Nancy A. Melville

March 30, 2015

NATIONAL HARBOR, MD — Despite being extensively marketed for everything from arthritis to clinical dentistry and hair replacement, and supported by no shortage of anecdotal reports, platelet-rich plasma (PRP) for musculoskeletal pain intervention continues to lack the randomized, controlled trials needed to turn its many sceptics into believers, according to several speakers here at the American Academy of Pain Medicine (AAPM) 31st Annual Meeting.

Presenting the latest findings from one study evaluating the benefit of the injections as treatment for cervical and lumbar facet arthropathy, Roger S. Moon, MD, from the Department of Anesthesiology at the Stony Brook University Medical Center, New York, said long-term efficacy was not evident.

"In our study, PRP was shown to have a short-term effect but its benefits were not seen after a 90-day period," Dr Moon said.

Dr Roger S. Moon

With no previous studies having investigated PRP for facet joint arthropathy, Dr Moon and his colleagues treated 24 patients with the condition by using one injection of PRP under fluoroscopic guidance.

While scores on a numeric rating pain scale decreased after 1 and 3 months compared with baseline (P ≤ 0.01), the scores returned to baseline at months 6 and 12.

Likewise, disability scores on the Oswestry and Neck Disability Indices improved in the first month (both P < .01) but also returned to baseline at other follow-up points.

Dr Moon said that a fine-tuning of patients and conditions most likely to respond is necessary to determine who can truly benefit from the treatment.

"Additional studies are needed to identify a post-PRP patient subgroup that is most likely to respond to therapy, and a long term study that measures the management of pain is needed for measuring outcome," he said.

Biological Growth Factors

The basis of interest in PRP is the suggestion that the biological growth factors from the plasma can promote healing in various tissues and treat joint pain. However, in a separate talk on the issue, Tim J. Lamer, MD, an associate professor of anesthesiology and pain medicine in the Division and Multidisciplinary Spine Center at the Mayo Clinic, Rochester, Minnesota, noted that ongoing efforts to produce convincing evidence from randomized, controlled trials have been made — and continue to come up short.

Dr Tim J. Lamer

He cited the most recent studies, including a double-blind, placebo-controlled trial reported in the New England Journal of Medicine in 2014, in which 80 athletes with acute hamstring muscle injuries were treated with two 3-mL injections of PRP or saline as placebo. No difference over placebo was seen in the primary outcome of time until patients could resume their sports activity during 6 months of follow-up.

In addition, a recent review of 58 articles evaluating the array of nonsurgical treatments of lateral epicondylitis, or tennis elbow, published in December 2014, failed to show PRP performing much better than other treatments.

The review included randomized, controlled trials of such treatments as corticosteroid injection, injection technique, iontophoresis, botulinum toxin A injection, prolotherapy, PRP or autologous blood injection, bracing, physical therapy, shockwave therapy, and laser therapy.

The results for PRP showed that "platelet-rich plasma or autologous blood injections have been found to be both more and less effective than corticosteroid injections," and the authors concluded that "existing literature does not provide conclusive evidence that there is one preferred method of non-surgical treatment for this condition."

In light of the lack of substantive evidence, the cost of PRP injections is particularly notable, Dr Lamer said, pointing out that while clinicians typically charge $800 for a single injection and $600 for subsequent injections in the same area, patients typically pick up nearly the entire tab because insurance companies will likely not cover the cost.

"All major payers consider PRP for musculoskeletal conditions to be experimental," Dr Lamer said.

The lack of evidence, combined with the patient-unfriendly costs of treatments, leads to the conclusion that PRP is "not ready for prime time," Dr Lamer asserted.

"The current use of PRP seems driven as much by marketing and revenue as treatment efficacy," he concluded.

"We need to know what the optimal and effective contents of PRP are, and we need real outcome and safety data before selling this to patients."

Lack of Interest by Pharma?

Arguing on the pro side for PRP, Timothy T. Davis, MD, medical director of Orthopedic Pain Specialists in Santa Monica, California, said that the reasons it's been hard to confirm anecdotal reports of benefits include the varying types of systems and approaches.

Dr Timothy T. Davis

"There are about 40 different PRP systems out there, and the content of the PRP can have a wide variety of factors," he said.

"Another important thing I have found is the timing of the administration, which is considered even more important than the concentration of platelets or of white blood cells."

He noted that some randomized, controlled trials have shown benefits specifically for osteoarthritis, but he added that an important reason for the paucity of such trials is a lack of interest from the pharmaceutical industry.

"There's no money in this for them, so they're not investing in the kind of clinical trials that are needed," he said.

A meta-analysis of PRP injections in osteoarthritis of the knee published in November 2014 in the British Journal of Sports Medicine reviewed 10 randomized or nonrandomized controlled trials that show intra-articular PRP injections to be more effective for pain reduction compared with placebo at 6 months after injection. However, the authors reported that the level of evidence was limited because "almost all of the trials had a high risk of bias."

In addition, the review of PRP showed significant reductions in pain compared with hyaluronic acid injections and improvements in function compared with controls. For both the level of evidence was described as limited to moderate, again because of the high risk of bias.

"More large randomized studies of good quality and low risk of bias are needed to test whether PRP injections should be a routine part of management of patients with OA of the knee," the authors concluded.

The study received no external funding. Dr Lamer disclosed that he has received research support from Boston Scientific for spinal cord stimulation and from Vertos for minimally invasive percutaneous decompression. All funds were paid to his institution. Dr Moon has disclosed no relevant financial relationships. Dr Davis' disclosures are as follows: Alpha Diagnostics, Intraoperative NeuroMonitoring (salary—founder); Bioness (no compensation—subinvestigator); Boston Scientific (no compensation—principal investigator); Broadway Surgical Institute (distributions from ownership—board of directors); Johnson & Johnson (dividends—stock holder); Medtronic (honorarium—advisory boards member) and (honorarium—speaker bureau); Merck (purchased on public stock exchange—stock holder); Mesoblast (honorarium—scientific advisory board; purchased on public stock exchange—stock holder); MMX Medical Software Company (no compensation—stock holder); Nuvasive (purchased on public stock exchange—stock holder); Paradigm Spine (no compensation—stock holder); Pfizer (purchased on public stock exchange—stock holder); Prosydian (no compensation—stock holder); Small Bone Innovations (no compensation—stock holder); St. Jude Neuromodulation (honorarium—speaker bureau); Vertiflex (honorarium—advisory board member; honorarium—speaker bureau; honorarium—principal investigator); Wright Medical Group (purchased on public stock exchange—stock holder).

American Academy of Pain Medicine (AAPM) 31st Annual Meeting. Abstract 127. Presented March 20, 2015.

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