Association of frailty and 1-year postoperative mortality following major elective noncardiac surgery: a population-based cohort study

Importance — Single-center studies identify frailty as a risk factor for 30-day postoperative mortality. The long-term and population-level effect of frailty on postoperative mortality is, to our knowledge, poorly described, as are the interactions of frailty with important predictors of mortality.

Objective — To measure the population-level effect of patient frailty on, and its association with, 1-year postoperative mortality.

Design, Setting and Participants — Population-based retrospective cohort study in Ontario, Canada, with data collected between April 1, 2002 and March 31, 2012. Analysis was performed from December 2014 to March 2015. All patients were community-dwelling individuals aged 65 years or older on the day of elective, major noncardiac surgery.

Exposure — Frailty, as defined by the Johns Hopkins Adjusted Clinical Groups (ACG) frailty-defining diagnoses indicator. The ACG frailty-defining diagnoses indicator is a binary variable that uses 12 clusters of frailty-defining diagnoses.

Main Outcomes and Measures — One-year all-cause postoperative mortality.

Results — Of 202 811 patients, 6289 (3.1%) were frail (mean [SD] age, 77 [7] years). Within 1 year, 13.6% (n = 855) of frail and 4.8% (n = 9433) of nonfrail patients died. Adjustment for sociodemographic and surgical confounders resulted in a hazard ratio of 2.23 (95% CI, 2.08-2.40). The interaction between frailty and postoperative time demonstrated an increased relative hazard for death in frail patients (hazard ratio, 35.58; 95% CI, 29.78-40.19) on postoperative day 3. The association between frailty and increased risk of death decreased with patient age (HR, 2.66; 95% CI, 2.28-3.10 at age 65; HR, 1.63; 95% CI, 1.36-1.95 at age 90). Significant variations in the increased risk for death in frail patients existed between different surgery types and was strongest after total joint arthroplasty (HR, 3.79; 95% CI, 3.21-4.47 for hip replacement; HR, 2.68; 95% CI, 2.10-3.42 for knee replacement).

Conclusions and Relevance — At a population level, preoperative frailty-defining diagnoses were associated with a significantly increased risk of 1-year mortality that was particularly notable in the early postoperative period, in younger patients, and after joint arthroplasty.