Characteristics and Predictive Factors of Sleep Disorders in Sickle Cell patients in Yaounde

Chokote Tolo Samuel Eric (
Internal Medicine, University of Yaounde 1
June, 2013


Sleep disorders are of increasing concern, particularly in sickle cell patients. Though, sleep complaints are often neglected in favour of more acute manifestations such as pain and anemia, sleep disorders may significantly contribute to morbidity and mortality in sickle cell disease. Sleep disorders are today considered as independent risk factors for adverse cardiovascular events such as hypertension and stroke, decrease neurocognitive function in the general population; and even acute sickle cell crises in sickle cell patients.
The main objective of our study was to identify and characterize sleep disorders as well as their predictive factors, in a population of sickle cell patients in Yaounde, Cameroon. Specifically, we sought to: 1) Identify and characterize sleep disorders in a sample of sickle cell patients; 2) Assess the relationship between sleep disorders and blood pressure in sickle cell patients; 3) Determine the predictive factors for the occurrence of sleep disorders in a sample of sickle cell patients in Yaoundé.
To attain our objectives, we carried out a case-control study involving homozygous sickle cell patients and age/sex-matched non sickle-cell controls. The study ran from September 2012 to April 2013. Participants aged 2 to 18 years, whose parents signed a written consent form were included in our study. All participants (with parents) were invited to participate in the filling of a pre-established questionnaire including standard and validated diagnostic scales for certain sleep disorders, after which a thorough physical examination was done. Data was analyzed using SPSS version 20.0 and the level of statistical significance was fixed at 0.05.
A total of 90 participants were included in our study; 45 sickle cell patients considered as cases (SCD+) and 45 non sicklers considered as controls (SCD‒). The mean ages were 8.58 ± 4.22 in the case group compared to 8.87 ± 4.23 for the controls (P = 0.747).
Sleep disorders were significantly more frequent in sickle cell patients. The specific disease conditions identified were: Obstructive sleep apnea (OSA) with a prevalence of 26.7% vs 2.2% (P = 0.02; OR 16 95CI 1.98-129.28); Restless legs syndrome/ Periodic Limb Movement in Sleep (RLS/PLMS) 15.6 vs 0% (P = 0.012) and abnormal daytime sleepiness 25% vs 8.9% (P = 0.051 OR 3.41 95% CI 1.00-11.56). If for daytime sleepiness, the P value was of borderline significance, after adjusting for socioeconomic status (SES) and depression, it became strongly significant (AOR 9.62 95% 1.47-62.5, p=0.018). As concerns OSA on adjusting for SES the odds in the cases compared to the controls was 12.53 (95% CI: 1.41-114.43) and on adjusting further for depression 5.90 (0.48-72.54). With regards to RLS, on adjusting for SES and depression the OR became insignificant: AOR 8.19 (0.79-100.56). The means of systolic and diastolic blood pressure (BP) as well as proportion of pre-hypertension occurrence, were comparable amongst cases and controls (P = 0.419, 0.691 and 0.235 respectively). This was also true for OSA+ and OSA- sickle cell patients (P = 0.607, 0.154 and 1.000 respectively) as well as RLS+ and RLS- sicklers (P = 0.672, 0.691 and 1.000 respectively). There was a trend for higher daytime BP in patients with EDS than those without when considering mean systolic BP percentile values (P = 0.055). The presence of adenotonsillar hypertrophy (ATH) was significantly higher in sickle cell participants than in their controls (30.2% VS 4.4%; P = 0.001) and was an independent predictor for OSA in sickle cell (P= 0.014; OR of 106.19). Having more than 4 acute crises and 2 hospitalizations were also significantly associated with OSA (P = 0.015 and 0.035 respectively). The latter seemed to be a protective factor against OSA (OR = 0.002 95% CI 0.00-0.74).
In conclusion; Obstructive sleep apnea, Restless legs syndrome/ Periodic limb movement in sleep and daytime sleepiness are common sleep disorders identified in Cameroonian sickle cell patients; Abnormal sleepiness might be associated with higher daytime systolic blood pressure; Adenotonsillar hypertrophy and frequent yearly vaso-occlusive crises appear to be significant predictors of sleep disorders. We therefore recommend that physicians screen for OSA, RLS/PLMS and daytime sleepiness in sickle cell patients especially in vent of adenotonsillar hypertrophy and frequent vaso-occlusive crises; and systematically measure blood pressure in patients presenting with sleep disorders and take appropriate measures when necessary. Sleep medicine should be developed by including a module on sleep disorders in medical students’ training program; sleep specialists should be trained and well equipped sleep laboratories developed.