Secular trends in acute dialysis after elective major surgery--1995 to 2009

Abstract

Background: Acute kidney injury is a serious complication of elective major surgery. Acute dialysis is used to support life in the most severe cases. We examined whether rates and outcomes of acute dialysis after elective major surgery have changed over time.

Methods: We used data from Ontario's universal health care databases to study all consecutive patients who had elective major surgery at 118 hospitals between 1995 and 2009. Our primary outcomes were acute dialysis within 14 days of surgery, death within 90 days of surgery and chronic dialysis for patients who did not recover kidney function.

Results: A total of 552,672 patients underwent elective major surgery during the study period, 2231 of whom received acute dialysis. The incidence of acute dialysis increased steadily from 0.2% in 1995 (95% confidence interval [CI] 0.15-0.2) to 0.6% in 2009 (95% CI 0.6-0.7). This increase was primarily in cardiac and vascular surgeries. Among patients who received acute dialysis, 937 died within 90 days of surgery (42.0%, 95% CI 40.0-44.1), with no change in 90-day survival over time. Among the 1294 patients who received acute dialysis and survived beyond 90 days, 352 required chronic dialysis (27.2%, 95% CI 24.8-29.7), with no change over time.

Interpretation: The use of acute dialysis after cardiac and vascular surgery has increased substantially since 1995. Studies focusing on interventions to better prevent and treat perioperative acute kidney injury are needed.

Figure 1:

Selection of patients for the study. *Patients may have had more than one reason for exclusion. †For patients who underwent multiple surgeries during the study period, one surgery was randomly selected for the analysis.

Figure 2:

Multivariable logistic regression model for postoperative acute dialysis. CI = confidence interval, OR = odds ratio.

Figure 3:

Incidence of postoperative acute dialysis, 1995–2009, (A) by age and (B) by type of surgery. (C) Association between year of surgery and acute dialysis after surgery, using 1995 as the reference year. Error bars indicate 95% confidence intervals. The model was adjusted for year, age, Charlson Comorbidity Index, comorbid medical conditions (diabetes mellitus, peripheral vascular disease, chronic obstructive pulmonary disease, hypertension, coronary artery disease, cerebrovascular disease, chronic kidney disease, liver dysfunction, cancer, congestive heart failure) and type of surgery. OR = odds ratio.

Figure 4:

Time (mean, d) from index surgery to first dialysis treatment. Error bars indicate minimum and maximum values, and boxes indicate values for the interquartile range.

Figure 5:

Incidence of acute dialysis, 1995–2009, by type of dialysis received. Type of dialysis was defined as receipt of at least one treatment using the specified modality in the 14 days postsurgery. Because a patient could receive treatment with more than one modality during the postoperative period, the percentages of all modalities in a given year may exceed 100%. CRRT = continuous renal replacement therapy, IHD = intermittent hemodialysis, PD = peritoneal dialysis.

Figure 6:

(A) Incidence of death at 90 days among patients who received acute dialysis after surgery. (B) Association between year of surgery and death among patients who received acute dialysis, using 1995 as the reference year. Error bars indicate 95% confidence intervals. The model was adjusted for year, age, Charlson Comorbidity Index, comorbid medical conditions (diabetes mellitus, peripheral vascular disease, chronic obstructive pulmonary disease, hypertension, coronary artery disease, cerebrovascular disease, chronic kidney disease, liver dysfunction, cancer, congestive heart failure) and type of surgery.

Figure 7:

(A) Incidence of chronic dialysis among patients who received acute dialysis after surgery and survived beyond 90 days. (B) Association between year of surgery and chronic dialysis among patients who received acute dialysis, using 1995 as the reference year. Error bars indicate 95% confidence intervals. The model was adjusted for year, age, Charlson Comorbidity Index, comorbid medical conditions (diabetes mellitus, peripheral vascular disease, chronic obstructive pulmonary disease, hypertension, coronary artery disease, cerebrovascular disease, chronic kidney disease, liver dysfunction, cancer, congestive heart failure) and type of surgery.