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The use of combined glucosamine and chondroitin sulfate significantly decreased the loss of cartilage volume in knee osteoarthritis (OA) over a 6-year period, Canadian researchers found.
Compared with individuals who had never taken the supplements and whose cartilage loss in the lateral compartment at 6 years was -8.85%, those with 1 year of exposure to the medications had a loss of -8.21%, according to Johanne Martel-Pelletier, PhD, of the University of Montreal, and colleagues.
In addition, patients with 2 to 3 years of exposure had a loss of -6.66%, while those with 4 to 6 years of exposure showed a loss in the lateral compartment of -6.90% (P<0.0001 for trend), the researchers reported in Arthritis Care & Research.
Previous research into the use of glucosamine and chondroitin for knee OA has had conflicting results.
In a double-blind, NIH-sponsored study known as GAIT, more than 1,500 patients with painful knee OA were randomized to receive glucosamine, chondroitin, both, celecoxib (Celebrex), or placebo for 6 months.
In that study, neither of the supplements, alone or in combination, led to significant reductions in pain, although a subgroup analysis suggested the possibility of benefits for those with moderate-to-severe pain at baseline.
However, in a systematic review of randomized studies evaluating chondroitin with or without glucosamine, the medication was associated with greater improvements in pain than placebo. A second meta-analysis of glucosamine and chondroitin found "moderate to large effects," but the quality of the studies was a concern, as was the likelihood of publication bias.
Yet another meta-analysis found no improvements in pain and "minute" changes in joint space, and the Swiss authors concluded that health authorities and payers should not cover the costs of the treatment, and patients should be discouraged from taking them.
But some of the studies thus far have suggested that the effects on disease progression might be clearer with a longer intervention, so Martel-Pelletier and colleagues sought longer-term outcomes, analyzing data from the longitudinal Osteoarthritis Initiative.
Patients included in the analysis had at least 6 years' follow-up, had at least 1 mm of joint space width at baseline, and also had MRI evidence of medial meniscal extrusion, indicating that structural changes were already present.
The primary outcome was change in cartilage volume using automated quantitative MRI, but clinical information on pain, stiffness, and function also was assessed, using the Western Ontario and McMaster (WOMAC) arthritis index.
A total of 96 patients had taken glucosamine/chondroitin for 1 year, 38 for 2 to 3 years, and 112 for 4 to 6 years. The "not exposed" (control) group included 183 individuals.
Participants' mean age was 63, and mean body mass index was 30 kg/m2. Mean joint space width at baseline was 3.4 mm, and mean cartilage volume for the global knee was 9,673 mm3.
In addition to the decreased cartilage loss in the lateral compartment, there also was significantly less loss for the global knee among patients with 4 to 6 years of exposure to glucosamine/chondroitin compared with no exposure (-8.83% versus -10.03%, P=0.048).
No effects were seen for the medial compartment, where changes in cartilage volume were 11.51% for 4 to 6 years of exposure and -11.49% with no exposure. This lack of effect might reflect severe damage already being present in the medial compartment, the researchers suggested.
There also was no benefit for symptoms, although that was not a primary analysis of the study. Improvement in WOMAC pain scores were -2.7 with 1 year of exposure, -2.2 for 2 to 3 years of exposure, -2.5 for 4 to 6 years, and -2.8 for the non-exposed group (P=0.269). However, the observational nature of the study provided no control over analgesia intake, they pointed out.
They noted that the MRI-detected structural changes were "relatively small." And while the differences were statistically significant, the question as to whether this can translate into a positive clinical impact is not yet known. Nonetheless, one study found that every 1% increase in the rate of cartilage loss over 2 years was associated with a 20% higher risk of needing a total knee arthroplasty after 4 years.
The researchers concluded, "These data are consistent with the hypothesis that individuals with knee OA, at a moderate stage of the disease, could benefit from long-term structure modifying agents such as glucosamine/chondroitin."
A limitation of the study was the lack of information about the dosages or quality of the medications used.
The study was supported by grants from Bioiberica and the Osteoarthritis Research Unit and the Chair in Osteoarthritis of the University of Montreal.
Martel-Pelletier and some co-authors disclosed relevant relationships with Bioiberica and ArthroLab. Some co-authors are employees of ArthroLab.
- Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner
Arthritis Care & ResearchSource Reference: Raynauld J-P, et al "Long-term effects of glucosamine/chondroitin sulfate on the progression of structural changes in knee osteoarthritis: 6-year follow-up data from the Osteoarthritis Initiative" Arthritis Care Res 2016; DOI: 10.1002/acr.22866.