Long-Term Changes in Sleep Disordered Breathing in Renal Transplant Patients: Relevance of the BMI.

Francesca Mallamaci,Carmine Zoccali,Giovanni Tripepi,Carmela Marino,Rocco Tripepi,Gaetana Porto,Maria Cristina Sanguedolce,Graziella D'Arrigo,Maria Carmela Versace

doi:10.3390/jcm9061739

Abstract

Sleep disordered breathing (SDB), as defined by the Apnea Hypopnea Index (AHI), is a highly prevalent disturbance in end stage kidney disease. SDB improves early on after renal transplantation but long-term changes in AHI in these patients have not been studied. We studied the long-term changes in AHI in a series of 221 renal transplant patients (mean age: 47 ± 12 years; 70% males) over a median follow up of 35 months. Data analysis was made by the generalized estimating equations method (GEE). On longitudinal observation, the median AHI rose from 1.8 (Interquartile range: 0.6–5.0) to 2.9 (IQR: 1.0–6.6) and to 3.6 (IQR: 1.7–10.4) at the second and third visit, respectively (p = 0.009 by the GEE model and the proportion of patients with moderate to severe SDB rose from 8% to 20%. Longitudinal changes in minimum oxygen saturation (minSaO2) mirrored those in the AHI. In adjusted analyses, repeated measurements of BMI (p < 0.009) emerged as the strongest independent longitudinal correlate of AHI and MinSaO2. The AHI worsens over time in renal transplant patients and longitudinal changes of this biomarker are directly related to simultaneous changes in BMI. Overweight/obesity, a potentially modifiable risk factor, is an important factor underlying the risk of SDB in this population.

Highlights

Sleep disordered breathing (SDB) is a complex disorder which impacts on neurocognitive function, metabolism, cardiovascular health and quality of life and significantly increases the risk of cardiovascular events in the general population [1]
We found that 8% of the renal transplant patients studied, after having achieved clinical stability after kidney grafting, had moderate to severe SDB and an additional 17% had mild SDB
These figures are substantially less than those typically seen in dialysis patients where moderate to severe SDB has a 56% prevalence [5] and are similar to those in age, sex- and Body Mass Index (BMI)-matched individuals in the general population [12,31]

Summary

Introduction

Sleep disordered breathing (SDB) is a complex disorder which impacts on neurocognitive function, metabolism, cardiovascular health and quality of life and significantly increases the risk of cardiovascular events in the general population [1]. SDB is increasingly common when CKD progresses to more severe stages [3] and associates with mortality in the pre-dialysis CKD population [4]. In patients maintained on chronic dialysis, the prevalence of this disturbance attains 56% [5] and entails a high risk of cardiovascular mortality [6,7]. Kidney transplantation restores renal function, corrects fluid overload, metabolic alterations and uremic toxicity and may reverse SDB. In a case–control study the prevalence of SDB among renal transplant patients was similar to that in the general population [12]. Sodium (mEq/L) Potassium (mEq/L) Cholesterol (mg/dL) HDL cholesterol (mg/dL) LDL cholesterol (mg/dL)

Methods

Results

Conclusion