Abstract: Objective  Constipation is a common gastrointestinal symptom that is prevalent in dialysis patients. It is well known that many factors affect constipation in dialysis patients, but whether muscle mass affects constipation is unknown. The aim of this study was to explore the relationship between muscle mass and constipation in dialysis patients.  Methods   A total of 428 dialysis patients from three dialysis centers were enrolled in this cross-sectional study. Constipation was assessed by the constipation assessment scale (CAS). Muscle mass was determined using computed tomography (CT) at the L1 vertebral level. Multivariate logistic regression was used to assess the effect of muscle mass on constipation.   Results   A total of 428 dialysis patients were enrolled in the study. The mean age was 56.09±15.17 years, and the prevalence of constipation was 62.38% in dialysis patients. Multivariate logistic regression results showed that dialysis years (OR=0.942,95% CI:0.910～0.976,P＜0.001) and low attenuation muscle (LAM) density (OR=0.825,95% CI:0.771～0.961,P=0.008) were the protective factors influencing constipation, while diabetes history (OR=2.331,95% CI:1.290～4.212,P＜0.001) was a risk factor for constipation. We also performed sex subgroup analyses. In male dialysis patients, a younger dialysis age (OR=0.946,95% CI:0.903～0.990,P=0.017) and a lower LAM density (OR=0.868,95% CI:0.777～0.970,P=0.014) were the risk factors for constipation based on CAS score. In female dialysis patients, a younger dialysis age (OR=0.934,95% CI:0.884～0.987,P=0.015) and a lower LAM density (OR=0.784,95% CI:0.675～0.911,P=0.002) were the risk factors for constipation based on CAS scores.   Conclusions   The present study shows that dialysis patients have a higher incidence of constipation and that LAM density is an independent risk factor for constipation in dialysis patients. Our study provides a new perspective to understand the cause of susceptibility to constipation in dialysis patients.

Key words: Constipation, Hemodialysis, Peritoneal dialysis, Computed tomography, Low attenuation muscle density