Summing up a talk about the placebo effect in osteoarthritis by renowned rheumatologist Joel Block, of Rush University, at an American College of Rheumatology symposium in Chicago, John Gever, managing editor of MedPage Today, paraphrased: “So what?”

“The placebo effect is still an effect and a very important one, [Block] argued repeatedly in addressing current knowledge about therapies, largely unregulated, now marketed nationwide in newspapers and online as ‘disease-modifying,’” Gever writes.

Placebo refers to a psychological improvement with “no clear explanation for why some persons experience measurable improvement when given an inert substance for treatment,” per Britannica. “Research has indicated that the effect may be caused by the person’s expectations about the treatment rather than being a direct effect of the treatment itself.”

In his talk at the ACR event, Block discussed three approaches to treating osteoarthritis that fall into the domain of placebo effect: platelet-rich plasma, stem cell treatments, and prolotherapy.

“Although these are typically marketed as halting or reversing joint degeneration in osteoarthritis, there is virtually no evidence that they actually do,” Gever writes. “Yet it’s impossible to discount the countless reports from patients that the treatments helped them in terms of pain and function.” He quotes Block saying “Placebo is active treatment,” and that physicians ought to help patients “regardless of whether it’s better than placebo, or is placebo.”

In treatment with platelet-rich plasma (PRP), doctors essentially remove a small amount of a patient’s blood, spin it in a centrifuge, and separate the plasma rich in platelets, which help blood clot. The concentrated platelets are then injected into the patient, and, “In theory, the growth factors that platelets secrete (not including human growth hormone) spur tissue recovery,” reports Scientific American. A 2007 paper titled “Platelet Rich Plasma: Myth or Reality?” had concluded that a “paucity of critical scientific data regarding the beneficial effects of platelet rich plasma in clinical procedures” remains. More than a decade later, Block couldn’t find measurable evidence of of those benefits, but he said that the placebo effect needs to be respected among the many patients who will feel improvement.

Stem cell therapies can be even murkier than PRP, Block said, and Gever notes that this treatment and PRP can cost $5,000 each time and aren’t covered by insurance. “Block also noted that (in one of the seedier aspects of these treatments) marketing claims may include suggestions of FDA approval. In fact, no PRP or stem cell treatment has been submitted to the FDA for evaluation of efficacy and safety,” Gever writes. “But the equipment and processes used in preparing materials for injection are regulated by the FDA, typically through 510(k) clearance, providing a basis — however misleading — for claiming FDA approval.”

In prolotherapy, a sugar solution is injected repeatedly into part of a joint, according to the Mayo Clinic, and “is thought to trigger growth in the connective tissue of the joint, eventually leading to reduced pain.” Questions remain about this treatment, notes the Arthritis Foundation. “One hint that this is nonsense on a physiological level, Block suggested, is that some studies have shown benefit in pain and function even when injections are periarticular — that is, not even within the joint,” Gever writes. But here again Block noted that patients often report positive outcomes, and that should not be ignored even if the scientific evidence isn’t there.