Table 3

Characteristics of observational studies comparing early intervention versus conservative management

Study	Study design	Study population	Age (years)	Follow-up period	Outcomes	Adjustment methods
Pai et al11	Retrospective cohort study	338	71±15	7.6 months	All-cause mortality.	Cox proportional hazards model (variables adjusted for age, MR grade 3 or 4, CKD and aspirin use).
Kang et al12	Prospective cohort study	104	63±12	49.3 months	Operative mortality and cardiovascular death during follow-up.	Propensity score-matched analysis.
Le Tourneau et al13	Retrospective cohort study	694	71±11	Average more than 60 months	To assess the value of STS score in predicting short-term and long-term outcome.	Cox proportional hazards model.
Taniguchi et al (CURRENT AS registry)7	Retrospective cohort study (propensity score-matched analysis)	582	71.6±8.7 (AVR group) 73.1±9.3 (watchful waiting group)	45 months (median)	All-cause mortality and hospitalisation for heart failure.	Propensity score-matched analysis.
Masri et al14	Retrospective cohort study	533	66±13	82.8 months	All-cause mortality.	Cox proportional hazards model (variables adjusted for STS score, age-sex-predicted METs and heart rate recovery).
Bohbot et al15	Retrospective cohort study	281	73±10	42 months	All-cause mortality and cardiovascular death during follow-up.	Cox proportional hazards model (variables adjusted for age, sex, body surface area, hypertension, coronary artery disease, atrial fibrillation, Charlson Comorbidity Index, AVA, peak aortic jet velocity, EF and LV mass).
Campo et al16	Retrospective cohort study	265	68.1±11.7 (AVR group) 73±12.6 (watchful waiting group)	60 months	All-cause mortality.	Multivariable Cox regression model (variables adjusted for age, renal failure and ejection fraction).
Kim et al17	Retrospective cohort study	468	64.2±13	60.9 months	All-cause mortality, cardiovascular death and MACE.	Time-dependent Cox regression analysis (variables adjusted for age, BMI, anaemia, severe CKD, previous stroke, coronary artery disease, previous malignancy, left atrium diameter, LVMi and tricuspid regurgitation pressure gradient).

AVR, aortic valve replacement; BMI, body mass index; CKD, chronic kidney disease; CURRENT AS, Contemporary outcomes after Surgery and medical treatment in patients with severe Aortic Stenosis; EF, ejection fraction; LV, left ventricular; LVMi, left ventricular mass indexed; MACE, major adverse cardiac events; METs, metabolic equivalents; MR, mitral regurgitation; STS, Society of Thoracic Surgeons.