Prevalence of chronic obstructive pulmonary disease at high altitude: a systematic review and meta-analysis

Chronic obstructive pulmonary disease in East Africa: a systematic review and meta-analysis

Chronic obstructive pulmonary disease (COPD) is a common lung disease that causes restricted airflow and breathing problems. Globally, COPD is the third leading cause of death and low- and middle-income countries account for the majority of these deaths. There is limited information on COPD's prevalence in East Africa. Thus the purpose of this systematic review and meta-analysis is to estimate the pooled prevalence of COPD in East Africa.A computerized systematic search using multiple databases was performed in search of relevant English articles from the inception of the databases to August 2023. All the authors independently extracted the data. R and RStudio software were used for statistical analysis. Forest plots and tables were used to represent the data. The statistical heterogeneity was evaluated using I2 statistics. There was heterogeneity between the included articles. Therefore, a meta-analysis of random effects models was used to estimate the overall pooled prevalence of COPD in East Africa. A funnel plot test was used to examine possible publication bias.The database search produced 512 papers. After checking for inclusion and exclusion criteria, 43 full-text observational studies with 68 553 total participants were found suitable for the review. The overall pooled prevalence of COPD in East Africa was 13.322%. The subgroup analysis found the COPD pooled prevalence in the different countries was 18.994%, 7%, 15.745%, 9.032%, 15.026% and 11.266% in Ethiopia, Uganda, Tanzania, Malawi, Sudan, and Kenya, respectively. Additionally, the subgroup analysis of COPD by study setting among community-based studies was 12.132% and 13.575% for hospital-based studies.According to the study's findings, approximately one of every seven individuals in East Africa has COPD, indicating a notably high prevalence of the disease. Thus governments and other stakeholders working on non-communicable disease control should place an emphasis on preventive measures to minimize the burden of COPD.

Identifying risk factors for COPD and adult-onset asthma: an umbrella review

BACKGROUND

COPD and adult-onset asthma (AOA) are the most common noncommunicable respiratory diseases. To improve early identification and prevention, an overview of risk factors is needed. We therefore aimed to systematically summarise the nongenetic (exposome) risk factors for AOA and COPD. Additionally, we aimed to compare the risk factors for COPD and AOA.

METHODS

In this umbrella review, we searched PubMed for articles from inception until 1 February 2023 and screened the references of relevant articles. We included systematic reviews and meta-analyses of observational epidemiological studies in humans that assessed a minimum of one lifestyle or environmental risk factor for AOA or COPD.

RESULTS

In total, 75 reviews were included, of which 45 focused on risk factors for COPD, 28 on AOA and two examined both. For asthma, 43 different risk factors were identified while 45 were identified for COPD. For AOA, smoking, a high body mass index (BMI), wood dust exposure and residential chemical exposures, such as formaldehyde exposure or exposure to volatile organic compounds, were amongst the risk factors found. For COPD, smoking, ambient air pollution including nitrogen dioxide, a low BMI, indoor biomass burning, childhood asthma, occupational dust exposure and diet were amongst the risk factors found.

CONCLUSIONS

Many different factors for COPD and asthma have been found, highlighting the differences and similarities. The results of this systematic review can be used to target and identify people at high risk for COPD or AOA.

Development and validation of nomogram including high altitude as a risk factor for COPD: A cross-sectional study based on Gansu population

Background

Chronic Obstructive Pulmonary Disease (COPD) is a common and harmful disease that requires an effective tool to early screen high-risk individuals. Gansu has unique environments and customs, leading to the different prevalence and etiology of COPD from other regions. The association between altitude and COPD once attracted epidemiologists' attention. However, the prevalence in Gansu and the role of altitude are still unclarified.

Methods

In Gansu, a multistage stratified cluster sampling procedure was utilized to select a representative sample aged 40 years or older. The questionnaire and spirometry examination were implemented to collect participants' information. The diagnosis and assessment of COPD were identified by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criterion, while post-bronchodilator FEV₁/FVC < LLN was for sensitivity analysis. Furthermore, the effect of high altitude on COPD was evaluated by the logistic regression model after propensity score matching (PSM). Finally, the participants were randomly divided into training and validation sets. The training set was used to screen the relative factors and construct a nomogram which was further assessed by the receiver operating characteristic (ROC) curve, calibration curve, and decision curve analysis (DCA) in the two sets.

Results

There were 2,486 eligible participants in the final analysis, of which 1,584 lived in low altitudes and 902 lived in high altitudes. Based on the GOLD criterion, the crude and standardized prevalences in Gansu were 20.4% (18.7-22.0) and 19.7% (17.9-21.6). After PSM, the logistic regression model indicated that high altitude increased COPD risk [PSM OR: 1.516 (1.162-1.978)]. Altitude, age, sex, history of tuberculosis, coal as fuel, and smoking status were reserved for developing a nomogram that demonstrated excellent discrimination, calibration, and clinical benefit in the two sets.

Conclusions

COPD has become a serious public health problem in Gansu. High altitude is a risk factor for COPD. The nomogram has satisfactory efficiency in screening high-risk individuals.

Investigation and Analysis of Risk Factors and Psychological Status of Chronic Obstructive Pulmonary Disease in Permanent Residents Aged 40 or Older in Hongyuan County, Aba Prefecture, Sichuan Province

Background

COPD is an important public health problem worldwide, and there is a lack of epidemiological data on COPD in high-altitude areas in Sichuan province. Thus, we aimed to investigate the prevalence, risk factors and psychological status of COPD in Hongyuan County, Aba Prefecture, Sichuan Province, which is located at an average altitude of 3507 meters.

Methods

The 40 years old or greater permanent residents of Hongyuan County were selected by random sampling method, and the lung function test and questionnaires were conducted to determine the disease situation of COPD. The prevalence of COPD was compared among different factors of investigation, and multivariate logistic regression analysis was used for different factors to determine the independent influencing factors of COPD disease.

Results

A total of 456 permanent residents aged 40 years or older in Hongyuan County, 436 qualified for quality control, among which 53 cases confirmed COPD, the total prevalence was 12.16%, among which the prevalence was 14.55% for men and it was 8.07% for women. There were significant differences in different gender, ethnicity, age, smoking status, smoking years, educational level, heating style, history of tuberculosis, and prevalence of BMI (P <0.05). Binary logistic regression analysis showed that age ≥60 years (OR = 2.810, 95% CI: 1.0457.557), Han Nationality (OR: 3.238, 95% CI: 1.290-8.127), the heating method including biofuels (OR: 18.119, 95% CI: 4.140-79.303) and coals (OR: 6.973, 95% CI: 1.856-26.200), medical history of pulmonary tuberculosis (OR: 2.670, 95% CI: 1.278-5.578), the education level including junior high school (OR: 3.336, 95% CI: 1.2259.075), high school and above (OR: 5.910, 95% CI: 1.796-19.450), and smoking (OR: 10.774, 95% CI: 3.622-32.051) were independent risk factors for COPD disease. The prevalence of anxiety was 16.98%, and the prevalence of depression was 13.2%.

Conclusion

The prevalence of COPD in Hongyuan County was higher than the national level; age, ethnic group, education, smoking, heating method, and history of tuberculosis are the independent influencing factors of COPD in Hongyuan County. The prevalence of anxiety and depression is low.

Pulmonary Hypertension in Acute and Chronic High Altitude Maladaptation Disorders

Alveolar hypoxia is the most prominent feature of high altitude environment with well-known consequences for the cardio-pulmonary system, including development of pulmonary hypertension. Pulmonary hypertension due to an exaggerated hypoxic pulmonary vasoconstriction contributes to high altitude pulmonary edema (HAPE), a life-threatening disorder, occurring at high altitudes in non-acclimatized healthy individuals. Despite a strong physiologic rationale for using vasodilators for prevention and treatment of HAPE, no systematic studies of their efficacy have been conducted to date. Calcium-channel blockers are currently recommended for drug prophylaxis in high-risk individuals with a clear history of recurrent HAPE based on the extensive clinical experience with nifedipine in HAPE prevention in susceptible individuals. Chronic exposure to hypoxia induces pulmonary vascular remodeling and development of pulmonary hypertension, which places an increased pressure load on the right ventricle leading to right heart failure. Further, pulmonary hypertension along with excessive erythrocytosis may complicate chronic mountain sickness, another high altitude maladaptation disorder. Importantly, other causes than hypoxia may potentially underlie and/or contribute to pulmonary hypertension at high altitude, such as chronic heart and lung diseases, thrombotic or embolic diseases. Extensive clinical experience with drugs in patients with pulmonary arterial hypertension suggests their potential for treatment of high altitude pulmonary hypertension. Small studies have demonstrated their efficacy in reducing pulmonary artery pressure in high altitude residents. However, no drugs have been approved to date for the therapy of chronic high altitude pulmonary hypertension. This work provides a literature review on the role of pulmonary hypertension in the pathogenesis of acute and chronic high altitude maladaptation disorders and summarizes current knowledge regarding potential treatment options.

Prevalence and Risk Factors for COPD at High Altitude: A Large Cross-Sectional Survey of Subjects Living Between 2,100-4,700 m Above Sea Level

Aim of Study: Four hundred million people live at high altitude worldwide. Prevalence and risk factors for COPD in these populations are poorly documented. We examined the prevalence and risk factors for COPD in residents living at an altitude of 2,100–4,700 m.

Methods: We performed a cross-sectional survey in Xinjiang and Tibet autonomous region. A multistage stratified sampling procedure was used to select a representative population aged 15 years or older from eight high altitude regions. All participants underwent pre- and post-bronchodilator measurement of forced expiratory volumes. COPD was diagnosed according to 2019 Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria.

Results: Between June, 2015 and August 2016, 4,967 subjects were included. Median age was 38.0 years (range: 15–91 years; inter-quartile range: 28–49 years); 51.4% participants were female. Overall prevalence of spirometry-defined COPD was 8.2% (95% CI 7.4–8.9%): 9.3% in male (95% CI 8.2–10.4%), and 7.1% in female (95% CI 6.1–8.2%). By multivariable logistic regression analysis, COPD was significantly associated with being aged ≥40 years (odds ratio: 2.25 [95% CI 1.72–2.95], P < 0.0001), exposure to household air pollution (OR: 1.34 [95% CI 1.01–1.79], P = 0.043), and a history of tuberculosis (OR: 1.79 [95% CI 1.23–2.61], P = 0.030), while living at a higher altitude (OR: 0.45 [95% CI 0.33–0.61], P < 0.0001) and having a higher educational level (OR: 0.64 [95% CI 0.43–0.95], P = 0.025) were associated with a lower prevalence of COPD.

Conclusions: Our results show that the spirometry-defined COPD is a considerable health problem for residents living at high altitudes and COPD prevalence was inversely correlated with altitude. Preventing exposure to household air pollution and reducing the incidence of tuberculosis should be public health priorities for high altitude residents.