Copyright #ERS Journals Ltd 2004
European Respiratory Journal
ISSN 0903-1936
Eur Respir J 2004; 24: 116–121
DOI: 10.1183/09031936.04.00042603
Printed in UK – all rights reserved
Obesity and nocturnal gastro-oesophageal reflux are related to onset
of asthma and respiratory symptoms
M.I. Gunnbjörnsdóttir*, E. Omenaas#, T. Gı́slason}, E. Norrmanz, A-C. Olin§, R. Jõgiƒ, E.J. Jensen**,
E. Lindberg*, E. Björnsson}, K. Franklinz, C. Janson*, on behalf of the RHINE study group
The RHINE study group: E.J. Jensen, A. Gulsvik, B. Laerum, E. Omenaas, C. Svanes, A-C. Olin, K. Torén, A. Tunsäter, L. Lillienberg,
E. Björnsson, T. Gı́slason, D. Gı́slason, T. Blöndal, U.S. Björnsdottir, K.B. Jörundsdóttir, R. Jõgi, J. Talvik, B. Forsberg, K. Franklin,
B. Lundbäck, E. Norrman, M. Söderberg, M-C. Ledin, G. Boman, C. Janson, E. Lindberg, D. Norbäck, G. Wieslander, U. Spetz-Nyström,
K. Stenudd Cashelunge, E. Rydén, M.I. Gunnbjörnsdóttir
Obesity and nocturnal gastro-oesophageal reflux are related to onset of asthma and
respiratory symptoms. M.I. Gunnbjörnsdóttir, E. Omenaas, T.Gı́slason, E. Norrman,
A-C. Olin, R. Jõgi, E.J. Jensen, E. Lindberg, E. Björnsson, K. Franklin, C. Janson, on
behalf of the RHINE study group. #ERS Journals Ltd 2004.
ABSTRACT: Several studies have identified obesity as a risk factor for asthma in both
children and adults. An increased prevalence of asthma in subjects with gastrooesophageal reflux (GOR) and obstructive sleep apnoea syndrome has also been reported.
The aim of this investigation was to study obesity, nocturnal GOR and snoring as
independent risk factors for onset of asthma and respiratory symptoms in a Nordic
population.
In a 5–10 yr follow-up study of the European Community Respiratory Health Survey
in Iceland, Norway, Denmark, Sweden and Estonia, a postal questionnaire was sent to
previous respondents.
A total of 16,191 participants responded to the questionnaire. Reported onset of
asthma, wheeze and night-time symptoms as well as nocturnal GOR and habitual
snoring increased in prevalence along with the increase in body mass index (BMI). After
adjusting for nocturnal GOR, habitual snoring and other confounders, obesity (BMI
w30) remained significantly related to the onset of asthma, wheeze and night-time
symptoms. Nocturnal GOR was independently related to the onset of asthma and in
addition, both nocturnal GOR and habitual snoring were independently related to onset
of wheeze and night-time symptoms.
This study adds evidence to an independent relationship between obesity, nocturnal
gastro-oesophageal reflux and habitual snoring and the onset of asthma and respiratory
symptoms in adults.
Eur Respir J 2004; 24: 116–121.
*Dept of Medical Sciences: Respiratory Medicine and Allergology, Uppsala University,
z
Uppsala, Dept of Pulmonary Medicine and
Allergology, University Hospital of Northern
Sweden, Umeå, §Section of Occupational and
Environmental Medicine and Section of Allergology, Sahlgrenska University Hospital,
Gothenburg, Sweden, #Dept of Thoracic
Medicine and Centre for Clinical Research,
Haukeland University Hospital, Bergen,
Norway. }Dept of Allergy and Respiratory
Medicine, Landspitali University Hospital,
Reykjavik, Iceland. ƒFoundation Tartu University Clinics, Lung Clinic, Tartu, Estonia.
**
Dept of Respiratory Diseases, University
Hospital of Aarhus, Aarhus, Denmark.
Correspondence: M.I. Gunnbjörnsdóttir, Dept
of Medical Sciences: Respiratory Medicine and
Allergology, Akademiska Sjukhuset, SE 751 85
Uppsala, Sweden.
Fax: 46 186110228
E-mail: maria.gunnbjornsdottir@medsci.uu.se
Keywords: Asthma, epidemiology, gastrooesophageal reflux, habitual snoring, obesity,
respiratory symptoms
Received: April 15 2003
Accepted after revision: January 23 2004
The study was supported financially by the
Icelandic Research Council, the Swedish Heart
and Lung Foundation, the Vårdal Foundation
for Health Care Science and Allergy Research,
the Swedish Association against Asthma and
Allergy, the Norwegian Research Council, the
Norwegian Asthma and Allergy Association,
the Danish Lung Association and the Estonian
Science Foundation.
The prevalence of both asthma and obesity is increasing
worldwide [1–3]. Several studies have found that obesity is a
risk factor for asthma in both children and adults [4–7]. An
increased prevalence of asthma in subjects with gastrooesophageal reflux (GOR) [8, 9] and obstructive sleep
apnoea syndrome (OSAS) [10] has also been reported. As
both GOR and OSAS are related to obesity, it is possible that
this may explain the association between obesity and asthma.
However, intervention studies do indicate that obesity, GOR
and OSAS are independent risk factors of asthma. Weight
reduction in obese asthmatics was found to reduce airway
obstruction, as well as peak expiratory flow (PEF) variability
[11]. Conversely, medical and surgical anti-reflux treatment
reduces asthma symptoms and asthma medication requirement, even though there is little or no effect on lung function
[12, 13]. Furthermore, patients with both OSAS and coexisting asthma showed significant improvement in asthma
symptoms and recorded daily PEF rates when treated for
sleep apnoea with nasal continuous positive airway pressure
[14].
The aim of this study was to evaluate obesity, nocturnal
GOR and habitual snoring as independent risk factors for the
onset of asthma and respiratory symptoms in Northern
European adults. If obesity was associated with increased risk
OBESITY AND NOCTURNAL GASTRO-OESOPHAGEAL REFLUX
of asthma onset, the study would be taken one step further; to
assess whether this could be explained by reported nocturnal
GOR and/or habitual snoring.
Methods
The study design and target population
Respiratory Health in Northern Europe (RHINE) is a
follow-up study of participants in the European Community
Respiratory Health Survey (ECRHS) stage I, which took
place in 1990–1994 [15].
In stage I of the ECRHS, males and females aged 20–44 yrs
were randomly selected from the population register in each
participating centre. A postal questionnaire was sent to
3,000–4,000 subjects at each centre. Participating centres in
Northern Europe were located in the following cities:
Reykjavik (Iceland); Bergen (Norway); Aarhus (Denmark);
Gothenburg, Uppsala, Umeå (Sweden); and Tartu (Estonia).
The average response rate for the ECRHS stage I in the
Nordic centres was 83.7%.
The RHINE study was conducted in 1999–2001 in the same
seven Nordic centres. A postal questionnaire was sent to
eligible subjects (n=21,802). Subjects not responding to the
first mailing received two reminders. A total of 16,191 (74.3%)
subjects answered the questionnaire.
Responses from the RHINE study were used in the
calculations when analysing risk factors. The responses
from stage I of the ECRHS were also taken into account
when defining the onset of asthma and respiratory symptoms.
Case definition
An asthma case was defined by answering "yes" to one or
both of the questions: "Have you had an attack of asthma in
the last 12 months?" and/or "Are you currently taking any
medicine (including inhalers, aerosols or tablets) for
asthma?". Onset of asthma was defined as answering "no"
to both questions in 1990–1994 but "yes" to one or both
questions in 1999–2001.
Wheeze was defined as answering "yes" to the question:
"Have you had wheezing or whistling in your chest at any
time in the last 12 months?" Onset of wheeze was defined as
answering "no" to this question in 1990–1994 and answering
"yes" to the question in 1999–2001.
Night-time symptoms were defined as answering "yes" to
one or both of the questions: "Have you been woken by an
attack of shortness of breath at any time in the last 12
months?" and/or "Have you woken up with a feeling of
tightness in your chest at any time in the last 12 months?".
Onset of night-time symptoms were defined as answering "no"
to both questions in 1990–1994 but answering "yes" to either
or both questions in 1999–2001.
In the present study, the "onset of respiratory symptoms" is
used as a synonym for onset of wheeze and night-time
symptoms.
Body mass index
Body mass index (BMI) was calculated for each subject as
weight in kilograms divided by the squared height in meters
(kg?m-2). Four groups were defined with BMI 20–v25 used as
reference. Subjects with BMI v20, 25–v30 and o30 are
referred to, respectively, as being underweight, overweight
and obese.
117
Gastro-oesophageal reflux and snoring
The questionnaire contained seven multiple-choice questions in which the subjects were asked to estimate the
frequency of various sleep-related symptoms on the following
5-point scale: never; less than once a week; 1–2 nights a week;
3–5 nights a week; and almost every night.
The question asked regarding GOR was: "Do you have
heartburn or belching when you have gone to bed?". Subjects
reporting these symptoms o1–2 nights per week are, in this
study, referred to as reporting nocturnal GOR [16]. The
question asked regarding snoring was: "Do you snore loudly
and disturbingly?" Subjects reporting snoring o3–5 times per
week are referred to as reporting habitual snoring.
Smoking and rhinitis
The questions asked were: "Are you a smoker?" and "Are
you an ex-smoker?" Subjects were divided into three groups:
smokers, exsmokers and never-smokers, based on selfreported smoking status 1999–2001. Participants answering
"yes" to the question: "Do you have any nasal allergies
including hay fever?" in 1999–2001 are referred to as having
rhinitis.
Statistical analysis
The Chi-squared test and test for trend were used to
calculate associations between two nominal variables (univariate analysis). ANOVA with test for equality of variance
was used when comparing continuous data with nominal.
Multiple logistic regression analyses were performed to
analyse the influence of several risk factors, and the results
are presented as adjusted odds ratios (OR) with a 95% CI. In
order to detect heterogeneity between centres, the adjusted
ORs were calculated separately for each centre. Average effect
estimates were derived and potential heterogeneity between
centres was examined using standard methods for randomeffects meta-analysis. A p-value of v0.05 was regarded as
statistically significant.
Results
A total of 16,191 subjects participated in the study (a
response rate of 74.3%) and 8,587 (53.0%) of the participants
were female. The mean¡SD age of the participants was
39.6¡7.1 yrs. The mean follow-up time was 7.9 yrs. The
mean¡SD BMI was 24.8¡4.0 kg?m-2. The characteristics of
the study population are given in table 1.
Compared to the responders in the follow-up, the
nonresponders were younger (30.8¡7.1 versus 31.9¡7.1 yrs,
pv0.0001), reported wheeze more often (24.1% versus 21.5%,
pv0.0001), had more night-time symptoms in 1990–1994
(16.1% versus 13.9%, p=0.001) and were more often male
(53.4% versus 46.6%, p=0.001). No significant difference was
found between responders and nonresponders, however,
when looking at the prevalence of asthma in 1990–1994
(4.3% versus 4.7%, p=0.20).
The study population, stratified according to BMI groups,
is presented in table 2. Half of the population had a BMI
between 20–v25 kg?m-2. Obesity and being overweight
was more common in males, as 51.7% of males had a BMI
w25 kg?m-2 compared to 27.1% of females (pv0.0001).
Subjects in the lowest BMI group were significantly younger
(pv0.0001). The prevalence of nocturnal GOR increased
118
M.I. GUNNBJÖRNSDÓTTIR ET AL.
Table 1. – Characteristics of the study population
Centres
Subjects n
Participation rate
Mean follow-up time yrs
Age yrs
BMI kg?m-2
BMI o30
Nocturnal GOR w1?week-1
Snoring w3?week-1
Onset of asthma
Onset of wheeze
Onset of night-time symptoms
Reykjavik
Bergen
Aarhus#
Gothenburg
Uppsala
Umeå
Tartu
All
1969
67.9
8.5
40.9¡7.0
25.3¡4.0
11.6
5.2
20.7
4.4
9.1
7.4
2506
72.6
9.4
40.5¡6.8
24.7¡4.0
7.9
7.7
16.9
3.8
13.1
9.5
2608
71.0
7.7
39.1¡7.0
24.3¡4.2
8.1
6.7
17.7
4.0
11.3
2188
76.0
8.2
40.4¡7.3
25.0¡3.9
9.6
11.2
20.4
4.3
12.5
8.0
2572
81.8
8.2
40.4¡7.3
24.6¡3.9
6.8
7.4
18.6
4.2
11.1
8.2
2640
80.2
8.2
40.6¡7.3
25.2¡4.3
8.9
8.2
20.7
4.9
12.0
8.9
1708
69.4
5.3
35.6¡7.0
24.2¡4.2
9.1
7.4
12.0
1.3
14.4
13.8
16191
74.3
7.9
39.6¡7.1
24.8¡4.0
8.7
7.7
18.1
3.9
11.3
9.3
Data are presented as mean¡SD or per cent, unless otherwise stated. BMI: body mass index; GOR: gastro-oesophageal reflux. #: incomplete data.
Table 2. – Characteristics of participants in relation to body mass index (BMI)
Subjects n
Females
Age yrs
Nocturnal GOR w1?week-1
Snoring w3?week-1
Onset of asthma
Onset of wheeze
Onset of night-time symptoms
BMI v20
BMI o20–v25
BMI o25–v30
BMI o30
All
p-value
1222
83.8
37¡7.1
4.4
6.7
3.6
10.2
8.2
8158
57.9
39¡7.2
5.1
11.9
3.4
10.1
8.5
5201
38.1
40¡7.2
10.2
25.7
4.2
12.7
8.9
1393
51.3
41¡6.9
15.8
38.6
5.9
21.7
14.1
15974
52.8
39¡7.1
8.9
20.7
3.9
11.8
9.1
v0.0001
v0.0001
v0.0001
v0.0001
0.0003
v0.0001
v0.0001
Data are presented as mean¡SD or per cent, unless otherwise stated. GOR: gastro-oesophageal reflux.
with higher BMI, and the same pattern could be seen with
habitual snoring. Reported onset of asthma, wheeze and
night-time symptoms increased in prevalence along with the
BMI gradient, with the highest values in subjects with a BMI
w30 kg?m-2.
As presented in figure 1, the prevalence of asthma onset
gradually increased with increasing BMI in both males (p for
trend=0.02) and females (p for trend=0.03). Similarly, subjects
reporting nocturnal GOR (fig. 2) and habitual snoring (fig. 3)
exhibited a higher prevalence of asthma and respiratory
symptom onset.
The results of the multivariate logistic regression analyses
are presented in table 3. All values were adjusted for age,
centre, smoking, rhinitis and other variables in the table.
Obesity and nocturnal GOR were independent risk factors for
the onset of asthma, wheeze and night-time symptoms.
Habitual snoring was, however, found to be an independent
risk factor for the onset of wheeze and night-time symptoms,
but not for the onset of asthma. The OR for the onset of
asthma and respiratory symptoms in obese subjects (BMI
w30 kg?m-2) changed only slightly after adjustments for
nocturnal GOR and/or snoring (table 4). In the same
manner, the OR for nocturnal GOR and habitual snoring
was only slightly affected when adjusting for obesity.
The sex of the individual did not affect the associations
between the onset of asthma, respiratory symptoms, BMI,
7
25
6
#
20
5
#
Prevalence %
Prevalence %
#
¶
4
3
2
15
10
#
5
1
0
0
Males
Females
Fig. 1. – The prevalence of asthma onset in relationship to body mass
index (BMI) in males and females. h: BMI v20; u: BMI w25–v30;
q: BMI w25–v30; &: BMI w30. #: pv0.02; }: pv0.03.
Onset of asthma
Onset of wheeze
Onset of nighttime symptoms
Fig. 2. – The prevalence of asthma and respiratory symptom onset in
subjects with (p) and without (h) nocturnal gastro-oesophageal
reflux. #: pv0.0001.
119
OBESITY AND NOCTURNAL GASTRO-OESOPHAGEAL REFLUX
20
#
Prevalence %
15
#
10
5
0
¶
Onset of asthma
Onset of wheeze
Onset of nighttime symptoms
Fig. 3. – The prevalence of asthma and respiratory-symptom onset
in subjects with (p) and without (h) habitual snoring. #: pv0.0001;
}
: NS.
nocturnal GOR or habitual snoring. Neither were there any
significant interactions between BMI groups, nocturnal GOR
and habitual snoring in the association of these variables with
onset of asthma or respiratory symptoms.
The association between onset of asthma and respiratory
symptoms and obesity, nocturnal GOR and snoring in the
different centres was also assessed by meta-analysis. The
estimates were very similar to those derived when analysing
the pooled data, and no significant centre heterogeneity was
detected for any of the risk factors (obesity, nocturnal GOR
and habitual snoring) in relation to the onset of asthma or
respiratory symptoms.
Discussion
The central findings in this study were that subjects
reporting onset of asthma and respiratory symptoms
had higher prevalence of obesity, nocturnal GOR and
habitual snoring than subjects not reporting onset of
asthma or respiratory symptoms. After adjustments for
possible confounders, obesity and nocturnal GOR were
found to be independent risk factors for the onset of
asthma and respiratory symptoms. Habitual snoring was
found to be an independent risk factor for the onset of
respiratory symptoms but not for asthma. These risk factors
affected males and females in the same way.
Many studies have reported an association between asthma
and obesity in children [17–21]. An association between
increasing BMI and adult-onset asthma in females was found
in the Nurses9 Health Study II, and the same study also found
that weight gain after 18 yrs was also strongly associated with
incident asthma [6]. Two research groups have recently
reported associations between weight gain, obesity and
asthma diagnosis in females, but not in males [5, 22]. The
Italian National Health Survey did, however, find an
increased risk for asthma in males with BMI v20 and BMI
w30, but in females the association was more linear [23].
YOUNG et al. [24] found a linear relationship between BMI
and the risk of having asthma in both sexes. The current study
found an association between an increasing BMI and onset of
asthma in both males and females. This is an important
finding which can probably be explained by the large study
sample, which offers sufficient incident cases to demonstrate
such a relationship in both sexes.
Two publications have reported an association between
obesity, asthma and respiratory symptoms. The former found
that even though moderate (BMI 30–34.9) and severe obesity
(BMIw35) was a risk factor for asthma and wheeze in the last
12 months; the level of atopy, airway hyperresponsiveness
and airway obstruction was not higher in those two groups
[25]. The latter found obesity to be a risk factor for selfreported asthma, bronchodilator use and dyspnoea with
exertion, but obese participants had the lowest risk for
significant airflow obstruction [26]. These data suggest that
obstructive airway disease in obese subjects might be
overdiagnosed. As the current study is questionnaire-based
with no objective measurement, such as spirometry and/or
methacholine test, it can be assumed that the same applies for
the study population, and may possibly bias the results. The
Table 3. – Odds ratios (OR) for asthma and respiratory symptom onset
Females
BMI groups
v20
o20–v25
o25–v30
o30
Nocturnal GOR w1?week-1
Snoring w3?week-1
Onset of asthma
Onset of wheeze
Onset of night-time symptoms
1.28 (1.06–1.55)
1.10 (1.00–1.21)
1.19 (1.06–1.34)
1.01 (0.69–1.45)
1
1.14 (0.93–1.41)
1.67 (1.24–2.25)
1.82 (1.38–2.40)
1.12 (0.89–1.42)
0.96 (0.79–1.15)
1
1.24 (1.11–1.40)
2.23 (1.91–2.60)
2.04 (1.75–2.38)
1.53 (1.36–1.72)
1.03 (0.82–1.28)
1
1.08 (0.95–1.23)
1.56 (1.30–1.88)
3.05 (2.60–3.58)
1.60 (1.37–1.82)
Data are presented as OR (95% CI) and are adjusted for age, centre, smoking, rhinitis, sex, body mass index (BMI), nocturnal gastro-oesophageal
reflux (GOR) and snoring.
Table 4. – Odds ratios (OR) for asthma and respiratory symptom onset in subjects with body mass index (BMI) w30
Nocturnal GOR w1?week-1
Snoring w3?week-1
Nocturnal GOR and snoring
Neither
Onset of asthma
Onset of wheeze
1.78
1.80
1.67
1.96
2.47
2.43
2.27
2.66
(1.33–2.37)
(1.34–2.42)
(1.24–2.26)
(1.46–2.56)
(2.04–2.98)
(2.01–2.95)
(1.87–2.76)
(2.21–3.20)
Onset of night-time symptoms
1.69
1.67
1.53
1.89
(1.36–2.10)
(1.34–2.09)
(1.22–1.91)
(1.52–2.33)
Data are presented as OR (95% CI) and are adjusted for age, centre, smoking, rhinitis, sex, BMI, and for nocturnal gastro-oesophageal reflux (GOR)
and snoring separately, together or not at all.
120
M.I. GUNNBJÖRNSDÓTTIR ET AL.
prevalence of atopy in the present study population is also
unknown, but adjustment for rhinitis was carried out.
The association between obesity and onset of asthma was
relatively unaffected by adjustment for nocturnal GOR and
habitual snoring. This in turn indicates that the association is
probably not solely explained by the higher prevalence of
GOR and obstructive sleep apnoea in obese subjects. Other
explanatory mechanisms have been suggested, such as various
environmental factors like birth weight, diet and physical
activity. Obesity may also affect asthma by enhancing the
immune response, by genetic mechanisms or by hormones
[27].
Nocturnal GOR was an independent risk factor for onset
of asthma and respiratory symptoms in the current study. An
association between GOR and asthma has been identified in
children and adults, but a cause–effect relationship between
the two diseases has not been established [28]. It is also known
that the prevalence of GOR is higher among asthma patients
than it is among individuals without asthma, and that antireflux treatment can reduce asthma symptoms [29]. One study
found gastric ulcer and obesity as independent risk factors for
asthma [24]. As no obvious associations are known to exist
between asthma and gastric ulcer, the authors of the paper
speculated that perhaps some of those responding positively
to questions on gastric ulcer also suffered from GOR. Several
explanatory mechanisms as to the association between asthma
and GOR have been suggested, such as vagally-mediated
bronchoconstriction, heightened bronchial reactivity and
microaspiration [30].
Habitual snoring is a common condition with a prevalence
of 16–48% among males and 8–27% among females [31–34],
and is one of the main symptom of OSAS. Obesity and GOR
are common in subjects with OSAS [35, 36] and bronchial
hyperresponsiveness can be found in nonasthmatics with this
syndrome [37]. Habitual snoring was independently associated with onset of respiratory symptoms in the current
study, even after adjusting for obesity and nocturnal GOR.
This suggests a relationship between obstruction in the upper
and lower airways, but the mechanisms for these associations
remain unclear.
There are several methodological issues that must be
addressed regarding this study. It is not possible to determine
if obesity increases the risk for onset of asthma or if subjects
become obese after their asthma becomes active, because of
the cross-sectional nature of the study. The direction of the
cause–effect relationship between the two variables or
whether there is a true cause–effect relationship cannot be
determined. This applies to all other respiratory symptoms
and associations found in the study. Another study indicates
that asthma itself may increase the risk of experiencing GOR
[38]. The cause–effect relationship between reflux and asthma
thus remains unclear.
The study is questionnaire based with no objective
measurement. This makes it impossible to determine if
subjects reporting onset of asthma actually are asthmatics.
The questions used in the current study have nevertheless
been evaluated in other surroundings and have been found to
have high specificity for asthma [39].
It is also possible that an unmeasured variable may have
confounded the results. It was nevertheless possible to control
for the most important covariants, such as age, centre,
smoking and rhinitis. The study is multi-centred and in five
different languages, which introduces a possible translation
bias. A high internal consistency in the ECRHS questionnaire
has however been found, which suggests that international
comparisons are not affected by errors due to cross-cultural
variations in reporting of symptoms [40]. BMI was calculated
from self-reported weight and height, which can possibly
induce error. Self-reported height and weight can however be
used in epidemiological studies where the subjects are
f60 yrs old [41]. As the subjects participating in this study
are 24–53 yrs, it is proposed that this method of calculating
BMI does not cause any significant error in the study results.
The average respond rate was 74.3%, but only 60% of the
original population responded to both questionnaires, which
could, in turn, induce bias. In the first survey, nonresponders
were younger males with higher prevalence of wheeze and
night-time symptoms than responders. This difference might
bias the results, but no significant difference was found in the
prevalence of asthma between responders and nonresponders.
The strength of this study lies in the large sample size,
which gives sufficient power to control for many potential
cofounders simultaneously. The study is population based,
which suggests that findings can be applied to other similar
populations. The validity of the results is to some extent
strengthened by the fact that there were no significant
differences in the factors associated with asthma or respiratory symptoms, when the results from each study centre were
compared.
In conclusion, an independent relationship between onset
of asthma and respiratory symptoms with obesity and
nocturnal gastro-oesophageal reflux in both males and
females was found. Habitual snoring was an additional risk
factor for onset of respiratory symptoms, but not for onset of
asthma. This indicates that the previously described association between obesity and asthma is not only related to a
higher prevalence of gastro-oesophageal reflux and snoring in
obese subjects, and must be explained by other mechanisms.
References
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Woolcock AJ, Peat JK. Evidence for the increase in asthma
worldwide. Ciba Found Symp 1997; 206: 122–134.
Kuczmarski RJ, Flegal KM, Campbell SM, Johnson CL.
Increasing prevalence of overweight among US adults. The
national health and nutrition examination surveys, 1960 to
1991. JAMA 1994; 272: 205–211.
WHO. Obesity: preventing and managing the global
epidemic. Report of a WHO Consultation on Obesity.
Geneva, WHO, 1997.
Beckett W, Belanger K, Gent JF, Holford TR, Leaderer BP.
Asthma among Puerto Ricane Hispanics: a multi ethnic
comparison of risk factors. Am J Respir Crit Care Med 1996;
156: 894–899.
Beckett WS, Jacobs DR Jr, Yu X, Iribarren C, Williams OD.
Asthma is associated with weight gain in females but not
males, independent of physical activity. Am J Respir Crit
Care Med 2001; 164: 2045–2050.
Camargo CA Jr, Weiss ST, Zhang S, Willett WC, Speizer
FE. Prospective study of body mass index, weight change,
and risk of adult- onset asthma in women. Arch Intern Med
1999; 159: 2582–2588.
Shaheen SO, Sterne JA, Montgomery SM, Azima H. Birth
weight, body mass index and asthma in young adults. Thorax
1999; 54: 396–402.
Sontag SJ. Gastroesophageal reflux and asthma. Am J Med
1997; 103: 84S–90S.
Harding SM, Sontag SJ. Asthma and gastroesophageal
reflux. Am J Gastroenterol 2000; 95: Suppl. 8, S23–S32.
Gislason T, Janson C, Vermeire P, et al. Respiratory symptoms and nocturnal gastroesophageal reflux: a populationbased study of young adults in three European countries.
Chest 2002; 121: 158–163.
Hakala K, Stenius-Aarniala B, Sovijarvi A. Effects of weight
loss on peak flow variability, airways obstruction, and lung
volumes in obese patients with asthma. Chest 2000; 118:
1315–1321.
Field SK, Sutherland LR. Does medical antireflux therapy
OBESITY AND NOCTURNAL GASTRO-OESOPHAGEAL REFLUX
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
improve asthma in asthmatics with gastroesophageal reflux?:
a critical review of the literature. Chest 1998; 114: 275–283.
Field SK, Gelfand GA, McFadden SD. The effects of
antireflux surgery on asthmatics with gastroesophageal
reflux. Chest 1999; 116: 766–774.
Chan CS, Woolcock AJ, Sullivan CE. Nocturnal asthma:
role of snoring and obstructive sleep apnea. Am Rev Respir
Dis 1988; 137: 1502–1504.
Burney PG, Luczynska C, Chinn S. The European Community Respiratory Health Survey. Eur Respir J 1994; 7: 954–
960.
Janson C, Gislason T, De Backer W. Daytime sleepiness,
snoring and gastroesophageal reflux amongst young adults
in three European countries. J Int Med 1995; 237: 277–285.
Sommerville SM, Rona RJ, Chinn S. Obesity and respiratory
symptoms in primary school. Arch Dis Child 1984; 59: 940–
944.
Schwartz J, Gold D, Dockery D, Weiss ST, Speizer FE.
Predictors of asthma and persistent wheeze in a national
sample of children in the United States. Am Rev Respir Dis
1990; 142: 894–899.
Figueroa-Munoz JI, Chinn S, Rona RJ. Association between
obesity and asthma in 4-11 year old children in the UK.
Thorax 2001; 56: 133–137.
von Mutius E, Schwartz J, Neas LM, Dockery D, Weiss ST.
Relation of body mass index to asthma and atopy in
children: the National Health and Nutrition Examination
Study III. Thorax 2001; 56: 835–838.
von Kries R, Hermann M, Grunert VP, von Mutius E. Is
obesity a risk factor for childhood asthma? Allergy 2001; 56:
318–322.
Chen Y, Dales R, Tang M, Krewski D. Obesity may increase
the incidence of asthma in women but not in men:
longitudinal observations from the Canadian National
Population Health Surveys. Am J Epidemiol 2002; 155:
191–197.
Negri E, Pagano R, Decarli A, La Vecchia C. Body weight
and the prevalence of chronic diseases. J Epidemiol Community Health 1988; 42: 24–29.
Young SY, Gunzenhauser JD, Malone KE, McTiernan A.
Body mass index and asthma in the military population of
the northwestern United States. Arch Intern Med 2001; 161:
1605–1611.
Schachter LM, Salome CM, Peat JK, Woolcock AJ. Obesity
is a risk for asthma and wheeze but not airway hyperresponsiveness. Thorax 2001; 56: 4–8.
Sin DD, Jones RL, Man SF. Obesity is a risk factor for
dyspnea but not for airflow obstruction. Arch Intern Med
2002; 162: 1477–1481.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
121
Tantisira K.G., Weiss S.T. Complex interactions in complex
traits: obesity and asthma. Thorax 2001; 56: Suppl. II, ii64–
ii74.
Sontag SJ. Why do the published data fail to clarify the
relationship between gastroesophageal reflux and asthma?
Am J Med 2000; 108: Suppl. 4a, 159S–169S.
Richter JE. Gastroesophageal reflux disease and asthma: the
two are directly related. Am J Med 2000; 108: Suppl. 4a,
153S–158S.
Harding SM. Gastroesophageal reflux and asthma: insight
into the association. J Allergy Clin Immunol 1999; 104: 251–
259.
Gislason T, Almqvist M, Eriksson G, Taube A, Boman G.
Prevalence of sleep apnea syndrome among Swedish men –
an epidemiological study. J Clin Epidemiol 1988; 41: 571–576.
Lindberg E, Taube A, Janson C, Gislason T, Svardsudd K,
Boman GA. 10-year follow-up of snoring in men. Chest
1998; 114: 1048–1055.
Enright PL, Newman AB, Wahl PW, Manolio TA, Haponik
EF, Boyle PJ. Prevalence and correlates of snoring and
observed apneas in 5,201 older adults. Sleep 1996; 19: 531–
538.
Jennum P, Sjol A. Epidemiology of snoring and obstructive
sleep apnoea in a Danish population, age 30-60. J Sleep Res
1992; 1: 240–244.
Kerr P, Shoenut JP, Millar T, Buckle P, Kryger MH. Nasal
CPAP reduces gastroesophageal reflux in obstructive sleep
apnea syndrome. Chest 1992; 101: 1539–1544.
Samuelson CF. Gastroesophageal reflux and obstructive
sleep apnea. Sleep 1989; 5: 475–476.
Lin CC, Lin CY. Obstructive sleep apnea syndrome and
bronchial hyperreactivity. Lung 1995; 173: 117–126.
Zerbib F, Guisset O, Lamouliatte H, Quinton A,
Galmiche JP. Effects of bronchial obstruction on lower
esophageal sphincter motility and gastroesopageal reflux in
patients with asthma. Am J Respir Crit Care Med 2002; 166:
1206–1211.
de Marco R, Cerveri I, Bugiani M, Ferrari M, Verlato G. An
undetected burden of asthma in Italy: the relationship
between clinical and epidemiological diagnosis of asthma.
Eur Respir J 1998; 11: 599–605.
Sunyer J, Basagana X, Burney P, Anto JM. International
assessment of the internal consistency of respiratory symptoms. Am J Respir Crit Care Med 2000; 162: 930–935.
Kuczmarski MF, Kuczmarski RJ, Najjar M. Effects of age
on validity of self-reported height, weight, and body mass
index: findings from the Third National Health and
Nutrition Examination Survey, 1988-1994. J Am Diet
Assoc 2001; 101: 28–34.