Mickael Essouma

Is air pollution a risk factor for rheumatoid arthritis

Rheumatoid arthritis is a chronic inflammatory debilitating disease triggered by a complex interaction involving genetic and environmental factors. Active smoking and occupational exposures such as silica increase its risk, suggesting that initial inflammation and generation of rheumatoid arthritis-related autoantibodies in the lungs may precede the clinical disease. This hypothesis paved the way to epidemiological studies investigating air pollution as a potential determinant of rheumatoid arthritis. Studies designed for epidemiology of rheumatoid arthritis found a link between traffic, a surrogate of air pollution, and this disease. Furthermore, a small case–control study recently found an association between wood smoke exposure and anticyclic citrullinated protein/peptide antibody in sera of patients presenting wood-smoke-related chronic obstructive pulmonary disease. However, reports addressing impact of specific pollutants on rheumatoid arthritis incidence and severity across populations are somewhat conflicting. In addition to the link reported between other systemic autoimmune rheumatic diseases and particulate matters/gaseous pollutants, experimental observation of exacerbated rheumatoid arthritis incidence and severity in mice models of collagen-induced arthritis after diesel exhaust particles exposure as well as hypovitaminosis D-related autoimmunity can help understand the role of air pollution in rheumatoid arthritis. All these considerations highlight the necessity to extend high quality epidemiological researches investigating different sources of atmospheric pollution across populations and particularly in low-and-middle countries, in order to further explore the biological plausibility of air pollution’s effect in the pathogenesis of rheumatoid arthritis. This should be attempted to better inform policies aiming to reduce the burden of rheumatoid arthritis.

Therapeutic potential of folic acid supplementation for cardiovascular disease prevention through homocysteine lowering and blockade in rheumatoid arthritis patients

Rheumatoid arthritis (RA) is a chronic inflammatory disease that preferentially affects joints, and characterized by an approximately two-fold increased risk of cardiovascular diseases compared with the general population. Beyond classical cardiovascular risk factors, systemic inflammatory markers are primarily involved. Hence, anti-inflammatory strategies such as homocysteine-lowering interventions are warranted. Indeed, hyperhomocysteinemia is commonly found in RA patients as a result of both genetic and non-genetic factors including older age, male gender, disease-specific features and disease-modifying antirheumatic drugs. Most importantly in the pathophysiology of hyperhomocysteinemia and its related cardiovascular diseases in RA, there is a bi-directional link between immuno-inflammatory activation and hyperhomocysteinemia. As such, chronic immune activation causes B vitamins (including folic acid) depletion and subsequent hyperhomocysteinemia. In turn, hyperhomocysteinemia may perpetrate immuno-inflammatory stimulation via nuclear factor ƙappa B enhancement. This chronic immune activation is a key determinant of hyperhomocysteinemia-related cardiovascular diseases in RA patients. Folate, a homocysteine-lowering therapy could prove valuable for cardiovascular disease prevention in RA patients in the near future with respect to homocysteine reduction along with blockade of subsequent oxidative stress, lipid peroxidation, and endothelial dysfunction. Thus, large scale and long term homocysteine-lowering clinical trials would be helpful to clarify the association between hyperhomocysteinemia and cardiovascular diseases in RA patients and to definitely state conditions surrounding folic acid supplementation. This article reviews direct and indirect evidence for cardiovascular disease prevention with folic acid supplementation in RA patients.

The highly neglected burden of resistant hypertension in Africa: a systematic review and meta-analysis

Objective The hypertension epidemic in Africa collectively with very low rates of blood pressure control may predict an incremented prevalence of resistant hypertension (RH) across the continent. The aim of this study was to determine the prevalence of RH and associated risk factors in Africa. Data sources We conducted a comprehensive search of electronic databases (PubMed, EMBASE, Africa Wide Information and Africa Index Medicus) completed by manual search of articles, regardless of language or publication date. Methods We included studies which have reported the prevalence and/or risk factors for RH in Africa from inception to 19 May 2016. Forest plots were drawn to visualise the combined prevalence of RH and extent of statistical heterogeneity between studies. Results Out of 259 retrieved studies, only 5 from Cameroon, Nigeria, Burkina Faso, Lesotho and Algeria with a total population of 4 068 patients were finally included in this review. There was no study from the Eastern part of Africa. Though the definition of RH was not similar across studies, its prevalence was respectively 11.7%, 4.9%, 14.6%, 14.3% and 19.0%, with an overall pooled prevalence of 12.1% (95% CI 8.0% to 17.7%). Potential risk factors were: non-compliance to treatment, ageing, male sex, dyslipidaemia, metabolic syndrome, previous cardiovascular events, physical inactivity and stress, but not excessive salt intake, alcohol and coffee ingestions. Moreover, diabetes, smoking, obesity and renal insufficiency yielded discrepant results. Conclusions There is a huge dearth of research on the epidemiology of RH in Africa. Thereby, an extensive study of RH prevalence and risk factors is still largely warranted to curtail the high and continuously increasing burden of hypertension across Africa.

Targeting Household Air Pollution for Curbing the Cardiovascular Disease Burden: A Health Priority in Sub-Saharan Africa.

Household air pollution (HAP) is a major public health problem, particularly in sub‐Saharan Africa where most of the populations still rely on solid fuels for cooking, heating, and lighting. This narrative review highlights the direct and indirect evidence of the important role of HAP in cardiovascular disease, especially in sub‐Saharan African countries where highest rates of major cardiovascular disease and death are observed, and thus provides ample reason for promotion of preventive interventions to reduce HAP exposures in the region. There is an urgent need for efficient strategies to educate populations on the health issues associated with this health hazard, to provide affordable clean cooking energy for poor people and to promote improved household ventilation. High‐quality data on household energy practices and patterns of HAP and related health issues are still needed for efficient policy making in this region.

Hypertension prevalence, incidence and risk factors among children and adolescents in Africa: a systematic review and meta-analysis protocol

Introduction The African adult population is facing a growing epidemic of hypertension. Establishment of accurate epidemiological data on hypertension in African children and adolescents may have important implications for hypertension preventive strategies in Africa. Methods and analysis This systematic review and meta-analysis will follow the MOOSE Guidelines. Relevant abstracts published in English/French from 1 January 1985 to 31 July 2015 will be searched in PubMed, Google Scholar and Online African journals. Full texts of eligible studies will then be accessed through PubMed, Google Scholar, HINARI and the respective journals’ websites. Relevant unpublished papers and conference proceedings will also be checked. Data will be analysed using R statistical software. The study-specific estimates will be pooled through a random-effects meta-analysis model to obtain an overall summary estimate of the prevalence/incidence of hypertension across studies. Also, we will assess the association between risk factors and hypertension. Heterogeneity of studies will be evaluated by the χ2 test on Cochranes Q statistic. Funnel plots analysis and Eggers test will be done to detect publication bias. Results will be presented by geographic region (central, eastern, northern, southern and western Africa). A p value less than 0.05 will be considered significant for factors that predicted hypertension. Ethics and dissemination The current study is based on published data, and thus ethical approval is not required. This systematic review and meta-analysis is expected to serve as input for designing early life preventive and control strategies, and as a guide for future research based on existing gaps. The final report of the systematic review in the form of a scientific paper will be published in peer-reviewed journals. Findings will further be presented at conferences and submitted to relevant health authorities. Trial registration number CRD42015019029.

Heart failure in sub-Saharan Africa: A contemporaneous systematic review and meta-analysis

OBJECTIVE To summarise available data on the prevalence, aetiology, treatment and prognosis of heart failure (HF) in sub-Saharan Africa (SSA). SETTING This systematic review and meta-analysis included data from individuals recruited in primary to tertiary health facilities in SSA. PARTICIPANTS All published and unpublished literatures between January 1, 1996 and June 23, 2017, of individuals aged 12years and older and residing in sub-Saharan Africa. They must be of African descent. OUTCOME Number of heart failure admissions into general wards or HF clinics; number of cases of the different aetiologies of HF; number of participants on the different medications for HF; number of cases of all-cause mortality in participants with HF, and the predictors of all-cause mortality. Due to a limited word count, only results on the aetiologies of HF will be presented in the abstract. RESULTS Thirty five full text articles were selected after screening of an initial 3785 titles and abstract. Hypertensive heart disease (HHD) (39.2% [95% CI=32.6-45.9]) was the commonest cause of HF in SSA, followed by cardiomyopathies (CMO) (21.4% [95% CI=16.0-27.2]) and rheumatic heart disease (RHD) (14.1% [95% CI=10.0-18.8]). Ischaemic heart disease (7.2% [95% CI=4.1-11.0]) was rare. CONCLUSION HHD, CMO and RHD are the most common causes of HF in SSA, with HHD and CMO responsible for over 50% of the cases. Also, the last two decades have witnessed a relative reduction in the prevalence of RHD below 15.0%.

Data on the epidemiology of heart failure in Sub-Saharan Africa

In Sub-Saharan Africa (SSA), chronic non-communicable diseases and cardiovascular diseases in particular, are progressively taking over infectious diseases as the leading cause of morbidity and mortality. Heart failure is a major public health problem in the region. We summarize here available data on the prevalence, aetiologies, treatment, rates and predictors of mortality due to heart failure in SSA.

Prevalence of elevated blood pressure in children and adolescents in Africa: a systematic review and meta-analysis

BACKGROUND Despite substantial attention paid to the threat of elevated blood pressure in children and adolescents in high-income countries and the epidemic of hypertension in African adult populations, data on the burden of elevated blood pressure in African children and adolescents have not yet been synthesised. We did a systematic review and meta-analysis to provide estimates of the prevalence of elevated blood pressure and assess associated factors among children and adolescents in Africa. METHODS We searched Embase, PubMed, African Journals Online, and African Index Medicus to identify articles published from Jan 1, 1996, to Feb 2, 2017, and searched the reference list of retrieved articles. Each study was independently reviewed for methodological quality. We used a random-effects model to estimate the prevalence of elevated blood pressure across studies and heterogeneity (I2) was assessed via the χ2 test on Cochrans Q statistic. This review is registered with PROSPERO, number CRD42015019029. FINDINGS We included 51 studies in qualitative synthesis and 25 in the meta-analysis reporting data of a pooled sample of 54 196 participants aged 2-19 years. Study quality was high with only four medium-quality studies and no low-quality studies. Prevalence of elevated blood pressure varied widely across studies (range 0·2-24·8%). The pooled prevalence of elevated blood pressure (systolic or diastolic blood pressure ≥95th percentile) was 5·5% (95% CI 4·2-6·9), whereas that of slightly elevated blood pressure (systolic or diastolic blood pressure ≥90th percentile and <95th percentile) was 12·7% (2·1-30·4). The prevalence of elevated blood pressure was largely associated with body-mass index (BMI), with a prevalence of elevated blood pressure six times higher in obese (30·8%, 95% CI 20·1-42·6) versus normal-weight children (5·5%, 3·1-8·4; p<0·0001). INTERPRETATION This study suggests a high prevalence of elevated blood pressure among children and adolescents in Africa, with overweight and obesity being an important risk factor. Efforts to address this burden of elevated blood pressure in children and adolescents should mainly focus on primary prevention at the community level, by promoting healthy lifestyles and avoiding other cardiovascular risk factors, especially overweight and obesity. This study also stresses the need for more elaborate studies using uniform and reliable diagnostic methods to reliably map the burden of elevated blood pressure in children and adolescents in Africa. FUNDING None.

Are Systematic Screening for Vitamin D Deficiency and Vitamin D Supplementation Currently Feasible for Ankylosing Spondylitis Patients

Beyond its role in calcium and phosphorus metabolism for healthy bone mineralization, there is increasing awareness for vitamin D contribution in modulation of immune reactions. Given that ankylosing spondylitis (AS) is a chronic inflammatory disease involving excess immune/inflammatory activity and posing great therapeutic challenges, it is conceivable to claim that vitamin D treatment may be a safe and effective treatment to influence or modify the primary disease and its related comorbidities. Nevertheless, consistent body of research supporting this hypothesis is still lacking. In this paper, we examine whether systematic screening and treatment for vitamin D deficiency are feasible at present. We will review the immunomodulatory role of vitamin D and its contribution in initiation and progression of AS, as well as how they would determine the occurrence of comorbid conditions. Our conclusion is that despite the overwhelmed interest about vitamin D treatment in AS patients, systematic screening and treatment for vitamin D deficiency of all AS patients are not feasible as yet. This stresses the need for further extensive well-designed research to prove vitamin D efficacy in AS beyond bone protection. And if utility is proven, personalized treatment regimes, duration of treatment, and threshold values for vitamin D should be provided.

Household Air Pollution, Intermediate Outcomes, and Major Adverse Cardiovascular Events.

To the Editor: We read with interest the letter by Baumgartner and Clark that points to an important omission of the growing body of research linking household air pollution (HAP) with subclinical indicators of cardiovascular disease (CVD) risk including blood pressure, carotid atherosclerotic plaque, and arterial stiffness in our recent review “Targeting Household Air Pollution for Curbing the Cardiovascular Disease Burden: A Health Priority in Sub-Saharan Africa.” We are delighted to know that this review is already a topic of scientific discussions. We particularly welcome Baumgartner and Clark’s information on up-to-date studies linking HAP to important subclinical indicators such as carotid atherosclerotic plaques and arterial stiffness. However, as clearly stated in our paper, we aimed to highlight the direct evidence of the important role of HAP in the occurrence of CVDs and indirect evidence from epidemiologic and mechanistic observations linking cardiovascular events with exposures to other air pollutant mixtures that have been more extensively studied, with an emphasis on sub-Saharan African countries where the highest rates of major CVDs and death are observed. The relationship between HAP and modifiable traditional cardiovascular risk factors such as high blood pressure was therefore out of the scope of our review; this relationship could be discussed within a specific review given the escalating body of epidemiologic and clinical evidence on the topic. Indeed, we reviewed the relationship between HAP and CVD including coronary heart disease and stroke, but not the relationship between HAP and cardiovascular risk factors, which is largely demonstrated as well and, hence, needs to be addressed in a whole article. With respect to our objective, we concluded that there is a link between HAP and major adverse cardiovascular events. However, we could not confirm whether this association is causal or not. Nonetheless, we speculated that HAP, which shares several common aspects with cigarette smoke exposure and ambient outdoor air pollution, is likely also causally associated with CVD through the same pathophysiological mechanisms. While we acknowledge that the growing body of research evaluating the association between HAP and subclinical indicators of cardiovascular risk push forward our understanding of the role of HAP in the development of CVD and the triggering of acute cardiac events, direct evidence of this role remains highly needed. In particular, whether HAP affects only intermediate outcomes such as blood pressure or also directly impacts the occurrence of cardiovascular events is still to be elucidated. HAP has been postulated as one of the major nontraditional risk factors that may independently account for the significant proportion of cardiovascular events––10% to 25% incidence of coronary disease––that is unexplained by traditional risk factors. Along this line, a recent study suggested that traditional cardiovascular risk factors (eg, high blood pressure and diabetes) alone cannot explain the huge burden of CVD in lowand middle-income countries. Taken together, direct mechanistic evidence from robust epidemiological and clinical research linking HAP and major CVDs and death (and not merely extrapolations from studies of HAP and intermediate outcomes) is still largely warranted to identify whether HAP directly affects the development of CVD.