Clinical Screening and Identification of Sarcopenic Obesity in Adults with Knee Osteoarthritis

• Author / Creator

  Godziuk, Kristine D.

• Background: Obesity [defined using body mass index (BMI)] is associated with knee osteoarthritis (OA) and increased surgical infection risk in total knee arthroplasty (TKA). However sarcopenic obesity, a phenotype of low muscle mass with high fat mass, may have greater relevance and implications for adverse outcomes in this clinical population. This condition may be present in patients with knee OA but not identified using BMI measures alone. Sarcopenic obesity is associated with surgical infection, disability, and risk of mortality in other clinical populations, but not well-examined in clinical populations with OA. The purpose of this thesis was to examine sarcopenic obesity in adults with knee OA with respect to prevalence, diagnostic screening, and functional implications.
  Objectives: 1) determine the current breadth and extent of evidence on sarcopenic obesity in adults with knee OA; 2) assess the prevalence of sarcopenic obesity in a clinical cohort of adults with end-stage knee OA using accepted diagnostic criteria. Further, determine if there are differences in pain, physical function and quality of life between those identified with and without sarcopenic obesity, and; 3) determine which strength or physical function measures and patient characteristics are associated with low muscle mass (relevant to sarcopenic obesity), and could be used to screen patients with knee OA and obesity in clinical practice.
  Methods: This thesis includes three separate but inter-related studies: 1) a scoping review; 2) a cross-sectional clinical study, and; 3) an additional analysis of the cross-sectional cohort. The scoping review utilized a systematic search of Medline, CINAHL, Web of Science and EMBASE databases for keywords and subject headings related to obesity, sarcopenia and osteoarthritis. The cross-sectional study included adults with a BMI ≥30 kg/m2 and unilateral or bilateral knee OA. Body composition was measured in 151 patients (59% female, mean age 65.1±7.9 years, mean BMI 37.1±5.5 kg/m2) using dual-energy x-ray absorptiometry (DXA). Appendicular skeletal muscle mass (ASM) (adjusted to height2, weight, and BMI) was used to identify muscle mass, and was compared to previously established sex-specific cut-points. Strength and physical performance were assessed with gait speed over four metres, the six-minute walk test, and maximal handgrip strength (absolute, and relative, adjusted by BMI). Patient-reported pain and function were assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and health-related quality of life was assessed using the EuroQol Foundation 5-dimension 5-level instrument (EQ-5D-5L).
  Results: The scoping review found only three clinical studies on sarcopenic obesity in adults with knee OA, identifying a knowledge gap and need to clarify prevalence in a North American clinical sample. The cross-sectional study found the prevalence of sarcopenic obesity varied depending on diagnostic approach (1.3% using ASM/height2, 14.6% using ASM/weight, 27.2% using ASM/BMI, and 8.6% using a combined approach with low muscle and low strength or function). Regardless of the diagnostic approach used, patients with sarcopenic obesity had lower walking speed and endurance, and a higher proportion reported problems on the self-care dimension of the EQ-5D, compared to patients without this condition. In the analysis from the third study, relative grip strength and sex were associated with low muscle mass in this sample. Relative grip strength cut-points of <0.65 kg/m2 in females and <1.1 kg/m2 in males were identified as discriminators of low strength. When used in combination with low ASM/BMI, the prevalence of sarcopenic obesity was 19.9%. Patients identified with sarcopenic obesity had slower walking speed, lower walking endurance, and poorer health-related quality of life.
  Conclusions: This research demonstrates that sarcopenic obesity was present in a sample of adults with obesity and knee OA. Prevalence varied depending on diagnostic approach, however sarcopenic obesity negatively influenced mobility and quality of life in this patient population. Early identification of sarcopenic obesity in the clinical setting is important to prevent and minimize further muscle loss. Relative grip strength could be used to screen for low strength in patients with knee OA and obesity. Patients with low strength could then complete a body composition assessment to determine the presence of low muscle mass, and confirm or refute the identification of sarcopenic obesity.

• Subjects / Keywords

  • Sarcopenic obesity
  • Osteoarthritis

• Graduation date

  Fall 2019

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-sjsb-8955

• License

  Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.