Is chronic obstructive pulmonary disease different in females as compared to males?

Rita Vijaykumar Bothara; Madhuri Prashant Holay

doi:10.4103/injms.injms_118_21

ORIGINAL ARTICLE

Year : 2022 | Volume : 13 | Issue : 2 | Page : 82-86

Is chronic obstructive pulmonary disease different in females as compared to males?

Rita Vijaykumar Bothara, Madhuri Prashant Holay
Department of Medicine, Government Medical College, Nagpur, Maharashtra, India

Date of Submission	12-Oct-2021
Date of Decision	17-Nov-2021
Date of Acceptance	06-Dec-2021
Date of Web Publication	21-Mar-2022

Correspondence Address:
Dr. Rita Vijaykumar Bothara
Department of Medicine, Government Medical College, Nagpur, Maharashtra
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/injms.injms_118_21

Abstract

Background: Recent years have witnessed a major shift in the sex profile of the chronic obstructive lung disease (COPD). In India, while smoking remains a significant risk factor, COPD due to nonsmoking causes (like biomass exposure) accounts for 30%–50% of all COPD cases. There is a lack of studies on characteristics of women with COPD exposed to biomass smoke and the degree to which they differ from COPD in men from the Indian context. Aim: The aim was to study clinical profile, risk factors, and severity of COPD in females and compare the same with COPD in males. Materials and Methods: 100 cases of COPD were divided into two groups – 50 Females and 50 males and were analyzed further for clinical profile and were graded as per the GOLD criteria and BODE index. Results: The mean age of presentation in females was 62 years. Biomass smoke exposure was the most common risk factor in females and that in males was smoking. Females had more severe dyspnea as compared to males (P = 0.022). There was a significant statistical difference in the performance of 6-min walk test (P = 0.005) and number of exacerbations in the past year in females (mean 4.5) and males (mean 3.58) (P = 0.034). Majority of female patients belonged to GOLD Groups B and D. Mean BODE index was 4.98 in females and 4.24 in males, and the difference was statistically significant (P = 0.014). Conclusion: There are gender-related differences in COPD risk, progression, and outcomes. Females have more symptoms, more severe obstruction, more number of exacerbations, and more functional disability as compared to males.

Keywords: Biomass exposure, chronic obstructive lung disease, functional disability, gender

How to cite this article:
Bothara RV, Holay MP. Is chronic obstructive pulmonary disease different in females as compared to males?. Indian J Med Spec 2022;13:82-6

How to cite this URL:
Bothara RV, Holay MP. Is chronic obstructive pulmonary disease different in females as compared to males?. Indian J Med Spec [serial online] 2022 [cited 2023 Mar 29];13:82-6. Available from: http://www.ijms.in/text.asp?2022/13/2/82/340032

Introduction

The increased morbidity and mortality from chronic obstructive lung disease (COPD) during the last few decades are partly driven by their increase in women. This is usually attributed to the delayed rise of smoking prevalence in women or their increased susceptibility to the risk factors.^[1],[2] In addition, women may be at particular risk of underdiagnosis because of prevailing notion that COPD primarily affects men. This influence of gender on the expression of COPD has received limited attention.

Furthermore, there is a lack of studies on characteristics of women with COPD exposed to biomass smoke and the degree to which they differ from COPD in men (mainly due to tobacco smoking) from the Indian context. Hence, we conducted the present study.

Materials and Methods

This hospital-based cross-sectional observational study was conducted from January 2018 to October 2019 at a tertiary care hospital in central India.

The study was aimed at clinical profile and risk factors in cases of COPD in females and compare the same with COPD in males and to assess the severity of COPD in females by BODE index and GOLD staging and compare it with COPD in males.^[3],[4]

Plan of study

Patients with a history of cough with expectoration for 3 months for at least 2 consecutive years and/or breathlessness with clinical evidence of obstructive airway disease (Bronchospasm, pursed-lip breathing, barrel-shaped chest) were recruited as per the above eligibility criteria and were subjected to pulmonary function tests (PFT).^[5]

Cases (total 100) were divided into two groups – females with COPD (50) and males with COPD (50) and were analyzed further for clinical profile, risk factors, indoor air pollution exposure (biomass fuel, wood and coal), occupational exposures (crop and animal farming), and dust and chemical exposures and were graded as per the BODE index and GOLD criteria.^[3],[4]

Spirometry was done and parameters recorded were FVC, FEV1, and ratio of FEV1/FVC. Postbronchodilator spirometry was performed in patients who had evidence of airflow limitation on baseline spirometry. Cases having postbronchodilator FEV1/FVC <0.7 were diagnosed as COPD and included in the study. Patients showing only restrictive or restrictive plus obstructive pattern on PFT, cases suffering from Ischemic heart disease, cases of COPD admitted with other medical emergencies, cases of active tuberculosis, cases who were critically ill requiring parenteral antibiotics/ventilation, cases of acute exacerbation of COPD, and cases in whom spirometry cannot be performed for any other reason were excluded. Cases were asked the appropriate history of symptoms so as to classify them according to MMRC score.^[6] 6-min walk test was performed, total distance walked was recorded.^[7] The factors included in the BODE index are weight (body mass index [BMI]), airway obstruction (FEV1), dyspnea (Medical Research Council dyspnea score), and exercise capacity (6-min walk test).^[7] Each component was graded and a score out of 10 was obtained. Based on the symptom severity and number of exacerbations in the past 1 year (high risk or low risk), the patients were classified into GOLD's stages A, B, C, and D.^[8]

Statistical analysis

Continuous and categorical variables were compared by performing independent t-test and Chi-square test, respectively. For small numbers, Fisher's exact test was used wherever applicable. Pearson's correlation coefficient (R-value) was assessed to determine the nature and magnitude of correlation of BODE index with age, biomass exposure index for normalized variables, and Spearman's correlation coefficient (rho-value) for nonnormalized variables. Univariate analysis was performed to determine risk factors associated with patients with COPD.

Results

On comparing the baseline characteristics of subjects, the mean age of presentation of COPD in females was 62 years (±6.49) and in males was 59.52 years (±5.93), and the difference was statistically significant (P = 0.002). Female patients had significantly lower BMI (mean BMI-18.22) than male patients (mean BMI-19.24) (P < 0.0001). There was no statistically significant difference with respect to systolic blood pressure (P = 0.1651), diastolic blood pressure (P = 0.0647), respiratory rate (P = 0.8597), and O₂ saturation (P = 0.3455) [Table 1].

Table 1: Baseline characteristics of cases of chronic obstructive pulmonary disease (n=100)

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Symptoms of cough and breathlessness were reported in all females (100%). All 50 males reported symptoms of breathlessness, whereas cough was present in 40 (80%) males. The difference was statistically significant (P = 0.001). There was no statistically significant difference with respect to other symptoms such as swelling over feet and productive cough. It was observed that 4% females and 16% males had raised JVP, and the difference was statistically significant (P = 0.042), implying that right heart failure was more common in males.

On modified MRC dyspnea scale, females reported more severe dyspnea when compared to males, this difference was statistically significant (P = 0.022) [Table 1].

When number of exacerbations of COPD in the past 1 year was compared, the mean number in females was 4.5 and that in males was 3.58. Females had statistically significant (P = 0.034) more exacerbations as compared to males. However, the mean number of hospitalizations per 1 year in females was 2.28 and that in males was 2.24, and the difference was statistically not significant (P = 0.831) [Table 1].

Out of 50 females, 46 (92%) had a history of biomass smoke exposure (average biomass exposure index: 137.82). There were no female smokers in our study. Out of 50 males, 42 (84%) were smokers (average smoking index: 28.76) and 8 (16%) were nonsmokers. The most common type of biomass fuel used was mixed (60%) (agricultural crop residues, wood, cow dung, charcoal). Twenty out of 50 females and 46 out of 50 males also had occupational exposure. The most common occupational exposure was farming/livestock workers [Table 2].

Table 2: Distribution of cases of chronic obstructive pulmonary disease according to the risk factors (n=100)

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After multiple logistic regression analysis, it was observed that, biomass exposure index (P = 0.008, adjusted odds ratio 6.40, 95% confidence interval [CI] 1.61–25.29) and age of the patient (P < 0.001, adjusted odds ratio 1.39, 95% CI 1.21–1.59) were statistically significant and independently associated with risk of severe COPD [Table 3].

Table 3: Multiple logistic regression analysis for predicting risk factors of severe chronic obstructive pulmonary disease

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On-6 min walk test, the mean distance covered by females was 253.6 m and that by males was 288.8 m. The difference was statistically significant (P = 0.005) [Table 4].

Table 4: Comparison of 6-min walk distance test, pulmonary function test, GOLD staging and BODE index between females and males with chronic obstructive pulmonary disease (n=100)

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The mean FEV1 in females was 52.12 with a standard deviation [SD] of 9.29 and that in males was 57.68 with a SD of 12.0. This difference was also statistically significant (P = 0.011) [Table 4].

There was no statistically significant difference between radiological and ECG findings between females and males except for hyperinflation, which was observed more in males (P = 0.028).

Majority of female patients belonged to GOLD Group D and majority of male patients belonged to GOLD Groups B and D. The difference was statistically significant.(P = 0.033). The mean BODE index was 4.98 in females and 4.24 in males and the difference was statistically significant (P = 0.014) [Table 4].

The strength of association between age and severity of the disease in females with COPD was studied. We found a significantly positive correlation between age of the patient and BODE index (r = 0.6391, P < 0.0001) and GOLD's staging (Rho = 0.6414, P < 0.0001). We also found a significantly positive correlation between biomass exposure index of the patient and BODE index (r = 0.7275, P < 0.0001) and GOLD's staging (Rho = 0.5793, P < 0.0001) [Table 5].

Table 5: Correlation of Age and Biomass Exposure Index with BODE index and GOLD's staging in Females with COPD (n=50)

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Discussion

For many years, COPD was considered as a disease of men, with higher global prevalence in men than in women. Today, the number of women with COPD is rapidly increasing. This development has been attributed to changes in the historical differences in smoking behavior and chronic exposure to indoor air pollution. Recent research has suggested that women may be more susceptible to the lung-damaging effects of smoking, but the findings are inconsistent.

Analysis of the data from 100 individuals (50 males and 50 females) with COPD demonstrated that females presented at slightly later age 62 years than males 59.52 years. This was similar to the observations made in the study by Olloquequi et al. which compared COPD associated with tobacco smoking with biomass exposure and found that the mean age in years for tobacco smoking was less than that for biomass exposure.^[9] However, in one of the previous studies,^[10] females with COPD were younger than males (mean age: 58.34 + 9.99 years vs. 61.57 + 10.37 years P < 0.001). The author gave an explanation that this could be because biomass exposure begins early in females who start cooking using wood stoves at a very early age and also sleep and eat in the same room where they cook. The present study is tertiary hospital based and one of the reasons for more age of presentation of females in our study could be the late referral of females from peripheral hospitals or gender inequalities in the primary care of COPD leading to underdiagnosis in females, as observed in the study by Delgado et al.^[11]

Among the various risk factors for COPD in females, various authors have found smoking as an important risk factor.^{[12],[13],[14]} There is an indirect evidence suggesting that for a given level of risk exposure, women are more susceptible to developing COPD or have more rapid disease progression than men. In our study, there were no female smokers. We observed biomass smoke exposure as the most common risk factor in females in our study. Forty-six (92%) females were exposed to smoke from biomass burning versus only 04 (08%) males (P ≤ 0.001 h). Studies conducted by Camp, et al., Tan et al. in CanCOLD study, and Dal Negro et al. showed that exposure to biomass fuel is an independent risk factor for COPD in women and they can have clinical characteristics and prognosis similar to that of smokers.^{[15],[16],[17]}

Analysis of data of symptomatology demonstrated that females manifested with more severe dyspnea, worse mMRC dyspnea score, more number of exacerbations, more severe airflow limitation, and more severe GOLD classification as compared to males. The results suggest that females are more significantly burdened by symptoms of COPD than men. This was in accordance with the reports from previous studies,^{[10],[18],[19]} probably displaying a severe expression of COPD in females.

A similar kind of observation was also reported by various authors.^{[20],[21],[22]} These differences between females and males observed in the study may be related either to gender-specific differences to susceptibility to the disease or to differential exposure to risk factors such as biomass fuels and tobacco exposure or to different thresholds of symptom awareness and reporting for men and women.

Mean 6-min walk distance in females was significantly less in females as compared to males, which has been observed previously.^[23],[24]

Abnormal pulmonary function test was seen in both the groups, but FEV1 was significantly lower in females as compared to males with COPD. This emphasized that the adverse effects of biomass smoke exposure on lungs were as significant as cigarette smoke exposure. This finding was consistent with results from previous studies.^[25],[26]

DeMeo et al. observed in their study that younger women had higher odds of being classified in GOLD Group D versus as compared to younger men, despite lower pack-years of smoking.^[27] As per the GOLD staging, the number of females was significantly more in GOLD Group D as compared to males with COPD. This different distribution between genders may reflect that women tend to report symptoms more often than men or experience higher exacerbations than males. This parameter was hardly analyzed in previous studies.

A similar result was seen for BODE'S index in the present study. It was consistent with the results reported by de Torres et al., who found that women had worse dyspnea, exercise capacity, and nutritional status at an earlier stage of the disease.^[28] We found a significantly positive correlation between age of the patient and BODE index. A positive correlation between COPD risk and age has been reported previously also^[29] (as the age increases, the severity of COPD also increases).

COPD can be sequelae of pulmonary tuberculosis (PTB). PLATINO study (2007) showed that COPD patients with a history of TB had more severe symptoms, poorer lung function, and more frequent exacerbations.^[30],[31] However, past history of PTB and its gender interaction was not analyzed in this study. We could not find a significantly positive correlation between the past history of PTB in females and BODE index and GOLD's criteria.

After multiple logistic regression analysis, it was observed that biomass exposure index and age of the patient were independently associated with risk of severe COPD. A study conducted by Balcan et al. revealed that the correlation analysis of FEV₁/FVC and FEV1 was statistically significant for the duration of exposure to biomass smoke, as the duration of biomass exposure increased, FEV₁/FVC and FEV1 were negatively affected.^[32]

Conclusion

We conclude that there are gender-related differences in COPD risk, progression, and outcomes. Females have more symptoms, more severe obstruction, more number of exacerbations, and more functional disability as compared to males with COPD. Females with COPD have biomass smoke exposure as the most common risk factor, leading to deranged pulmonary function test as significant as seen in smokers. Females with COPD have more severe disease at the time of presentation.

The causal relationship of these observed gender-specific differences could not be established in our study.

Study limitation

Few limitations of our study should be acknowledged. Our study had a small sample size and it was hospital-based study, so selection bias cannot be excluded. We presented results from a cross-sectional study with lung function measurements from only one time point. The fact that we did not find any female smokers limited the ability to assess the tobacco smoking effect in females.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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