Reduced Long-Term Relative Survival in Females and Younger Adults Undergoing Cardiac Surgery: A Prospective Cohort Study

Tone Bull Enger; Hilde Pleym; Roar Stenseth; Guri Greiff; Alexander Wahba; Vibeke Videm

doi:10.1371/journal.pone.0163754

Reduced Long-Term Relative Survival in Females and Younger Adults Undergoing Cardiac Surgery: A Prospective Cohort Study

PLoS One. 2016 Sep 28;11(9):e0163754. doi: 10.1371/journal.pone.0163754. eCollection 2016.

Authors

Tone Bull Enger^{1

2}, Hilde Pleym^{3

4}, Roar Stenseth^{3

2}, Guri Greiff^{3

2}, Alexander Wahba^{3

5}, Vibeke Videm^{1

6}

Affiliations

¹ Department of Laboratory Medicine, Children's and Women's Health, Faculty of Medicine, NTNU-Norwegian University of Science and Technology, Trondheim, Norway.
² Department of Cardiothoracic Anaesthesia and Intensive Care, St. Olavs University Hospital, Trondheim, Norway.
³ Department of Circulation and Medical Imaging, Faculty of Medicine, NTNU-Norwegian University of Science and Technology, Trondheim, Norway.
⁴ Clinic of Anaesthesia and Intensive Care, St. Olavs University Hospital, Trondheim, Norway.
⁵ Clinic of Cardiothoracic Surgery, St. Olavs University Hospital, Trondheim, Norway.
⁶ Department of Immunology and Transfusion Medicine, St. Olavs University Hospital, Trondheim, Norway.

Abstract

Objectives: To assess long-term survival and mortality in adult cardiac surgery patients.

Methods: 8,564 consecutive patients undergoing cardiac surgery in Trondheim, Norway from 2000 until censoring 31.12.2014 were prospectively followed. Observed long-term mortality following surgery was compared to the expected mortality in the Norwegian population, matched on gender, age and calendar year. This enabled assessment of relative survival (observed/expected survival rates) and relative mortality (observed/expected deaths). Long-term mortality was compared across gender, age and surgical procedure. Predictors of reduced survival were assessed with multivariate analyses of observed and relative mortality.

Results: During follow-up (median 6.4 years), 2,044 patients (23.9%) died. The observed 30-day, 1-, 3- and 5-year mortality rates were 2.2%, 4.4%, 8.2% and 13.8%, respectively, and remained constant throughout the study period. Comparing observed mortality to that expected in a matched sample from the general population, patients undergoing cardiac surgery showed excellent survival throughout the first seven years of follow-up (relative survival ≥ 1). Subsequently, survival decreased, which was more pronounced in females and patients undergoing other procedures than isolated coronary artery bypass grafting (CABG). Relative mortality was higher in younger age groups, females and patients undergoing aortic valve replacement (AVR). The female survival advantage in the general population was obliterated (relative mortality ratio (RMR) 1.35 (1.19-1.54), p<0.001). Increasing observed long-term mortality seen with ageing was due to population risk, and younger age was independently associated with increased relative mortality (RMR per 5 years 0.81 (0.79-0.84), p<0.001)).

Conclusions: Cardiac surgery patients showed comparable survival to that expected in the general Norwegian population, underlining the benefits of cardiac surgery in appropriately selected patients. The beneficial effect lasted shorter in younger patients, females and patients undergoing AVR or other procedures than isolated CABG. Thus, the study identified three groups that need increased attention for further improvement of outcomes.

Grants and funding

This study was funded by the Medical Faculty at NTNU-Norwegian University of Science and Technology (TBE; 249/2015; http://www.ntnu.edu/dmf). The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.