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Saudi Journal of Kidney Diseases and Transplantation
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Year : 2019  |  Volume : 30  |  Issue : 5  |  Page : 1097-1102
Risk of obstructive sleep apnea among senegalese dialysis patients

1 Internal Medicine and Nephrology Department, UFR des Sciences de la Santé, University Gaston Berger Saint-Louis, Saint-Louis; Equipe SETA, Unité Mixte Internationale UMI-3189 (ESS), Université Cheikh AntaDiop, Dakar, Sénégal
2 Nephrology Department, University Abdou Moumouni, Niamey, Niger
3 Internal Medicine and Nephrology Department, UFR des Sciences de la Santé, University Gaston Berger Saint-Louis, Saint-Louis, Sénégal
4 Nephrology Department, University Cheikh AntaDiop, Dakar, Sénégal

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Date of Submission04-May-2018
Date of Decision11-Jul-2018
Date of Acceptance14-Jul-2018
Date of Web Publication4-Nov-2019


Obstructive sleep apnea syndrome (OSAS) is a common condition in patients undergoing chronic dialysis and is associated with increased cardiovascular morbidity and mortality. This study aimed to determine the prevalence and risk factors of OSAS in Senegalese dialysis patients. In a cross-sectional study including 128 patients (75 men and 53 women) dialyzed since ≥6 months in four dialysis units. Data were collected during the dialysis session in the units. OSAS was assessed with the Berlin Questionnaire. Factors associated with OSAS risk were identified by multivariate logistic regression. The mean age of patients was 46.8 ± 16.9 ¥16–85 years). OSAS was found in 53 patients (overall prevalence of 41.4%) with predominance among individuals aged ≥50 years (52.6%). Hypertension and diabetes were more frequent in patients with OSAS, while the prevalence of obesity and sedentary was not different. The majority of patients were not aware of their disease before the survey, and none was treated. After multivariate regression analysis, age >50 years [odds ratio (OR) = 1.09, P = 0.02], neck circumference >45 cm (OR= 1.25, P= 0.03), and daytime hypersomnia (OR = 1.18, P= 0.02) were significantly associated with OSAS. This study showed that OSAS is frequent among Senegalese dialysis patients but is usually under-diagnosed. Older age, excessive daytime sleepiness, and neck circumference are the main associated factors.

How to cite this article:
Seck SM, Moussa Tondi ZM, Niang S, Ould Lemraboot AT, Ka EF. Risk of obstructive sleep apnea among senegalese dialysis patients. Saudi J Kidney Dis Transpl 2019;30:1097-102

How to cite this URL:
Seck SM, Moussa Tondi ZM, Niang S, Ould Lemraboot AT, Ka EF. Risk of obstructive sleep apnea among senegalese dialysis patients. Saudi J Kidney Dis Transpl [serial online] 2019 [cited 2021 Oct 18];30:1097-102. Available from: https://www.sjkdt.org/text.asp?2019/30/5/1097/270265

   Introduction Top

Sleep apnea syndrome (SAS) is characterized by repeated interruption of breathing secondary to partial (hypopnea) or complete (apnea) pharyngeal collapse during the sleep period.[1],[2] Reported prevalence of SAS in healthy young men and women is respectively 4% and 2%.[3] This prevalence is higher in patients with chronic kidney disease (CKD) due to the presence of classical risk factors like obesity but also to factors peculiar to uremia and dialysis.[2],[4] Moreover, the presence of obstruetive SAS (OSAS) increases the risk of cardiovascular death in patients with CKD.[4],[5] Previous studies in the United States have suggested a higher frequency of OSAS in African American patients, but data about OSAS are scarce in dialysis patients living in Africa. The aim of this study was to determine the prevalence of OSAS among dialysis patients in Senegal and to identify its associated factors.

   Subjects and Methods Top

We conducted a descriptive cross-sectional study during a three months' period in four dialysis units in Senegal (2 located in the capital city and 2 in other regions).

Volunteer patients who have been in dialysis since at least six months and who had at least two weekly dialysis sessions were included. For each patient, socio-demographical, clinical, and hemodialysis (HD) or peritoneal dialysis (PD) parameters were collected using a questionnaire administered by the nephrologist during a dialysis session. In this study, obesity was defined as a body mass index ≥30 kg/m2 and abdominal obesity was defined by a waist circumference >102 cm in males or >88 cm in females. Sedentary was defined as <30 min of moderate activity per week or <20 min of vigorous activity three times per week or the equivalent. The screening of OSAS was performed using the Berlin Questionnaire that has already been validated in dialysis patients.[6] Collected data were analyzed using Statistical Package for the Social Sciences (SPSS) version 16.0 software (SPSS Inc., Chicago, IL., USA). Comparison of patients with and without OSAS was done using different tests such as Student’s t-test, Chi-square test, and Mann–Whitney test according to the type of variable. The factors associated with OSAS were identified after multivariate logistic regression analysis. All tests were considered statistically significant if P ≤0.05.

   Results Top

During the study, we included 128 patients (120 HD patients and eight PD patients). The mean age of patients was 46.8 ± 16.9 (16–85 years) and sex-ratio was 1.5. Nephrosclerosis, diabetes, and chronic glomerulonephritis were the main causes of end-stage renal disease (ESRD) found respectively in 47.6%, 29.6%, and 14.8% of cases.

Fifty-three patients (52 on HD and 1 on PD presented OSAS (overall prevalence of 41.4%). OSAS was more frequent after 50 years with a prevalence of 71.7% in this age group [Figure 1]. Sociodemographical, clinical, and biological characteristics of patients with and without OSAS is presented in [Table 1]. Hypertension and diabetes were more frequent in patients with OSAS, while the prevalence of obesity and sedentary were not different [Table 1].About 25.8% of patients were obese and 40.6% presented abdominal obesity. A neck circumference ≥45 cm was found in 44.5% of patients with a significant difference between those with and without OSAS (respectively 52.6% and 29.1%, P = 0.05). [Figure 2] shows the prevalence of sleep apnea according to neck circumference.
Figure 1: Prevalence of high risk of obstructive sleep apnea according to age group.

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Table 1: Sociodemographical, clinical, and biological characteristics of patients

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Figure 2: Risk of obstructive sleep apnea according to neck circumference.

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In bivariate analysis, OSAS was correlated with age, gender, hypertension, neck circumference, waist circumference, and excessive daytime sleepiness. However, there was no correlation between OSAS and body mass index, smoking, KT/V, or number of weekly dialysis sessions. Furthermore, comparison between patients with and without OSAS did not find a significant difference in biological parameters such as albumin and hemoglobin levels [Table 2].
Table 2: Factors associated with obstructive sleep apnea syndrome (multivariate analysis).

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Multivariate regression analysis showed that age >50 years, neck circumference >45 cm, and excessive day time sleepiness were significantly associated with OSAS [Table 2]. Only three patients were aware of their disease before the study, but 98.4% of patients were undiagnosed, and none of them was on treatment.

   Discussion Top

The prevalence of OSAS in our study is comparable to previous reports from other populations in Spain (44%)[7] and Switzerland (47%).[8] Many other studies in dialysis patients reported lower prevalence of sleep apnea in Saudi Arabia (44.2%),[9] the USA (3.4%),[10] China (14%),[11] Egypt (31.8%),[12] Brazil (36%), Germany (16.4%), and Italy (23.6%).[15]

The main reasons which explain the variability of prevalence in the different series are related to the definition of OSAS, methods used for diagnosis and difference in the study populations. Polysomnography is the gold standard methods but it is not available in many nonspecialized centers, so the questionnaires are more used in daily clinical practice. However, concordance between clinical and polysomnographical data is not well-established in dialysis patients.[16] The reported higher prevalence of OSAS in PD compared to HD[13] was not found in this study, probably because of the small number of PD patients included. Although OSAS is well-identified as associated with some major cardiovascular events, there are few works done in dialysis patients living Africa.[17] However, given the frequency of its risk factors in African populations, OSAS is probably underestimated in these patients. One recent study in patients treated for high blood pressure in Abidjan reported OSAS prevalence of 45% that is similar to our results.[1]

Compared to general population, dialysis patients do not have a higher prevalence of classical sleep apnea risk factors such as overweight, alcohol consumption, male sex, and snoring, but they are more prone to develop OSAS.[2] The main hypotheses explaining higher prevalence of sleep apnea in dialysis patients are water overload in upper airways, chronic metabolic acidosis, and accumulation of uremic toxins.[2],[4],[19]

Our study showed that age >50 years, a neck circumference >45 cm, and excessive daytime sleepiness were associated with OSAS. In many studies, excessive daytime sleepiness was associated with OSAS, but it is more likely a consequence rather than a cause of sleep apnea.[2] The link between aging and sleep apnea was already reported by many authors.[4],[9],[11],[12],[13] However, classical OSAS risk factors such as hypertension, obesity, dialysis sessions, anemia, and hypoalbuminemia[1],[9],[20] have not been significantly associated with OSAS in our patients.

Similarly, studies demonstrated that markers of jugular vein volume and neck circumference are correlated to OSAS.[9],[19] In dialysis patients, increased neck circumference is an indicator of fluid overload in the upper extremity of the body that would impair regulation of ventilation.[19] Thus, intensive ultrafiltration has been proposed by some authors for management of dialysis patients with OSAS.[21] Furthermore, the authors demonstrated that nocturnal long HD sessions could improve oxygen saturation and reduce the number of sleep apnea episodes.[4] In this study, no specific treatment was given to patients because the diagnosis of sleep apnea was not known. Early diagnosis and management of OSAS should be a real challenge for nephrologist following patients with ESRD. However, the best treatment for OSAS in uremic patients remains renal transplantation.[22]

Despite the importance of these results, our study presents some limitations related mainly to the method used to detect OSAS. In fact, the Berlin Questionnaire is not as accurate as polysomnography, which is the gold standard for diagnosis of OSAS.[1],[2] In addition, the cross-sectional design of this study does not allow any inference in the association between OSAS and identified risk factors.

   Conclusion Top

This study found that OSAS is common in dialysis patients in Senegal, especially those ≥50 years old. The main associated factors are age, neck circumference, and excessive daytime sleepiness. Effective management of sleep apnea requires early diagnosis and multidisciplinary care to improve the quality of life and reduce cardiovascular mortality in dialysis patients. Larger studies with polysomnographic exploration are needed to better describe the epidemiology of sleep apnea Senegalese dialysis patients.

   References Top

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Muller ME, Heinzer R, Pruijm M, Wuerzner G, Burnier M. Rev Med Suisse 2012:8:458-6.  Back to cited text no. 2
Young T, Palta M, Dempsey J, et al. The occurrence of sleep-disordered breathing among middle-aged adults. N Engl J Med 1993:328:1230-5.  Back to cited text no. 3
Hanly P. Sleep apnea and daytime sleepiness in end-stage renal disease. Semin Dial 2004: 17:109-14.  Back to cited text no. 4
Floras JS. Hypertension and sleep apnea. Can J Cardiol 2015:31:889-97.  Back to cited text no. 5
Netzer NC, Stoohs RA, Netzer CM, Clark K, Strohl KP. Using the berlin questionnaire to identify patients at risk for the sleep apnea syndrome. Ann Intern Med 1999:131:485-91.  Back to cited text no. 6
Jurado-Gamez B, Martin-Malo A, Alvarez-Lara MA, et al. Sleep disorders are under-diagnosed in patients on maintenance hemodialysis. Nephron Clin Pract 2007;105:c35-42.  Back to cited text no. 7
Pfister M, Jakob SM, Marti HP, Frey FJ, Gugger M. Ambulatory nocturnal oximetry and sleep questionnaire-based findings in 38 patients with end-stage renal disease. Nephrol Dial Transplant 1999:14:1496-502.  Back to cited text no. 8
Wali SO, Alkhouli A, Howladar M, et al. Risk of obstructive sleep apnea among Saudis with chronic renal failure on hemodialysis. Ann Thorac Med 2015:10:263-8.  Back to cited text no. 9
Sim JJ, Rasgon SA, Kujubu DA, et al. Sleep apnea in early and advanced chronic kidney disease: Kaiser permanente Southern California cohort. Chest 2009:135:710-6.  Back to cited text no. 10
Hui DS, Wong TY, Li TS, et al. Prevalence of sleep disturbances in Chinese patients with end stage renal failure on maintenance hemodialysis. Med Sci Monit 2002;8:CR331-6.  Back to cited text no. 11
Sabry AA, Abo-Zenah H, Wafa E, et al. Sleep disorders in hemodialysis patients. Saudi J Kidney Dis Transpl 2010:21:300-5.  Back to cited text no. 12
Losso RL, Minhoto GR, Riella MC. Sleep disorders in patients with end-stage renal disease undergoing dialysis: Comparison between hemodialysis, continuous ambulatory peritoneal dialysis and automated peritoneal dialysis. Int Urol Nephrol 2015:47: 369-75.  Back to cited text no. 13
Kuhlmann U, Becker HF, Birkhahn M, et al. Sleep-apnea in patients with end-stage renal disease and objective results. Clin Nephrol 2000:53:460-6.  Back to cited text no. 14
Merlino G, Piani A, Dolso P, et al. Sleep disorders in patients with end-stage renal disease undergoing dialysis therapy. Nephrol Dial Transplant 2006;21:184-90.  Back to cited text no. 15
Beecroft JM, Pierratos A, Hanly PJ. Clinical presentation of obstructive sleep apnea in patients with end-stage renal disease. J Clin Sleep Med 2009;5:115-21.  Back to cited text no. 16
Ezzat H, Mohab A. Prevalence of sleep disorders among ESRD patients. Ren Fail 2015;37:1013-9.  Back to cited text no. 17
Konin C, Boka B, Adoubi A, et al. Presumption of sleep apnea in a black African hypertensive population: Importance of the Epworth sleepiness scale in the diagnostic approach. Ann Cardiol Angeiol (Paris) 2015; 64:268-72.  Back to cited text no. 18
Roumelioti ME, Brown LK, Unruh ML. The relationship between volume overload in endstage renal disease and obstructive sleep apnea. Semin Dial 2015;28:508-13.  Back to cited text no. 19
Stepanski E, Faber M, Zorick F, Basner R, Roth T. Sleep disorders in patients on continuous ambulatory peritoneal dialysis. J Am Soc Nephrol 1995;6:192-7.  Back to cited text no. 20
Lyons OD, Chan CT, Yadollahi A, Bradley TD. Effect of ultrafiltration on sleep apnea and sleep structure in patients with end-stage renal disease. Am J Respir Crit Care Med 2015;191:1287-94.  Back to cited text no. 21
Rodrigues CJ, Marson O, Togeiro SM, et al. Sleep-disordered breathing changes after kidney transplantation: A polysomnographic study. Nephrol Dial Transplant 2010;25:2011-5.  Back to cited text no. 22

Correspondence Address:
Sidy Mohamed Seck
Department of Internal Medicine and Nephrology, UFR des Sciences de la Santé, Université Gaston Berger, BP 234 Saint-Louis
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DOI: 10.4103/1319-2442.270265

PMID: 31696848

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  [Figure 1], [Figure 2]

  [Table 1], [Table 2]


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