Doctoral dissertation

Pyry Jämsä: Chronic Kidney Disease in Patients Undergoing Hip or Knee Joint Replacement

Pyry Jämsä
The doctoral dissertation of M.D. Pyry Jämsä sought to ascertain how common renal impairment and postoperative acute kidney injury (AKI) are and whether serum creatinine (SCr) value discriminates between patients with chronic kidney disease (CKD) and those without CKD. The study also examined the risk factors associated with AKI and ascertained whether long-term mortality or implant survival is associated with renal function.

Chronic kidney disease is a common comorbidity in patients undergoing hip or knee replacement. Kidney function can be classified into five different CKD stages, where CKD stage 1 denotes normal function, and CKD stage 5 denotes kidney failure. CKD stages 3-5 correspond to the traditional definition of CKD; glomerular filtration rate (GFR) lower than 60mL/min/1.73m2. CKD increases postoperative morbidity, affects drug dosages and perioperative care, predisposes to risk for postoperative kidney injury and the most severe forms of CKD are known to be associated with increased postoperative mortality. It is not known whether the most CKD stages 2-3, affects mortality or not after total joint arthroplasty.

It is not known if renal impairment reduces implant survival in the long term, while earlier studies reporting on implant survival have not considered the competing risk of death in CKD patients. Also, there are some unclear risk factors for postoperative acute kidney injury.

The study used a large cohort of patient and follow-up data from a single centre with all its consecutive hip and knee replacements to answer the study questions. Mortality data was linked to the study from the exclusive national Population Register Centre.

Supported by earlier literature, prevalence of CKD varied from nine to thirteen percent depending on the calculation method, while two thirds of patients had decreased kidney function (CKD stage > 1). Preoperative CKD was most common in older female patients, knee replacement patients and also in patients with other comorbidities. If clinicians were to use increased SCr to filter CKD, they would miss up to 7% of CKD patients.

However, among older female patients and older normal weight patients, a remarkable amount (up to 70%) of CKD would have gone unnoticed. Incidence of postoperative AKI was only 3.3/1,000 (95% CI 2.5-4.5/ 1,000 operations). In multivariable analysis, independent risk factors associated with postoperative AKI were duration of the operation, ASA-class, body mass index (BMI) and preoperative eGFR, in which duration of the operation was not reported earlier. Early prosthetic joint infections (PJIs) were most dominantly found to be the main trigger for AKI.

When considering confounding factors, at median follow-up of 7.8 years, when comparing to patients with CKD stage 1, adjusted Hazard Ratio for death was 1.9 (95% CI 1.8-2.1) in stage 2, 3.8 (95% CI 3.4-4.2) in stage 3, and 8.1 (95% CI 6.3-10.3) in patients with stage 4-5. CKD patients had a surprisingly high mortality rate; at five and ten years postoperatively, 21% and 68% of the patients with CKD stage 3 had died, while the corresponding numbers were 47% and 87% in patients with CKD 4-5.

However, renal function had no significant association with implant survival or infection free survival even when considering high mortality of patients with CKD stages 3-5 as a competing risk. Due to a lack of patients with the most severe forms of CKD (CKD stages 4-5) it was not possible to show if these patients are at increased risk for revision.

In clinical practice, after taking note of the results of this study, it is recommended always to calculate eGFR when considering a TJA. eGFR based classification of CKD stages should be reviewed alongside with other major comorbid conditions when assessing the risks and benefits of the operation. In order to prevent AKI, we could recommend considering patients’ BMI, ASA grade, BMI preoperatively and initiate interventions prior to. Postoperatively, it might be useful to pay attention to patients’ SCr and urine output whenever the operating time exceeds two hours.

The doctoral dissertation of M.D. Pyry Jämsä titled Chronic Kidney Disease in Patients Undergoing Hip or Knee Relpacement will be publicly examined at the Faculty of Medicine and Health Technology of Tampere University at 13 o'clock on Friday 26 November, 2021. The venue is Arvo building auditorium F115, address: Arvo Ylpön katu 34. Docent Petri Virolainen from University of Turku will be the opponent while Professor Niku Oksala will act as the custos.

The dissertation is available online at
http://urn.fi/URN:ISBN:978-952-03-2139-0

 

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