Periodic limb movements among dialysis and non-dialysis chronic kidney disease patients: a comparative study

Abstract
Background
Periodic leg movement disorder is defined as periodic episodes of repetitive limb movements during sleep that mainly occurs in the lower limb, including the hips, knees, and toes, and sometimes affects the upper limb. It may be accompanied by frequent nocturnal arousals, and if so, this sleep disturbance may cause excessive daytime sleepiness. Chronic kidney disease patients are at risk of periodic leg movements and common causes are iron deficiency, anemia, raised serum calcium, and central and peripheral nervous system disorders. This study aimed to screen the prevalence of periodic limb movements among chronic kidney disease patients using full-night attended polysomnography, compare dialysis with non-dialysis CKD patients, and correlate PLM prevalence with the HGB level and degree of renal impairment.

Results
This cross-sectional study was carried out on one hundred chronic kidney disease patients during the period between May 2017 and March 2020. The patients were subdivided into two groups: group I included patients on regular hemodialysis (n = 50), and group II included patients not on dialysis. All patients were screened for periodic limb movement using full-night attended polysomnography. Our study revealed a high prevalence of periodic limb movements in both groups of chronic kidney disease patients (60% in dialysis and 66% in non-dialysis patients) with mean PLM indices insignificantly higher in group I than group II (29.90 ± 19.19/h vs. 17.54 ± 13.56/h, P-value = 0.748). Moreover, there was a significant positive correlation between periodic leg movements and serum urea level (r-value = 0.38 and 0.33 and P-value = 0.04 and 0.030 in group I and group II consequently). Also, we reported a significant negative correlation between periodic leg movements and hemoglobin level (r = −0.251 and −0.291 and P-value = 0.037 and 0.010 in group I and group II consequently).

Conclusion
Periodic leg movement disorder is highly prevalent among CKD patients either on dialysis or not, and good management of renal dysfunction and anemia in those patients can help in the management of PLM.