SAN DIEGO – Knee osteoarthritis is too frequently underdiagnosed and undertreated by primary care physicians and bariatric surgeons in obese patients considering weight loss surgery.
That’s the conclusion Dr. Janice Lin and her coinvestigators at New York University reached based upon their prospective study in which 408 consecutive patients scheduled for bariatric surgery at NYU Langone Medical Center and Bellevue Hospital were screened for this common form of arthritis.
The researchers found that 54% of the obese patients reported significant knee pain. Of these 221 patients, 26 weren’t interested in further evaluation, but 115 were deemed likely to have knee osteoarthritis (OA) on the basis of a brief screen indicating they had knee pain on more than 15 days per month for longer than 1 month, had a visual analog scale (VAS) pain score of at least 30 out of 100, and didn’t have lupus, bilateral knee replacement, crystal disease, psoriasis, or an inflammatory arthritis. These 115 patients formed the study population for this ongoing prospective investigation.
The primary care physicians of only 47% of these 115 patients had evaluated their knee pain. Bariatric surgeons had similarly not addressed the knee pain in about half of cases. Indeed, fewer than one-third of these obese patients with knee pain had been assessed via knee x-rays in accord with guideline-recommended practice.
"In the bariatric population, knee pain is often attributed to mechanical load from obesity without proper evaluation or treatment. Patients are rarely referred to rheumatologists or other appropriate specialists, though they may benefit from such evaluation and management," according to Dr. Lin.
In fact, only 3% of these patients with significant knee pain had been referred to a rheumatologist and 15% to an orthopedic surgeon.
ACR treatment guidelines were for the most part not being followed. Although roughly three-quarters of patients were taking NSAIDs and/or acetaminophen, only 31% of the group had been referred for physical therapy, 14% had received a steroid injection, 11% used a topical NSAID, and 1% had undergone viscosupplementation, recommended as a second-line therapy.
All 115 study participants got a baseline posterior-anterior standing bilateral knee x-ray scored for Kellgren-Lawrence grade. Based on the findings, 19% of patients were determined to not have knee OA, 21% had mild Kellgren-Lawrence grade 1 disease, and the rest had more advanced knee OA.
The group’s mean baseline VAS pain score was 64.5. Their Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) mean pain, stiffness, and function scores were 268, 102, and 938, respectively.
This ongoing study builds upon an earlier retrospective study by Dr. Lin’s coinvestigators at New York University, who reported that 51% of 192 patients who underwent bariatric laparoscopic banding surgery had complete improvement in knee OA pain 19 months later.In the ongoing prospective study, participants will repeat the WOMAC and other validated measures of knee OA pain and function 1, 3, and 6 months after laparascopic banding, sleeve gastrectomy, or gastric bypass. They will also have follow-up knee x-rays. Dr. Lin and her coworkers will be eager to see if any of the three types of bariatric surgery is advantageous in terms of its impact on knee pain, she said.
She reported having no relevant financial conflicts.