Sleep Apnoea and Kidney Disease

Recent studies suggest up to 50% of patients with any form of kidney impairment have obstructive sleep apnoea (OSA). The presence of this condition appears to also accelerate further damage to the kidney.

Prevalence of OSA

OSA occurs at a higher rate in people with chronic kidney disease (CKD). In the dialysis population, prevalence of OSA occurs in 50%-90% of individuals.1,2 There is emerging data as well, revealing a higher prevalence of OSA in early CKD patients (not on dialysis).

OSA appears to be highly prevalent in all forms of CKD. Identifying and treating this condition in individuals with CKD can improve patient survival and quality of life.

Underdiagnosed and Undertreated

The prevalence of OSA in the general population is estimated at 2%-4%. However 80%-90% of OSA remains undiagnosed.

The prevalence of OSA in CKD patients is much greater than estimated in the general population. In dialysis patients, various studies have demonstrated that patients on either haemodialysis (HD) or peritoneal dialysis (PD) have an OSA prevalence of between 30% - 90%1,7 A recent study matching dialysis patients to those not on dialysis but with similarities based on age, gender, race, and body mass found that dialysis patients were four times more likely to have OSA than those without CKD.1 Within the dialysis population, the prevalence of OSA appears to be the similar in PD and HD patients. Interestingly, dialysis patients with OSA had a higher prevalence of central SA (up to 44%) compared to less than 10% in the general population.8 They also tended to be underweight compared to the general population.7

Cause or Effect?

The high rate of OSA in dialysis raises the question of whether the uraemia (urea and protein byproducts) from kidney failure causes or contributes to OSA. Case reports have shown resolution of OSA after patients have received a renal transplant.9 This also raised the issue of whether more aggressive dialysis may control OSA in dialysis patients.

Renal Transplant: Friend or Foe?

Although a few patients have been described to have had their OSA cured with renal transplant, the post-transplant state also appears to be a risk factor for OSA. A recent study found that 27% of renal transplant patients had a high likelihood for OSA based on the Berlin questionnaire. This was comparable to the 33% who were on the transplant waiting list, including dialysis patients.12

In lung and heart transplant patients, the post-transplant state has been associated with a significant amount of weight gain in those individuals with OSA.13 Therefore, the post transplant state due to multiple factors such as medications (prednisone) along with improved nutrition and appetite may represent another risk factor for OSA.

The Early CKD Question

Early chronic kidney disease (CKD) patients have not been well studied in terms of the prevalence of OSA. Recent studies published suggest they have a greater prevalence, although it may not be as high as the numbers observed in the dialysis population.

A recent study by Markou, et al, demonstrated a OSA prevalence of 54% in patients with CKD.14 The Kaiser Permanente Southern California database of renal patients revealed 30% had OSA, controlling for age, gender, sex, and body mass.

Conclusion

Obstructive sleep apnea is highly prevalent in CKD patients throughout all stages, including CKD, dialysis, and transplantation. OSA causes complications in many different organs and also has a negative impact on the daily functioning of the individuals who suffer from this condition.

“Kidneys are susceptible to increasing and cumulative damage with repeated loss in normal oxygen supply in patient with OSA, just like the brain and heart” agrees Dr Andrew Scott, Sleep Physician. “I now have a number of patients with chronic renal disease have been successfully treated for OSA, with unexpected improvements in renal function parameters”. Further studies are highly recommended.

Although OSA is receiving more attention the number of undiagnosed cases remains high. Patients with chronic renal disease are at greater risk, and if they have any symptoms of sleep apnoea should discuss this further with their GP and renal specialist.

References

1.         Sleep apnoea in patients on conventional thrice-weekly hemodialysis: comparison with matched controls from the Sleep Heart Health Study. Journal of the American Society of Nephrology 2006.
2.         A comparison of sleep-disordered respiration in ESRD patients receiving hemodialysis and peritoneal dialysis. Advances in Peritoneal Dialysis 1992
3.         Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem. Institute of Medicine of the National Academies, 2006.
4.         Using the Berlin Questionnaire to identify patients at risk for the sleep apnea syndrome. Annals of Internal Medicine 1999
5.         Underdiagnosis of sleep apnea syndrome in U.S. communities. Sleep Breath 2002.
6.         Population-based study of sleep-disordered breathing as a risk factor for hypertension. Archives of Internal Medicine 1997
7.         Sleep-apnea in patients with end-stage renal disease and objective results. Clinical Nephrology 2000.
8.         Sleep apnea syndrome in chronic renal disease. American Journal of Medicine 1989
9.         Reversal of sleep apnea hypopnea syndrome in end-stage renal disease after kidney transplantation. American Journal of Kidney Diseases 1999
10.       Improvement of sleep apnea in patients with chronic renal failure who undergo nocturnal hemodialysis. New England Journal of Medicine 2001
11.       Alleviation of Sleep Apnea in Patients with Chronic Renal Failure by Nocturnal Cycler-Assisted Peritoneal Dialysis Compared with Conventional Continuous Ambulatory Peritoneal Dialysis. Journal of the American Society of Nephrology 2006
12.       High prevalence of patients with a high risk for obstructive sleep apnoea syndrome after kidney transplantation association with declining renal function. Nephrology Dialysis Transplantation 2007
13.       Prevalence of obstructive sleep apnoea and periodic limb movement in 45 subjects with heart transplantation. European Heart Journal 2004
14.       Sleep-disordered breathing in nondialyzed patients with chronic renal failure. Lung 2006
15.      A new method for measuring daytime sleepiness: the Epworth sleepiness scale. Sleep  1991