Introduction

Chronic obstructive pulmonary disease (COPD) is a chronic lung disease that is preventable and treatable [1]. COPD is a major cause of disability, reduced quality of life, and mortality throughout the world, and is the 4^th most common cause of death in the United States by 2020, accounting for more than 120,000 deaths [2]. COPD is known not only as a disease of the lungs, but it also affects many organs and tissues [3], and patients typically have 1 or more components of metabolic syndrome [4–9].

Abdominal obesity and particularly visceral obesity is the key feature of metabolic syndrome that is also associated with many chronic diseases, particularly cardiovascular, and respiratory diseases [10]. In order to predict the severity of illness and the functional limitations of lungs, specific anthropometric measurements are very valuable because of ease, availability, and cost-effectiveness [11]. Likewise, body mass index (BMI), waist circumference (WC), and waist-to-hip ratio can be used to estimate the abdominal visceral fat measurement [12].

Generally, lack of physical activity is one of the highest causes of visceral fat accumulation in patients with COPD [13]. The visceral fat tissues are identified as the source of pro-inflammatory cytokines such as Interleukin-6 that can induce

C-reactive protein (CRP) synthesis in hepatocytes. Subsequently, accumulation of visceral fat leads to high levels of Interleukin-6 and tumor necrosis factor alpha, and low levels of adiponectin (an anti-inflammatory cytokine that reduces the risk of heart disease) [14]. Furthermore, systemic inflammation is associated with the pathogenesis of metabolic syndrome and COPD [5] and metabolic syndrome is prevalent in COPD patients [15, 16].

WC assessment is a good indicator of individuals with a health risk due to the accumulation of extra fat around the internal organs, and with increasing age, men tend to gain fat around the waist, whilst women accumulate fat in buttocks, gluteal regions, and around the thighs and hips. As we know a waist circumference of 102 centimeters (40 inches) or more in men, or 88 centimeters (35 inches) or more in women, is associated with health problems such as type 2 diabetes, heart disease and high blood pressure. WC measures abdominal fat but it can also give information about distribution of body fat. WC may affect mechanical ventilation of the lungs that leads to a restriction of movement of the diaphragm [16]. Measurements of obesity may indicate the progression and severity of COPD, and WC may be a predictive factor of visceral fat accumulation which plays a role in the inflammatory process. The objective of this study was to investigate the impact of WC on the severity of the obstruction of airways, forced expiratory volume in the first second (FEV1)/forced vital capacity (FVC) and FEV1 by spirometry analysis.

Materials and Methods

1. Ethics approval and patient consent

Research ethics were approved for this study on 2015-10-06, (IR.GUMS.REC.1394.272). This prospective cross-sectional study was carried out on 180 patients with COPD who were admitted to Razi Hospital, Rasht, Iran, between 2014 and 2015. COPD was confirmed in patients according to the global initiative for chronic obstructive lung disease (GOLD) score, and the patients were enrolled consecutively after giving written informed consent.

2. Inclusion/exclusion criteria

Patients who were included in the study had been diagnosed with COPD. Patients excluded in the study had cystic fibrosis, tuberculosis, bronchial asthma, bronchogenic carcinoma, external lung tissue disease, pulmonary surgery, cardiovascular disease, diabetes mellitus, uremia, or sarcoidosis. Patients who used azithromycin, long-term, and patients who were prescribed antiepileptic drugs were also excluded.

3. Demographic data

A checklist including details of gender, age, hypertension, diabetes, cigarette smoking, high-density lipoprotein (HDL), cholesterol, triglyceride, fasting blood sugar (FBS), and CRP test was recorded. The height was measured by stadiometer and weight of patients was measured by scales. BMI was calculated by dividing weight by the square of height (kg/m²). The WC was measured at the lower edge of the rib and the iliac spine, and the hip circumference was determined at widest point above the buttocks, using a standard tape measure.

4. Lung volume measurements

Lung volume measurements were conducted using a spiroanalyser (MIR Spirolab spirometer, Italy), in a sitting position, with help from a nurse at the Razi hospital. The patients performed maximum and appropriate deep breaths. The observations from the spirometry examination were expressed as forced vital capacity (FVC), FEV1 and FEV1/FVC was calculated. The grading of COPD was carried out according to the latest report of GOLD criteria. The disease quality control questionnaire was completed based on COPD assessment and the COPD assessment test (CAT) score.

5. CAT Score

CAT score is a complementary tool used alongside methods such as FEV1 to assesses COPD [17]. The CAT score results from a short and simple 8-item questionnaire that the patient completes. This test is commonly used in clinical practice to determine the health status of patients with COPD [18].

6. Statistics analysis

Variables were analyzed using a normality test. Parametric tests such as the “T test” were used to compare WC and severity of COPD (based on GOLD score). Otherwise, the non-parametric “Mann Whitney U test” was applied. Estimating the normal distribution of variables was analyzed using “Pearson’s correlation coefficient test” to study the relationship between WC and the spirometry data. Otherwise, “Spearman’s coefficient test” was applied. The Scatter plot was drawn to demonstrate the dependence distribution. The multiple linear regression method was utilized to determine the predicted spirometry values based on WC. An alpha of 0.05 was applied as the cut off for statistical significance (p < 0.05).

Results

There were 180 patients with COPD included in this study, of which 69.4% were males who had a mean age of 35.6 years (61–70 years; Table 1). There were 46.7% of patients who had a healthy BMI (kg/m²). It was observed that 49.4% of patients had a overweight WC. As shown in Table 1, 68.3% of the patients were cigarette smokers (Table 1). The mean BMI of the patients was 34.5 ± 43.26 kg/m². The average WC in women and men were 95.11 ± 94.1 cm and 46.10 ± 11.108 cm, respectively. The mean disease duration in COPD patients was 49.16 ± 2.27 months. The average consumption of cigarettes smoking was 24.7 ± 15.6 (Table 1). The mean CAT score in COPD patients was 94.7 ± 36.18. On the other hands, Figure 1 demonstrate relationships between BMI (A), consumption cigarette smoking (B), gold score (C), CAT score (D), and waist circumference of patients with COPD (Figure 1).

Positive correlations were observed between cigarette smoking, BMI, CAT scores, and GOLD scores, and WC in patients with COPD (Table 2). Predictive factors for the severity of COPD in patients with normal and overweight WC were assessed according to the GOLD scores. There is a significant difference between the mean of overweight WC and normal weight WC in the severity of patients with COPD based on GOLD score (p = 0.045; Table 3). This study showed that there is a significantly difference between WC and FEV1/FVC (p = 0.036; Table 3). We also showed significantly difference between WC and CAT score in patients with COPD (p = 0.045; Table 3). Ordinal logistic regression analysis of predictive factors for the severity of patients with COPD based on FVC (Table 4). Table 4 showed that there is a correlation between WC (p = 0.004), age (p = 0.027), duration of disease (p = 0.038), men gender (p < 0.001), and CRP (p < 0.001) with FVC as a predicting factor in severity COPD (Table 4).

Discussion

In the current study, pulmonary function and WC were investigated in 180 COPD patients. Clinical studies have showed that COPD patients typically have 1 or more components of metabolic syndrome. Abdominal obesity and particularly visceral obesity, have been shown to be key features of metabolic syndrome, which is also related to chronic diseases [10]. A correlation between coronary artery disease and abdominal obesity has been observed [10]. It has also been reported that in those people who smoke cigarettes and who have a high WC, there is an increased risk of developing heart disease [19]. Furthermore, several studies have indicated that WC, but not BMI, was associated with chronic heart failure, and that abdominal fat tissue was a stronger risk factor for obesity [19, 20]. It was also observed that the ratio of WC to FEV1/FVC might potentially have a higher predictive value [19, 20]. Gibson [20] and Chen et al [21] showed that there is a significant difference between obesity and coronary artery disease score in women and men.

A previous study of COPD [17] reported that physical inactivity may lead to dyspnea, which may explain why many patients lead an inactive and sedentary life. In addition, excess fat tissue may act as an additional mediator of inflammation [22, 23]. Other studies have reported that visceral fat, in the absence of obesity (especially in the advanced stages of the disease), was significantly higher in patients with COPD [22]. Furutate et al [17] showed that patients with COPD suffer from muscular atrophy and excessive accumulation of visceral fat, especially in the severe stages of COPD and emphysema. In advanced stages of COPD when energy consumption is high, it was reported that muscle mass was reduced [20]. Reduced physical activity (due to dyspnea) and capacity to exercise, inadequate dietary intake, or systemic inflammation leads to decreased muscle mass. Physical inactivity results in excessive accumulation of visceral fat, especially in more advanced stages of COPD, and severe emphysema. Visceral obesity was reported to be typically associated with dyslipidemia leading to systemic inflammation [20]. Excessive visceral fat was also another source of systemic inflammation in COPD patients. Reducing lung function in the COPD patients, lead to hypoxemia.

Patients with COPD may be more susceptible to hypoxemia, because systemic inflammation may be associated with systemic oxygen deficiency [23]. In the current study, the WC of patients with COPD showed a significant relationship between the FVC and FEV1 (p = 0.036) (Table 4). However, WC was not associated with FEV1/FVC. In fact, when WC increased by 1 cm, the values of FVC, FEV1 decreased by 13 mL and 11 mL, respectively (Figure 1). In this current study BMI, cigarette smoking, CAT score and GOLD score, had a positive correlation with WC in patients with COPD. Likewise, increasing BMI, cigarette smoking, CAT score, and GOLD score, led to increased WC. Finally, the study showed that poor lung function would be associated with higher levels of abdominal fat (WC) in COPD patients (Figure 1). The limitations of this study were the small sample size, and low power to detect an effect of WC on lung function in COPD patients.

Conclusion

In the current study, positive correlations were detected between the WC and BMI, cigarette smoking, CAT score, and GOLD score. Meanwhile, the predictive factors for COPD severity were WC, age, CRP, duration of the disease, and being male. WC, which is an easily measured parameter, can be used to estimate pulmonary function rate in patients with COPD.

Article information

Conflicts of Interest

The authors declare that they have no competing interests.

References

• 1. Magnussen H, Watz H. Systemic inflammation in chronic obstructive pulmonary disease and asthma: relation with comorbidities. Proc Am Thorac Soc 2009;6(8). 648−51. PMID: 10.1513/pats.200906-053DP. PMID: 20008868.ArticlePubMed
• 2. _Buist AS, McBurnie MA, Vollmer WM, et al. International variation in the prevalence of COPD (the BOLD Study): A population-based prevalence study. Lancet 2007;370(9589). 741−50. PMID: 10.1016/S0140-6736(07)61377-4. PMID: 17765523.ArticlePubMed
• 3. _Piazzolla G, Castrovilli A, Liotino V, et al. Metabolic syndrome and Chronic Obstructive Pulmonary Disease (COPD): The interplay among smoking, insulin resistance and vitamin D. PLoS One 2017;12(10). e0186708PMID: 10.1371/journal.pone.0186708. PMID: 29065130. PMID: 5655494.ArticlePubMedPMC
• 4. Chung JH, Hwang HJ, Han CH, et al. Association between sarcopenia and metabolic syndrome in chronic obstructive pulmonary disease: The Korea National Health and Nutrition Examination Survey (KNHANES) from 2008 to 2011. COPD 2015;12(1). 82−9. PMID: 10.3109/15412555.2014.908835.ArticlePubMed
• 5. Budnevsky AV, Isaeva YV, Malysh EY, et al. Pulmonary rehabilitation as an effective method for optimizing therapeutic and preventive measures in patients with chronic obstructive pulmonary disease concurrent with metabolic syndrome. Ter Arkh 2016;88(8). 25−9. [in Russian]. PMID: 10.17116/terarkh201688825-29. PMID: 27636923.Article
• 6. Al-Jameil N, Hassan AA, Hassanato R, et al. The prevalence of PI*S and PI*Z SERPINA1 alleles in healthy individuals and COPD patients in Saudi Arabia: A case-control study. Medicine (Baltimore) 2017;96(42). e8320PMID: 10.1097/MD.0000000000008320.ArticlePubMedPMC
• 7. Kokturk N, Polatli M, Oguzulgen IK, et al. Adherence to COPD treatment in Turkey and Saudi Arabia: results of the ADCARE study. Int J Chron Obstruct Pulmon Dis 2018;13:1377−88. PMID: 10.2147/COPD.S150411. PMID: 29731625. PMID: 5927343.ArticlePubMedPMC
• 8. Alsubaiei ME, Frith PA, Cafarella PA, et al. COPD care in Saudi Arabia: physicians’ awareness and knowledge of guidelines and barriers to implementation. Int J Tuberc Lung Dis 2017;21(5). 592−5. PMID: 10.5588/ijtld.16.0656. PMID: 28399976.ArticlePubMed
• 9. Gooneratne NS, Patel NP, Corcoran A. Chronic obstructive pulmonary disease diagnosis and management in older adults. J Am Geriatr Soc 2010;58(6). 1153−62. PMID: 10.1111/j.1532-5415.2010.02875.x. PMID: 20936735.ArticlePubMed
• 10. Beekman E, Mesters I, Hendriks EJ, et al. Exacerbations in patients with chronic obstructive pulmonary disease receiving physical therapy: A cohort-nested randomised controlled trial. BMC Pulm Med 2014;14(1). 71PMID: 10.1186/1471-2466-14-71. PMID: 24767519. PMID: 4108017.ArticlePubMedPMCPDF
• 11. Dewar M, Curry RW Jr. Chronic obstructive pulmonary disease: Diagnostic considerations. Am Fam Physician 2006;73(4). 669−76. PMID: 16506711.PubMed
• 12. Adeyeye OO, Ogvera AO, Ogunleye OO, et al. Understanding asthma and the metabolic syndrome-a Nigerian report. Int Arch Med 2012;5(1). 20PMID: 10.1186/1755-7682-5-20. PMID: 22726248. PMID: 3499319.ArticlePubMedPMC
• 13. Groenewegen KH, Dentener MA, Wouters EF. Longitudinal follow-up of systemic inflammation after acute exacerbations of COPD. Resp Med 2007;101(11). 2409−15. PMID: 10.1016/j.rmed.2007.05.026.Article
• 14. Hill A, Gompertz S, Stockley R. Factors influencing airway inflammation in chronic obstructive pulmonary disease. Thorax 2000;55(11). 970−7. PMID: 10.1136/thorax.55.11.970. PMID: 11050270. PMID: 1745630.ArticlePubMedPMC
• 15. Sato M, Shibata Y, Abe S, et al. Retrospective analysis of the relationship between decline in FEV1 and abdominal circumference in male smokers: The Takahata Study. Int J Med Sci 2013;10(1). 1−7. PMID: 10.7150/ijms.5003. PMID: 23288999. PMID: 3534871.ArticlePubMed
• 16. Barnes P, Celli BR. Systemic manifestations and comorbidities of COPD. Eur Respir J 2009;33(5). 1165−85. PMID: 10.1183/09031936.00128008. PMID: 19407051.ArticlePubMed
• 17. Furutate R, Ishii T, Wakabayashi R, et al. Excessive visceral fat accumulation in advanced chronic obstructive pulmonary disease. Int J Chron Obstruct Pulmon Dis 2011;6:423−30. PMID: 21857782. PMID: 3157945.PubMedPMC
• 18. Molenaar EA, Massaro JM, Jacques PF, et al. Association of lifestyle factors with abdominal subcutaneous and visceral adiposity: the Framingham Heart Study. Diabetes Care 2009;32(3). 505−10. PMID: 10.2337/dc08-1382. PMID: 2646037.ArticlePubMedPMC
• 19. Marallu HG, Sadeghieh-ahari S, Lari SM. The relationship between COPD assessment test (CAT) scores and severity of airflow obstruction in stable COPD patients. Eur Respiratory Soc 2012;40(suppl 56). P2287.
• 20. Gibson GJ. Obesity, respiratory function and breathlessness. Thorax 2000;55(suppl 1). S41−4. PMID: 10.1136/thorax.55.suppl_1.S41. PMID: 10943638. PMID: 1765949.ArticlePubMedPMC
• 21. Chen R, Tunstall-Pedoe H, Bolton-Smith C, et al. Association of dietary antioxidants and waist circumference with pulmonary function and airway obstruction. Am J Epidemiol 2001;153(2). 157−63. PMID: 10.1093/aje/153.2.157. PMID: 11159161.ArticlePubMed
• 22. Wehrmeister FC, Menezes AM, Muniz LC, et al. Waist circumference and pulmonary function: A systematic review and meta-analysis. Syst Rev 2012;1:55PMID: 10.1186/2046-4053-1-55. PMID: 23153289. PMID: 3534560.ArticlePubMedPMCPDF
• 23. Wannamethee SG, Shaper AG, Whincup PH. Body fat distribution, body composition, and respiratory function in elderly men. Am J Clin Nutr 2005;82(5). 996−1003. PMID: 10.1093/ajcn/82.5.996. PMID: 16280430.ArticlePubMedPDF

Figure 1

Distribution chart of BMI (A) cigarette smoking (B), gold score (C), CAT score (D), and WC of patients with COPD.

BMI = body mass index; CAT = COPD assessment test; COPD = chronic obstructive pulmonary disease; WC = waist circumference.

Table 1

The demographic characteristics of the patients with COPD.

Variable	State	N	%
Gender	Female	55	30.6
	Male	125	69.4
Age group (y)	< 50	27	15.0
	51–60	39	21.7
	61–70	64	35.6
	> 70	50	27.8
BMI	< 19 (underweight)	7	3.9
	19–25 (healthy)	84	46.7
	25–30 (overweight)	40	22.2
	> 30 (obese)	49	27.2
WC* (cm)	Normal	35	19.4
	Overweight, obese	145	80.6
Cigarette smoking (pack/y)	Yes	123	68.3
	No	57	31.7

BMI = body mass index; COPD = chronic obstructive pulmonary disease; WC = waist circumference.

^* Normal WC in men: 78–94 cm, Normal WC in women: 64–80 cm, overweight WC in men: 94–102 cm, overweight WC in women: 80–88 cm, obese WC in men: ≥102 cm, obese WC in women: ≥88 cm.

Table 2

Correlation of variables with waist circumference in patients with COPD*.

Variable	WC
	Spearman correlation	p	Correlation
Age (y)	0.027	0.721	No
BMI	0.723	< 0.001	Positive
Cigarette smoker	0.199	0.027	Positive
FEV1	0.108	0.150	No
FVC	0.106	0.156	No
FEV1/FVC	−0.115	0.124	No
CAT score	0.161	0.031	Positive
Gold score	0.194	0.009	Positive
CRP	0.073	0.329	No
Systolic BP	0.080	0.285	No
Diastolic BP	0.009	0.908	No
FBS	< 0.001	0.995	No
TG	−0.026	0.731	No
HDL	0.014	0.853	No
Duration of disease (mo)	0.143	0.056	No

BMI = body mass index; BP = blood pressure; CAT = COPD assessment test; COPD = chronic obstructive pulmonary disease; CRP = C-reactive protein test; FBS = fasting blood sugar; FEV = forced expiratory volume; FVC = forced vital capacity; HDL = high-density lipoprotein; TG = triglyceride; WC = waist circumference.

^* Spearman test.

Table 3

Spirometric parameters and severity of patients with COPD in normal and overweight waist circumference.

		Wrist circumference
		Overweight WC			Normal weight WC			p
		Mean	%	N	Mean	%	N
I-mild			4.8	7		11.4	4	0.045 *
IIA-medium	Gold scores	94.3	75.2	109	74.77	85.7	30
III-severe			16.6	24		2.9	1
IV-very severe			3.4	5		0	0
FEV1/FVC %		86.50	88.10 ± 78.56		9.107	74.8 ± 3.60		0.036
FEV1		88.13	71.0 ± 72.1		3.100	62.0 ± 83.1		0.215
FVC		87.19	18.1 ± 88.2		91.100	74.1 ± 27.3		0.118
FEV1 %		78.63	82.14 ± 34.62		2.90	9.10 ± 62.66		0.204
CAT		94.31	3.8 ± 99.18		70.74	65.5 ± 74.15		0.045

CAT = COPD assessment test; COPD = chronic obstructive pulmonary disease; FEV = forced expiratory volume; FVC = forced vital capacity; WC = waist circumference.

^* “Fisher’s exact test” was used to compare the mean of overweight WC and normal weight WC in the severity of patients with COPD based on GOLD score. “Mann Whitney U test” was applied to compare non-parametric variables.

Table 4

Ordinal logistic regression analysis of predictive factors for the severity of patients with COPD based on forced vital capacity (FVC).

Ordinal logistic regression	CI (95%) OR		OR	*p	SE	Estimate
	Upper	Lower
WC (cm)	1.10	1.02	1.06	0.004	0.020	0.057
Age (y)	1.11	1.03	1.07	0.027	0.020	0.064
CRP	3.47	1.79	2.49	< 0.001	0.168	0.091
Systolic BP	1.08	1.00	1.04	0.056	0.021	0.039
TG	1.00	0.99	0.10	0.085	0.004	−0.007
Duration of disease (mo)	1.12	1.044	1.08	0.038	0.017	0.076
Men	22.62	3.08	8.36	< 0.001	0.508	2.123
Women		-	1.00	-	-	-

BP = blood pressure; COPD = chronic obstructive pulmonary disease; CRP = C-reactive protein test; FVC = forced vital capacity; TG = triglyceride; WC = waist circumference.

Figure & Data

References

Citations

Citations to this article as recorded by  

• The role of abdominal obesity in the development of cardiopulmonary disorders in aluminum industry workers
  Egor S. Filimonov, Olga Yu. Korotenko, Evgeniya V. Ulanova
  Hygiene and sanitation.2023; 102(4): 328.     CrossRef
• Blood Levels of Indicators of Lower Respiratory Tract Damage in Chronic Bronchitis in Patients with Abdominal Obesity
  Elena V. Kashtanova, Yana V. Polonskaya, Evgeniia V. Striukova, Liliia V. Shcherbakova, Evgenii A. Kurtukov, Viktoriya S. Shramko, Ekaterina M. Stakhneva, Yulia I. Ragino
  Diagnostics.2022; 12(2): 299.     CrossRef
• Prevalence of Metabolic Syndrome in Chronic Obstructive Pulmonary Disease and its Correlation with Body Mass Index, Airflow Obstruction, Dyspnea, and Exercise Index and C-Reactive Protein
  D. Suresh Kumar, Richard Samuel, Viola Savy DSouza, Madhu Keshava Bangera
  Indian Journal of Respiratory Care.2022; 11(4): 314.     CrossRef
• Prevalence of chronic bronchitis against a background of abdominal obesity in young people aged 25–44 in Novosibirsk
  Yu. I. Ragino, E. A. Kurtukov, D. V. Denisova, Ya. V. Polonskaya, L. V. Shcherbakova
  Bulletin of Siberian Medicine.2021; 20(1): 105.     CrossRef
• Abdominal obesity and the level of markers of lower respiratory tract damage in patients with chronic bronchitis
  E.V. Kashtanova, Ya.V. Polonskaya, L.V. Scherbakova, I.I. Logvinenko, E.F. Kurtukov, D.V. Denisova, Yu.I. Ragino
  Profilakticheskaya meditsina.2021; 24(5): 35.     CrossRef