Background: Sleep apnoea frequently affects patients with end-stage renal disease. However, it is still unclear whether or to what extent sleep disorders may affect functional capacity and quality of life in haemodialysis patients. We tested the hypothesis that apneic dialysis patients due to the lack of restorative sleep will have a further reduced functional capacity and further compromised quality of life compared to their non-apneic counterparts.
Methods: Forty-three clinically stable haemodialysis patients (13 F, 56.6+/-19.4 years) were examined. After polysomnographic analysis, patients were divided in two groups according to their calculated apnoea hypopnoea index (AHI; cutoff 5). Primary outcomes were intergroup differences in the following: (1) physical capacity and muscle performance, assessed by functional tests, (2) quality of life, assessed by the SF-36, (3) body composition, measured by DEXA and (4) muscle composition and size, as well as (5) visceral (VAT) and subcutaneous (SAT) adipose tissue, calculated by computed tomography.
Results: Twenty-two patients had AHI >5 (4 F, AHI=28.8+/-22.3). The adjusted analysis for age, BMI and years in dialysis therapy, showed that the low-AHI group (N=21, 9 F, AHI=1.8+/-1.3) had better functional capacity, and performed better in muscle strength and endurance tests compared to the high-AHI group. There were no differences in lean body mass and % total body fat between groups, however, values for VAT, VAT/TAT ratio and thigh muscles' fat infiltration were increased in the high-AHI group. VAT correlated with BMI (r=0.682, P=0.001), functional capacity (r=0.558, P=0.001) apnoea hypopnoea index (r=0.530, P=0.001). There were no statistical significant differences in quality of life between the two groups. To further account for age and BMI differences, a subgroup of patients was matched by age, sex and BMI (N=10/group). In the matched analysis, all the above statistical differences remained, between the low-AHI and high-AHI groups.
Conclusions: Haemodialysis patients with sleep apnoea syndrome demonstrate poorer functional capacity, physical performance and muscle composition, compared to non-apneic dialysis patients. Overall, sleep apnoea appears to partly contribute to the total diminished functional capacity of haemodialysis patients.