Chronic obstructive pulmonary disease (COPD) is characterized by
airflow obstruction that is not fully reversible. Spirometry is the gold
standard for diagnosing and monitoring progression of COPD which is
defined by irreversible lung function impairment with a reduced
FEV1/vital capacity (VC) ratio less than 70% of the predicted. The
Global Initiative for chronic obstructive lung disease (GOLD) criteria
classify COPD into four stages based primarily on lung function
impairments as stage I (FEV1>=80%), II (FEV1 50-79%), III (FEV1 30-50%)
and IV (FEV1<30% of the predicted) .
In COPD patients, unrelated disorders are relatively under recognized
. Those patients have much comorbiditiy like: cardiovascular
diseases, osteoporosis, diabetes, and metabolic syndrome, more commonly
than expected by chance. These associations are greater than expected
from common aetiological factors, such as smoking, suggesting that these
comorbidities may be causally associated with the mechanisms of COPD,
probably due to systemic inflammation [3, 4].
Metabolic syndrome is a set of risk factors that includes: abdominal
obesity, a decreased ability to process glucose (increased blood glucose
and/or insulin resistance), atherogenic dyslipidemia (elevated
triglycerides levels, small low-density lipoprotein [LDL] particles, low
high-density lipoprotein cholesterol [HDL-C] levels, raised blood
pressure and prothrombotic and inflammatory states . Patients who
have this syndrome have been shown to be at an increased risk of
developing cardiovascular disease and/or diabetes type 2. Recently, the
National Cholesterol Education Program (NCEP) Expert Panel on Detection,
Evaluation, and Treatment of High Blood Cholesterol in Adults (Adults
Treatment Panel III) (ATP III) have highlighted the importance of the
metabolic syndrome and provided guidelines for the screening of this
syndrome. The ATP III guidelines define the metabolic syndrome as a new
secondary target for cardiovascular risk reduction therapy beyond
low-density lipoprotein cholesterol (LDL-C) lowering. According to the
ATP III report, the diagnosis of the metabolic syn-drome requires 3 or
more of the following criteria: waist circumference exceeding 102 cm and
88 cm for men and women, respectively, fasting triglycerides of 150 mg/dL
or more (≥1.69 mmol/L), HDL-C less than 40 mg/dL (<1.0 mmol/L) for men
and less than 50 mg/dL (<1.3 mmol/L) for women, blood pressure exceeding
130/85 mm Hg, and fasting plasma glucose levels of 110 mg/dL or more
(≥6.1 mmol/L) .
The root cause of most cases of metabolic syndrome can be traced back to
poor eating habits and a sedentary lifestyle. Some cases occur in those
already diagnosed with hypertension and in those with poorly controlled
diabetes; a few are thought to be linked to genetic factors that are
still being researched . On the basis of this, we suspected that
patients with COPD would be at risk for the metabolic syndrome since
these patients are limited by respiratory symptoms and adopted to a
sedentary lifestyle, increasing their risk for weight gain and insulin
This study was undertaken to evaluate the presence of the metabolic
syndrome in COPD patients.
MATERIAL AND METHODS
In a year and a half period, among 232 patients suffering from COPD
we revealed 60 patients, who had metabolic syndrome according to the
criteria. The diagnosis of COPD was made previously according to the
GOLD criteria. Inclusion criteria apart from spirometric findings (FEV1/FVC<0.7,
and FEV1<=80% of predicted) were no signs of exacerbation and use of
systemic corticosteroid in the preceding 3 months. Among them, 57 were
Caucasians and 3 belonged to the Roma population. The NCEP APT III
criteria previously described was used for checking the presence of the
metabolic syndrome. Individuals also met the criteria for hypertension
if they were taking antihypertensive, and diabetes if they used oral
hypoglycemic agents or insulin. Body weight, height, and waist
circumference were obtained in all participants. Waist circumference was
measured by a single observer using an inelastic tape at the midpoint
between the lowest rib and the iliac crest. Blood pressure measurements
were taken according to the American Heart Association’s
recommendations. Blood pressure was taken from both arms and the higher
measurement was used for te analysis [6, 7]. Participants were asked to
fast for 12 hours before blood sampling. We analyzed serum glucose
concentration, triglycerides, HDL-C and LDL-C levels and a standard
pulmonary function test (spirometry-three consecutive measurement),
arterial PaO2 and PaCO2.
Descriptive statistics were used to evaluate baseline characteristics.
Data are reported as mean ±SD or proportions and 95% confidence
Statistical analysis was performed by unpaired t test, chi square test
and Fisher exact test. A value of P <0.05 was considered statistically
The pulmonary function tests of the COPD group are presented in Table
1. Mean values for arterial PaO2 and PaCO2 were
within normal range.
Baseline characteristics of all participants are given in Table 2. All
women were postmenopausal. No woman was on hormone replacement therapy (HRT).
Statistically important difference among women and men was found in HDL
levels, usage of antihypertensive, hypolipemic and oral hypoglicemic
therapy, as well as in obesity (p<0.05). Abdominal obesity, elevated
blood pressure, and elevated triglycerides were the principal features
of the metabolic syndrome observed in this group of COPD patients.
Table 1. Characteristic of parameters of pulmonary function test and
||Women (n =24)
|FVC, % predicted
|FEV1, % predicted
|FEV1/FVC, % predicted
|PaO2, mm Hg
|PaCO2, mm Hg
FVC indicates forced vital capacity; FEV1, forced expiratory volume
in first second;FEV1/FVC, forced expiratory volume in first second
/forced vital capacity ratio; PaO2, partial pressure of
oxygen; and PaCO2, partial pressure of carbon dioxide. Values
are mean ± SD.
All the features of the metabolic syndrome were present in the same
proportion of COPD men and COPD women Indeed, 58.3% patients had central
obesity, hypertension had 85% pts, dyslipidemic were 52%, 37% had
diabetes mellitus, 43.3% were smokers, 13.3% non smokers, and 43.4
ex-smokers. Metabolic syndrome had almost 2/3 pts.
Table 2. Characteristics of patients suffered from COPD and metabolic
|HDL cholesterol, mmol/L
|LDL cholesterol, mmol/L
||2.97 ± 0.74
|Fasting glucose, mmol/
|Antihypertensive agents, %
|Oral hypolipemic agents, %
|Oral anti diabetic agents, %
Obesity is defined as a BMI ≥ 30 kg/m2.
To our knowledge, there are a few reports regarding the metabolic
syndrome in COPD patients. Our results suggest that the presence of the
metabolic syndrome may be frequent in patients with COPD, especially in
older population. In our study, the overall prevalence of the metabolic
syndrome COPD patients is 25, 9 (men 15.5, women 10.3). Men smoked 46.78
packs/year and women 31.3. This could be one of explanations for higher
prevalence in men because smoking induces systemic inflammation which
may cause metabolic syndrome.
Also, this is a group of elderly pts (aged 68.78), with many comorbid
conditions, but 60% of metabolic syndrome is very high, which needs more
Interestingly, HDL-C levels were elevated in men with COPD. Tisi et al
reported a finding and hypothesized that the increased work of breathing
might constitute a chronic exercise stimulus for the respiratory
muscles, resulting in an increase in HDL-C levels . Although
possible, it is doubtful that respiratory muscles may have such a
systemic impact. It has also been suggested that the effects of some
drugs, such as β2-agonists, might be responsible for an increased level
of HDL-C . However, salbutamol administered at a 0.8 mg daily dosage
is not known to interfere with the lipoprotein profile Inhaled
corticosteroids could be responsible for the raised HDL-C levels,
although inhaled high-dose budesonide (1600 mcg daily) has no major
effect on lipid profile in patients with asthma . Other mechanisms
unknown at this time may be responsible for the increased HDL-C levels
encountered in COPD patients. In our study men had higher level of HDL-C
which could be explained with frequent physical activity. They walked
for more than 30 minutes daily unlike women. Apart from that, it is
interesting to emphasize that the features of the metabolic syndrome
were encountered in the same proportion between genders.
It is known that oral corticosteroid therapy induces visceral obesity
and diabetes and those glucocorticoids can be produced locally by the
visceral adipocyte from inactive 11-keto forms through the enzyme
11-hydroxysteroid dehydrogenase type 1 . An increased activity of
this enzyme produces a syndrome of central obesity accompanied by
diabetes, dyslipidemia, and hypertension. It is important to emphasize
that our patients did not use oral corticosteroid in the 3 months prior
the evaluation. COPD patients often result in a sedentary lifestyle and
physical deconditioning, which could explain the higher prevalence of
the metabolic syndrome.
In conclusion, our findings suggest that the features of the metabolic
syndrome may be equally frequent in men and women with COPD. These
findings provide a potential explanation for the increased risk for
cardiovascular disease in these patients. As the prevalence of metabolic
syndrome is high, it implies that screening for features of metabolic
syndrome is necessary. Screening can prevent and decrease mortality rate
of cardiovascular disease as well as of diabetes mellitus and all its
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