Study source	Confounders
Kim (2019) 134	Age, (gender), BMI, SBP, HR, HT, CHD, Hb, Na, Cre, NT‐proBNP, LVEF, medications
Chen (2018) 101	None
Cooper (2018) 102	Age, gender, race, BMI, SBP, HrR, NYHA, CHD, AF, PVD, COPD, CKD, ACE‐I, ARB, diuretics
Iorio (2018) 137	Age, gender
Kristensen (2018) 103	None
Retwinski (2018) 136	None
Rorth (2018) 104	Age, gender, education, IHD, AF, CKD, COPD, HT, stroke, cancer, medications
Sandesara (2018) 105	None
Takimura (2018) 135	Age, duration after previous HF, Hb, UA, LVEF, LAVI
Dauriz (2017) 106	Age, gender, smoking, BMI, SBP, eGFR, LVEF, IHD, HT, statin, stroke, COPD, Hb
Farre (2017) 107	Age, gender, recent HF, anaemia, valvular disease, IHD, CKD, dialysis, AF, cardiac conduction disorders, cancer, stroke, dementia, cirrhosis number of hospitalization, visits to emergency department
Kristensen (2017) 108	Age, gender, recent HF, LVEF, HrR, eGFR, NT‐proBNP, neutrophils, COPD, MI, ischaemic origin
Mohamedali (2017) 109	None
Echouffo‐Tcheugui (2016) 110	Age, gender, race, LVEF, NYHA, AF, ischaemic cardiomyopathy, ECG (LBBB, wide QRS), cardiac conduction disorders, HF duration, Cre, history of syncope, FH of sudden death, CHD, ventricular tachycardia medications
Kristensen (2016) 111	None
Ruigomez (2016) 112	Age, gender, smoking, alcohol, BMI, residence, IHD, stroke, HT, AF, hyperlipidaemia, COPD, asthma, RD, visiting hospital in the previous year
Kaneko (2015) 113	Age, IHD, DBP, HrR, diuretics
Takeda (2015) 114	None
Carrasco‐Sanchez (2014) 115	Age, NYHA, GFR, Na, BMI, anaemia, PVD, beta‐blocker, ACE‐Is, ARBs
Cubbon (2014) 116	Pulmonary congestion, previous HF, diuretics
Paoletti (2014) 117	None
Sakata (2014) 118	Age, gender, smoking, BMI, SBP, HT, dyslipidaemia, LVEF, HrR, Hb, Cre, BNP, medications
Larina (2013) 119	None
Sarma (2013) 120	Age, gender, smoking, BMI, SBP, EF, Na, BUN, QRS duration, BNP/NT‐proBNP, AF, HT, CKD, stroke, medications
Verbrugge (2012) 121	Obesity, HT, COPD, CKD, NYHA, right ventricular function, ischaemic aetiology of HF
Deedwania (2011) 122	Propensity‐matched for age, gender, smoking, BMI, SBP, DBP, HrR, others (multiple) (previous diseases, laboratory data, medications)
Martin (2011) 123	None
Aguilar (2010) 124	Age, gender, obesity, ischaemic origin, NYHA
Sze (2010) 125	Gender, NYHA, AF, wide QRS, HrR, one of renal function indicators, beta‐blocker, diuretics
MacDonald (2008) 126	32 covariates (including age, gender, smoking, SBP, DBP, NYHA, LVEF, HrR, IHD, stroke, AT, pacemaker, various medications)
Macdonald (2008) 127	Age, (gender), co‐morbidities (including CHD)
Ghali (2007) 128	None
Ruiz‐Ruiz (2007) 129	None
Formiga (2006) 130	Age, gender, SBP, PIP
Garcia (2005) 131	None
Domanski (2003) 132	Age, gender, BMI, race, Cre, SBP, aetiology of HF, cholesterol, diuretics, vasodilators
Shindler (1996) 133	Age, gender, race, EF, aetiology of left ventricular dysfunction, NYHA
Harnett (1995) 85	Age, IHD, EF, Hb, albumin, DBP, LV mass