Important covariates such as perioperative cardiac arrest or hemodynamic instability to reduce confounding

We read with interest and congratulate the authors for reporting largest retrospective study comparing endovascular open repair in treatment of ruptured abdominal aortic aneurysms.1Wang L.J. Locham S. Al-Nouri O. Eagleton M.J. Clouse W.D. Malas M.B. Endovascular aneurysm is superior to repair: propensity-matched analysis Vascular Quality Initiative.J Vasc Surg. 2020; 72: 498-507Abstract Full Text PDF PubMed Scopus (8) Google Scholar The performed propensity score matching compare matched cohorts patients who had undergone or found that surgery was associated increased 30-day mortality, myocardial infarction, respiratory complications, acute kidney injury. Propensity reduce bias by balancing confounding factors between groups. variables used were age, race, smoking status, congestive heart failure, chronic obstructive pulmonary disease, end-stage renal previous repair, preoperative medications, maximal diameter. believe a significant extent selection might still be inherent their because important clinical such as cardiac arrest hemodynamic instability not considered during matching. A patient presented greater experienced on presentation emergency room would have tendency undergoing instead repair. This group has been shown experience significantly mortality compared without arrest.2Harris D.G. Garrido D. Oates C.P. Kalsi R. Huffner M.E. Toursavadkohi et al.Repair after arrest.J 2016; 64: 1497-1502Abstract (6) Furthermore, Table II, reported proportion periprocedural low preintubation blood pressure, statistically difference both unmatched cohorts. Although did specify whether arrests occurred before intervention, it apparent these differences accounted study. strongly outcomes more conclusive relevant if included when performing