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0Egyptian Journal of Chest Diseases and Tuberculosis (2013) 62, 717-722
The Egyptian Society of Chest Diseases and Tuberculosis Egyptian Journal of Chest Diseases and Tuberculosis
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ORIGINAL ARTICLE
A six-year sleep lab experience in an Egyptian University Hospital
Maha Yousif *, Rana El-Helbawy
Chest Department, Faculty of Medicine, Minoufiya University, Egypt
Received 21 August 2013; accepted 4 September 2013 Available online 27 September 2013
KEYWORDS
Clinical epidemiology;
Respiratory neurobiology
and sleep;
Sleep apnea;
Sleep disorders;
Statistics;
Polysomnography
Abstract Background: Sleep disorders are common and the gold standard for diagnosis is through polysomnography (PSG) with standard 'scoring criteria. Published clinical and polysomnographic data reporting sleep disorders among Egyptian patients are lacking.
Aim: To study clinical and polysomnographic characteristics in Egyptian patients with suspected sleep disorders.
Patients and methods: All patients' polysomnographic records and sleep questionnaires were reviewed from November 2006: November 2012 at the Minoufiya University Hospital Sleep Disorders Unit.
Results: 421 patients were recruited among which 229 were males (54.4%); excessive daytime sleepiness and obesity were major features (ESS = 16, BMI = 33). Most of the patients were referred by a chest physician (81%). The most common symptoms were snoring (84.6%), witnessed apneas (78.6%), insomnia (70.9%) while the least was parasomnia (15.4%). 337 patients were diagnosed as having obstructive sleep apnea OSA (80%) of them, 70 (21%) had mild OSA, 75 (22%) had moderate OSA and 192 (57%) had severe OSA, The most common diseases accompanying OSA were: systemic hypertension (77%), diabetes (63%), COPD (57%), and coronary heart disease (49%).
Conclusions: Sleep medicine in Egypt is still lagging behind the developed world, awareness of sleep disorders among Egyptian physicians should be increased. Diabetes, HTN, IHD and COPD are the commonest predisposing factors for OSA among Egyptians especially snorers, obese and overweight patients.
© 2013 The Egyptian Society of Chest Diseases and Tuberculosis. Production and hosting by Elsevier
B.V. All rights reserved.
* Corresponding author. Tel.: +20 1008818827.
E-mail address: drmahayousif@gmail.com (M. Yousif).
Peer review under responsibility of The Egyptian Society of Chest
Diseases and Tuberculosis.
Introduction
Sleep occupies one third of people's lives. Nevertheless, sleep science and sleep medicine have only recently been established as scientific and medical disciplines. Advances in knowledge and treatment have been accelerating and have resulted in improvements in the quality of life of the human populace
0422-7638 © 2013 The Egyptian Society of Chest Diseases and Tuberculosis. Production and hosting by Elsevier B.V. All rights reserved. http://dx.doi.Org/10.1016/j.ejcdt.2013.09.006
[1]. Although many sleep disorders can be diagnosed clinically, some require further evaluation in a sleep laboratory. In suspected sleep-related breathing disorders, a full-night polysom-nogram (PSG) is recommended [2]. Standard PSG scoring rules using the criteria of Rechtschaffen and Kales [3] have recently been revised and updated by the American Academy of Sleep Medicine [4]. Obstructive events of the airway during sleep can either be partial (hypopnea) or complete (apnea). Sleep apnea or hypopnea is defined by a minimum duration often seconds to be scored. When these episodes are associated with clinical manifestations such as unrefreshing sleep, nocturnal sleep disruption, fatigue, or daytime sleepiness it is termed as obstructive sleep apnea syndrome (OSAS) [5].
To our knowledge, there are no published data reporting the results of sleep questionnaires and comprehensive sleep studies using standard scoring criteria for Egyptian patients. Accordingly, the aim of the current study was to study clinical and polysomnographic characteristics in Egyptian patients with suspected sleep disorders.
Patients and methods
This was a retrospective analysis of PSG and sleep questionnaire data in a large group of patients with suspected sleep disorders who underwent comprehensive diagnostic PSG evaluation in the Sleep disorders unit of a public tertiary Egyptian hospital. This study was approved by the hospital's Institutional Review Board. The studied population was 421 patients recruited from a consecutively encountered patient population seen over a 6-year period at the Minoufiya University Hospital Sleep Disorders Unit. This is a one-bedded sleep laboratory of a tertiary hospital, staffed by a team of pulmo-nologists who obtained special training in practicing sleep medicine and consultations can be obtained from various hospital consultants for help in the diagnosis of non-pulmonary sleep disorders including neurologists, ENT surgeons and psychiatrists. The sleep lab works 3 nights/week as a maximum.
On the day of the study and before electrode application the patient completes a sleep questionnaire which involves the list of his symptoms, anthropometric measures (height, weight and neck circumference), his sleep habits, concurrent diseases (as
DM, HTN, cardiac, pulmonary,____) a list of his medications,
and lastly the Epworth sleepiness scale. PSG was performed for patients with clinically suspected OSA who experienced any one of the following sleep-related symptoms: Excessive daytime sleepiness, snoring, witnessed apneas, choking or gasping in sleep, sleep maintenance insomnia, or un-refreshing sleep. For the patient to be familiar with the study, a full description of the study protocol was done by the well trained sleep technician. Overnight PSG was performed using Embla S4000 Medcare, Iceland. The system has Somnologica studio 3.3.2 software, electrodes and cables to record the electroencephalogram (EEG), electrooculogram (EOG), electromyo-gram (EMG) of the chin and bilateral tibialis anterior muscles, and electrocardiogram (ECG). Airflow was measured using nasal and oral thermistors, and a nasal pressure transducer. Respiratory effort was monitored with respiratory inductive polysomnography belts with thoracic and abdominal locks. Oximetry was measured using a disposable finger probe (oximeter flex sensor 8000 J) placed on the index finger. Snoring was recorded using snore microphones (piezo snoring
sensor) attached to the neck. Body position was monitored using body position sensor. All studies were analyzed by trained PSG technicians and sleep physicians using the criteria of Rechtschaffen and Kales, and in close concordance with scoring updates given by the American Academy of Sleep Medicine. The traditional Rechtschaffen and Kales terminology for the 5 sleep stages (i.e. stages 1, 2, 3, 4, and REM sleep, with stages 1 and 2 collectively referred to as ''light sleep'', stages 3 and 4 collectively referred to as ''deep sleep'') was used in this study. Apneas were scored when there was a complete cessation of airflow or P90% drop in the peak thermal sensor excursion for at least 10 s. Hypopneas were scored when there was a drop in nasal pressure by P30% of baseline lasting at least for 10 s with a P4% desaturation from pre-event baseline, or when there was a drop in nasal pressure signal excursion by P50% of baseline lasting at least for 10 s with a P3% desaturation from pre-event baseline. The apnea-hypo-pnea index (AHI) which is number of apnea-hypopnea events per hour was determined after the exclusion of periods with movements, which were considered to be wake periods. An ap-nea without chest or abdominal movements was classified as CSA and apnea with chest and abdominal movements was classified as OSA. Hypopneas were considered to be obstructive when there was evidence of upper airway obstruction, such as snoring, paradoxical respiratory band movement or inspira-tory flow limitation through the nasal cannula; central hypo-pnea, in contrast, was associated with in-phase respiratory movements and no evidence of inspiratory flow limitation. SDB was considered to be central if greater than 50% of apnea/hypopnea events were central and obstructive if greater than 50% were obstructive [4].
Statistical analysis
The data were analyzed collectively and presented as median and range for all patients and those with OSA. Some data as symptoms, referral, co-morbidities and diagnosis were presented as percent of total then data were grouped according to severity of sleep-disordered breathing and BMI. Pearson correlation coefficient was used to test the association between AHI and other parameters with statistical significance taken as P < 0.05. The data collected were analyzed by SPSS (statistical package for the social science software) statistical package version 14.
Results
The most frequent symptoms were snoring 84.6%, apnea 78.6%, insomnia 70.9%, excessive daytime sleepiness 68.4% and the least was parasomnia 15% (Fig. 1).
Most of the patients were referred by chest physicians (81%), 9% by ENT physicians, 6% by neuropsychiatry physicians and 4% by other specialties (cardiology, internal medicine, family physicians) (Fig. 2).
As regards the final diagnosis; the commonest was OSA (OSA alone 40.4%, OSA + Insomnia 23.7%, OSA + PLM 15.9%), followed by insomnia 12%, and the least frequent diagnosis was PLM disorder 0.7% (Fig. 3).
The patient characteristics and polysomnographic data of all the studied cases are shown in Table 1. Out of the studied 421 patients, 229 (54.4%) were males, excessive daytime
Chest ENT Neurology & cardiology General Internal
psychiatry practitioner medicine
Figure 1 Symptoms' frequency of all the studied patients.
100 80 60 40 20 0
□ No % ■ Yes %
Figure 2 Percent of referral by specialty physicians.
180 160 140 120 100 80 60 40 20 0
/ У / ^ У
Figure 3 Diagnosis frequency of all the studied patients.
sleepiness and obesity were major features (ESS = 16, BMI = 33). Regarding the polysomnographic data, the general features were reduced sleep efficiency, prolonged sleep latency, a high apnea-hypopnea, desaturation and arousal indices.
Table 2 shows significant positive correlations between AHI and each of BMI, ESS, DI, arousal index and PLM. However, a significant negative correlation was found between AHI and sleep efficiency.
Table 3 shows the patient characteristics and polysomno-graphic data of patients with OSA. Out of the 337 patients with OSA, 181 (53.7%) were males, excessive daytime sleepiness and obesity were major features (ESS = 16, BMI = 36). Regarding the polysomnographic data, the general features were reduced sleep efficiency, prolonged sleep latency, a high apnea-hypopnea, desaturation and arousal indices.
Fig. 4 shows the commonest co-morbidities in patients with OSA. The highest frequencies are systemic hypertension (HTN) (77%), diabetes (63%), COPD (57%) and coronary heart disease (49%). While, all other diagnoses such as bronchial asthma, interstitial pulmonary fibrosis, hepatitis C virus infection, and hypothyroidism represent 38%.
Table 1 Patient characteristics and polysomnographic data of all studied cases.
Patients' characteristics Number Percentage
Sex: male (n, %) 229 54.4
Female (n, %) 192 45.6
Median Range
Age (Median) (range) 54 14-88
ESS (Median) (range) 16 0-24
BMI (Median) (range) 33 16-86
Polysomnography data
Sleep efficiency% 59 3-99
Sleep latency 14 0-477
REM latency 99 0-544
AHI 27 0-150
Desaturation index 27 0-157
Light sleep% 35 0.5-100
Deep sleep% 53 0-99
REM% 6 0-55
Arousal index 34 0-174
Baseline O2 94 8-99
Average O2 91 8-99
Lowest O2 80 50-88
Flow limitation index 15 0-100
PLM 6 0-50
ESS: Epworth sleepiness scale, BMI: body mass index, REM rapid eye movement, AHI: apnea-hypopnea index, PLM: periodic limb movement.
Regarding the categorization of OSA patients according to AHI; the patients with OSA were grouped into mild OSA (21%), moderate OSA (22%) and severe OSA (57%) (Fig. 5).
Discussion
The total number of patients recruited in this study along 6 years was 421 patients. This may be a small number compared to the period of recruitment. This may be due to the reduced awareness of sleep disorders, the complexity, the cost of a full polysomnographic recording, so the referral rate was low especially at the beginning and limited resources of our sleep unit (one-bedded sleep lab, works 3 nights/week as a maximum) but still it is a study with a relatively large sample size.
The prevalence of OSA is estimated to be 4-10% in middle-aged general populations of predominantly Caucasian origin
Table 2 Pearson correlation between apnea-hypopnea index and some other variables.
AHI BMI ESS SE DI Arousal index PLM
r p-Value r p-Value r p-Value r p-Value r p-Value r p-Value
0.65 0.001 0.58 <0.001 -0.31 0.011 0.92 <0.001 0.81 <0.001 0.5 <0.001
BMI body mass index, ESS: Epworth sleepiness scale, SE: sleep efficiency, DI: desaturation index, PLM; periodic limb movement.
Table 3 Patient characteristics and Polysomnographie data of
patients with OSA.
Patients' characteristics Number % of OSA
Sex: male (n, %) 181 53.7
Female 156 46.3
Median Range
Age (Median) (range) 55 14-85
ESS (Median) (range) 16 0-24
BMI (Median) (range) 36 16-86
Polysomnography data
Sleep efficiency% 59 3-99
Sleep latency 13 0-477
REM latency 90 0-544
AHI 36 5-150
Desaturation index 38 1-157
Light sleep% 35 1-100
Deep sleep% 53 0-99
REM% 7 0-55
Arousal index 41 0-174
Baseline O2 94 8-99
Average O2 90 8-99
Lowest O2 78 50-88
Flow limitation index 7 0-100
PLM 3 0-50
OSA: obstructive sleep apnea, ESS: Epworth sleepiness scale, BMI:
body mass index, REM rapid eye movement, AHI: apnea-hypo-
pnea index, PLM: periodic limb movement.
% of all OSA patients
80 70 60 50 40 30 20 10 0
IHD Others
Figure 4 Co-morbidities of patients with OSA.
[6]. Although our study included a selected pool of patients who were referred for snoring and the possibility of OSA and we have not determined the prevalence of OSA in Egypt, we have shown that the condition is perhaps not uncommon in Egyptian snorers.
The most frequent symptoms were snoring 84.6%, apnea 78.6%, insomnia 70.9%, excessive daytime sleepiness 68.4% and the least was parasomnia 15% (Fig. 1). This matches the results of Abisheganaden et al. [7] which showed that all their patients (n = 125) had a history of snoring (100%) while those
□ mild
□ moderate
□ severe
Figure 5 Categorization of OSA patients according to AHI.
with OSA (n = 72), 78% also had excessive daytime sleepiness. This can be explained by the fact that most of the patients were referred by chest and ENT physicians and by the criteria of referral which were snoring and sleep apneas. About insomnia, it is usually an accompanying symptom of most sleep disorders.
Most of the patients were referred by chest physicians (81%), 9% by ENT physicians, 6% by neuro-psychiatrists and 4% by other specialties (cardiology, internal medicine, family physicians) (Fig. 2). The commonest diagnosis was OSA (OSA alone 40.4%, OSA + Insomnia 23.7%, OSA + PLM 15.9%), followed by insomnia 12%, the least frequent diagnosis was PLM disorder 0.7% (Fig. 3). As the main symptoms that alert attention of sleep disordered breathing are snoring and sleep apneas, the suspicion of sleep apnea was the criterion for referral to the lab. This matches the results got by BaHammam [8]. In his study, referrals by otolar-yngologists represented 8% of OSA patients, compared to 17.4% in the United States [9]. BaHammam explained this finding by (1) reduced awareness of some of the otolaryngologists of the importance of PSG to confirm the diagnosis and severity of suspected OSA to tailor treatment according to the patient's needs; (2) some may feel that their clinical assessment is enough to assess the severity of the illness, (3) or there is a communication gap between otolaryngologists and sleep specialists.
The median age of all the studies patients was 54 years (Table 1) and for those with OSA it was 55 years (Table 3). This revealed an increased prevalence of sleep disordered breathing (SDB) among elderly. Ip et al. [10] reported that, the prevalence of SDB increased nearly 12 folds in the 5060 year old group, compared to 30-39 year old group. Martin et al. [11] study showed that SDB is common among elderly and a potential risk factor for mortality during sleep. The physiological changes that occur with advancing age in the form of reduction in upper airway size, with increased its col-lapsibility, inadequate compensatory action of upper airway dilator muscles, decreased vital capacity and altered ventila-tory control contribute to occurrence of SDB in the elderly.
Excessive daytime sleepiness and obesity were major features for all the patients [(ESS = 16, BMI = 33) Table 1] and for those with OSA [(ESS = 16, BMI = 36) Table 3], with significant positive correlations between AHI and each of ESS and BMI (Table 2).
Marry [12] and Uribe et al. [13] evaluated the validity of ESS in diagnosing SDB, and found that there was a positive significant correlation between ESS and AHI. They concluded that if ESS was more than 10, SDB should be suspected. They also advised to assess ESS in SDB to rule out or prove OSA and hence manage it early in the course of the disease.
The BMI has been one of the most typical parameters in evaluating the relationship between OSA and obesity. The risk of OSA also increases with increasing body weight; a 10% weight gain increases the risk of developing OSA by six-times [14,15]. Our results match those got by Lim et al. [16] who studied the PSG data of Singaporean patients evaluated for OSA in 1-year from a local tertiary sleep disorders unit. They demonstrated a fair degree of correlation between AHI and BMI among their patients. Moreover, Sin et al. [17] demonstrated that the most important risk factor in men for OSA was increased BMI; this can be related to an increased fat deposition around the neck which may contribute to pharyn-geal narrowing and collapsibility.
Regarding the polysomnographic data, the general features of all patients (Table 1) and of those with OSA (Table 3) were reduced sleep efficiency, prolonged sleep latency, a high ap-nea-hypopnea, desaturation and arousal indices with a significant negative correlation between AHI and sleep efficiency (Table 2). This can be explained by the fact that, SDB disrupted sleep continuity (frequent arousals) due to recurrent ap-nea, leg movement, or oxygen desaturation during sleep are a potential stimulus for arousal and poor sleep efficiency [18].
Fig. 4 showed the commonest co-morbidities in patients with OSA were systemic hypertension (HTN) (77%), diabetes (63%), COPD (57%) and coronary heart disease (49%). However, all other diagnoses such as bronchial asthma, interstitial pulmonary fibrosis, hepatitis C virus infection, and hypothy-roidism represent 38%.
Ip mary et al. [19] who studied the polysomnographic and clinical characteristics of their local patients found that the common associated medical conditions were hypertension (34%), diabetes mellitus (10%), ischemic heart disease (9%), hyperlipidemia (6%) while Jonczak et al. [20] who studied 2052 patients referred to their sleep lab along ten years because of OSA suspicion found that the most common diseases accompanying OSA were: systemic hypertension (46%), coronary heart disease (29%), diabetes (12%), and COPD (9%). This is can be due to the fact that, OSA is an independent risk factor for hypertension and other cardiovascular complications and, the more severe the OSA, the more common and severe the hypertension. Moreover, Obstructive sleep apnea also may impair glucose tolerance. Patients with OSA have higher levels of fasting blood glucose, insulin, and glycosylated hemoglobin, independent of body weight [21,22].
In this study, 21% of the patients had mild OSA, 22% had moderate OSA while 57% had severe OSA (Fig. 5). In Jonczak et al. [20] study 1194 subjects were diagnosed as having OSA (AHI > 10), 36% had mild OSA (AHI 11-25), 20% had moderate OSA (AHI 26-40), and 44% had severe OSA (AHI > 40). Lim et al. [16] found that 419 patients of the stud-
ied population had OSA (AHI 6 5) Of those, 31% had mild OSA (AHI 5-15), 26% had moderate OSA (AHI 15-30), and 43% had severe OSA (AHI > 30), The explanation of this high percent of patients with severe OSA may be the delay in seeking medical advice for the symptom such as snoring which is considered by most of the patients to be a quite normal personal finding and therefore they delay seeking medical attention until loud disruptive snoring and excessive daytime sleepiness shown as outstanding symptoms.
This retrospective study was performed based on the data from a real clinical setting with a relatively large sample size. Therefore, the clinical characteristics and polysomnographic findings of our Egyptian patients could have a number of clinical implications. However, the patients were referred to the clinic for evaluation of possible sleep apnea. Thus, the results may have been influenced by referral bias and survivorship effects.
Conflict of interest
None declared. References
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