|Year : 2013 | Volume
| Issue : 2 | Page : 58-61
A study of correlation between body mass index and GOLD staging of chronic obstructive pulmonary disease patients
Mrinmoy Mitra1, Santanu Ghosh2, Kaushik Saha2, Arnab Saha2, Prabodh Panchadhyayee3, Anirban Biswas2, Tarasankar Malik2, Arnab Roy2, Pratik Barma2
1 Department of Pulmonary Medicine, AMRI, Kolkata, West Bengal, India
2 Department of Pulmonary Medicine, Burdwan Medical College and Hospital, Burdwan, West Bengal, India
3 Department of Pulmonary Medicine, Apollo Gleneagles Hospital, Kolkata, West Bengal, India
|Date of Web Publication||18-Dec-2013|
D-60, Aurobinda Park, P. O. Bansdroni, Kolkata - 700 070, West Bengal
Source of Support: None, Conflict of Interest: None
Background: The association between low body mass index (BMI) and poor prognosis of patients with chronic obstructive pulmonary disease (COPD) is a common clinical observation and it varies with different stages of COPD. Aims: To find out any correlation between BMI and severity of obstruction (Global Initiative for Chronic Obstructive Lung Disease (GOLD) staging) of COPD patients. Settings and Design: We conducted a cross-sectional, observational study among 101 male patients of COPD, attending the chest medicine department in our medical college during the period from March 2011 to February 2012. Materials and Methods: We classify the severity of obstruction in COPD patients according to GOLD staging through spirometry. BMI of all the patients was measured. Correlation between BMI and severity of obstruction (post bronchodilator forced expiratory volume in 1 st second (FEV 1 ) % predicted) in COPD patients was determined. Statistical Analysis: Analysis was carried out using Statistical Package for Social Sciences (SPSS) 20.0 software for windows. Pearson correlation, one way analysis of variance (ANOVA) analysis and post hoc Turkey test were used to determine the relationship between BMI and post bronchodilator FEV 1 %predicted. Results: Mean age of the study subject was 58.18 ± 9.29 years. Commonest age group was 50-59 years (40%). Mean BMI of stage 1 COPD subjects was 26.21, stage 2 was 22.91, stage 3 was 20.78, and stage 4 was 15.71. One-way ANOVA showed that BMI of the patients were decreasing with increasing severity of the disease (GOLD) and it was statistically significant (P < 0.05). The post hoc Turkey test also indicated that there were significant differences present in different GOLD stages of COPD in respect to BMI. Conclusion: There was positive correlation between severity of airway obstruction and BMI in COPD patients.
Keywords: Body mass index, bronchodilator, chronic obstructive pulmonary disease, global initiative for chronic obstructive lung disease, spirometry
|How to cite this article:|
Mitra M, Ghosh S, Saha K, Saha A, Panchadhyayee P, Biswas A, Malik T, Roy A, Barma P. A study of correlation between body mass index and GOLD staging of chronic obstructive pulmonary disease patients. J Assoc Chest Physicians 2013;1:58-61
|How to cite this URL:|
Mitra M, Ghosh S, Saha K, Saha A, Panchadhyayee P, Biswas A, Malik T, Roy A, Barma P. A study of correlation between body mass index and GOLD staging of chronic obstructive pulmonary disease patients. J Assoc Chest Physicians [serial online] 2013 [cited 2019 Jul 17];1:58-61. Available from: http://www.jacpjournal.org/text.asp?2013/1/2/58/123217
| Introduction|| |
Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death worldwide that causes more than 2.7 million deaths in 2000 and it will be the third leading cause of death worldwide by 2020. , COPD is a systemic disease. Malnutrition in COPD is due to increased metabolic demands caused by basal oxygen consumption, release of cachexia producing cytokines like tumor necrosis factor α, interleukin-6, etc. , The association between low body mass index (BMI) and poor prognosis of patients with COPD is a common clinical observation and it varies with different stages of COPD. Nutritional depletion and weight loss are features of COPD. There are many studies documented the prognostic value of low body weight in patients with COPD. , Patients with low BMI are at increased risk for developing severity of COPD.  Low BMI is also an independent negative determinant of survival in patients with COPD.  To the best of our knowledge a limited studies have been conducted in India to show the correlation between BMI and Global Initiative for Chronic Obstructive Lung Disease (GOLD) staging in COPD patients. The specific objectives of our study were to classify the severity of obstruction in COPD patients according to GOLD staging through spirometry, to find out the BMI of patients and to find out any correlation between severities of obstruction in COPD patients (through spirometry) with their body mass indices.
| Materials and Methods|| |
This was a cross-sectional, observational study. The study was conducted in our medical college during the period from March 2011 to February 2012.
The study population was selected from among 101 consecutive patients of COPD, who attended our Chest Medicine Department. The subjects who were enrolled in the study were smokers and male patients of ≥40 years of age with symptoms of COPD (dyspnea, chronic cough or sputum production, forced expiratory volume in 1 st second/forced vital capacity (FEV 1 /FVC) <0.7 on spirometry, and without any significant post-bronchodilator FEV 1 reversibility, that is, less than 12% and 200 ml). Patients who were suffering from or who were known to have tuberculosis (acid fast bacilli (AFB) smear positive or negative), bronchiectesis, pneumonia, lung cancer, interstitial lung diseases, occupational lung diseases, respiratory failure, and who had recent history of eye surgery, retinal detachment, or myocardial infarction within 1 month were excluded from our study.
Detailed history of all the patients was taken that included severity of symptoms, duration of the illness, detailed smoking status, and occupational history. Past history was also taken thoroughly to exclude past history of tuberculosis or lung cancer. Examination of the respiratory system was also done thoroughly in all patients. Chest X-ray posteroanterior (CXR-PA) view were done in all the patients to see for radiological changes associated with COPD like signs of hyperinflation, hyperlucency of the lungs, and also to exclude other diseases like tuberculosis (present or past), lung cancer, bronchiectesis, and interstitial lung disease. BMI (weight in kg/height in meter 2 ) was measured in each patient. Pre- and post-bronchodilator spirometry of all the patients was done. Patients with post-bronchodilator FEV 1 /FVC less than 0.7 and significant reversibility (improvement of 12% and 200 ml of FEV 1 ) were excluded. Patients without significant reversibility were selected. They were classified according to GOLD staging in stage 1 (post-bronchodilator FEV1 ≥ 80%), stage 2 (post-bronchodilator FEV1 ≥ 50% and <80%), stage 3 (post-bronchodilator FEV1 ≥ 30 and 50%), and stage 4 (post-bronchodilator FEV1 < 30%). In our study we want to find out the correlation between BMI and severity of obstruction in COPD patients. Mean BMI of the COPD patients in different GOLD staging were compared with the help of different statistical method and a correlation was determined.
Data analysis was carried out using statistical package for social sciences (SPSS 20.0 for windows). Mean, standard deviation (SD), and confidence interval were determined. Pearson correlation and one-way analysis of variance (ANOVA) analysis were used to determine the relationship between BMI and post-bronchodilator FEV 1 %predicted. A P < 0.05 was considered statistically significant. The post hoc Tukey test was also done to find out any significant differences present in different GOLD stages of COPD in respect to BMI.
| Results|| |
All the patients of the study population were in age range of 40-80 years. The mean age of all the patients was 58.10 (SD ± 9.29) years. Commonest age group was 50-59 years (40%) [Figure 1]. All the patients of our study were male. In our study among whole study population (n = 101) we found different comorbid conditions such as five (4.95%) patients had congestive cardiac failure, 17 (16.83%) had diabetes mellitus, another 47 (46.54%) had hypertension, and 32 (31.68%) had no associated comorbidities. The COPD patients were classified by their post-bronchodilator FEV 1 % predicted in four stages according to GOLD. Among 101 study population, 18 (17.8%) patients were in stage 1, 32 (31.7%) in stage 2, 29 (28.7%) in stage 3, and 22 (21.8%) in stage 4. In our study we found the mean ages of the study population in different stages of COPD were different. The mean ages of the patients in four stages of COPD were shown in [Table 1]. The mean age of stage 1 was 47.15 (SD ± 4.38), stage 2 was 57.00 (SD ± 8.00) years, stage 3 was 59.41 (SD ± 7.74) years, and stage 4 was 67.12 (SD ± 4.41) years. From the above table and by applying one-way ANOVA, it was found that severity of obstruction increases with age of the patients which was statistically significant (P < 0.05). The mean pack years of smoking of the COPD patients was different in different stages of COPD. By applying one-way ANOVA we found that mean pack years of smoking is increased with severity of obstruction (determined by post-bronchodilator FEV 1 % predicted) which is statistically significant (F = 19.912, P < 0.05). In [Table 1] we also showed the mean BMI of the COPD patients in their different GOLD stages. Applying the Pearson correlation test we found that BMI and post FEV 1 %predicted were positively correlated (R = 0.902, P < 0.05). Now by applying one-way ANOVA, we found that BMI of the patients were decreasing with severity of the disease (GOLD) and it was statistically significant (F = 149.473, P < 0.05). The post hoc Turkey test also indicated that there were significant differences present in different GOLD stages of COPD in respect to BMI. The scatter diagram in [Figure 2] also shows that there was positive correlation present in between post FEV 1 %predicted and BMI in COPD patients. The BMI was better in the study populations where post FEV 1 %predicted value was higher.
|Figure 2: Scatter diagram showing correlation between body mass index (BMI) and post force expiratory volume in 1st second %predicted in chronic obstructive pulmonary disease patients|
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|Table 1: Mean ages and mean BMI with standard deviation (SD) of different stages of COPD patients (n=101)|
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| Discussion|| |
Though COPD has been considered a respiratory condition mainly, it has important manifestations beyond the lungs, the so-called systemic effects. These include unintentional weight loss, skeletal muscle dysfunction, increased risk of cardiovascular disease, osteoporosis, gastroesophageal reflux disorder, and depression, among others. ,, Nutritional depletion and weight loss are the features of COPD. The exact mechanisms are uncertain,  but decreased food intake and increased energy expenditure in breathing are the most important.  Hypoxia has been shown to stimulate the production of inflammatory mediators and to contribute to the development of malnutrition in COPD patients.  There are several studies ,, which have documented the association between low body mass and poor prognosis and mortality in patients with established COPD. In addressing the association between BMI and severity of obstruction of COPD (GOLD), Nemery et al.,  raised the possibility that subjects who are susceptible to COPD may be leaner than subjects who were not susceptible. Thus, it is not clear whether low body weight is a risk factor for COPD or merely a consequence of established lung disease.
The mean age of study population was 58.10 (SD ± 9.29) years and maximum number of the patients were more than 50 years of age, which was consistent with the previous literatures as the disease has highest prevalence in 5 th and 6 th decades of life. , As COPD is more common in male in our country, all the patients in our study were male.  In 2009, Kohansal et al.,  that severity of airflow obstruction increases more with age. The study was consistent to our study as we showed that with increase severity of GOLD staging average age of the patient was also increasing. In 2009, Qiu et al.,  demonstrated that there was a positive correlation present in between BMI and FEV 1 /FVC, FEV 1 % predicted. Sahebjami et al.,  also demonstrated a correlation between BMI and pulmonary function tests and they recommended BMI as a criterion to evaluate the nutritional status of COPD patients. Thus these above studies are consistent with our present study. In the Platino study,  a population-based epidemiologic study conducted in five Latin American cities (2008) showed that up to normal BMI (i.e., BMI up to 25.00 kg/m 2 ) FEV 1 %predicted is positively and linearly correlated with BMI, that is, with increase in FEV 1 %predicted, BMI also increased and vice versa. But in cases of pre-obese or obese patients they are not linearly correlated. In our study the mean BMI of the population is 21.36 (SD ± 3.84) kg/m 2 . And thus our study is consistent with the above study. A study conducted by Vestbo et al., Findings from the Copenhagen City Heart Study  showed that there was no correlation between BMI and post-bronchodilator spirometry (post FEV 1 /FVC, post %predicted), that is, severity of obstruction. In the above study total number of population was 1,898 that was large scale study. But in our study total number of cases was 101. We need further studies involving larger sample size is required to confirm the correlation between BMI and severity of obstruction (GOLD) in COPD patients. Another study published by Ischaki et al.,  also demonstrated that there was no correlation between BMI and severity of obstruction (determined by spirometry) in COPD patients. Moreover, our study was cross-sectional study and we believe longitudinal study is also required to find out the correlation between BMI and severity of obstruction (GOLD) in COPD patients.
| Conclusion|| |
COPD is a systemic disease. The association between BMI and poor prognosis of patients with COPD is a common clinical observation and it varies with different stages of COPD. In our study we found out that there was a positive correlation present in between BMI and severity of obstruction in COPD patients. With severity of the obstruction (GOLD staging) BMI of the patient decreases and it was statistically significant.
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[Figure 1], [Figure 2]