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Knee pain lasting 1 year predicts faster cartilage loss, higher OA risk
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Fluctuating and persistent knee pain over 1 year predicts accelerated cartilage loss as well as an increased risk for incident and progressive radiographic osteoarthritis, according to data published in Arthritis Research & Therapy.
“There have been data supporting the notion that knee pain is not only a consequence of structural deterioration in OA, but also contributes to structural progression,” Yuanyuan Wang, MD, PhD, MBBS, of Monash University, Melbourne, Australia, told Healio Rheumatology. “Clarifying this is important because if this is the case, targeting the factors causing knee pain may offer a potential strategy for slowing the disease progression of OA.”
“While previous studies have predominantly focused on whether structural changes predict knee pain in people with knee OA, the relatively few studies examining whether knee pain is a predictor of structural progression of knee OA have shown conflicting results,” she added. “The inconclusive results may be due to differences in study population, sample size, assessment of knee pain, duration of follow-up, and measures of structural progression.”
To determine whether knee pain over a period of 1 year was a predictor of cartilage loss, as well as the incidence and progression of radiographic OA, the researchers extracted data from the NIH Osteoarthritis Initiative (OAI), which contains data on 4,796 patients with or at risk for knee OA at baseline. Wang and colleagues focused on 2,249 participants with radiographic OA and 2,120 without.
The researchers assessed knee pain at baseline and 1 year using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Patients were categorized based on knee pain, with the groups including “no pain,” with a WOMAC score of less than 5 at baseline and 1 year; “fluctuating pain,” with a WOMAC score greater than5 at either time point; and “persistent pain,” denoting a WOMAC score greater than 5 at both time points. Cartilage volume, as well as the incidence and progression of radiographic OA, were evaluated using MRI and X-rays at baseline and 4 years.
According to the researchers, among patients with and without radiographic OA, greater baseline WOMAC knee pain scores were associated with increased medial and lateral cartilage volume loss (P .001), as well as the incidence (OR = 1.07; 95% CI, 1.01-1.13) and progression (OR = 1.07; 95% CI, 1.03-1.1) of radiographic OA. In addition, patients with and without radiographic OA, with fluctuating and persistent knee pain, demonstrated increased cartilage volume loss, compared with those with no pain (P .01).
Those without radiographic OA with fluctuating knee pain demonstrated an increased risk for incident radiographic OA (OR = 1.62; 95% CI, 1.04–2.54), corresponding to a number needed to harm of 19.5. Among those with the condition, the risk for progressive radiographic OA increased in participants with persistent knee pain (OR = 1.82; 95% CI, 1.28–2.6), corresponding to a number needed to harm of 9.6.
“These data suggest that knee pain is an important predictive factor for the deterioration of knee structural outcomes,” Wang said. “Treating patients with knee pain early in the disease course and controlling knee pain over time by targeting the underlying mechanisms may be important for preserving knee structure and reducing the burden of knee OA.” – by Jason Laday
Disclosure: Wang reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.
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