UK
LACE index (validation)30-day all-cause readmissionRetrospective cohort
centralised database
507 patientsMean=85201017.8%
Regression modelRetrospective cohort
centralised database
502 patients (validation cohort)14.8%
Khan et al24
USA
Rehospitalisation Risk Score30-day all-cause readmissionRetrospective cohort
10 hospitals/EMRs
227 patientsAverage=79Single day on 26 January 201115%
Lee25
Korea
Unnamed28-day all-cause readmissionRetrospective cohort
1 tertiary hospital
11 951 patients
Derivation (70%); Validation (30%)
Ranged from 0 to 70+200928.9%
van Walraven et al26
Canada
CMG score (case-mix groups)30-day all-cause readmissionRetrospective cohort
4 health databases
Random 200 000 patients of 3 277 033
Derivation: 100 000
Validation: 100 000
Mean age of
Derivation: 58
Validation: 57.9
1 April 2003–31 March 20096.8%
LACE index (validation)
Combined CMG score and LACE index
van Walraven et al27
Canada
LACE+
LACE+ with CMG score
30-day all-cause readmissionRetrospective cohort
4 health databases
Random 500 000 of 3 277 033 patients then 1/2 derivation and ½ validationMean=57.9 (derivation); 57.9 (validation)1 April 2003–31 March 200914%
Cardiovascular disease-related UHRs including pneumonia (11)
Hebert et al15
USA
CHF model
PNA model
AMI model
Combined model
30-day readmission on
Congestive heart failure/pneumonia/acute myocardial infarction
Retrospective cohort
A tertiary medical centre
A total of 3968 patients
Derivation: 3572
Mean=611 August 2009–31 July 201116.2%
Historical validation: 17561 August 2008–31 July 200917.7%
Random sample: 39616.2%
Iannuzzi et al28
USA
Vascular surgery readmission risk score30-day readmission on patients after vascular surgeryRetrospective cohort
National Surgical Database
24 929 patientsMean=69.5 (UHRs); 69.7 (no UHRs)201110.1%
Keyhani et al29
USA
CMS-based model30-day readmission on patients with strokeRetrospective cohort
114 hospitals
3436 patientsMean=69.5 (UHRs); 66.9 (no UHRs)200712.8%
CMS-based model plus social Risk factors
CMS-based model plus social risk and clinical factors
Rana et al30
Australia
Electronic medical record (EMR) model30-day readmission on ischaemic heart disease of patients after AMIRetrospective cohort
A regional health service—tertiary hospital
1660 AMI admissions
Derivation cohort: 1107
Validation cohort: 553
Mean=67.8 (derivation cohort); validation cohort: 68.4January 2009–December 20116.3%
HOSPITAL score (validation)
Comorbidities (validation)
Shahian et al31
USA
Unnamed30-day readmission post coronary artery bypass graftingRetrospective cohort
National Database (846 hospitals)
162 572 admissions≥652008–201012.6–23.6%
Shams et al32
USA
Potentially avoidable readmission (PAR)30-day avoidable readmission on pneumonia/HF/AMI/
COPD
Retrospective cohort
Veterans Health Administration data
5600 admissionsHF: mean=71.3 (PAR); vs 68.6 (no UHRs)
AMI: mean=73.3 (PAR) vs 69.3 (no UHRs)
2011–201213.09%
Internal validation
External validation478 patientsAugust and September 2012
CMS endorsed model (validation)30-day readmission
Sharif et al33
USA
Unnamed30-day readmission on patients aged 40–64 years with COPDRetrospective cohort
A large national commercial insurance database
8263 patientsMean=57 (UHRs); no UHRs—age not reportedJanuary 2009–November 20118.9%
Lucas et al34
USA
Complex all-variable model; parsimonious readmission score30-day readmissions on patients post general, vascular, and thoracic surgeryRetrospective cohort
National Surgery Database
A total of 230 864 patients
Derivation: 162 159 (70%): Validation: 68 705 (30%)
Median=5620115–16% across surgical specialties
Wallmann et al35
Spain
Unnamed30-day readmission on cardiac-related diseaseRetrospective cohort
1 tertiary centre
35 531 admissions
Derivation cohort: 24 881
Validation cohort: 10 650
Mean=67.92003–2009Derivation: 4.4%; Validation: 4.7%
Wasfy et al36
USA
Risk score for 30-day readmission after PCI (parsimonious)30-day readmission after percutaneous coronary interventionRetrospective cohort
centralised database
36 060 surviving to dischargeMean=68.1 (UHRs); 64.3 (no UHRs)1 October 2005–30 September 30 200810.4%
Krumholz et al37
USA
Claims model30-day readmission on acute myocardial infarction (AMI)Retrospective cohort
Medicare Claims Database
Derivation cohort: 100 465
Validation cohort: 321 088
Mean=78.7Half of 200618.9%
Medical record modelDerivation cohort: 130 944
Validation cohort: 130 944
2005 and half of 200619.96%
Cardiovascular disease-related UHRs including pneumonia—heart failure only (11)
Betihavas et al38
Australia
Unnamed28-day readmission on patients with chronic heart failureRetrospective cohort
Multicentre
280 patients
94 (no UHRs); 37 (28-D UHRs)
Mean=69 (no UHRs); 79 (UHRs)Not reported13%
Di Tano et al39
Italy
Unnamed30-day readmission on acute HFProspective cohort
National Registry Database
1520 patientsMean=72Not reported6.25%
Huynh et al40
Australia
The non-clinical model
The clinical model
The combined model
30-day readmission on HFRetrospective cohort
state-wide data linkage
Non-clinical—1537 patients
Clinical—977 patients available
Mean=802009–201225.4%
Raposeiras-Roubin et al41
Spain
GRACE risk score30-day readmission on HF after acute coronary syndromeRetrospective cohort
A single centre
4429 patientsMean=77 (UHRs); 68 (no UHRs)2004–20101.3%
Sudhakar et al42
USA
Readmission Risk score30-day readmission on patients with CHFRetrospective cohort
A tertiary hospital/chart review
1046 admissions from 712 patientsMean=65.2September 2011–August 201335.28%
Fleming et al43
USA
Unnamed30-day readmission on patients with HFRetrospective cohort
1 tertiary medical centre
3413 admissions
Derivation: Validation=3:1
(2566:847)
Mean=74 (derivation cohort); validation cohort: 74.61 October 2007–30 August 201124.2% (derivation)
Wang et al44
USA
LACE index (validation)30-day readmission on patients with CHFRetrospective cohort
An urban public hospital
253 patientsMean: 57.67 (no UHRs); 56.17 (UHRs)June 2012–June 201324.5%
Eapen et al45
USA
Unnamed30-day readmission on heart failureRetrospective cohort
Centers for Medicare database
33 349 patient
70% in derivation cohort
30% in validation cohort
Median=801 January 2005–31 December 200922.8%
Zai et al46
USA
The telemonitoring-based readmission model; the psychosocial readmission model (validation)30-day readmission on heart failureRetrospective cohort
Patients enrolled in the telemonitoring program
100 patientsAverage age of 66.8July 2008–November 201138%
Au et al47
Canada
Five administrative data-based models: Charlson; CMS Krumholz
Keenan; LACE; LACE+
30-day readmission on HFRetrospective cohort
4 health databases
59 652 patientsMean=76April 1999 and 200919%
Watson et al48
USA
The psychosocial readmission model30-day readmission on HFRetrospective cohort
1 tertiary hospital
729Mean=71.41 October 2007–30 September 200813.3% (all female)
Cardiovascular disease-related UHRs including pneumonia—pneumonia only (2)
Mather et al49
USA
Hartford Hospital model
CMS Model (validation)
30-day readmission on pneumoniaRetrospective cohort
A tertiary hospital
956 index admissions≥65January 2009–March 201215.5%
Lindenauer et al50
USA
Administrative claims model30-day readmission on pneumoniaRetrospective cohort
Medicare enrolment database
Derivation cohort: 226 545
Validation cohort: 762 721
Mean=80Half of 200617.4%
Medical record model47 429 casesHalf of 2006 and 200517.0%
General medical condition-related UHRs (10)
Shadmi et al51
Israel
Preadmission Readmission Detection Model30-day readmission on medical patientsRetrospective cohort
Clalit Health Services/EMR
Total: 33 639 admissions
Derivation: 22 406
Validation: 11 233
Mean=68.2; 67.5 (no UHRs); 72.5 (UHRs)1 January 2010–31 March 201016.8%
Tsui et al52
Hong Kong
Unnamed28-day readmission on elderly medical patientsRetrospective cohort
41 hospitals/EMS
Total: 327 529 episodes
Derivation: 165 216
Validation: 162 313
≥65Derivation: 2005
Validation: 2006
7.8%
7.6%
Donzé et al53
USA
Unnamed30-day readmission on medical patients due to end-of-life careRetrospective cohort
1 tertiary medical centre including 3 hospitals
10 275 admissionsMean=61.5 (no UHRs); 60.8 (potentially avoidable readmissions (PARs)1 July 2009–30 June 2010Total:22.3%; 8%—PARs
He et al54
USA
Unnamed30-day readmission on medical patients and chronic pancreatitis (CP)Retrospective cohort
JHH (tertiary centre)
BMC (community hospital)
Medical patients: 26 091 (JHH)+16 194 (BMC)Mean=50.3 (JHH)
51.5 (BMC)
Medical patients: January 2012–April 2013;11.5% (JHH)
8.7% (BMC)
Patients with CP: 3218 (JHH)+706 (BMC)Mean age: 51.4 (JHH)
51.4 (BMC)
CP discharged from January 2007–April 201315.6% (JHH)
7.8% (BMC)
Taha et al55
USA
Readmission Risk Score (RRS)30-day readmission on general internal medicine servicesRetrospective cohort
4 teaching and 2 non-teaching general internal medicine services
858 index hospitalisations
Derivation cohort: 613
Validation cohort: 245
Mean=54 (derivation); validation cohort: 541 April 2010–30 June 201016%
Donzé et al14
USA
HOSPITAL score30-day readmissions on general medical patientsRetrospective cohort
Multicentre health services
10 731 dischargesMean=61.31 July 2009–30 June 20108.5%
Tan et al56
Singapore
LACE index (validation)30-day readmission on general medical patientsRetrospective
The largest tertiary general hospital
127 550 patients≥211 January 2006–31 December 20104.87–18.43%
Billings et al11
USA
PARR-3030 days readmission on general medical patientsRetrospective cohort
centralised database
576 868 admissionsAdult1 April 2008 and 31 March 200912.2%
Zapatero et al57
Spain
SEMI INDEX30-day readmission on general medical patientsRetrospective cohort
National Health Database
Derivation cohort: 999 089 patients; Validation cohort: 510 588 patients (internal)Median=70 for two cohortsJanuary 2006–December 200712.4%
200812.5%
Gruneir et al58
Canada
LACE index (validation)30-day readmission on general medical patientsRetrospective cohort
6 hospitals
26 045 patients18–105200712.6%
Medical condition UHRs—cirrhosis only (2)
Singal et al59
USA
Unnamed30-day readmissions on patients with cirrhosisRetrospective cohort
1 large safety-net hospital
A total of 838 patients with 1291 admissions
Derivation: 968
Validation: 323
Mean=52.5January 2008–December 200927%
Volk et al60
USA
Cirrhosis readmission prediction model30-day readmission on cirrhosisRetrospective cohort
1 tertiary hospital
402 patients≥181 July 2006–1 July 200941%, 22% of which are PARs
Medical condition UHRs—chronic kidney disease only (1)
Perkins et al61
USA
Unnamed30-day readmission on patients with CKD second to HFRetrospective cohort
2 inpatient facilities
607 patients with chronic kidney diseaseMean=72.3 (UHRs); 74.1 (no UHRs)1 July 2004–28 February 201019.1%
Medical condition UHRs—HIV only (1)
Nijhawan et al62
USA
Unnamed30-day readmission on HIV-infected patientsRetrospective cohort
1 tertiary hospital
2402 index admissions randomly split (1/2) into derivation vs validationMean=43March 2006–November 200824.4%
Medical condition UHRs—acute pancreatitis (1)
Whitlock et al63
USA
Unnamed30-day readmission on acute pancreatitisRetrospective cohort
2 hospitals
Derivation cohort: 248
Validation cohort: 198
Mean=51.6 derivation
Validation: 52.3
1 June 2005–31 December 2007
1 January 2008–31 October 2009
19%
23%
Surgical condition-related UHRs (6)
Taber et al64
USA
30DRA with fixed variable vs 30DRA with fixed variables and dynamic clinical data30-day readmission on patients following kidney transplantationRetrospective cohort
An institution
1147 patients Derivation; internal validation using random iteration of 50% samplingMean=51 (no UHRs); 52 (UHRs)2005–201211%
Lawson et al65
USA
Unnamed
(demographic, preoperative and postoperative risk factors)
30-day readmission on patients following colectomyRetrospective cohort
NSQIP
12 981 patients≥652005–200813.5%
Iannuzzi et al66
USA
Endocrine surgery Readmission Risk Score30-day readmission on patients following cervical endocrine operationsRetrospective cohort
NSQIP—a large national clinical database
34 046 cases
Derivation and validation cohort (numbers were not specified)
Mean=54 (no UHRs); 55 (UHRs)2011–20122.8%
Mesko et al67
USA
Unnamed30-day readmission on total hip and knee arthroplastyRetrospective cohort
A readmission database
1291 admissions/1236 patientsMean=65.6 (UHRs); 68.3 (no UHRs)1 May 2010–30 April 20113.6%
Moore et al68
Canada
Unnamed (quality indicator based)30-day readmission on traumaRetrospective cohort
57 trauma centres
57 524 patients≥161 April 2005–28 February 20106.6%
Graboyes et al69
USA
Unnamed30-day readmission on otolaryngology patientsRetrospective cohort
A tertiary hospital
1058 patients—1271 hospital admissionsMean=52 (no UHRs); 56 (UHRs)1 January 2011–31 December 20117.3%
Mental health condition-related UHRs (1)
Vigod et al70
Canada
READMIT (41 points)30-day readmission after discharge from acute psychiatric unitsRetrospective cohort
National health data
Derivation: 32 749 patients
Validation: 32 750 patients
Median=41 (UHRs); 44 (no UHRs)1 April 2008–31 March 20118.42–10%
  • ACS, acute coronary syndrome; AMI, acute myocardial infarction; AP, acute pancreatitis, CHF, congestive heart failure; CKD, chronic kidney disease; COPD, common obstructive pulmonary disease; EMRs, electronic medical records; GRACE, global registry of acute coronary events; HF, heart failure; PCI, percutaneous coronary intervention; PREADM, preadmission readmission detection model; PNA, peptide nucleic acid.