Session Type: Abstract Submissions (ACR)
Background/Purpose: We have previously identified differences in associations between joint metabolism biomarkers and radiographic features of the lumbar spine (disc space narrowing (DSN) and osteophytes (OST)). Due to anatomical differences, there may be distinct associations between biomarkers and different phenotypes of osteoarthritis (OA) in the spine. Therefore, our aim was to determine if differences exist in the associations between biomarkers and OA in the spine, defined as 1) facet osteoarthritis (FOA) and 2) the combination of DSN and OST at the same level; we further explored variations by gender, race and low back symptoms.
Methods: Of the 1,015 participants enrolled in the Johnston County OA Project from 2003-04, 547 participants had complete data for serum hyaluronan (sHA), serum Cartilage Oligometric Matrix Protein (sCOMP), serum collagen neoepitope (sC2C), serum C-propeptide (sCPII), and urinary N-terminal telopeptide (uNTX-I); 529 participants had complete data for urinary cross-linked C-telopeptide of type II collagen (uCTX-II). The mean age and body mass index (BMI) were 62 (SD 10) years and 30 (SD 6) kg/m2, respectively; 62% were female, 38% were African American (AA), 29% had knee OA, 24% hip OA, 28% hand OA and 49% low back symptoms. Each lumbar spine level was graded for OST and DSN in a semi-quantitative fashion (0-3) and FOA was graded as present or absent according to the Burnett Atlas. Spine OA was defined as the presence of DSN and OST grade 1 or more at the same lumbar level. Biomarkers were natural log (ln) transformed. Linear regression was used to determine adjusted geometric mean values of biomarkers and binary logistic regression models were used to estimate adjusted odds ratios (aOR) and 95% confidence intervals (CI) between biomarkers and spine radiographic variables. All analyses were adjusted for demographic (age, race, gender), clinical (BMI) and radiographic (knee, hip, hand and spine OA or FOA) variables. Interactions were tested with likelihood ratio tests at a p-value<0.05.
Results: FOA was present at least at one level of the lumbar spine in 57% of participants, while spine OA was present in 49%. Geometric mean biomarker levels of lnHA were significantly (p=0.04) greater in the presence of FOA while lnCTX-II levels were significantly (p<0.01) greater with in presence of spine OA. Significant associations were found between lnHA and FOA (aOR=1.26 ((95% CI 1.02, 1.55)) whereas lnCTX-II was significantly associated with spine OA (aOR=1.64 ((95% CI 1.22, 2.21)). The association between lnHA and FOA was significantly (interaction p<0.01) greater among Caucasians (aOR=1.56 ((95% CI 1.18, 2.05)) than with AA (aOR=0.92 ((95% CI 0.68, 1.25)). The association between lnCOMP and spine OA was significantly greater (interaction p=0.03) among those with low back symptoms (aOR=2.14 ((95% CI 1.08, 4.28)), than those without (aOR=0.76 ((95% CI 0.51, 1.68)).
Conclusion: Joint metabolism biomarkers reflect the anatomical (HA with FOA and CTX-II with spine OA), demographic (HA with race and FOA) and clinical (COMP with spine OA and symptoms) differences between FOA and a composite definition of spine OA. This may indicate a different pathophysiologic process exists for these two phenotypes of OA in the lumbar spine.
A. P. Goode,
A. E. Nelson,
V. B. Kraus,
J. B. Renner,
J. M. Jordan,
Trinity Partners, Inc. ,
Osteoarthritis Research Society International,
Chronic Osteoarthritis Management Initiative of US Bone and Joint Initiative,
Interleukin Genetics, Inc. ,
Algynomics, Inc. ,
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/biomarkers-reflect-differences-in-osteoarthritis-phenotypes-of-the-lumbar-spine-the-johnston-county-osteoarthritis-project/