Evaluation of Persistent Organ Dysfunction Plus Death As a Novel Composite Outcome in Cardiac Surgical Patients

Abstract

Objectives: Validated composite outcomes after complicated cardiac surgery are poorly established. Therefore, the authors evaluated a novel composite endpoint, persistent organ dysfunction (POD)+death, which is defined as any need for life-sustaining therapies or death at any time within 28 days from surgery.

Design: Secondary analysis extracted from a large-scale prospective randomized trial of critically ill cardiac surgery patients.

Setting: Multi-institutional, university hospitals.

Participants: Ninety-five cardiac surgery patients with complicated postoperative courses.

Interventions: Cardiac surgery with cardiopulmonary bypass.

Measurements and main results: At 28 days following surgery, the prevalence of POD was 15%, and 23% of patients had died (POD+death = 38%). Patients alive with POD at day 28 exhibited a significantly higher extent of organ injury and longer ICU (33 v 7 days; p<0.001) and hospital lengths of stay (49 v 21 days; p<0.001) compared to patients without POD at day 28. At 3 and 6 months, quality-of-life scores (by Short Form 36 questionnaire) showed a significantly reduced rating for most components in patients with POD at day 28 compared to those without POD. The 6-month mortality rate was 21% among patients alive with POD at day 28 compared to 5% among patients alive without POD (p = 0.05). The calculated number of patients needed per arm to detect a 25% relative risk reduction for mortality alone was 762 compared to 386 per arm for POD+ death.

Conclusions: POD+death at day 28 following cardiac surgery may be a valid composite endpoint and offers statistical efficiencies in terms of sample size calculations for cardiac surgical trials.

Keywords: cardiac surgery; composite outcome measurements; organ dysfunctions.