Low serum creatinine level associated with higher presence of knee OA in both men and women: Study

Knee OA is a very common condition, but it affects mainly older adults. It consists of degeneration of the articular cartilage and underlying bone of the joints. This often results in pain, stiffness, and limitation in mobility-all factors that highly affect quality of life. Whereas the exact pathophysiology of knee OA is complex and multifactorial, recent studies have discussed the possibility of serum creatinine levels serving as a biomarker for the disease. Serum creatinine, the waste product formed from the normal breakdown of muscle tissue, is usually used to assess kidney function. However, its relation to musculoskeletal diseases such as knee OA has not been greatly analyzed. This study assessed the association of serum creatinine level with the presence and severity of knee OA, considering possible confounding variables.

The investigators performed a cross-sectional study based on data from the Korea National Health and Nutrition Examination Survey from 2009 to 2011. For this study, there were 3,428 participants aged ≥50 years. The Kellgren-Lawrence grading system is one of the most widely used and accepted systems for assessing the presence and severity of radiographic OA; this was used to grade knee OA. Logistic regression and receiver operating characteristic analyses tested the association between serum creatinine levels and the presence of knee OA, whereas ordinal regression tested the effect of creatinine on the severity of OA.

For this study, the participants were diagnosed with knee OA using radiographic imaging, and then the severity of the disease was determined based on the Kellgren-Lawrence scale. The level of serum creatinine was determined and logistic regression analysis conducted in order to ascertain the odds ratio of presence of knee OA according to levels of creatinine. It also used ordinal regression analysis to examine how creatinine level might influence the severity of knee OA according to K-L grades. All of these analyses also included stratification by sex, to indicate any possible difference between men and women.

Results

• The significant association of low serum creatinine with the radiographic presence of knee OA observed in this study was similarly present among men and women.

• Knee OA was significantly associated with low serum creatinine levels, with ORs of 0.118 (95% CI 0.045-0.314, p<0.001) for men and 0.148 (95% CI 0.040-0.549, p=0.004) for women.

• Low levels of serum creatinine were also significantly associated with increasing knee OA severity according to the K-L grading.

• The K-L scale-measured severity of knee OA was inversely related to the levels of serum creatinine: β -1.923 (SE, 0.478; p<0.001) for men and -1.532 (SE, 0.575; p=0.008) for women.

This study demonstrated that lower levels of serum creatinine are associated with a higher prevalence and greater severity of radiographic knee osteoarthritis among men and women aged 50 years and older. Their findings indicate that serum creatinine can potentially act as an important biomarker for classifying risk and disease progression of knee OA and may offer some advantages in early detection and management of this common condition.

Reference

Lim, C. W., Ryu, D. J., & Suh, Y. J. (2024). Association between low serum creatinine levels and knee osteoarthritis in Koreans without renal insufficiency. Yonsei Medical Journal, 65(9), 519. https://doi.org/10.3349/ymj.2023.0456