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Symptoms related to obstructive sleep apnoea are common in subjects with asthma, chronic bronchitis and rhinitis in a general population
RESPIRATORY MEDICINE (2001) 95, 423–429 doi:10.1053/rmed.2001.1054, available online at http://www.idealibrary.com on
Report
Symptoms related to obstructive sleep apnoea are common in subjects with asthma, chronic bronchitis and rhinitis in a general population L.-G. LARSSON*{, A. LINDBERG*{, K. A. FRANKLIN{}
AND
B. LUNDBA¨CK{}}
*Division of Respiratory Medicine and Allergy, and {The OLIN Study Group, Department of Medicine, Sunderby Central Hospital of Norrbotten, Lulea˚; Departments of {Internal Medicine and }Respiratory Medicine and Allergy, University Hospital, Umea˚; }Respiratory Unit, Department of Occupational Medicine, National Institute for Working Life, Stockholm, Sweden The purpose of this study was to examine the prevalence of self-reported snoring, apnoeas and daytime sleepiness in relation to chronic bronchitis, recurrent wheeze, physician-diagnosed asthma and rhinitis. This was a questionnaire study in a representative sample of a general population. The study was a part of the Obstructive Lung Disease in Northern Sweden Studies (OLIN). A total of 5424 subjects aged 20–69 years, born on the 15th day of each month, participated in the study. Eligible answers were obtained from 4648 subjects (85?7%). Having snoring as a problem was reported by 10?7%. Among subjects with chronic bronchitis it was reported by 25?9%, with recurrent wheeze by 21?3%, with physician-diagnosed asthma by 17?9%, and with rhinitis by 14?7%. Relatives’ concerns of witnessed apnoea was reported by 6?8% of all subjects, while among subjects with chronic bronchitis it was reported by 18?1%, with recurrent wheeze by 17?1%, with physician-diagnosed asthma by 14?3%, and with rhinitis by 9?1%. After correction for age, gender and smoking habits, chronic bronchitis, rhinitis, asthma, and current smoking were significantly related, with snoring as a problem and with relatives’ concern of witnessed apnoeas. Symptoms of daytime sleepiness were significantly related with concern of witnessed apnoeas, chronic bronchitis, snoring as a problem, recurrent wheeze and age 50–59 years. In conclusion, respiratory symptoms and conditions affecting mainly the lower respiratory tract, such as chronic bronchitis and asthma, were related with symptoms common in obstructive sleep apnoea. Key words: snoring; sleep apnoea; chronic bronchitis; rhinitis; asthma; epidemiology. RESPIR. MED. (2001) 95, 423–429
Introduction Sleep-disordered breathing (SDB) is an old reality but a new scientific entity. During the last decades it has been recognized and defined as partial or complete upper airway collapse including snoring, hypopnoeas and apnoeas. It is referred to as a progressive disorder continuing from snoring to obstructive sleep apnoea (OSA), with daytime sleepiness as the main symptom (1–3). Habitual snoring is reported by 44–63% of men and by 27–36% of women in a general population (4–6). Obstructive sleep apnoea syndrome, defined as apnoea– hypopnoeas index (AHI) 10 h71 together with daytime Received 8 November 2000 and accepted in revised form 9 February 2001. Correspondence should be addressed to: Lars-Gunnar Larsson, M.D., Department of Medicine, Division of Respiratory Medicine and Allergy, Sunderby Central Hospital of Norrbotten, SE-971 80 Lulea˚, Sweden. Fax: +46-920 283350; E-mail: [email protected]
0954-6111/01/050423+07 $35?00/0
# 2001 HARCOURT PUBLISHERS LTD
symptoms, has been estimated at 2?3% in men 30–60 years old and at 1?1% in women (5). There is evidence that SDB is related to increased morbidity from automobile accidents (7), cardiovascular diseases and, in combinations with chronic obstructive pulmonary disease (COPD), with pulmonary hypertension (8–13). Asthma and chronic bronchitis are also common disorders and causes of morbidity and mortality. The prevalence of asthma among adults in Northern Sweden is around 8% (14), and of chronic bronchitis around 10% (15). Studies have found an increased prevalence of snoring in bronchitic subjects (16–19). There is, however, no evidence that obstructive sleep apnoea is more common in subjects with COPD (20,21). The Obstructive Lung Disease in Northern Sweden Studies (OLIN) have studied obstructive lung diseases and allergic conditions by cross-sectional and longitudinal population-based studies since 1985. The OLIN studies give opportunities to investigate the prevalence and co-variation # 2001 HARCOURT PUBLISHERS LTD
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of obstructive lung disorders and rhinitis with signs of increased upper airway resistance, such as snoring and witnessed sleep apnoeas. The aim of this study was to examine the relation between reported snoring as a problem and witnessed sleep apnoeas with chronic bronchitis, asthma and rhinitis in a general population sample.
4.
Material and methods
1.
The study was conducted simultaneously with a follow-up study of asthma (22). The study area was the most northern province of Sweden, Norrbotten, and it has been described extensively (23).
2.
The questionnaire also included four questions related to obstructive sleep apnoea, previously used in a prevalence study in a bronchitic cohort (18). The definitions of symptoms related to OSAS were:
3. 4.
STUDY POPULATION
ANALYSIS Statistical analyses were performed by using the Statistical Package for Social Sciences (SPSS). The chi-square test was used for bivariate comparisons. Multiple logistic regression analysis was used to assess the simultaneous influences of the different independent variables, including respiratory symptoms and diseases on the various symptoms caused by sleep disturbances. A P-value 50?05 was considered as statistically significant.
METHODS The questionnaire was developed from a revised version (24) of the British Medical Research Council’s questionnaire (25) after influences from the ATS (26) and the Tucson studies questionnaires (27), and has been frequently used in Nordic countries (14,28). The questionnaire (23) has previously been validated (29,30). Four items were chosen from the questionnaire regarding respiratory symptoms and diseases:
2.
3.
Snoring as a problem: ‘Do you snore so much that you think it is a problem?’ Worry of witnessed apnoeas: ‘Have relatives expressed worry about you stopping breathing while you are asleep?’ ‘Do you feel completely rested after a full night’s sleep?’ ‘Do you nod off during breaks in daytime activities?’
Subjects who gave a positive answer to question 4 and/or a negative answer to question 3 were regarded to have daytime sleepiness.
All 5682 subjects in the province aged 20–69 years, born on the 15th day of each month, were invited to complete a postal questionnaire survey. The questions included respiratory symptoms and diseases, smoking habits and profession. Of the 5682 subjects, 5424 also received questions about symptoms related to obstructive sleep apnoea. Two reminders were used. Eligible answers were obtained by 4648 subjects (85?7%; Table 1). The Ethics Committee of the University Hospital of Northern Sweden and the University of Umea˚ approved the study.
1.
Rhinitis: ‘Do you have or have you ever had allergic eye/nose catarrh (hay-fever)?’
Results PREVALENCE OF AIRWAY DISEASES AND SYMPTOMS Physician-diagnosed asthma was reported by 6?6% of men and by 7?6% of women. The prevalence of asthma was significantly most common in the 20–29-year-old respondents and lowest in the 40–59-year-olds in both men and women (Fig.1). The prevalence of recurrent wheeze was 12?1% in men and 11?5% in women, and increased significantly with age among men but not among women (Fig. 2). Chronic bronchitis increased significantly with age and was reported by 7?6% of men and 6?7% of women (Fig. 1). The prevalence of rhinitis was 18?5% in men and
Physician-diagnosed asthma: ‘Have you been diagnosed by a physician as having asthma?’ Recurrent wheeze: ‘Do you usually have wheezing, whistling, or a noisy sound in your chest when breathing?’ Chronic bronchitis: ‘Do you bring up phlegm when coughing on most days during periods of at least 3 months during at least 2 successive years?’
TABLE 1. Subjects invited and participated in the study by age and gender 20–29 years M
F
MþF
Invited 588 525 1113 Participated 478 462 940 Percent 81.3 88.0 84.5 M, male; F, female.
30–39 years M
F
MþF
645 567 1212 524 509 1033 81.2 89?8 85?2
40–49 years M
F
MþF
626 534 1160 541 497 1038 86?4 93?1 89?5
50–59 years M
F
MþF
485 467 952 421 426 847 86?8 91?2 89?0
460 years M
F
MþF
472 515 987 385 405 790 81?6 78?6 80?0
All M
F
MþF
2816 2608 5424 2349 2299 4648 83?4 88?2 85?7
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425
FIG. 1. Prevalence of chronic bronchitis (CB) and asthma in per cent in males and females, respectively.
FIG. 2. Prevalence of rhinitis and recurrent wheeze in per cent in males and females, respectively.
20?4% in women, and decreased with increasing age among both men and women (Fig. 2).
SMOKING The proportions of current smokers were 28?8% in men, and 32?4% in women. Of men, 24?1% were ex-smokers and 47?1% were non-smokers. In women, 15?9% were exsmokers and 51?6% were non-smokers (Fig. 3).
concomitant daytime symptoms was reported by 5?4%. The symptoms were significantly more common in men except daytime sleepiness, which was equally prevalent in men and women. Snoring as a problem and worry of witnessed apnoeas were more prevalent among the subjects having each of the respiratory symptoms and conditions used in the analyses, and among men in both ex- and current smokers (Table 2).
MULTI-VARIATE RELATIONSHIPS SYMPTOMS RELATED TO OBSTRUCTIVE SLEEP APNOEA Snoring as a problem was reported by 10?7%, relatives’ concern of witnessed apnoea during sleep by 6?8%, and daytime sleepiness by 28?3%. Snoring as a problem and
The influence on snoring as a problem, the combination of snoring and daytime sleepiness, and relatives’ worry of witnessed apnoeas during sleep, respectively, by age, gender, smoking habits, and different respiratory symptoms and diseases were analysed by using multiple logistic regression.
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FIG. 3. Smoking habits in percentage of in males and females, respectively. TABLE 2. The prevalence (%) of snoring as a problem, snoring as a problem with concomitant daytime sleepiness, and relatives’ worry of witnessed apnoeas in relation to smoking habits, age, and airway conditions in males (M) and females (F) respectively Snoring as a problem Variable Non-smokers Ex-smokers Current smokers P 20–29 30–39 40–49 50–59 60–69 P Chronic bronchitis Yes Chronic bronchitis No P Physician-diagnosed asthma Yes Physician-diagnosed asthma No P Wheezing Yes Wheezing No P Rhinitis Yes Rhinitis No P
years years years years years
M
F
10?4 16?5 20?1 50?001 4?6 11?5 20?1 23?5 14?0 50?001 31?5 13?3 50?001 21?9 14?1 0?008 28?1 12?8 50?001 20?0 13?4 50?001
6?2 6?4 7?5 0?552 1?7 5?7 7?6 9?6 9?1 50?001 18?8 5?8 50?001 14?4 6?0 50?001 14?0 5?7 50?001 9?8 5?9 0?002
Age, male gender, chronic bronchitis, physiciandiagnosed asthma, rhinitis and current smoking were significantly related to having snoring as a problem and also to the combination of snoring and daytime sleepiness (Table 3). When recurrent wheeze was included in the
Snoring and daytime sleepiness All
M
F
All
Relatives’ worry of apnoeas M
F
All
8?2 5?0 3?3 4?1 7?4 2?1 4?7 12?5 8?3 3?3 6?4 12?4 1?7 8?2 13?5 8?9 4?9 6?8 15?9 3?4 9?4 50?001 0?002 0?191 0?001 50?001 0?124 50?001 3?2 2?9 0?9 1?9 3?8 1?3 2?6 8?6 5?3 3?1 4?3 5?5 1?6 3?6 14?2 9?8 4?4 7?2 14?4 2?4 8?7 16?5 10?2 5?2 7?7 19?2 2?8 11?0 11?5 6?8 6?2 6?5 13?5 4?4 8?9 50?001 50?001 50?001 50?001 50?001 0?024 50?001 25?9 18?0 13?6 16?0 26?4 8?4 18?1 9?5 6?1 3?2 4?6 9?7 2?0 5?9 50?001 50?001 50?001 50?001 50?001 50?001 50?001 17?9 13?5 9?2 11?2 21?3 8?0 14?3 10?1 6?5 3?4 5?0 10?3 2?0 6?2 50?001 0?001 50?001 50?001 50?001 50?001 50?001 21?3 17?5 8?7 13?3 26?3 7?2 17?1 9?3 5?5 3?2 4?4 8?9 1?8 5?4 50?001 0?001 50?001 50?001 50?001 50?001 50?001 14?7 12?4 5?3 8?7 14?3 4?3 9?1 9?7 5?7 3?5 4?6 10?2 2?0 6?2 50?001 50?001 0?68 50?001 0?015 0?004 0?002
model, physician-diagnosed asthma became not significant. Instead of asthma, recurrent wheeze became significantly related with snoring and the combination of snoring as a problem and daytime sleepiness. Age, male gender, recurrent wheeze, chronic bronchitis, physician-diagnosed
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TABLE 3. Risks (OR and 95% CI) for snoring as a problem, snoring with concomitant daytime sleepiness, relatives’ worry of witnessed apnoeas, and daytime sleepiness, respectively, by multiple logistic regression analysis. The independent variables were gender, age, smoking habits, and the respiratory conditions chronic bronchitis, asthma, and rhinitis. When calculating risks for daytime sleepiness, snoring and apnoeas were also included in the model Independent variables
Dependent variables Snoring
95% CI
OR
Gender
Women Men
1 2?57 (2?09–3?17)
1 1?96 (1?49–2?58)
1 5?48 (4?05–7?43)
1 0?97 (0?84–1?11)
Age class (years)
20–29 30–39 40–49 50–59 60–69
1 2?86 5?12 6?48 4?37
1 2?22 4?04 4?34 3?81
1 1?37 3?61 5?31 4?19
1 1?06 1?16 1?14 1?15
Smoking habits
Non-smoker Ex-smoker Smoker
1 1?13 (0?87–1?46) 1?55 (1?24–1?94)
1 1?18 (0?83–1?67) 1?52 (1?12–2?06)
1 1?17 (0?85–1?62) 1?98 (1?49–2?62)
1 1?09 (0?91–1?30) 1?17 (1?01–1?37)
Respiratory condition
Chronic bronchitis Asthma Rhinitis
2?40 (1?80– 3?20)
2?74 (1?93–3?89)
2?39 (1?70–3?35)
2?02 (1?59–2?57)
1?62 (1?16–2?27) 1?77 (1?40–2?24)
1?73 (1?14–2?61) 2?02 (1?49–2?73)
2?36 (1?60–3?48) 1?63 (1?21–2?20)
1?17 (0?91–1?52) 1?21 (1?02–1?44)
Snoring
–
–
–
1?85 (1?47–2?32)
Apnoeas
–
–
–
2?30 (1?73–3?04)
(1?26–3?90) (2?37–6?90) (2?51–7?51) (2?17–6?69)
asthma, rhinitis, and current smoking were all significantly associated with relatives’ concern about witnessed apnoea during sleep. Daytime sleepiness was significantly related to relatives’ concern about witnessed apnoea, chronic bronchitis, snoring as a problem and recurrent wheeze, while rhinitis, smoking, and physician-diagnosed asthma were not. However, when recurrent wheeze was excluded from the model, rhinitis and current smoking became significant.
Discussion Asthmatics had significantly higher prevalence of reported snoring as a problem and worry of witnessed apnoeas than non-asthmatics in our study, and also after adjusting for age, sex, and smoking habits, asthma was still significantly related with apnoeas, and snoring. Others have found similar relation between asthma and witnessed apnoeas and also that asthmatics have more daytime sleepiness (31,32). However, we could not verify that daytime sleepiness is more common in subjects with asthma. We have not found studies supporting that asthmatics suffer from obstructive sleep apnoea more often than respiratory healthy subjects do. There are, however, reports that patients with nocturnal
OR
95% CI
Daytime sleepiness
Category
(1?85–4?40) (3?38–7?75) (4?25–9?86) (2?82–6?77)
OR
Apnoeas
Variables
OSA symptoms
95% CI
Snoringþdaytime sleepiness
(0?80–2?33) (2?24–5?82) (3?28–8?60) (2?55–6?90)
OR
95% CI
(0?86–1?30) (0?94–1?44) (0?92–1?43) (0?92–1?44)
asthma and concomitant obstructive sleep apnoea have been improved regarding their nocturnal asthma on treatment with nasal continuing positive airway pressure (CPAP) (33). Bronchial hyper-reactivity (BHR) was present in four of 16 subjects with obstructive sleep apnoea in one study, and treatment with nasal CPAP decreased their hyper-reactivity to metacholine (34). Others have not found any correlation between BHR and symptoms related to upper airway obstruction (32). As found by others, rhinitis was significantly correlated with reported snoring as a problem and worry of witnessed apnoeas in our study (35), and rhinitis was also significantly related to reported daytime symptoms. Rhinitis has in some studies also been found to be related with obstructive sleepapnoea, but with lack of linearity between nasal obstruction and severity of sleep-disordered breathing (36). Subjects with bronchitic symptoms had a higher prevalence of both snoring as a problem and worry of witnessed apnoea in our study. Bronchitic symptoms tended to correlate even stronger with snoring as a problem when daytime symptoms, as not being rested after a full night’s sleep or liability to ‘nod off ’ during the day, were added to snoring. This may indicate that snoring in bronchitic subjects inflicts more on daily life, with excessive daytime symptoms related to deteriorated sleep. The high
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prevalence of snoring as a problem in subjects with bronchitic symptoms in our population sample is in accordance with the high prevalence we found in a bronchitic cohort (18,19). There are indications that bronchitic subjects often have signs of obstruction of the upper airways (17–19). It is possible that the inflammation in bronchitis not only affects the lower airways in bronchitic subjects, but also the upper airway. It is generally considered that snoring and sleep apnoea are not more prevalent in subjects with chronic obstructive pulmonary disease than in a general population (20,21). Supporting that, in a previous study, we have found that snoring in a bronchitic cohort was correlated with bronchitic symptoms and not with loss of lung function (19). It is known that chronic obstructive pulmonary disease is highly over-represented among subjects with bronchitic symptoms, and there is some evidence that bronchitic symptoms may precede or at least occur simultaneously with the progressive loss of lung function seen in COPD (37). This, together with the indications that the combination of COPD and obstructive sleep apnoea may result in a more severe disease (7–9), makes it important to investigate obstructive sleep apnoea when a patient with COPD, or a patient with chronic bronchitis, presents symptoms giving suspicion of OSA. It is interesting that current smoking was significantly related with both snoring and witnessed apnoeas in men also after correction for obstructive airway conditions. Most reports have found a relation between snoring and smoking, and one hypothesis is that smoking acts via chronic bronchitis. In our study both smoking and chronic bronchitis were independently associated with snoring. It is possible that smoking causes inflammation of the upper airways. Another possible mechanism is decreased nicotine concentration during night-time and less positive muscular tone in the upper airways (38,39). It is hardly surprising that both respiratory symptoms and diseases, and symptoms related to obstructive sleep apnoea, cause daytime symptoms such as not being rested after a full night’s sleep or to have liability to ‘nodding off ’ in the daytime, since these disorders all may disturb sleep. It is more surprising that subjects with asthma did not express more daytime sleepiness symptoms, though they reported more snoring and apnoeas. Furthermore, other studies have found that asthmatics have a high degree of disrupted sleep due to night asthma (17,31,32,35,40). We expected that these factors together (snoring, apnoeas and night asthma) would give asthmatics more symptoms of daytime sleepiness, and we can not explain why our results could not confirm this. It is possible that these asthmatics were well controlled and had less night asthma. In conclusion, respiratory symptoms and conditions affecting mainly the lower respiratory tract, such as chronic bronchitis and asthma, as well as current smoking and history of rhinitis, were related with symptoms common in obstructive sleep apnoea such as having snoring as a problem and relatives being worried about witnessed apnoeas.
Acknowledgements The study was supported by grants from the Swedish Heart and Lung Foundation, the Swedish Association for Heart and Lung Patients, and Norrbottens Local Health Authority.
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Report
Symptoms related to obstructive sleep apnoea are common in subjects with asthma, chronic bronchitis and rhinitis in a general population L.-G. LARSSON*{, A. LINDBERG*{, K. A. FRANKLIN{}
AND
B. LUNDBA¨CK{}}
*Division of Respiratory Medicine and Allergy, and {The OLIN Study Group, Department of Medicine, Sunderby Central Hospital of Norrbotten, Lulea˚; Departments of {Internal Medicine and }Respiratory Medicine and Allergy, University Hospital, Umea˚; }Respiratory Unit, Department of Occupational Medicine, National Institute for Working Life, Stockholm, Sweden The purpose of this study was to examine the prevalence of self-reported snoring, apnoeas and daytime sleepiness in relation to chronic bronchitis, recurrent wheeze, physician-diagnosed asthma and rhinitis. This was a questionnaire study in a representative sample of a general population. The study was a part of the Obstructive Lung Disease in Northern Sweden Studies (OLIN). A total of 5424 subjects aged 20–69 years, born on the 15th day of each month, participated in the study. Eligible answers were obtained from 4648 subjects (85?7%). Having snoring as a problem was reported by 10?7%. Among subjects with chronic bronchitis it was reported by 25?9%, with recurrent wheeze by 21?3%, with physician-diagnosed asthma by 17?9%, and with rhinitis by 14?7%. Relatives’ concerns of witnessed apnoea was reported by 6?8% of all subjects, while among subjects with chronic bronchitis it was reported by 18?1%, with recurrent wheeze by 17?1%, with physician-diagnosed asthma by 14?3%, and with rhinitis by 9?1%. After correction for age, gender and smoking habits, chronic bronchitis, rhinitis, asthma, and current smoking were significantly related, with snoring as a problem and with relatives’ concern of witnessed apnoeas. Symptoms of daytime sleepiness were significantly related with concern of witnessed apnoeas, chronic bronchitis, snoring as a problem, recurrent wheeze and age 50–59 years. In conclusion, respiratory symptoms and conditions affecting mainly the lower respiratory tract, such as chronic bronchitis and asthma, were related with symptoms common in obstructive sleep apnoea. Key words: snoring; sleep apnoea; chronic bronchitis; rhinitis; asthma; epidemiology. RESPIR. MED. (2001) 95, 423–429
Introduction Sleep-disordered breathing (SDB) is an old reality but a new scientific entity. During the last decades it has been recognized and defined as partial or complete upper airway collapse including snoring, hypopnoeas and apnoeas. It is referred to as a progressive disorder continuing from snoring to obstructive sleep apnoea (OSA), with daytime sleepiness as the main symptom (1–3). Habitual snoring is reported by 44–63% of men and by 27–36% of women in a general population (4–6). Obstructive sleep apnoea syndrome, defined as apnoea– hypopnoeas index (AHI) 10 h71 together with daytime Received 8 November 2000 and accepted in revised form 9 February 2001. Correspondence should be addressed to: Lars-Gunnar Larsson, M.D., Department of Medicine, Division of Respiratory Medicine and Allergy, Sunderby Central Hospital of Norrbotten, SE-971 80 Lulea˚, Sweden. Fax: +46-920 283350; E-mail: [email protected]
0954-6111/01/050423+07 $35?00/0
# 2001 HARCOURT PUBLISHERS LTD
symptoms, has been estimated at 2?3% in men 30–60 years old and at 1?1% in women (5). There is evidence that SDB is related to increased morbidity from automobile accidents (7), cardiovascular diseases and, in combinations with chronic obstructive pulmonary disease (COPD), with pulmonary hypertension (8–13). Asthma and chronic bronchitis are also common disorders and causes of morbidity and mortality. The prevalence of asthma among adults in Northern Sweden is around 8% (14), and of chronic bronchitis around 10% (15). Studies have found an increased prevalence of snoring in bronchitic subjects (16–19). There is, however, no evidence that obstructive sleep apnoea is more common in subjects with COPD (20,21). The Obstructive Lung Disease in Northern Sweden Studies (OLIN) have studied obstructive lung diseases and allergic conditions by cross-sectional and longitudinal population-based studies since 1985. The OLIN studies give opportunities to investigate the prevalence and co-variation # 2001 HARCOURT PUBLISHERS LTD
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of obstructive lung disorders and rhinitis with signs of increased upper airway resistance, such as snoring and witnessed sleep apnoeas. The aim of this study was to examine the relation between reported snoring as a problem and witnessed sleep apnoeas with chronic bronchitis, asthma and rhinitis in a general population sample.
4.
Material and methods
1.
The study was conducted simultaneously with a follow-up study of asthma (22). The study area was the most northern province of Sweden, Norrbotten, and it has been described extensively (23).
2.
The questionnaire also included four questions related to obstructive sleep apnoea, previously used in a prevalence study in a bronchitic cohort (18). The definitions of symptoms related to OSAS were:
3. 4.
STUDY POPULATION
ANALYSIS Statistical analyses were performed by using the Statistical Package for Social Sciences (SPSS). The chi-square test was used for bivariate comparisons. Multiple logistic regression analysis was used to assess the simultaneous influences of the different independent variables, including respiratory symptoms and diseases on the various symptoms caused by sleep disturbances. A P-value 50?05 was considered as statistically significant.
METHODS The questionnaire was developed from a revised version (24) of the British Medical Research Council’s questionnaire (25) after influences from the ATS (26) and the Tucson studies questionnaires (27), and has been frequently used in Nordic countries (14,28). The questionnaire (23) has previously been validated (29,30). Four items were chosen from the questionnaire regarding respiratory symptoms and diseases:
2.
3.
Snoring as a problem: ‘Do you snore so much that you think it is a problem?’ Worry of witnessed apnoeas: ‘Have relatives expressed worry about you stopping breathing while you are asleep?’ ‘Do you feel completely rested after a full night’s sleep?’ ‘Do you nod off during breaks in daytime activities?’
Subjects who gave a positive answer to question 4 and/or a negative answer to question 3 were regarded to have daytime sleepiness.
All 5682 subjects in the province aged 20–69 years, born on the 15th day of each month, were invited to complete a postal questionnaire survey. The questions included respiratory symptoms and diseases, smoking habits and profession. Of the 5682 subjects, 5424 also received questions about symptoms related to obstructive sleep apnoea. Two reminders were used. Eligible answers were obtained by 4648 subjects (85?7%; Table 1). The Ethics Committee of the University Hospital of Northern Sweden and the University of Umea˚ approved the study.
1.
Rhinitis: ‘Do you have or have you ever had allergic eye/nose catarrh (hay-fever)?’
Results PREVALENCE OF AIRWAY DISEASES AND SYMPTOMS Physician-diagnosed asthma was reported by 6?6% of men and by 7?6% of women. The prevalence of asthma was significantly most common in the 20–29-year-old respondents and lowest in the 40–59-year-olds in both men and women (Fig.1). The prevalence of recurrent wheeze was 12?1% in men and 11?5% in women, and increased significantly with age among men but not among women (Fig. 2). Chronic bronchitis increased significantly with age and was reported by 7?6% of men and 6?7% of women (Fig. 1). The prevalence of rhinitis was 18?5% in men and
Physician-diagnosed asthma: ‘Have you been diagnosed by a physician as having asthma?’ Recurrent wheeze: ‘Do you usually have wheezing, whistling, or a noisy sound in your chest when breathing?’ Chronic bronchitis: ‘Do you bring up phlegm when coughing on most days during periods of at least 3 months during at least 2 successive years?’
TABLE 1. Subjects invited and participated in the study by age and gender 20–29 years M
F
MþF
Invited 588 525 1113 Participated 478 462 940 Percent 81.3 88.0 84.5 M, male; F, female.
30–39 years M
F
MþF
645 567 1212 524 509 1033 81.2 89?8 85?2
40–49 years M
F
MþF
626 534 1160 541 497 1038 86?4 93?1 89?5
50–59 years M
F
MþF
485 467 952 421 426 847 86?8 91?2 89?0
460 years M
F
MþF
472 515 987 385 405 790 81?6 78?6 80?0
All M
F
MþF
2816 2608 5424 2349 2299 4648 83?4 88?2 85?7
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425
FIG. 1. Prevalence of chronic bronchitis (CB) and asthma in per cent in males and females, respectively.
FIG. 2. Prevalence of rhinitis and recurrent wheeze in per cent in males and females, respectively.
20?4% in women, and decreased with increasing age among both men and women (Fig. 2).
SMOKING The proportions of current smokers were 28?8% in men, and 32?4% in women. Of men, 24?1% were ex-smokers and 47?1% were non-smokers. In women, 15?9% were exsmokers and 51?6% were non-smokers (Fig. 3).
concomitant daytime symptoms was reported by 5?4%. The symptoms were significantly more common in men except daytime sleepiness, which was equally prevalent in men and women. Snoring as a problem and worry of witnessed apnoeas were more prevalent among the subjects having each of the respiratory symptoms and conditions used in the analyses, and among men in both ex- and current smokers (Table 2).
MULTI-VARIATE RELATIONSHIPS SYMPTOMS RELATED TO OBSTRUCTIVE SLEEP APNOEA Snoring as a problem was reported by 10?7%, relatives’ concern of witnessed apnoea during sleep by 6?8%, and daytime sleepiness by 28?3%. Snoring as a problem and
The influence on snoring as a problem, the combination of snoring and daytime sleepiness, and relatives’ worry of witnessed apnoeas during sleep, respectively, by age, gender, smoking habits, and different respiratory symptoms and diseases were analysed by using multiple logistic regression.
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FIG. 3. Smoking habits in percentage of in males and females, respectively. TABLE 2. The prevalence (%) of snoring as a problem, snoring as a problem with concomitant daytime sleepiness, and relatives’ worry of witnessed apnoeas in relation to smoking habits, age, and airway conditions in males (M) and females (F) respectively Snoring as a problem Variable Non-smokers Ex-smokers Current smokers P 20–29 30–39 40–49 50–59 60–69 P Chronic bronchitis Yes Chronic bronchitis No P Physician-diagnosed asthma Yes Physician-diagnosed asthma No P Wheezing Yes Wheezing No P Rhinitis Yes Rhinitis No P
years years years years years
M
F
10?4 16?5 20?1 50?001 4?6 11?5 20?1 23?5 14?0 50?001 31?5 13?3 50?001 21?9 14?1 0?008 28?1 12?8 50?001 20?0 13?4 50?001
6?2 6?4 7?5 0?552 1?7 5?7 7?6 9?6 9?1 50?001 18?8 5?8 50?001 14?4 6?0 50?001 14?0 5?7 50?001 9?8 5?9 0?002
Age, male gender, chronic bronchitis, physiciandiagnosed asthma, rhinitis and current smoking were significantly related to having snoring as a problem and also to the combination of snoring and daytime sleepiness (Table 3). When recurrent wheeze was included in the
Snoring and daytime sleepiness All
M
F
All
Relatives’ worry of apnoeas M
F
All
8?2 5?0 3?3 4?1 7?4 2?1 4?7 12?5 8?3 3?3 6?4 12?4 1?7 8?2 13?5 8?9 4?9 6?8 15?9 3?4 9?4 50?001 0?002 0?191 0?001 50?001 0?124 50?001 3?2 2?9 0?9 1?9 3?8 1?3 2?6 8?6 5?3 3?1 4?3 5?5 1?6 3?6 14?2 9?8 4?4 7?2 14?4 2?4 8?7 16?5 10?2 5?2 7?7 19?2 2?8 11?0 11?5 6?8 6?2 6?5 13?5 4?4 8?9 50?001 50?001 50?001 50?001 50?001 0?024 50?001 25?9 18?0 13?6 16?0 26?4 8?4 18?1 9?5 6?1 3?2 4?6 9?7 2?0 5?9 50?001 50?001 50?001 50?001 50?001 50?001 50?001 17?9 13?5 9?2 11?2 21?3 8?0 14?3 10?1 6?5 3?4 5?0 10?3 2?0 6?2 50?001 0?001 50?001 50?001 50?001 50?001 50?001 21?3 17?5 8?7 13?3 26?3 7?2 17?1 9?3 5?5 3?2 4?4 8?9 1?8 5?4 50?001 0?001 50?001 50?001 50?001 50?001 50?001 14?7 12?4 5?3 8?7 14?3 4?3 9?1 9?7 5?7 3?5 4?6 10?2 2?0 6?2 50?001 50?001 0?68 50?001 0?015 0?004 0?002
model, physician-diagnosed asthma became not significant. Instead of asthma, recurrent wheeze became significantly related with snoring and the combination of snoring as a problem and daytime sleepiness. Age, male gender, recurrent wheeze, chronic bronchitis, physician-diagnosed
OBSTRUCTIVE SLEEP APNOEA SYMPTOMS IN ASTHMA, CHRONIC BRONCHITIS AND RHINITIS PATIENTS
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TABLE 3. Risks (OR and 95% CI) for snoring as a problem, snoring with concomitant daytime sleepiness, relatives’ worry of witnessed apnoeas, and daytime sleepiness, respectively, by multiple logistic regression analysis. The independent variables were gender, age, smoking habits, and the respiratory conditions chronic bronchitis, asthma, and rhinitis. When calculating risks for daytime sleepiness, snoring and apnoeas were also included in the model Independent variables
Dependent variables Snoring
95% CI
OR
Gender
Women Men
1 2?57 (2?09–3?17)
1 1?96 (1?49–2?58)
1 5?48 (4?05–7?43)
1 0?97 (0?84–1?11)
Age class (years)
20–29 30–39 40–49 50–59 60–69
1 2?86 5?12 6?48 4?37
1 2?22 4?04 4?34 3?81
1 1?37 3?61 5?31 4?19
1 1?06 1?16 1?14 1?15
Smoking habits
Non-smoker Ex-smoker Smoker
1 1?13 (0?87–1?46) 1?55 (1?24–1?94)
1 1?18 (0?83–1?67) 1?52 (1?12–2?06)
1 1?17 (0?85–1?62) 1?98 (1?49–2?62)
1 1?09 (0?91–1?30) 1?17 (1?01–1?37)
Respiratory condition
Chronic bronchitis Asthma Rhinitis
2?40 (1?80– 3?20)
2?74 (1?93–3?89)
2?39 (1?70–3?35)
2?02 (1?59–2?57)
1?62 (1?16–2?27) 1?77 (1?40–2?24)
1?73 (1?14–2?61) 2?02 (1?49–2?73)
2?36 (1?60–3?48) 1?63 (1?21–2?20)
1?17 (0?91–1?52) 1?21 (1?02–1?44)
Snoring
–
–
–
1?85 (1?47–2?32)
Apnoeas
–
–
–
2?30 (1?73–3?04)
(1?26–3?90) (2?37–6?90) (2?51–7?51) (2?17–6?69)
asthma, rhinitis, and current smoking were all significantly associated with relatives’ concern about witnessed apnoea during sleep. Daytime sleepiness was significantly related to relatives’ concern about witnessed apnoea, chronic bronchitis, snoring as a problem and recurrent wheeze, while rhinitis, smoking, and physician-diagnosed asthma were not. However, when recurrent wheeze was excluded from the model, rhinitis and current smoking became significant.
Discussion Asthmatics had significantly higher prevalence of reported snoring as a problem and worry of witnessed apnoeas than non-asthmatics in our study, and also after adjusting for age, sex, and smoking habits, asthma was still significantly related with apnoeas, and snoring. Others have found similar relation between asthma and witnessed apnoeas and also that asthmatics have more daytime sleepiness (31,32). However, we could not verify that daytime sleepiness is more common in subjects with asthma. We have not found studies supporting that asthmatics suffer from obstructive sleep apnoea more often than respiratory healthy subjects do. There are, however, reports that patients with nocturnal
OR
95% CI
Daytime sleepiness
Category
(1?85–4?40) (3?38–7?75) (4?25–9?86) (2?82–6?77)
OR
Apnoeas
Variables
OSA symptoms
95% CI
Snoringþdaytime sleepiness
(0?80–2?33) (2?24–5?82) (3?28–8?60) (2?55–6?90)
OR
95% CI
(0?86–1?30) (0?94–1?44) (0?92–1?43) (0?92–1?44)
asthma and concomitant obstructive sleep apnoea have been improved regarding their nocturnal asthma on treatment with nasal continuing positive airway pressure (CPAP) (33). Bronchial hyper-reactivity (BHR) was present in four of 16 subjects with obstructive sleep apnoea in one study, and treatment with nasal CPAP decreased their hyper-reactivity to metacholine (34). Others have not found any correlation between BHR and symptoms related to upper airway obstruction (32). As found by others, rhinitis was significantly correlated with reported snoring as a problem and worry of witnessed apnoeas in our study (35), and rhinitis was also significantly related to reported daytime symptoms. Rhinitis has in some studies also been found to be related with obstructive sleepapnoea, but with lack of linearity between nasal obstruction and severity of sleep-disordered breathing (36). Subjects with bronchitic symptoms had a higher prevalence of both snoring as a problem and worry of witnessed apnoea in our study. Bronchitic symptoms tended to correlate even stronger with snoring as a problem when daytime symptoms, as not being rested after a full night’s sleep or liability to ‘nod off ’ during the day, were added to snoring. This may indicate that snoring in bronchitic subjects inflicts more on daily life, with excessive daytime symptoms related to deteriorated sleep. The high
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prevalence of snoring as a problem in subjects with bronchitic symptoms in our population sample is in accordance with the high prevalence we found in a bronchitic cohort (18,19). There are indications that bronchitic subjects often have signs of obstruction of the upper airways (17–19). It is possible that the inflammation in bronchitis not only affects the lower airways in bronchitic subjects, but also the upper airway. It is generally considered that snoring and sleep apnoea are not more prevalent in subjects with chronic obstructive pulmonary disease than in a general population (20,21). Supporting that, in a previous study, we have found that snoring in a bronchitic cohort was correlated with bronchitic symptoms and not with loss of lung function (19). It is known that chronic obstructive pulmonary disease is highly over-represented among subjects with bronchitic symptoms, and there is some evidence that bronchitic symptoms may precede or at least occur simultaneously with the progressive loss of lung function seen in COPD (37). This, together with the indications that the combination of COPD and obstructive sleep apnoea may result in a more severe disease (7–9), makes it important to investigate obstructive sleep apnoea when a patient with COPD, or a patient with chronic bronchitis, presents symptoms giving suspicion of OSA. It is interesting that current smoking was significantly related with both snoring and witnessed apnoeas in men also after correction for obstructive airway conditions. Most reports have found a relation between snoring and smoking, and one hypothesis is that smoking acts via chronic bronchitis. In our study both smoking and chronic bronchitis were independently associated with snoring. It is possible that smoking causes inflammation of the upper airways. Another possible mechanism is decreased nicotine concentration during night-time and less positive muscular tone in the upper airways (38,39). It is hardly surprising that both respiratory symptoms and diseases, and symptoms related to obstructive sleep apnoea, cause daytime symptoms such as not being rested after a full night’s sleep or to have liability to ‘nodding off ’ in the daytime, since these disorders all may disturb sleep. It is more surprising that subjects with asthma did not express more daytime sleepiness symptoms, though they reported more snoring and apnoeas. Furthermore, other studies have found that asthmatics have a high degree of disrupted sleep due to night asthma (17,31,32,35,40). We expected that these factors together (snoring, apnoeas and night asthma) would give asthmatics more symptoms of daytime sleepiness, and we can not explain why our results could not confirm this. It is possible that these asthmatics were well controlled and had less night asthma. In conclusion, respiratory symptoms and conditions affecting mainly the lower respiratory tract, such as chronic bronchitis and asthma, as well as current smoking and history of rhinitis, were related with symptoms common in obstructive sleep apnoea such as having snoring as a problem and relatives being worried about witnessed apnoeas.
Acknowledgements The study was supported by grants from the Swedish Heart and Lung Foundation, the Swedish Association for Heart and Lung Patients, and Norrbottens Local Health Authority.
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