ISR Autumn Meeting 2017
Poster Presentations - 2nd Prize
A comparative study of lean muscle mass in patients with newly diagnosed Inflammatory Arthritis and established Inflammatory Arthritis
Bernie McGowan1,3, Mary Jane Reodica1, Sarah McDonald1, Keunjae Ahn2, Noreen Harrington1, Miriam O Sullivan1,2, Bryan Whelan1,2, Carmel Silke1,2
1. The North Western Rheumatology Unit, Our Lady’s Hospital, Manorhamilton, Co Leitrim, Ireland 2. Dept of Medicine, National University of Ireland Galway 3. The Department of Pharmacology and Therapeutics, Trinity College Dublin
Low lean muscle mass has been commonly identified in patients with chronic inflammatory diseases. Studies however, evaluating changes in lean muscle mass at different stages of disease progression are limited.
1) To identify differences in lean mass in two separate patient groups attending the NWRU, one group newly diagnosed with Inflammatory Arthritis (IA) and a second group of patients with established Inflammatory Arthritis.
In total N=196 patients attending the NWRU were included in the study. The mean age of the patients was 59.2 yrs (+14.8), males n=73(37%) and females n=123 (63%). In total 86 (44%) of patients had established Inflammatory Arthritis and 108 (56%) were newly diagnosed patients with Inflammatory Arthritis (rheumatoid arthritis and psoriatic arthritis). Anthropometric measurements were recorded including weight, height and BMI. Body Composition analyses including Appendicular Lean Mass was measured using Dual-Energy-X-ray-Absorptiometry (DXA) scan. We used the Sarcopenia definition in order to quantify low lean muscle mass. Sarcopenia is quantified as appendicular skeletal mass divided by height squared (ASM/H²) and considered present if the calculated skeletal muscle mass index (SMI) is two standard deviations (SD) below the mean for a population of young adults as based on the Rosetta study. The cut-off points for sarcopenic muscle mass are gender-specific: SMI of <7.26 kg/m2 for males and <5.5 kg/m2 for females. All data was recorded and analysed on SPSS version 23.0. Factors associated with low SMI in the two patient groups were assessed using Independent T tests.
A total of 56 patients (29%) had low lean muscle mass and 138 (71%) of patients had normal muscle mass. The SMI in females was significantly lower in the established IA group compared to females newly diagnosed with IA (P=.038). The mean SMI of male patients was also lower in the established IA group than the newly diagnosed IA group however the difference was not statistically significant. In the established Inflammatory Arthritis patients (N=86) further analyses did not identify any statistical significant differences in the SMI of patients treated with biologic therapy compared to patients not on biologic therapy.
A total of 56 (29%) of patients with inflammatory arthritis attending the NWRU were identified as having low lean muscle mass. SMI of females in the established IA group was significantly lower than the SMI of females in the newly diagnosed IA group. This would suggest that efforts should be made to address loss of lean muscle mass in established IA and it may explain why outcomes are still poor in patients with established IA despite the availability of some excellent treatments.