|Year : 2020 | Volume
| Issue : 1 | Page : 1-5
Impact of obstructive sleep apnea and sleep parameters on level of asthma control
Ramakant Dixit, Satyadeep Verma, Mukesh Goyal
Department of Respiratory Medicine, J. L. N. Medical College, Ajmer, Rajasthan, India
|Date of Submission||26-Feb-2019|
|Date of Decision||01-Aug-2019|
|Date of Acceptance||13-Oct-2019|
|Date of Web Publication||11-Feb-2020|
Prof. Dr. Ramakant Dixit
Department of Respiratory Medicine, J. L. N. Medical College, Ajmer-305001
Source of Support: None, Conflict of Interest: None
Background and Objective: Several studies support high prevalence of obstructive sleep apnea (OSA) symptoms in patients with asthma. Our objective was to evaluate the relationship between OSA severity and level of asthma control if any and analyze sleep parameters in patients having different levels of asthma control. Methods: A cross-sectional study among asthma patients having symptoms of sleep-related breathing disorders. Eligible patients were assessed clinically and with sleep questionnaire including asthma control followed by level 1 Polysomnography. Results: Among 53 patients of asthma (mean age 48.16 years), OSA was present in 84.21% of uncontrolled asthma, 35% in partially controlled asthma, and 7.14% in well-controlled asthma. Uncontrolled asthma patients were associated with higher apnea/hypopnea index (AHI) (30.8±17.6 vs. 3.7±1.2; p-value < 0.0001), more time spent in non rapid eye movement (NREM) 1 stage (18.5±11.9% vs. 13.0±11.2% of total sleep time), higher nocturnal desaturation episodes (152.5±13 vs. 22.1±16.7; p-value < 0.001), and severe OSA in supine position (AHI 33.1±17.7 vs. 9.2±9.7; p-value < 0.001) compared with well-controlled asthma. Conclusion: There seems a strong relationship between desaturation events and higher AHI with poor level of asthma control, especially during supine position. OSA must be suspected in patients with uncontrolled asthma. An early detection and treatment of OSA may improve the level of asthma control as well as quality of life in such patients.
Keywords: Asthma, asthma control, obstructive sleep apnea
|How to cite this article:|
Dixit R, Verma S, Goyal M. Impact of obstructive sleep apnea and sleep parameters on level of asthma control. J Assoc Chest Physicians 2020;8:1-5
|How to cite this URL:|
Dixit R, Verma S, Goyal M. Impact of obstructive sleep apnea and sleep parameters on level of asthma control. J Assoc Chest Physicians [serial online] 2020 [cited 2020 Aug 10];8:1-5. Available from: http://www.jacpjournal.org/text.asp?2020/8/1/1/278123
| Introduction|| |
Asthma and obstructive sleep apnea (OSA) are common in general population. Several studies have suggested a link between asthma and OSA. Patients of asthma appear to have an increased risk for OSA than general population. A recent epidemiological study has shown that asthma is associated with an increased risk of new onset of OSA. There are increasing evidences to suggest that OSA is associated with poor asthma control, more nocturnal symptoms, and frequent exacerbations in asthma patients. Despite having enough evidences that OSA is not uncommon among asthma patients, OSA largely remains under-recognized in patients having uncontrolled asthma and is poorly investigated.
Most of the asthma patients are affected with mild to moderate disease that can be easily controlled by conventional management and prevention of risk factors. However, some patients have uncontrolled asthma despite adequate medical management. Severe asthma affects about 3.6–10% of people with asthma. OSA is generally linked with worse asthma outcomes. Mechanism that links the two diseases remains hypothetical; obesity, upper airway inflammation, gastro-esophageal reflux, and several other factors may be implicated in the development of both diseases. National Asthma Education and Prevention Program Expert Panel Report also recommend evaluation for OSA as a potential contributor to poor asthma control.. Therefore, the aim of this study was to assess correlation between OSA severity and level of asthma control if any and its impact on various sleep parameters, as such kind of in-depth studies are largely lacking in Indian literature.
| Methodology|| |
This study was conducted to assess sleep-disordered breathing in patients with asthma at our institution over a period of one year after ethical committee approval. Adult patients of asthma attending the outpatient clinic of the department, presenting with signs, symptoms, and history suggestive of asthma and willing to participate in the study were enrolled after proper counseling. The diagnosis of bronchial asthma was based on clinical history, physical examination, and assessment of respiratory functions including spirometry and reversibility testing. The procedure was explained to the patients and attender. Informed written consent was obtained from each eligible patient.
- Adult patients of asthma (as per Global Initiative for Asthma guideline) diagnosed and managed by specialist.
- Asthma patients on optimal standard treatment and compliance with varying degree of asthma control.
- Patients of asthma having other associated chronic lung disease such as COPD, bronchiectasis, pulmonary tuberculosis, silicosis, etc.
- Chronic renal and hepatic disorders.
- Patients in acute condition.
- Those with poor treatment compliance and faulty inhalation technique.
Patients were subjected to clinical evaluation with special attention on:
- Epworth Sleepiness Score (ESS) to assess the presence of day time sleepiness. In this test, people advised to rate, on a four-point scale (0–3), their usual chances of falling asleep in eight different situations or activities that most people experienced in their daily routine work. The total ESS score was recorded between 0 and 24. The higher ESS is considered to be linked with higher level of person’s daytime sleepiness.
- Berlin Questionnaire (B.Q.) for the identification of patients who may be at high risk for OSA. It consists of ten questions separated into three categories. This scale includes questions about snoring (category I), daytime sleepiness (category II), hypertension, and BMI (category III). The overall B.Q. was determined from the response to the three categories; when two or more categories are classified as positive, the patients seemed to be at high risk for OSA.
- Body Mass Index (BMI) derived from the weight and height formula. [BMI = Weight (kg)/height (meter2)]
- Assessment of level of asthma control as per GINA 2016 guidelines. Questions such as (a) daytime asthma symptoms more than twice/week, (b) any night waking due to asthma, (c) reliever needed for symptoms more than twice/week, and (d) any activity limitation due to asthma were asked to every patient and based on number of “yes” answer to above questions in past four weeks, the level of asthma control was classified as below:
- None of these = Well controlled
- 1–2 of these = Partially controlled
- 3–4 of these = Uncontrolled
- Overnight Polysomnography (Level 1) at sleep lab using Alice PDX diagnostic system, to screen the patients for OSA. Alice PDX is a portable, diagnostic recording device for screening and follow-up of OSA patients having color-coded labels around its perimeter and a light indicator to correctly connect the various sensor leads. OSA was diagnosed if apnea/hypopnea index (AHI) was more than five events per hour of sleep associated with symptoms like excessive day time sleepiness, snoring, disturbed sleep and fatigue, etc. Severity of OSA was further classified according to the AHI value as below:
- Mild OSA = AHI ≥5 to <15
- Moderate OSA = ≥15 to ≤30
- Severe OSA = >30
- Various other sleep parameters were also recorded separately for each patient.
Statistical analysis was performed with the SPSS, Trial version 23 for Windows statistical software package (SPSS inc., Chicago, USA) and Primer. The categorical data were presented as numbers (percent) and were compared among groups using Chi-square test. The quantitative data were presented as mean and standard deviation and were compared using ANOVA test for more than two groups.
| Results|| |
53 patients of asthma visiting our outpatient department during one-year period who were willing to participate and fulfill the eligibility criteria as per methodology constituted the final study population. The mean age of patients was 48.1 years (age range 30–68 years) with male-to-female ratio of 1:2. The mean BMI value in study participants was 27.8; 58.3% of patients were overweight and 33.3% were obese. 24 out of 53 patients were having OSA. The FEV1 (% predicted mean ±SD) in OSA group was 71.4±3.7 and in non-OSA group was 78.1±2.6 (p < 0.001).
[Table 1] shows the distribution of asthma patients in groups with and without having OSA as per their level of asthma control. A higher prevalence of OSA was observed in patients having uncontrolled asthma compared to those with partially controlled asthma, that is 84.2% versus 35%. Well-controlled asthma patients had only 7.1% prevalence of OSA. These findings were statistically significant (p = 0.001).
|Table 1 Distribution of asthma patients according to OSA status and level of asthma control|
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Out of 24 patients having OSA, the contribution of ESS in diagnosis was only in 9 patients (37.5%) while that of B.Q. was in 17 patients (70.8%) (p = 0.00004). The sensitivity of ESS to identify OSA was 39.1% with specificity of 88.8%, positive predictive value of 75%, and negative predictive value of 63.1%. On the other hand, the sensitivity, specificity, positive predictive value, and negative predictive value of B.Q. was much better, that is 69.5%, 85.1%, 80%, and 76.6% respectively (p < 0.0001).
[Table 2] shows supine AHI, lateral AHI, number of de-saturation episodes, and de-saturation index in asthma patients having different levels of asthma control. Mean AHI in well-controlled asthma was 3.7±1.2 and in uncontrolled asthma, it was 30.8±17.6 (p < 0.0001) which shows that uncontrolled asthma state is associated with more obstructive apnea episodes. Uncontrolled asthma was significantly associated with increased AHI in supine as well as lateral position, which suggests that increased AHI was not posture dependent during sleep. Uncontrolled asthma patients were also associated with more desaturation index as compared to those with partial or well-controlled asthma (31.2±21.2, 9.0±10.4, and 3.8±3.2, respectively, p < 0.001). As the de-saturation index is a direct indicator of severity of OSA, these results show that there was a decrease in saturation to a significant extent during sleep in patients having uncontrolled asthma.
[Table 3] shows sleep stages among patients having different levels of asthma control. The mean times spent in non rapid eye movement (NREM) 1 sleep by well-controlled, partially controlled, and uncontrolled asthma were 13.0±11.2%, 16.1±9.6 %, and 18.5±11.9 % respectively. Uncontrolled asthma patients spent more time in NREM 1 stage, while patients with well-controlled asthma symptoms spent relatively more time during NREM stage 2; this suggests that poorly controlled asthma patients do not undergo normal sleep cycles and had repeated arousals. However, this difference was statistically non-significant (p = 0.81). Other sleep parameters, that is sleep efficiency, sleep onset latency, etc., were almost same in patient having different levels of asthma control whereas REM onset latency was higher in uncontrolled and partially controlled asthma compared to those with well-controlled asthma in a non-significant manner (90.2±116.9, 128.7±99.1, and 20.5±16.7; ANOVA test 1.03; p = 0.3).
| Discussion|| |
In this study, patients with uncontrolled asthma had highest prevalence of OSA, that is 84.2% followed by those with partially controlled asthma (35%) and well-controlled asthma (7.1%). Study done by Zidan et al. in 2015 also showed that most of the asthma patients with OSA had partially controlled asthma (61%), followed by uncontrolled asthma (33.3%), and only 5.6% having well-controlled asthma. In an abstract publication of conference proceedings, Umashankar et al. mentions a prevalence of OSA in well, partial, and uncontrolled asthma to be 0%, 17.4%, and 68.4% respectively. However, the correlation between AHI, desaturation episodes, and time spent in different sleep stages with the level of asthma control was not mentioned. Overall, available data show that OSA contributes to poor level of asthma control.
Poor controls of asthma symptom were associated with high AHI in our study. Mean AHI in well-controlled asthma was 3.7±1.2 and in uncontrolled asthma it was 30.8±17.6 which shows that uncontrolled asthma was linked with more obstructive apnea episodes (p < 0.0001). Position of patients during sleep greatly affects sleep architecture and sleep quality. In our study, we also observed that patients spending more time in lateral position were associated with moderate type of OSA, while those with more time in supine position were having severe OSA among uncontrolled asthma group (p = 0.001), although the AHI values were higher in both positions compared to those with partial and well-controlled asthma. Uncontrolled asthma patients were having more desaturation episodes (152.5±13) as compared to well-controlled asthma (22.1±16.7). De-saturation index in poorly controlled asthma group was quite high than controlled asthma population (31.2±21.2 and 3.8±3.2 respectively, p-value < 0.001). Julien et al., Taille et al., and Shaarawy et al. also observed poor control asthma linked with high desaturation index.
In our study, difficult to treat patients (uncontrolled asthma) spent more time in NREM stage 1 (18.5±11.9 %) as compared to those with well-controlled asthma who spent more time in NREM stage 2 (48.0±9.7) and NREM stage 3 (30.6±14.3). A home-based study by Julien et al. in 2009 on 26 asthma patients observed that severe asthma patients spent more time in NREM 1 and 2 while controlled asthma patients had more sleep in NREM 3 and REM stage. This comparison demonstrates that all patients are likely to be influenced by first night effect, which commonly occurs in patients evaluated in a sleep lab.
| Strength and limitations|| |
Our strength of this study is that we could demonstrate that OSA is not an uncommon association in asthma patients and is linked with poor level of asthma control. Our study also has few limitations. Firstly the study participants were selected from hospital outpatient department setting who were willing to participate. Secondly, there were very few younger asthmatic patients. Many patients were reluctant to stay at hospital for overnight level 1 PSG and this resulted in a small sample size. Further, we adopted convenient sampling where all the asthma patients of different age groups from community did not have equal chance of selection; therefore, findings of this study can’t be generalized. Large sample sizes with multicenter data may estimate an actual impact of OSA on the level of asthma control in these patients and explore further details in this direction. But despite these limitations, our study highlights the OSA as an important risk factor that affects level of asthma control in these patients and can be recognized by certain sleep parameters.
In conclusion, this study in the background of available literature strongly confirms by level 1 PSG that presence of OSA is a significant factor that is associated with poor level of asthma control. Therefore, it is important to screen patients having poor asthma control despite optimal management, especially for OSA when other factors known to affect asthma control are excluded. This will definitely improve quality of life, reduce treatment-related cost, and morbidity among such patients. OSA is largely under-recognized in patients having uncontrolled bronchial asthma, therefore there is a need for awareness in this direction. Despite few limitations, ours is a unique study as it links the impact of OSA and disturbed sleep on the level of asthma control. Owing to the rising trend of bronchial asthma, more of such kind of studies with increased number of patients is warranted to support these data.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]