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Conducting clinical trials in osteoarthritis: ORS
Medical expert of the article
Last reviewed: 04.07.2025
The Osteoarthritis Research Society (ORS) recommendations are based on the division of anti-arthrosis drugs, as proposed by WHO and ILAR, into two groups - symptomatic (fast- and slow-acting) and cartilage structure-modifying. It is obvious that the demonstration of the benefits of these drugs will largely depend on the study design and the chosen efficacy criteria. At the same time, the study design will depend on the mechanism of action of the drug and the expected result.
When planning a study, the following factors should be considered:
- pharmacodynamics of the drug,
- time from the start of taking the drug until the effect appears,
- the duration of the effect obtained as a result of treatment after the drug is discontinued,
- route of administration of the drug (local, internal, parenteral, etc.),
- frequency and severity of side effects,
- influence on pain syndrome,
- effect on inflammation,
- influence on other symptoms of the disease.
Most of the committee members who took part in the study of this issue were inclined to think that in relation to the design of clinical trials of osteoarthritis there is no need to divide symptomatic drugs into two subclasses - fast-acting and slow-acting. The first class includes non-narcotic analgesics and NSAIDs, the second class includes drugs for which the symptomatic effect is not the main one - hyaluronic acid, chondroitin sulfate, glucosamine, diacerein. Thus, in these recommendations the term "symptomatic drugs" is used for both fast-acting and slow-acting symptomatic drugs. When drawing up a study protocol, it should be borne in mind that a symptomatic drug may have properties to modify the structure of cartilage (favorable and unfavorable).
Regardless of its effect on disease symptoms, a drug may affect the structure or function of the affected joint. A protocol for studying the efficacy of drugs that are likely to modify the pathological process in osteoarthritis should include criteria that reflect changes in joint structure. Such drugs may:
- prevent the development of osteoarthritis and/or
- prevent, slow down the progression of existing osteoarthritis or stabilize the patient's condition.
A drug with a pathogenetic effect does not necessarily have to affect the symptoms of osteoarthrosis. The symptomatic effect of such a drug should be expected only after a long period of treatment. The objectives of the study of the effectiveness of a drug that modifies the structure of cartilage do not necessarily include the study of its symptomatic effect.
Drugs that have the potential to modify cartilage structure are called "chondroprotectors," "disease-modifying OA drugs" (DMOADs), "anatomy-modifying drugs," "morphology-modifying drugs," etc. Unfortunately, there is no consensus on the term that would most fully reflect the action of these agents. ORS uses the term "structure-modifying drugs" in its recommendations and notes that to date, no agent has been proven to modify cartilage structure in vivo in humans.
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