Lack of association between objectively assessed sleep disorders and inflammatory markers among kidney transplant recipients

Purpose In patients on dialysis, the results of studies examining the association between sleep disorders and inflammation are controversial. We assessed the association between inflammatory markers and different sleep disorders in a large sample of kidney transplant recipients. Methods Cross-sectional study of 100 randomly selected kidney transplant patients who underwent one-night polysomnography (sleep disorders evaluation in patients after kidney transplantation study'') to diagnose obstructive sleep apnea (OSA) and periodic limb movements in sleep (PLMS). Athens Insomnia Scale (AIS) was utilized to assess the prevalence of insomnia. Sociodemographic information and data about medication, comorbidity and laboratory parameters were collected. Levels of inflammatory markers, such as C-reactive protein, serum albumin, white blood cell count, interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha), were measured. Results The mean age was 51 +/- 13 years, 43% were women, and the prevalence of diabetes was 19%. We found no significant difference in the levels of inflammatory markers between patients with versus without OSA and PLMS. Apnea-hypopnea index showed a significant association with white blood cell count (rho = 0.23), and weak (rho < |0.15|), non-significant correlation with the other inflammatory markers. PLM index showed weak (rho < |0.15|), non-significant correlation with all markers of inflammation. The serum IL-6 level was significantly higher in patients with insomnia (AIS >= 10) than in non-insomniacs [median (IQR): 3.2(2.6-5.1) vs. 1.7(1.2-2.9) ng/l; P = 0.009]. The levels of other inflammatory markers were similar between insomniacs and non-insomniacs. Conclusions We did not find any association between the presence of objectively assessed sleep disorders and inflammatory markers in kidney transplant patients.