Moderate to Severe Renal Insufficiency Is Associated With High Mortality After Hip and Knee Replacement
Authors: Jämsä Pyry , Jämsen Esa , Huhtala Heini , Eskelinen Antti , Oksala Niku 
Published: June 2018

Background
In patients having elective hip or knee replacements, many comorbid conditions, including diabetes, cardiovascular disease, and congestive heart failure, are associated with postoperative mortality. Renal failure and a history of renal transplantation also increase mortality. However, the effect of different stages of chronic kidney disease on patients’ prognoses is unclear.

Questions/purposes
(1) What is the risk of postoperative mortality in different stages of chronic kidney disease after elective hip or knee replacement and does the risk increase with mild renal insufficiency? (2) How severe is the risk of death in patients with chronic kidney disease compared with other major medical comorbidities such as diabetes, cardiovascular disease, and congestive heart failure? (3) Are there risk factor combinations associated with especially poor survival?

Methods
Using longitudinally maintained databases, the records of 18,575 patients (median age 69 years, 63% female, median body mass index 29 kg/m2) undergoing elective hip and knee replacements from a single center between 2002 and 2011 were analyzed in this retrospective study. A total of 6519 (35%) patients had Stage I, 9917 (53%) Stage II, 2023 (11%) Stage III, 81 (0.4%) Stage IV, and 35 (0.2%) Stage V chronic kidney disease. Kaplan-Meier analysis was used to analyze mortality at different stages of the disease. Cox regression analysis was performed to compare the risk of death associated with the comorbid conditions of interest. Comorbid conditions with greatest risk for death (diabetes, coronary artery disease, and congestive heart failure) were combined separately with chronic kidney disease using logistic regression. According to data from the Finnish Population Register Centre, a total of 4055 deaths occurred in our patient cohort during the followup period. The median followup was 7.8 years (range, 0-14 years; interquartile range, 5.8-10.0 years).

Results
The mean survival time was 13 years (95% confidence interval [CI], 12.5-12.7 years) in Stage I, 11 years (95% CI, 11.3-11.5 years) in Stage II, 9 years (95% CI, 9.2-9.7 years) in Stage III, 7 years (95% CI, 5.6-7.5 years) in Stage IV, and 6 years (95% CI, 4.9-8.0 years) in Stage V (p < 0.001). Compared with Stage I chronic kidney disease, the risk of death increased with every step of the disease (adjusted hazard ratio [HR], 1.9 [95% CI, 1.76-2.10]; HR, 3.8 [95% CI, 3.39-4.19]; and HR, 8.1 [95% CI, 6.33-10.31] in Stages II, III, and IV-V, respectively). Compared with congestive heart failure (HR, 2.11 [95% CI, 1.81-2.45], p < 0.001), coronary disease (HR, 1.54 [95% CI, 1.40-1.69], p < 0.001), diabetes (HR, 1.71 [95% CI, 1.54-1.90], p < 0.001), and hypertension (HR, 1.35 [95% CI, 1.26-1.45], p < 0.001), Stage III and Stage IV to V chronic kidney disease are associated with poorer survival. The combination of chronic kidney disease and diabetes (odds ratio [OR], 8.15 [95% CI, 4.9–13.51]) had a synergistic effect on the risk of death compared with chronic kidney disease (OR, 2.36 [95% CI, 1.70–3.28]) or diabetes alone (OR, 1.19 [95% CI, 0.70–2.03]) during the first postoperative year.

Conclusions
All stages of chronic kidney disease have a harmful effect on long-term life expectancy in joint replacement recipients. The risk becomes clinically meaningful in the most severe forms of the disease, but also in moderate chronic kidney disease when it is accompanied by diabetes, coronary disease, or congestive heart failure. It should be recognized that these patients achieve fewer quality-adjusted life-years even if clinical outcomes were similar. The effect of chronic kidney disease on cost-effectiveness of hip and knee replacements should be investigated in future studies.

Level of Evidence
Level III, therapeutic study.