Background/Purpose:   Knee osteoarthritis (KOA) in the obese population is underdiagnosed and routinely undertreated, as providers often attribute pain to excess weight without considering articular pathology.  The literature does not speculate if obese and non-obese patients are offered the same treatment options for their KOA.  Using a retrospective chart review, we compared approaches to KOA treatment across BMI subgroups as well as between physician specialties: rheumatology, orthopedics, sports medicine, physiatry, and internal medicine.

Methods:   We searched the NYU electronic medical record between January 1 and December 31, 2013 for patients seen for KOA by selected physicians in the 5 specialties.  From the resulting list of 4,486 patients, we reviewed the first 1,500 charts and selected for clinical and radiographic KOA while excluding patients with bilateral knee replacements, trauma within 6 weeks, or concurrent rheumatoid arthritis, psoriatic arthritis, gout, pseudogout, or bursitis.  From this cohort we found 702 who met criteria (191 patients seen by rheumatology, 162 by orthopedics, 198 by sports medicine, 132 by physiatry, and 20 by internal medicine).  We recorded BMIs, comorbidities, KOA characteristics, and KOA management including acetaminophen, NSAIDs/COX-2 inhibitors, physical therapy referrals, and intra-articular injections of steroids or hyaluronic acid (HA).  We analyzed differences in overall KOA treatment of non-obese vs. obese patients (BMI <30 vs ≥30 kg/m²), and between the 5 physician specialties regardless of patient BMI.

Results:   The resulting cohort of 702 patients had an overall mean BMI of 29.1 (±7).  The mean age was 60.5 (±14) with 75% females.  Surprisingly, we did not find any significant differences in KOA treatment of non-obese (BMI<30) vs obese patients when aggregating scores across physician specialties; this held true when comparing the non-obese with the morbidly obese (BMI>35).  Our data do suggest that rheumatologists recommend acetominophen for KOA far more often than do the combined cohort of orthopedists, physiatrists and sports medicine physicians (37% vs 3%, p<0.001); internists (at 43%) are even greater proponents of acetaminophen. We did not identify any significant difference between specialties in the percentage of KOA patients prescribed NSAIDs or COX-2 inhibitors, referrals to physical therapy, or the use of corticosteroid injections. With regards to HA, rheumatologists in our cohort inject less than orthopedists (17% vs 26%, p=0.06), sports medicine physicians (17% vs 30%, p=0.004), and physiatrists (17% vs 29%, p=0.02). We also found no reportable difference in specialty-specific KOA treatment between the BMI sub-groups.

Conclusion: In treating KOA, rheumatologists and internists are more likely to prescribe acetaminophen for KOA while orthopedists, sports medicine physicians, and physiatrists are more like to inject HA.  Despite preconceived bias, we did not identify significant differences in the KOA treatment of non-obese vs obese patients, in aggregate or within any of the subspecialties.  Nevertheless, identification of divergent treatment patterns between specialties warrants discussion to optimize algorithms across musculoskeletal care.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/comparison-of-knee-osteoarthritis-treatment-in-the-non-obese-versus-obese-populations-across-different-medical-specialties/