Presence of synovitis may not predict steroid therapy success
by Judy George
Contributing Writer, MedPage Today May 21, 2017
Osteoarthritis (OA) patients who had severe knee damage were less likely than patients with mild structural damage to respond to intra-articular steroid injections, according to a study from England.
In an open-label study to discover whether structural factors affected steroid injections for knee OA in the short term (2 weeks) and longer term (6 months), Higher meniscal damage (OR=0.74, 95% CI 0.55-0.98), increasing Kellgren-Lawrence (KL) maximal grade (OR=0.43, 95% CI 0.23-0.82), and joint space narrowing maximal score (OR=0.60, 95% CI 0.36-0.99) were each associated with lower odds of longer-term response to knee steroid injections. As maximal joint space narrowing score increased from grade 0 to grade 3, the odds of longer-term response dropped from 38% to 12%, according to Terence O’Neill of the University of Manchester, and colleagues.
In addition, the presence of synovitis did not appear to predict whether steroid injection therapy would be successful, they noted.
“There are few studies that have looked at the influence of structural factors on response to intra-articular steroid injections,” the authors wrote in Arthritis Research & Therapy. “Our study of intra-articular steroid injection predictor of response was larger in scale and longer in follow-up than prior studies, and also involved scoring of individual features through contrast-enhanced MRI, offering the opportunity to identify other OA features and synovial factors affecting intra-articular steroid injection treatment.”
The O’Neill group studied 199 patients who reported moderate knee pain for more than 48 hours or met criteria based on Knee Injury and Osteoarthritis Outcome Score (KOOS). They confirmed OA either radiologically with a KL score of at least 2, or by MRI or arthroscopy. In the MRI and arthroscopy cases, the researchers looked for changes typically associated with OA and evidence of cartilage loss. Patients with gout, septic arthritis, or inflammatory arthritis were excluded, as were those who had hyaluronic acid or steroid injections in the previous 3 months or knee surgery in the previous 6 months.
The average age of study participants was 63.2 and 51.6% were female. At baseline, median KOOS was 44.4 points.
Of the 199 patients studied, 188 had knee x-rays and 120 had MRI scans. Among the MRI patients, the researchers looked at the whole-organ MRI score (WORMS) of 109 people and synovial tissue volume of 111 individuals.
The researchers assessed short-term and long-term response rate using Outcome Measures in Rheumatology-Osteoarthritis Research Society International (OMERACT-OARSI) responder criteria, based KOOS and a global Likert scale. They defined a “responder” as someone who had one of the following:
• At least 20% change in KOOS and a “slightly” or “much better” score on a 5-point Likert scale for pain
• At least 50% change in KOOS
Patients whose pain rebounded to within 20% of their baseline KOOS were considered to be “relapsed.” The authors classified patients whose pain did not return to this level at 6 months of follow-up as “longer-term responders.”
Overall, 73.4% of patients responded in the short term after an intra-articular steroid injection, and 20.1% were longer-term responders. Using OMERACT-OARSI criteria, the investigators saw no-short term structural predictors of response.
However, they observed that in the longer term, patients with severe knee damage on MRI scans and x-rays were less likely to respond to steroid injections than patients with mild structural damage.
Using radiographic and MRI data, O’Neill’s group derived a predictive table of short-term and longer-term response to steroid injections, but warned that short-term x-ray probabilities should be viewed with caution due to non-significant results and wide confidence intervals.
“Our predictive probabilities suggest people with advanced radiographic disease are unlikely to benefit from intra-articular steroid injections in the longer term,” they wrote. “Based on the degree of joint space narrowing observed on radiographs, the odds of having longer-term response is increased from around 10% to almost 40% as the disease becomes less severe.”
The authors also noted that as maximal meniscal scores increased from 0 to 6, the odds of longer-term response dropped from 28% to 6%.
The study had several limitations. Because it evaluated individuals who had steroid injections only, some response may be due to a placebo effect. The researchers used conventional non-standardized images to evaluate malalignment, not full-limb weight-bearing x-rays, which are the gold standard.
In addition, they optimized MRI sequences to detect bone marrow lesions, which might have contributed to negative findings with other knee structures. Finally, x-rays could have been taken up to 24 months before the steroid injections. This means that OA severity might have been underestimated and misclassified in a small proportion of patients.