Predictive and concurrent validity of cartilage thickness change as a marker of knee osteoarthritis progression: data from the Osteoarthritis Initiative.

ABSTRACT

OBJECTIVE: To investigate the predictive and concurrent validity of magnetic resonance imaging (MRI)-based cartilage thickness change between baseline (BL) and year-two (Y2) follow-up (predictive validity) and between Y2 and Y4 follow-up (concurrent validity) for symptomatic and radiographic knee osteoarthritis (OA) progression during Y2→Y4. METHODS: 777 knees from 777 Osteoarthritis Initiative (OAI) participants (age 61.3 ± 9.0 years, BMI 30.1 ± 4.8 kg/m2) with Kellgren Lawrence (KL) grade 1-3 at Y2 (visit before progression interval) had cartilage thickness measurements from 3T MRI at BL, Y2 (n = 777), and Y4 (n = 708). Analysis of covariance and logistic regression were used to assess the association of pain progression (≥9 WOMAC units [scale 0-100], n = 205/572 with/without progression) and radiographic progression (≥0.7 mm minimum joint space width (mJSW) loss, n = 166/611 with/without progression) between Y2 and Y4 with preceding (BL→Y2) and concurrent (Y2→Y4) change in central medial femorotibial (cMFTC) compartment cartilage thickness. RESULTS: Symptomatic progression was associated with concurrent (Y2→Y4 -305 ± 470 µm vs -155 ± 346 µm, Odds ratios (OR) = 1.5 [1.2, 1.7]) but not with preceding cartilage thickness loss in cMFTC (-150 ± 276 µm vs -151 ± 299 µm, OR = 0.9 95% CI [0.8, 1.1]). Radiographic progression, in contrast, was significantly associated with both concurrent (-542 ± 550 µm vs -98 ± 255 µm, OR = 3.4 [2.6, 4.3]) and preceding cMFTC thickness loss (-229 ± 355 µm vs -130 ± 270 µm, OR = 1.3 [1.1, 1.5]). CONCLUSIONS: These results extend previous reports that did not discern predictive vs concurrent associations of cartilage thickness loss with OA progression. The observed predictive and concurrent validity of cartilage thickness loss for radiographic progression and observed concurrent validity for symptomatic progression provide an important step in qualifying cartilage thickness loss as a biomarker of knee OA progression. CLINICALTRIALS. GOV IDENTIFICATION NCT00080171.