. 2021 Aug 17;11(8):e047576. doi: 10.1136/bmjopen-2020-047576

Table 1.

Study characteristics

Study	Model	Data source	Development	Validation	Sample size		Population	Average age	Outcome	Readmission (%)
Study	Model	Data source	Development	Validation	Dev	Val	Population	Average age	Outcome	Dev	Val
Moretti et al⁵⁷	EuroHeart PCI score	Hospital database	NA	Ext	–	1192	ACS	71 (7)	30d		4.7
Asche et al⁴⁶	NR	Retrospective cohort	Yes	Split	2446	612	AMI	65 (15)	30d	8.9
Cediel et al⁵⁸	TARRACO Risk score	Retrospective cohort	Yes	No	611	401	AMI type 2, ischaemia	D: 78 (17) V: 60 (21)	30d	2.6
		Retrospective cohort	Yes	No	611	401	AMI type 2, ischaemia	D: 78 (17) V: 60 (21)	180d	7.9
Chotechuang et al³⁶	GRACE	Retrospective cohort	NA	Ext	–	152	AMI	60.5 (6.3)	30d		5.3
	GRACE	Retrospective cohort	NA	Ext	–	152	AMI	60.5 (6.3)	180d		9.2
Hilbert et al⁵⁹	AMI decision tree	Registry	Yes	Ext	10 848	10 701	AMI	NR	30d	20.6	19.7
Dodson et al¹⁸	SILVER-AMI 30-day readmission calculator	Prospective cohort	Yes	Split	2004	1002	AMI	81.5 (5.0)	30d	18.2
Kini et al⁶⁰	NR	Registry	Yes	Split	60 742	26 107	AMI	76.5 (8.0)	90d	27.5
Nguyen et al¹⁹	AMI READMITS score	Retrospective cohort	Yes	Split	661	165	AMI	65.5 (12.8)	30d	13
	Full-stay AMI model	Retrospective cohort	Yes	Split	661	165	AMI	65.5 (12.8)	30d	13
	CMS AMI administrative model	Retrospective cohort	NA	Ext	–	826	AMI	65.5 (12.8)	30d		13
Krumholz et al²⁰	CMS AMI administrative model	Registry	Yes	Split, Ext	100 465	321 088	AMI	78.7 (8.0)	30d	18.9	20.0 (Ext) NR (split)
	CMS AMI medical model	Registry	Yes	Split	130 944	130 944	AMI	76.2 (7.3)	30d	20
Rana et al³³	Elixhauser index	Hospital database	NA	Ext	–	1660	AMI	67.9	30d		6.3
	HOSPITAL score	Hospital database	NA	Ext	–	1660	AMI	67.9	30d		6.3
Atzema et al⁴⁷	AFTER Part 2 scoring system	Retrospective cohort	Yes	Split	2343	1167	Arrhythmia, AF	D: 68.6 (14.7) V: 68.3 (15.1)	30d	7	7.6
Lahewala et al⁴⁰	CHADS2	Administrative	NA	Ext	–	116 450	Arrhythmia, AF	<75	30d		15.8
	CHADS2	Administrative	NA	Ext	–	116 450	Arrhythmia, AF	<75	90d		25.1
	CHA2DS-VASc	Administrative	NA	Ext	–	116 450	Arrhythmia, AF	65–74	30d		15.8
	CHA2DS-VASc	Administrative	NA	Ext	–	116 450	Arrhythmia, AF	65–74	90d		25.1
Benuzillo et al⁶¹	CRSS	Hospital database	Yes	Boot, Ext	2589	896 (Ext) 500 (Boot)	CABG	66.7 (9.9)	30d	9.1	8.2 (Ext) 9.1 (Boot)
Deo et al⁶²	30-day CABG readmission calculator	Administrative	Yes	Boot	155 054	1000	CABG	65.4 (10.4)	30d	12.5
Engoren et al⁵⁵	NR	Hospital database	Yes	Split	2644	2711	CABG	NR	30d	7.6	8
Lancey et al⁶³	NR	Registry	Yes	Split	2341	2520	CABG	64.5 (10.5)	30d	8.8	9.5
Rosenblum et al⁴¹	The STS PROM score	Hospital database	NA	Ext	–	21 719	CABG	63.5 (10.7)	30d		9.3
Zitser-Gurevich et al⁶⁴	NR	Prospective cohort	Yes	Split	2266.5	2266.5	CABG	65–74	30d	13.3
	NR	Prospective cohort	Yes	Split	2266.5	2266.5	CABG	65–74	100d	24.1
Zywot et al⁴²	CABG risk scale	Administrative	Yes	Ext	126 519	94 318	CABG	D: 70–74 V: 70–74	30d	23	21
Ahmad et al²¹	CMS HF administrative model	Prospective cohort	NA	Ext	–	183	HF	61 (18)	30d		22.4
Amarasingham et al²²	ADHERE	Hospital database	NA	Ext	–	1372	HF	56.5	30d		24.1
	CMS HF administrative model	Hospital database	NA	Ext	–	1372	HF	56.5	30d		24.1
	Tabak mortality score	Hospital database	NA	Ext	–	1372	HF	56.5	30d		24.1
Au et al²³	Administrative claims model: HF 30-day mortality	Administrative	NA	Ext	59 652	59 652	HF	75.8 (12.7)	30d		15.9
	Charlson Comorbidity Score	Administrative	NA	Ext	59 652	59 652	HF	75.8 (12.7)	30d		15.9
	CMS HF administrative model	Administrative	NA	Ext	59 652	59 652	HF	75.8 (12.7)	30d		15.9
	LACE	Administrative	NA	Ext	59 652	59 652	HF	75.8 (12.7)	30d		15.9
Bardhan et al⁶⁵	NR	Hospital database	Yes	No	40 983	–	HF	69.2 (15.7)	30d	7
Betihavas et al⁶⁶	NR	RCT secondary analysis	Yes	Boot	280	200	HF	74 (64–81)	28d	18
Cox et al²⁴	CMS HF administrative model	Hospital database	No	Ext	–	1454	HF	75 (12)	30d		21.5
	CMS HF medical model	Hospital database	No	Ext	–	1454	HF	75 (12)	30d		21.5
Delgado et al⁶⁷	15-day CV readmission risk score	Prospective cohort	Yes	Boot	1831	500	HF	72.4 (12.1)	15d	7.1
	30-day CV readmission risk score	Prospective cohort	Yes	Boot	1831	500	HF	72.4 (12.1)	30d	13.9
Formiga et al³⁰	CMS HF medical model	Hospital database	NA	Ext	–	719	HF	78.1 (9)	30d		7.6
	CMS HF medical model	Hospital database	NA	Ext	–	719	HF	78.1 (9)	90d		14.4
Frizzell et al²⁵	CMS HF administrative model	Registry	NA	External	–	56 477	HF	80 (2)	30d		21.2
Hammill et al²⁶	CMS HF administrative model	Registry	NA	Ext	–	24 163	HF	81	30d		21.9
Hilbert et al⁵⁹	HF decision tree	Registry	Yes	Ext	39 682	38 409	HF	NR	30d	25.5	25.2
Hummel et al³¹	CMS HF medical model	Prospective cohort	NA	Ext	–	1807	HF	79.8 (7.6)	30d		27
Huynh et al⁴⁸	NR	Prospective cohort	Yes	Ext	430	1046	HF	D: 75 (19) V: 67 (17)	30d	21	24
	NR	Prospective cohort	Yes	Ext	430	1046	HF	D: 75 (19) V: 67 (17)	90d	43	42
Ibrahim et al³⁴	HOSPITAL score	Retrospective cohort	NA	Ext	–	692	HfpEF	68.3 (11.8)	30d		27.3
	LACE/LACE+ index	Retrospective cohort	NA	Ext	–	692	HfpEF	68.3 (11.8)	30d		27.3
Keenan et al²⁷	CMS HF administrative model	Registry	Yes	Split, Ext.	28 319	845 291	HF	79.9 (7.8)	30d	23.6	23.7 (Ext) NR (Split)
	CMS HF medical model	Registry	Yes	Split, Ext.	64 329	64 329	HF	75–84	30d	23.7
Kitamura et al⁵³	FIM	Retrospective cohort	NA	Ext	–	113	HF	80.5 (6.7)	90d		20.4
Leong et al⁶⁸	30-day HF readmission risk score	Retrospective cohort	Yes	Split	888	587	HF	D: 70.0 (12.7) V: 69.1 (12.8)	30d	9.9
Li et al⁴⁹	NR	Retrospective cohort	Yes	Split	51 783	25 887	HF	D: 84 (12) V: 84 (11)	30d	24.2
Lim et al⁶⁹	NR	Registry	Yes	No	4566	–	HF	70.5 (12.0)	30d	6.6 (car) 13 (all)
Reed et al²⁸	AH model	Administrative	Yes	Split	NR	NR	HF	NR	30d	NR
	CMS HF administrative model	Administrative	NA	Split	–	NR	HF	NR	30d		NR
	Hasan	Administrative	NA	Split	–	NR	HF	NR	30d		NR
	LACE	Administrative	NA	Split	–	NR	HF	NR	30d		NR
	PARR-30	Administrative	NA	Split	–	NR	HF	NR	30d		NR
Salah et al⁷⁰	ELAN-HF score	Prospective cohort secondary analysis	Yes	No	1301	–	HF	74 (16)	180d	36.1
Sudhakar et al³²	CMS HF medical model	Hospital database	NA	Ext	–	1046	HF	65.2 (16.6)	30d		35.3
Tan et al⁷¹	NR	Hospital database	Yes	Split	246	104	HF	D: 67.7 (12.3) V: 69.0 (12.9)	90d	24.5	11.7
Wang et al⁷²	NR	Hospital database	Yes	No	4548	–	HF	68.5 (27.6)	30d	25.1
Wang et al³⁸	LACE	Retrospective cohort	NA	Ext	–	253	HF	56.6 (11.5)	30d		24.5
Yazdan-Ashoori et al²⁹	CMS HF administrative model	Prospective cohort	NA	Ext	–	378	HF	73.1 (13.1)	30d		26
	LACE	Prospective cohort	NA	Ext	–	378	HF	73.1 (13.1)	30d		26
Disdier Moulder et al⁷³	NR	Prospective cohort	Yes	No	258		HF, ACS, NR	70.5 (23)	30d	17
	NR	Prospective cohort	Yes	No	258		HF, ACS, NR	70.5 (23)	180d	38
Raposeiras-Roubín et al³⁷	GRACE	Retrospective cohort	NA	Ext	–	4229	HF, ACS	68.2 (18.7)	30d		2.6
Burke et al³⁵	HOSPITAL score	Retrospective cohort	NA	Ext	–	HF: 3189 AMI: 767	HF, AMI	65.8 (16.8)	30d		HF: 18.2 AMI: 17.4
Minges et al⁷⁴	NR	Registry	Yes	Split	193 899	194 179	HF, PCI	65+	30d	11.4
Pack et al⁷⁵	NR	Administrative	Yes	Split	30 826	7706	HVD	64.9 (12.2)	90d	12.8
Oliver-McNeil et al⁷⁶	ICD readmission-risk score	Registry	Update	Ext	182	–	ICD	69 (11)	30d		17.6
Wasfy et al⁵²	Pre-PCI model	Registry	Yes	Split	24 052	12 008	NR	64.8 (12.5)	30d	10.4
Barnett et al⁷⁷	NR	Registry	Update	Ext	19 964	19 964	Surgical	65.3 (12.4)	30d	11.4
Brown et al⁴³	STS augmented clinical model	Prospective cohort	Update	Boot	1046	NR	Surgical	65.4 (9.8)	30d	NR
	STS 30-day readmission model	Prospective cohort	NA	Ext	–	1194	Surgical	73.3 (10.1)	30d		NR
Espinoza et al⁷⁸	30-day readmission score after cardiac surgery	Retrospective cohort	Yes	Split	2529	2567	Surgical	65.1 (11.5)	30d	11.9
Ferraris et al⁵⁴	READMIT	Prospective cohort	Yes		2574		Surgical	63 (11)	30d	9.8
Kilic et al⁷⁹	NR	Retrospective cohort	Yes	Split	3898	1295	Surgical	D:61.9 (14.7) V: 61.6 (15.1)	30d	10	11
Stuebe et al⁸⁰	NR	Hospital database	Yes	No	4800		Surgical	60–69	30d	12
Tam et al⁴⁴	NR	Retrospective cohort	Yes	Boot	63 336	NR	Surgical	66.2 (10.7)	30d	11.3
Khera et al⁴⁵	TAVR 30-Day readmission risk model	Administrative	Yes	Boots, Ext	39 305	40 (Boot) 885 (Ext)	TAVR	D: 81.3 V: 81.7	30d	16.2	16.2 (Boot) 18.9 (Ext)
Sanchez et al⁵⁰	NR	Registry	Yes	Split	6903	3442	TAVR	D: 81.1 (7.9) V: 81.3 (7.9)	30d	9.8	10.7

Age is reported as mean (SD); median (IQR) or average age as reported in the study.

ACS, acute coronary syndrome; ADHERE, Acute Decompensated Heart Failure Registry; AF, atrial fibrillation; AH, Adventist Health Off-the-shelf model; AMI, acute myocardial infarction; Boot, bootstrapping; CABG, coronary artery bypass grafting; Car, cardiac-related; CHA2DS2-VASc, congestive heart failure, hypertension, age ≥ 75 years, diabetes mellitus, stroke or transient ischemic attack (TIA), vascular disease, age 65 to 74 years, sex category; CMS, Centers for Medicare and Medicaid Services; CRSS, CABG Readmission Risk Score; d, days; Dev, development; ELAN-HF, European Collaboration on Acute Decompensated Heart Failure; Ext, external validation; FIM, motor and cognitive Functional Independence Measure; GRACE, Global Registration of Acute Coronary Events; HF, heart failure; HFpEF, heart failure with preserved ejection fraction; HVD, heart valve disease; ICD, implantable cardioverter defibrillator; LACE, Length of stay, acuity of the Admission, Comorbidity of the patient and Emergency department use in the duration of 6 months before admission; NA, not applicable; NR, not reported; PARR-30, Patients at Risk of Re-admission within 30 days; PCI, percutaneous coronary intervention; READMITS, Renal Function, Elevated Brain Natriuretic Peptide, Age, Diabetes Mellitus, Nonmale Sex, Intervention with Timely Percutaneous Coronary Intervention, and Low Systolic Blood Pressure; SILVER-AMI, Comprehensive Evaluation of Risk Factors in Older Patients with AMI; Split, random split; STS PROM, Society of Thoracic Surgeons Predicted Risk of Mortality; TARRACO, Troponin Assessment for Risk stRatification of patients without Acute COronary atherothrombosis; TAVR, transcatheter aortic valve replacement; Val, validation.