Pathogenesis of chronic obstructive pulmonary disease : an African perspective

CITATION: Allwood, B. & Calligaro, G . 2015. Pathogenesis of chronic obstructive pulmonary disease : an African perspective. South African Medical Journal, 105(9):789, doi:10.7196/SAMJnew.8424.The original publication is available at http://www.samj.org.zaThe importance of chronic obstructive pulmonary disease (COPD) as a global health problem cannot be overstated. According to the latest World Health Organization statistics (2005), 210 million people suffer from COPD worldwide, and 5% of all deaths globally are estimated to be caused by this disease. This corresponds to >3 million deaths annually, of which 90% are thought to occur in low- and middle-income countries. While cigarette smoking remains the major risk factor, and much of the increase in COPD is associated with projected increases in tobacco use, epidemiological studies have demonstrated that in the majority of patients in developing countries the aetiology of COPD is multifactorial. This article summarises the epidemiology of and risk factors for COPD in Africa, including influences other than cigarette smoking that are important contributors to chronic irreversible airflow limitation in our setting.AFRIKAANSE OPSOMMING: Geen opsomming beskikbaarhttp://www.samj.org.za/index.php/samj/article/view/9973Publisher's versio

Endoscopic lung volume reduction in severe emphysema

Therapeutic options in severe emphysema are limited. Endoscopic lung volume reduction (ELVR) refers to bronchoscopically inducing volume loss to improve pulmonary mechanics and compliance, thereby reducing the work of breathing. Globally, this technique is increasingly used as treatment for advanced emphysema with the aim of obtaining similar functional advantages to surgical lung volume reduction, while reducing risks and costs. There is a growing body of evidence that certain well-defined subgroups of patients with advanced emphysema benefit from ELVR, provided that a systematic approach is followed and selection criteria are met. In addition to endobronchial valves, ELVR using endobronchial coils is now available in South Africa. The high cost of these interventions underscores the need for careful patient selection to best identify those likely to benefit from such procedures

Recommendations for the use of endoscopic lung volume reduction in South Africa: Role in the treatment of emphysema.

Emphysema is a very common cause of morbidity and mortality in South Africa (SA). Therapeutic options in severe emphysema are limited. Endoscopic lung volume reduction (ELVR) is increasingly being used internationally for the treatment of advanced emphysema in a subset of patients with advanced disease, aiming to obtain the same functional advantages as surgical lung volume reduction while reducing risks and costs. In addition to endobronchial valves, ELVR using endobronchial coils is now available in SA. The high cost of these interventions underscores the need for careful patient selection to best identify those who may or may not benefit from ELVR-related procedures. The Assembly on Interventional Pulmonology of the South African Thoracic Society appointed a committee comprising both local and international experts to extensively review all relevant evidence and provide advice on the use of ELVR in SA based on published evidence, expert opinion and local access to the various devices

Obstructive pulmonary disease in patients with previous tuberculosis: Pathophysiology of a community-based cohort

Background. An association between chronic airflow limitation (CAL) and a history of pulmonary tuberculosis (PTB) has been confirmed in epidemiological studies, but the mechanisms responsible for this association are unclear. It is debated whether CAL in this context should be viewed as chronic obstructive pulmonary disease (COPD) or a separate phenotype. Objective. To compare lung physiology and high-resolution computed tomography (HRCT) findings in subjects with CAL and evidence of previous (healed) PTB with those in subjects with smoking-related COPD without evidence of previous PTB. Methods. Subjects with CAL identified during a Burden of Obstructive Lung Disease (BOLD) study performed in South Africa were studied. Investigations included questionnaires, lung physiology (spirometry, body plethysmography and diffusing capacity) and quantitative HRCT scans to assess bronchial anatomy and the presence of emphysema (–200 HU). Findings in subjects with a past history and/or HRCT evidence of PTB were compared with those in subjects without these features. Results. One hundred and seven of 196 eligible subjects (54.6%) were enrolled, 104 performed physiology tests and 94 had an HRCT scan. Based on history and HRCT findings, subjects were categorised as no previous PTB (NPTB, n=31), probable previous PTB (n=33) or definite previous PTB (DPTB, n=39). Subjects with DPTB had a lower diffusing capacity (Δ=–17.7%; p=0.001) and inspiratory capacity (Δ=–21.5%; p=0.001) than NPTB subjects, and higher gas-trapping and fibrosis but not emphysema scores (Δ=+6.2% (p=0.021), +0.36% (p=0.017) and +3.5% (p=0.098), respectively). Conclusions. The mechanisms of CAL associated with previous PTB appear to differ from those in the more common smoking-related COPD and warrant further study..info:eu-repo/semantics/publishedVersio

The burden and determinants of post-TB lung disease in Tanzanian adults: a cross-sectional study

BACKGROUND: Post-TB lung disease (PTLD) is an important but under-recognised chronic respiratory disease in high TB burden settings such as Tanzania. METHODS: This was a cross-sectional survey of adults within 2 years of completion of TB treatment in Kilimanjaro, Tanzania. Data were collected using questionnaires (symptoms and exposures), spirometry and chest radiographs to assess outcome measures, which were correlated with daily life exposures, including environment and diet. RESULTS: Of the 219 participants enrolled (mean age: 45 years ± 10; 193 [88%] males), 98 (45%) reported chronic respiratory symptoms; 46 (22%) had received treatment for TB two or more times; and HIV prevalence was 35 (16%). Spirometric abnormalities were observed in 146 (67%). Chest X-ray abnormalities occurred in 177 (86%). A diagnosis of PTLD was made in 200 (91%), and half had clinically relevant PTLD. The prevalence of ≥Grade 3 modified Medical Research Council chronic bronchitis and dyspnoea was respectively 11% and 26%. Older age, multiple episodes of TB and poverty indicators were linked with clinically relevant PTLD. CONCLUSIONS: We found a substantial burden of PTLD in adults who had recently completed TB treatment in Tanzania. There is a pressing need to identify effective approaches for both the prevention and management of this disease

An investigation into the correlation of vitamin D status and management outcomes in patients with severe COVID-19 at a South African tertiary hospital

Background: Severe coronavirus disease 2019 (COVID-19) has a poor prognosis, and biomarkers may predict disease severity. The aim of this study was to assess the effect of baseline vitamin D (VitD) inadequacy on the outcomes of patients with severe COVID-19 admitted to the intensive care unit (ICU) of a tertiary hospital in South Africa. // Methods: Patients with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were recruited during wave II of the pandemic in Cape Town. Eighty-six patients were included in the study. They were categorized into three groups: VitD deficient, VitD insufficient, and VitD sufficient. The VitD deficient and VitD insufficient groups were combined to form a ‘VitD inadequate’ group. Cox regression analysis was done to assess the association between VitD status and mortality. Factors with P < 0.05 in the adjusted multivariable Cox regression analysis were considered statistically significant. // Results: The proportion of VitD inadequacy was 64% (55/86); this group had a significantly higher proportion with hypertension (66%; P = 0.012). The Kaplan–Meier curve showed no significant difference in the probability of survival among the COVID-19 patients admitted to the ICU with or without VitD inadequacy. However, patients with elevated serum creatinine were significantly more at risk of dying (adjusted hazard ratio 1.008, 95% confidence interval 1.002–1.030; P = 0.017). // Conclusions: This study found a high prevalence of VitD inadequacy (combined deficiency and insufficiency) in COVID-19 patients admitted to the ICU. This may indicate a possible risk of severe disease. Whilst there was no statistically significant relationship between VitD status and mortality in this cohort, baseline VitD may be an important prognostic biomarker in COVID-19 patients admitted to the ICU, particularly in those with comorbidities that predispose to VitD deficiency

Obstructive pulmonary disease in patients with previous tuberculosis: Pathophysiology of a community-based cohort

Background. An association between chronic airflow limitation (CAL) and a history of pulmonary tuberculosis (PTB) has been confirmed in epidemiological studies, but the mechanisms responsible for this association are unclear. It is debated whether CAL in this context should be viewed as chronic obstructive pulmonary disease (COPD) or a separate phenotype.Objective. To compare lung physiology and high-resolution computed tomography (HRCT) findings in subjects with CAL and evidence of previous (healed) PTB with those in subjects with smoking-related COPD without evidence of previous PTB.Methods. Subjects with CAL identified during a Burden of Obstructive Lung Disease (BOLD) study performed in South Africa were studied. Investigations included questionnaires, lung physiology (spirometry, body plethysmography and diffusing capacity) and quantitative HRCT scans to assess bronchial anatomy and the presence of emphysema (&lt;–950 HU), gas trapping (&lt;–860 HU) and fibrosis (&gt;–200 HU). Findings in subjects with a past history and/or HRCT evidence of PTB were compared with those in subjects without these features.Results. One hundred and seven of 196 eligible subjects (54.6%) were enrolled, 104 performed physiology tests and 94 had an HRCT scan. Based on history and HRCT findings, subjects were categorised as no previous PTB (NPTB, n=31), probable previous PTB (n=33) or definite previous PTB (DPTB, n=39). Subjects with DPTB had a lower diffusing capacity (Δ=–17.7%; p=0.001) and inspiratory capacity (Δ=–21.5%; p=0.001) than NPTB subjects, and higher gas-trapping and fibrosis but not emphysema scores (Δ=+6.2% (p=0.021), +0.36% (p=0.017) and +3.5% (p=0.098), respectively).Conclusions. The mechanisms of CAL associated with previous PTB appear to differ from those in the more common smoking-related COPD and warrant further study

The utility of high-flow nasal oxygen for severe COVID-19 pneumonia in a resource-constrained setting: A multi-centre prospective observational study.

BACKGROUND: The utility of heated and humidified high-flow nasal oxygen (HFNO) for severe COVID-19-related hypoxaemic respiratory failure (HRF), particularly in settings with limited access to intensive care unit (ICU) resources, remains unclear, and predictors of outcome have been poorly studied. METHODS: We included consecutive patients with COVID-19-related HRF treated with HFNO at two tertiary hospitals in Cape Town, South Africa. The primary outcome was the proportion of patients who were successfully weaned from HFNO, whilst failure comprised intubation or death on HFNO. FINDINGS: The median (IQR) arterial oxygen partial pressure to fraction inspired oxygen ratio (PaO2/FiO2) was 68 (54-92) in 293 enroled patients. Of these, 137/293 (47%) of patients [PaO2/FiO2 76 (63-93)] were successfully weaned from HFNO. The median duration of HFNO was 6 (3-9) in those successfully treated versus 2 (1-5) days in those who failed (p<0.001). A higher ratio of oxygen saturation/FiO2 to respiratory rate within 6 h (ROX-6 score) after HFNO commencement was associated with HFNO success (ROX-6; AHR 0.43, 0.31-0.60), as was use of steroids (AHR 0.35, 95%CI 0.19-0.64). A ROX-6 score of ≥3.7 was 80% predictive of successful weaning whilst ROX-6 ≤ 2.2 was 74% predictive of failure. In total, 139 patents (52%) survived to hospital discharge, whilst mortality amongst HFNO failures with outcomes was 129/140 (92%). INTERPRETATION: In a resource-constrained setting, HFNO for severe COVID-19 HRF is feasible and more almost half of those who receive it can be successfully weaned without the need for mechanical ventilation

Clinical features and outcomes of COVID-19 admissions in a population with a high prevalence of HIV and tuberculosis: a multicentre cohort study

Background There is still a paucity of evidence on the outcomes of coronavirus disease 2019 (COVID-19) among people living with human immunodeficiency virus (PWH) and those co-infected with tuberculosis (TB), particularly in areas where these conditions are common. We describe the clinical features, laboratory findings and outcome of hospitalised PWH and human immunodeficiency virus (HIV)-uninfected COVID-19 patients as well as those co-infected with tuberculosis (TB). Methods We conducted a multicentre cohort study across three hospitals in Cape Town, South Africa. All adults requiring hospitalisation with confirmed COVID-19 pneumonia from March to July 2020 were analysed. Results PWH comprised 270 (19%) of 1434 admissions. There were 47 patients with active tuberculosis (3.3%), of whom 29 (62%) were PWH. Three-hundred and seventy-three patients (26%) died. The mortality in PWH (n = 71, 26%) and HIV-uninfected patients (n = 296, 25%) was comparable. In patients with TB, PWH had a higher mortality than HIV-uninfected patients (n = 11, 38% vs n = 3, 20%; p = 0.001). In multivariable survival analysis a higher risk of death was associated with older age (Adjusted Hazard Ratio (AHR) 1.03 95%CI 1.02–1.03, p < 0.001), male sex (AHR1.38 (95%CI 1.12–1.72, p = 0.003) and being “overweight or obese” (AHR 1.30 95%CI 1.03–1.61 p = 0.024). HIV (AHR 1.28 95%CI 0.95–1.72, p 0.11) and active TB (AHR 1.50 95%CI 0.84–2.67, p = 0.17) were not independently associated with increased risk of COVID-19 death. Risk factors for inpatient mortality in PWH included CD4 cell count < 200 cells/mm3, higher admission oxygen requirements, absolute white cell counts, neutrophil/lymphocyte ratios, C-reactive protein, and creatinine levels. Conclusion In a population with high prevalence of HIV and TB, being overweight/obese was associated with increased risk of mortality in COVID-19 hospital admissions, emphasising the need for public health interventions in this patient population

Trace elements at the intersection of marine biological and geochemical evolution

Life requires a wide variety of bioessential trace elements to act as structural components and reactive centers in metalloenzymes. These requirements differ between organisms and have evolved over geological time, likely guided in some part by environmental conditions. Until recently, most of what was understood regarding trace element concentrations in the Precambrian oceans was inferred by extrapolation, geochemical modeling, and/or genomic studies. However, in the past decade, the increasing availability of trace element and isotopic data for sedimentary rocks of all ages has yielded new, and potentially more direct, insights into secular changes in seawater composition – and ultimately the evolution of the marine biosphere. Compiled records of many bioessential trace elements (including Ni, Mo, P, Zn, Co, Cr, Se, and I) provide new insight into how trace element abundance in Earth's ancient oceans may have been linked to biological evolution. Several of these trace elements display redox-sensitive behavior, while others are redox-sensitive but not bioessential (e.g., Cr, U). Their temporal trends in sedimentary archives provide useful constraints on changes in atmosphere-ocean redox conditions that are linked to biological evolution, for example, the activity of oxygen-producing, photosynthetic cyanobacteria. In this review, we summarize available Precambrian trace element proxy data, and discuss how temporal trends in the seawater concentrations of specific trace elements may be linked to the evolution of both simple and complex life. We also examine several biologically relevant and/or redox-sensitive trace elements that have yet to be fully examined in the sedimentary rock record (e.g., Cu, Cd, W) and suggest several directions for future studies