Background/Purpose:

 Osteoarthritis (OA) is a disease that is thought to be the result of many factors, which includes inflammatory causes.  A recent study examined the relation of knee OA, synovial uric acid levels, and how it relates to NLRP3 inflammasome activity.  It was demonstrated that synovial uric acid concentration is strongly correlated with markers of inflammasome activity and knee osteoarthritis.  In addition, baseline synovial TNF alpha and synovial IL-18 was associated with changes in the osteophyte scores in 3 year longitudinal models of knee.  This main focus of our research project is to examine the relation of serum uric acid concentration (SUA) and the severity of radiographic knee osteoarthritis.  We hypothesized that higher concentrations of SUA is positively associated with the severity of radiographic knee OA as measured by Kellgren/Lawrence grades.

Methods:

We used the National Health and Nutrition Examination Survey  (NHANES III) database to carry out our research.  Patients over the age of 60 had bilateral, non weight bearing knee films done.  Our database was created by merging variable datasets provided by the NHANES III, which included lab values, knee imaging, demographics, as well as physical exam findings.  A total of 2188 survey participants were in our database after excluding patients who either had gout or were on allopurinol. We performed correlative analyses between serum uric acid concentrations and different measurements of knee osteoarthritis using SAS Enterprise Guide version 2.3.  The correlation between serum uric acid concentration and knee osteoarthritis was examined with Pearson’s score of correlation.  Co-variates were taken into account using generalized linear modeling.  The NHANEs survey design was taken into account by applying sampling weights to our variables.

Results:

A statistically significant correlation was seen in univariate analyses between serum uric acid concentration and measurements of radiographic knee OA, which included the  combined total KL score (R=0.086, p<0.001), the combined total medial tibial sclerosis score (R=0.053, p=.01), and the combined total osteophyte score (R=0.069, p=0.001).  Linear regression modeling was then preformed between the measurements of knee osteoarthritis and serum uric acid concentration to account for age, gender, body mass index (BMI), serum creatinine (Cr).  Statistical significance was lost when accounting for these covariates.

Conclusion:  

In conclusion, our study showed a statistically significant correlation between serum uric acid concentration and radiographic measurements of knee osteoarthritis.  This relationship was lost while accounting for age, gender, BMI, and serum creatinine.  It is likely that soluble uric acid acts locally in increasing risk for OA.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/knee-osteoarthritis-and-serum-uric-acid-concentration-the-third-national-health-and-examination-survey/