Talyta Cortez Grippe1, Dario Alhares1*, Lisiane Seguti Ferreira1,2 and Andrea Schappo Bonavides1
1University Hospital of Brasília. SGAN 604, 70910-900, Brasília, DF, Brazil 2Hospital de Base de Brasília. SMHS qd 101. 70330-150, Brasília, DF, Brazil
Received: 13 May, 2016; Accepted: 22 July, 2016; Published: 27 July, 2016
Dario Palhares, University Hospital of Brasília. SGAN 604, 70910-900, SQS 416 bl i ap. 294. Asa Sul, Brasília, DF, Brazil, Tel: 55-61-32423638; E-mail:
Grippe TC, Palhares D, Ferreira LS, Bonavides AS (2016) Weak Correlation between Clinical Parameters and Polysomnography Findings. Arch Otolaryngol Rhinol 2(1): 047-050. DOI: 10.17352/2455-1759.000023
© 2015 Grippe TC, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Sleep apnea; Sleep disorder; Snoring; Arrhythmia
Purpose: since about only 30% of polysomnography results confirm the indications, it would be useful to identify clinical data predictive of positive results. The objective is to evaluate the correlation between clinical data and polysomnography findings in a cohort of patients.
Methods: 237 polysomnographies and the related clinical data from 226 patients were evaluated retrospectively.
Results: the clinical suspicion and the polysomnography findings presented a positive correlation of 69%. However, none of the clinical parameters studied – age, body mass index, neck circumference and Epworth index - was a good predictor of examination.
Conclusion: Clinical diagnosis of the syndrome is more important than an isolated assessment of any factor.
Sleep disorders comprise a group of conditions with different clinical origins and expressions, including insomnia and respiratory or motor disorders. Their prevalence in the population is variable, but the most common disorder is Obstructive Sleep Apnea Syndrome (OSAS), followed by insomnia and restless legs syndrome . The diagnosis can be made based on clinical and/or laboratory parameters. Polysomnography (PSG) is the most accurate of the tests available for sleep assessment .
PSG records multiple physiological parameters of sleep and aims to access cardiorespiratory and neurologic variables, which allow the quantity and quality of sleep to be assessed as well as the identification of several cardiac, respiratory, and motor events and their repercussions [1,2].
The main complaints of patients who undergo this examination are the usual symptoms of OSAS, including snoring  and excessive daytime sleepiness . However, the low frequency of OSAS diagnosis by PSG (31%) is not consistent with the high frequency (71%) of daytime sleepiness reported by patients for whom PSG is recommended.
This discrepancy raises the question of whether data from a medical history and physical examination can predict PSG outcomes and improve indications for PSG examination. Thus, the objective of the present study was to retrospectively compare the request of the sleep exam and the diagnosis of the sleep apnea and other sleep disorders and also to test the correlations between clinical parameters such as body mass index (BMI) [2,5,6], neck circumference [7-9], age  and the presence or severity of OSAS.
This clinical descriptive retrospective study assessed 237 PSG examinations on a seven-month period. The following factors were evaluated: sex, age, weight, height, BMI, neck circumference, Epworth Questionnaire score (which measures daytime sleepiness) [4,11] and quality of sleep on the night of the PSG examination compared to sleep at home.
The examinations were performed by trained PSG technicians and were analyzed by senior sleep medicine specialists in accordance with the rules of the 2nd International Classification of Sleep Disorders . The PSGs were separated into two categories: those with diagnostic and non-diagnostic intentions as expressed by the physician requesting the examination. The PSGs were considered to have a diagnostic intention when the main indication was sleep-related respiratory diseases, respiratory diseases, narcolepsy, sleep disorders related to seizures, restless legs syndrome, sleep-related periodic limb movements, insomnia, circadian rhythm disorders, or a pre-operative examination prior to bariatric surgery. The PSGs were considered non-diagnostic when they were used to evaluate continuous positive airway pressure (CPAP) or the efficacy of intra-oral appliances.
Among the diagnostic PSGs, the indications were considered to be in agreement with the polysomnographic diagnosis when the clinical suspicion reported in the requirement was confirmed by the PSG exam, or if the test reflected consequences related to the pathophysiological mechanism of the reported symptom. They were also considered concordant if there were indications of snoring, obesity, or hypertension and a diagnosis of OSAS.
The PSG outcomes were considered to be discordant with the clinical suspicion in the following situations: (a) non-specific and/or too broad indications, such as “unspecified sleep disorder” or “unspecified respiratory disorder,” since these statements are merely common terms used to obtain health insurance; (b) exams with normal outcomes or unspecific findings, such as changes in sleep architecture; (c) results independent of, and unrelated to, the indication expressed in the requirement; or (d) OSAS as an indication and “snoring” as the sole finding, given that primary snoring is only characterized after the exclusion of sleep disordered breathing by PSG .
Patients were classified as with OSAS when the apnea-hypopnea index (AHI) was > 5. They were classified as suffering from mild OSAS (AHI 5-15), moderate OSAS (AHI 15-30), or severe OSAS (AHI>30) based on the American Academy of Sleep Medicine criteria. The clinical parameters, including sex, age, BMI, neck circumference, and Epworth score, were compared with the AIH values (Table 1).
Statistical analyses were performed using the Chi-square test and kappa statistic with Prism® 5 software; outcomes were considered significant if the p value was <0.05.
The mean age of the patients was 52 years (range, 20–88 years). They were stratified by age into the following groups (n, %): 20–40 years (54–23%), 41–60 years (99–43%), and >60 years (78–34%). PSGs were performed for 134 men (58%) and 97 women (42%). The mean BMI was 31.12 (range, 15.57–54.96). Patient perceptions of the quality of sleep during the test compared to at home was worse in 118 (52%), the same in 60 (26%), and improved in 51 (22%).
Regarding the diagnostic polysomnography. Table 2 shows the clinical data of patients who underwent a diagnostic PSG. More than 50 different indications for the exam were identified. These are listed in Table 3. The main results of the 144 diagnostic PSGs are shown in Table 4.
The similarity between the indication and the diagnostic PSG results was 69% (n = 109). Among the 49 discordant results, 15 (31%) were due to clinical suspicion of OSAS with only snoring founded in PSG, 15 (31%) due to nonspecific results in PSG, 10 (20%) due to lack of relation between indication and PSG outcome and 9 (18 %) due to unspecific indication in the request. Four PSGs were performed using an expanded EEG montage, three based on a suspicion of nocturnal frontal lobe epilepsy with concordant results.
The most prevalent diagnosis was OSAS. The clinical data as BMI, sex, age, the score in the Epworth sleep scale, neck and waist circumference was compared to the AHI index. According to the correlation index of Spearman, the age (p<0,0001), neck (p=0.0002) and waist circumference (p=0.0073) were significantly correlated with the AIH index, as shown in Figure 1. None of the clinical parameters was suitable for predicting AIH >15, which was independent of all factors or combinations of factors tested. Factors including age >55 years, female sex and age >55 years, and male sex with a BMI >35 kg/m² showed a trend towards statistical significance. The K index, however, only showed a weak correlation with these factors, indicating that it was not possible to predict the outcome of the PSG AIH measure based on these factors.
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