A nationwide comparative analysis of medical complications in fibromyalgia patients following total knee arthroplasty

Abstract

BACKGROUND Fibromyalgia is a disease primarily characterized by chronic widespread pain and associated symptoms of fatigue, mild cognitive impairment, and sleep disturbance. The condition affects 1% to 6% of the general population in the United States and is more commonly diagnosed in women (2:1 ratio). There is evidence to suggest that fibromyalgia patients may be more at risk of postoperative complications. The rate of total knee arthroplasties (TKAs) performed worldwide is escalating and thus it is expected that the proportion of fibromyalgia patients under orthopaedic care will increase accordingly. However, the literature on TKA outcomes in this subpopulation is limited. We assessed whether fibromyalgia patients have a higher likelihood of developing medical complications compared to a matched cohort of non-fibromyalgia patients following TKA. Specifically, we assessed the likelihood of developing (I) any medical complication and (II) specific medical complications. METHODS Using the Medicare Standard Analytical Files of the PearlDiver supercomputer, patients who underwent a TKA between 2005 and 2014 were queried. Propensity score matching was used to match patients with and without fibromyalgia in a 1:1 ratio based on age, sex, and the Charlson Comorbidity Index (CCI). A total cohort of 305,510 patients (female =242,198; male =59,810; and unknown =3,502) with (n=152,755) and without fibromyalgia (n=152,755) was identified. Statistical analyses involved the calculation of odds ratios, 95% confidence intervals (95% CI), and P values (<0.05) were utilized to evaluate the occurrence of any and specific medical complications. RESULTS Compared to a matched cohort of non-fibromyalgia patients, fibromyalgia patients had increased odds of developing any medical complication following TKA [odds ratio (OR): 1.95, 95% CI: 1.86-2.04, P<0.001]. Furthermore, compared to a matched cohort, these patients had significantly greater odds of developing urinary tract infections (OR: 2.08, 95% CI: 1.89-2.29, P<0.001), acute post-hemorrhagic anemia (OR: 1.56, 95% CI: 1.41-1.73, P<0.001), thoracic or lumbosacral neuritis or radiculitis (OR: 5.85, 95% CI: 4.82-7.10, P<0.001), shortness of breath (OR: 3.02, 95% CI: 2.60-3.51, P<0.001), other diseases of lung not elsewhere classified (OR: 2.32, 95% CI: 1.77-3.03, P<0.001), other respiratory abnormalities (OR: 3.49, 95% CI: 2.87-4.24, P<0.001), transfusion of packed cells (OR: 1.69, 95% CI: 1.36-2.10, P<0.001), pneumonia (OR: 2.17, 95% CI: 1.71-2.76, P<0.001), acute kidney failure (OR: 1.27, 95% CI: 1.02-1.57, P<0.05), and neuralgia neuritis and radiculitis (OR: 5.29, 95% CI: 3.53-7.92, P<0.001). CONCLUSIONS As the number of fibromyalgia patients under orthopaedic care is expected to rise, it is imperative that the TKA outcomes of these patients are tracked in order to provide optimal patient care. This study identified fibromyalgia as a risk factor for a number of medical complications following TKA. Orthopaedic surgeons must be aware of the potential for poor TKA outcomes among these patients and should provide them with appropriate medical care and pre-operative guidance.