Physiological markers and multimorbidity: A systematic review

Biomarkers of aging in frailty and age-associated disorders: State of the art and future perspective

According to the Geroscience concept that organismal aging and age-associated diseases share the same basic molecular mechanisms, the identification of biomarkers of age that can efficiently classify people as biologically older (or younger) than their chronological (i.e. calendar) age is becoming of paramount importance. These people will be in fact at higher (or lower) risk for many different age-associated diseases, including cardiovascular diseases, neurodegeneration, cancer, etc. In turn, patients suffering from these diseases are biologically older than healthy age-matched individuals. Many biomarkers that correlate with age have been described so far. The aim of the present review is to discuss the usefulness of some of these biomarkers (especially soluble, circulating ones) in order to identify frail patients, possibly before the appearance of clinical symptoms, as well as patients at risk for age-associated diseases. An overview of selected biomarkers will be discussed in this regard, in particular we will focus on biomarkers related to metabolic stress response, inflammation, and cell death (in particular in neurodegeneration), all phenomena connected to inflammaging (chronic, low-grade, age-associated inflammation). In the second part of the review, next-generation markers such as extracellular vesicles and their cargos, epigenetic markers and gut microbiota composition, will be discussed. Since recent progresses in omics techniques have allowed an exponential increase in the production of laboratory data also in the field of biomarkers of age, making it difficult to extract biological meaning from the huge mass of available data, Artificial Intelligence (AI) approaches will be discussed as an increasingly important strategy for extracting knowledge from raw data and providing practitioners with actionable information to treat patients.

COPD and multimorbidity: recognising and addressing a syndemic occurrence

Most patients with chronic obstructive pulmonary disease (COPD) have at least one additional, clinically relevant chronic disease. Those with the most severe airflow obstruction will die from respiratory failure, but most patients with COPD die from non-respiratory disorders, particularly cardiovascular diseases and cancer. As many chronic diseases have shared risk factors (eg, ageing, smoking, pollution, inactivity, and poverty), we argue that a shift from the current paradigm in which COPD is considered as a single disease with comorbidities, to one in which COPD is considered as part of a multimorbid state-with co-occurring diseases potentially sharing pathobiological mechanisms-is needed to advance disease prevention, diagnosis, and management. The term syndemics is used to describe the co-occurrence of diseases with shared mechanisms and risk factors, a novel concept that we propose helps to explain the clustering of certain morbidities in patients diagnosed with COPD. A syndemics approach to understanding COPD could have important clinical implications, in which the complex disease presentations in these patients are addressed through proactive diagnosis, assessment of severity, and integrated management of the COPD multimorbid state, with a patient-centred rather than a single-disease approach.

Association of cardiovascular health using Life's Essential 8 with noncommunicable disease multimorbidity

Cardiovascular health (CVH) is closely associated with various noncommunicable diseases (NCDs) and comorbidity; however, the influence of CVH on NCD multimorbidity was not fully elucidated. We aimed to examine the association between CVH using Life's Essential 8 (LE8) and NCD multimorbidity among adults, males, and females in the United States, conducting a cross-sectional analysis using data involving 24,445 participants from the National Health and Nutrition Examination Survey (NHANES) from 2007 to 2018. LE8 was categorized into low, moderate, and high CVH groups. Multivariate logistic regressions and restricted cubic spline regressions were used to estimate the association between LE8 and NCD multimorbidity. Overall, 6162 participants had NCD multimorbidity, of which 1168 (43.5%), 4343 (25.9%), and 651 (13.4%) had low, moderate, and high CVH, separately. After multivariable adjustment, LE8 was negatively associated with NCD multimorbidity among adults (odds ratio (OR) for per 1 standard deviation (SD) increase in LE8 and 95% confidence interval (CI), 0.67 (0.64, 0.69)), and the top 3 NCDs associated with CVH were emphysema, congestive heart failure, stroke, and the dose-response relationships between LE8 and NCD multimorbidity were observed among adults (overall P < 0.001). Similar patterns were also identified among males and females. Higher CVH measured by the LE8 score was associated with lower odds of NCD multimorbidity among adults, males, and females.

Multi-morbidity and its association with common cancer diagnoses: a UK Biobank prospective study

BACKGROUND

Whilst multi-morbidity is known to be a concern in people with cancer, very little is known about the risk of cancer in multi-morbid patients. This study aims to investigate the risk of being diagnosed with lung, colorectal, breast and prostate cancer associated with multi-morbidity.

METHODS

We investigated the association between multi-morbidity and subsequent risk of cancer diagnosis in UK Biobank. Cox models were used to estimate the relative risks of each cancer of interest in multi-morbid participants, using the Cambridge Multimorbidity Score. The extent to which reverse causation, residual confounding and ascertainment bias may have impacted on the findings was robustly investigated.

RESULTS

Of the 436,990 participants included in the study who were cancer-free at baseline, 21.6% (99,965) were multi-morbid (≥ 2 diseases). Over a median follow-up time of 10.9 [IQR 10.0-11.7] years, 9,019 prostate, 7,994 breast, 5,241 colorectal, and 3,591 lung cancers were diagnosed. After exclusion of the first year of follow-up, there was no clear association between multi-morbidity and risk of colorectal, prostate or breast cancer diagnosis. Those with ≥ 4 diseases at recruitment had double the risk of a subsequent lung cancer diagnosis compared to those with no diseases (HR 2.00 [95% CI 1.70-2.35] p for trend < 0.001). These findings were robust to sensitivity analyses aimed at reducing the impact of reverse causation, residual confounding from known cancer risk factors and ascertainment bias.

CONCLUSIONS

Individuals with multi-morbidity are at an increased risk of lung cancer diagnosis. While this association did not appear to be due to common sources of bias in observational studies, further research is needed to understand what underlies this association.

A conceptual framework for characterising lifecourse determinants of multiple long-term condition multimorbidity

Objective

Social, biological and environmental factors in early-life, defined as the period from preconception until age 18, play a role in shaping the risk of multiple long-term condition multimorbidity. However, there is a need to conceptualise these early-life factors, how they relate to each other, and provide conceptual framing for future research on aetiology and modelling prevention scenarios of multimorbidity. We develop a conceptual framework to characterise the population-level domains of early-life determinants of future multimorbidity.

Method

This work was conducted as part of the Multidisciplinary Ecosystem to study Lifecourse Determinants and Prevention of Early-onset Burdensome Multimorbidity (MELD-B) study. The conceptualisation of multimorbidity lifecourse determinant domains was shaped by a review of existing research evidence and policy, and co-produced with public involvement via two workshops.

Results

Early-life risk factors incorporate personal, social, economic, behavioural and environmental factors, and the key domains discussed in research evidence, policy, and with public contributors included adverse childhood experiences, socioeconomics, the social and physical environment, and education. Policy recommendations more often focused on individual-level factors as opposed to the wider determinants of health discussed within the research evidence. Some domains highlighted through our co-production process with public contributors, such as religion and spirituality, health screening and check-ups, and diet, were not adequately considered within the research evidence or policy.

Conclusions

This co-produced conceptualisation can inform research directions using primary and secondary data to investigate the early-life characteristics of population groups at risk of future multimorbidity, as well as policy directions to target public health prevention scenarios of early-onset multimorbidity.

Home-built environment interventions and inflammation biomarkers: a systematic review and meta-analysis protocol

BACKGROUND

Inflammation control is a fundamental part of chronic care in patients with a history of cancer and comorbidity. As the risk-benefit profile of anti-inflammatory drugs is unclear in survivors of cancer, GPs and patients could benefit from alternative non-pharmacological treatment options for dysregulated inflammation. There is a potential for home-built environment (H-BE) interventions to modulate inflammation; however, discrepancies exist between studies.

AIM

To evaluate the effectiveness of H-BE interventions on cancer-associated inflammation biomarkers.

DESIGN & SETTING

A systematic review and meta-analysis of randomised and non-randomised trials in community-dwelling adults.

METHOD

PubMed and MEDLINE, Embase, Web of Science, and Google Scholar will be searched for clinical trials published in January 2000 onwards. The study will include H-BE interventions modifying air quality, thermal comfort, non-ionising radiation, noise, nature, and water. No restrictions to study population will be applied to allow deriving expectations for effects of the interventions in cancer survivors from available source populations. Outcome measures will be inflammatory biomarkers clinically and physiologically relevant to cancer. The first reviewer will independently screen articles together with GPs and extract data that will be verified by a second reviewer. The quality of studies will be assessed using the Cochrane risk-of-bias tools. Depending on the clinical and methodological homogeneity of populations, interventions, and outcomes, a meta-analysis will be conducted using random-effects models.

CONCLUSION

Findings will determine the effectiveness of H-BE interventions on inflammatory parameters, guide future directions for its provision in community-dwelling survivors of cancer and support GPs with safer anti-inflammatory treatment options in high-risk patients for clinical complications.

Improving the prognostic value of multimorbidity through the integration of selected biomarkers to the comprehensive geriatric assessment: An observational retrospective monocentric study

Background

Multimorbidity (MM) burdens individuals and healthcare systems, since it increases polypharmacy, dependency, hospital admissions, healthcare costs, and mortality. Several attempts have been made to determine an operational definition of MM and to quantify its severity. However, the lack of knowledge regarding its pathophysiology prevented the estimation of its severity in terms of outcomes. Polypharmacy and functional impairment are associated with MM. However, it is unclear how inappropriate drug decision-making could affect both conditions. In this context, promising circulating biomarkers and DNA methylation tools have been proposed as potential mortality predictors for multiple age-related diseases. We hypothesize that a comprehensive characterization of patients with MM that includes the measure of epigenetic and selected circulating biomarkers in the medical history, in addition to the functional capacity, could improve the prognosis of their long-term mortality.

Methods

This monocentric retrospective observational study was conducted as part of a project funded by the Italian Ministry of Health titled “imProving the pROgnostic value of MultimOrbidity through the inTegration of selected biomarkErs to the comprehensive geRiatric Assessment (PROMOTERA).” This study will examine the methylation levels of thousands of CpG sites and the levels of selected circulating biomarkers in the blood and plasma samples of older hospitalized patients with MM (n = 1,070, age ≥ 65 years) recruited by the Reportage Project between 2011 and 2019. Multiple statistical approaches will be utilized to integrate newly measured biomarkers into clinical, demographic, and functional data, thus improving the prediction of mortality for up to 10 years.

Discussion

This study's results are expected to: (i) identify the clinical, biological, demographic, and functional factors associated with distinct patterns of MM; (ii) improve the prognostic accuracy of MM patterns in relation to death, hospitalization-related outcomes, and onset of new comorbidities; (iii) define the epigenetic signatures of MM; (iv) construct multidimensional algorithms to predict negative health outcomes in both the overall population and specific disease and functional patterns; and (v) expand our understanding of the mechanisms underlying the pathophysiology of MM.

Mapping human disease-associated enzymes into Reactome allows characterization of disease groups and their interactions

According to databases such as OMIM, Humsavar, Clinvar and Monarch, 1494 human enzymes are presently associated to 2539 genetic diseases, 75% of which are rare (with an Orphanet code). The Mondo ontology initiative allows a standardization of the disease name into specific codes, making it possible a computational association between genes, variants, diseases, and their effects on biological processes. Here, we tackle the problem of which biological processes enzymes can affect when the protein variant is disease-associated. We adopt Reactome to describe human biological processes, and by mapping disease-associated enzymes in the Reactome pathways, we establish a Reactome-disease association. This allows a novel categorization of human monogenic and polygenic diseases based on Reactome pathways and reactions. Our analysis aims at dissecting the complexity of the human genetic disease universe, highlighting all the possible links within diseases and Reactome pathways. The novel mapping helps understanding the biochemical/molecular biology of the disease and allows a direct glimpse on the present knowledge of other molecules involved. This is useful for a complete overview of the disease molecular mechanism/s and for planning future investigations. Data are collected in DAR, a database that is free for search and available at https://dar.biocomp.unibo.it .

Systemic Inflammation Is Associated With Future Risk of Fatal Infection: An Observational Cohort Study

BACKGROUND

Many diseases are associated with chronic inflammation, resulting in widening application of anti-inflammatory therapies. Although they are effective as disease-modifying agents, these anti-inflammatory therapies increase the risk of serious infection; however, it remains unknown whether chronic systemic inflammation per se is also associated with fatal infection.

METHODS

Using serum C-reactive protein (CRP) data from 461 052 UK Biobank participants, we defined incidence rate ratios (IRRs) for death from infection, cardiovascular disease, or other causes and adjusted for comorbidities and the use of anti-inflammatory therapies.

RESULTS

Systemic inflammation, defined as CRP ≥2 mg/L, was common in all comorbidities considered. After adjusting for confounding factors, systemic inflammation was associated with a higher IRR point estimate for infection death (1.70; 95% confidence interval [CI], 1.51-1.92) than cardiovascular (1.48; CI, 1.40-1.57) or other death (1.41; CI, 1.37-1.45), although CIs overlapped. C-reactive protein thresholds of ≥5 and ≥10 mg/L yielded similar findings, as did analyses in people with ≥2, but not <2, comorbidities.

CONCLUSIONS

Systemic inflammation per se identifies people at increased risk of infection death, potentially contributing to the observed risks of anti-inflammatory therapies in clinical trials. In future clinical trials of anti-inflammatory therapies, researchers should carefully consider risks and benefits in target populations, guided by research into mechanisms of infection risk.

Combined use of the GRACE ACS risk score and comorbidity indices to increase the effectiveness of hospital mortality risk assessment in patients with acute coronary syndrome

Aim. To assess the possibilities of using comorbidity indices together with the GRACE (Global Registry of Acute Coronary Events) scale to assess the risk of hospital mortality in acute coronary syndrome (ACS). Materials and methods. The registry study included 2,305 patients with ACS. The frequency of coronary angiography was 54.0%, percutaneous coronary intervention (PCI) 26.9%. Hospital mortality with ACS was 4.8%, with myocardial infarction 9.4%. All patients underwent a comorbidity assessment according to the CIRS system (Cumulative Illness Rating Scale), according to the CCI (Charlson Comorbidity Index) and the CDS (Chronic Disease Score) scale, according to their own scale, which is based on the summation of 9 diseases (diabetes mellitus, atrial fibrillation, stroke, arterial hypertension, obesity, peripheral atherosclerosis, thrombocytopenia, anemia, chronic kidney disease). All patients underwent a mortality risk assessment using the GRACE ACS Risk scale. Results. It was found that the CDS and CIRS indices are not associated with the risk of hospital mortality. With CCI3, the frequency of death outcomes increased from 4.1 to 6.1% (2=4.12, p=0.042). With an increase in the severity of comorbidity from minimal (no more than 1 disease) to severe (4 or more diseases) according to its own scale, hospital mortality increased from 1.2 to 7.4% (2=23.8, p0.0001). In contrast to other scales of comorbidity, our own model more efficiently estimates the hospital prognosis both in the conservative treatment group (2=8.0, p=0.018) and in the PCI group (2=28.5, p=0.00001). It was in the PCI subgroup that the comorbidity factors included in their own model made it possible to increase the area under the ROC curve of the GRACE scale from 0.80 (0.740.87) to 0.90 (0.850.95). Conclusion. CCI and its own comorbidity model, but not CDS and CIRS, are associated with the risk of hospital mortality. The model for assessing comorbidity on a 9-point scale, but not CCI, CDS and CIRS, can significantly improve the predictive value of the GRACE scale.

Multimorbidity

Multimorbidity (two or more coexisting conditions in an individual) is a growing global challenge with substantial effects on individuals, carers and society. Multimorbidity occurs a decade earlier in socioeconomically deprived communities and is associated with premature death, poorer function and quality of life and increased health-care utilization. Mechanisms underlying the development of multimorbidity are complex, interrelated and multilevel, but are related to ageing and underlying biological mechanisms and broader determinants of health such as socioeconomic deprivation. Little is known about prevention of multimorbidity, but focusing on psychosocial and behavioural factors, particularly population level interventions and structural changes, is likely to be beneficial. Most clinical practice guidelines and health-care training and delivery focus on single diseases, leading to care that is sometimes inadequate and potentially harmful. Multimorbidity requires person-centred care, prioritizing what matters most to the individual and the individual's carers, ensuring care that is effectively coordinated and minimally disruptive, and aligns with the patient's values. Interventions are likely to be complex and multifaceted. Although an increasing number of studies have examined multimorbidity interventions, there is still limited evidence to support any approach. Greater investment in multimorbidity research and training along with reconfiguration of health care supporting the management of multimorbidity is urgently needed.

The Role of Extracellular Vesicles as a Shared Disease Mechanism Contributing to Multimorbidity in Patients With COPD

Chronic obstructive pulmonary disease (COPD) is one of the leading causes of death worldwide. Individuals with COPD typically experience a progressive, debilitating decline in lung function as well as systemic manifestations of the disease. Multimorbidity, is common in COPD patients and increases the risk of hospitalisation and mortality. Central to the genesis of multimorbidity in COPD patients is a self-perpetuating, abnormal immune and inflammatory response driven by factors including ageing, pollutant inhalation (including smoking) and infection. As many patients with COPD have multiple concurrent chronic conditions, which require an integrative management approach, there is a need to greater understand the shared disease mechanisms contributing to multimorbidity. The intercellular transfer of extracellular vesicles (EVs) has recently been proposed as an important method of local and distal cell-to-cell communication mediating both homeostatic and pathological conditions. EVs have been identified in many biological fluids and provide a stable capsule for the transfer of cargo including proteins, lipids and nucleic acids. Of these cargo, microRNAs (miRNAs), which are short 17-24 nucleotide non-coding RNA molecules, have been amongst the most extensively studied. There is evidence to support that miRNA are selectively packaged into EVs and can regulate recipient cell gene expression including major pathways involved in inflammation, apoptosis and fibrosis. Furthermore changes in EV cargo including miRNA have been reported in many chronic diseases and in response to risk factors including respiratory infections, noxious stimuli and ageing. In this review, we discuss the potential of EVs and EV-associated miRNA to modulate shared pathological processes in chronic diseases. Further delineating these may lead to the identification of novel biomarkers and therapeutic targets for patients with COPD and multimorbidities.

Multimorbidity and Regional Volumes of the Default Mode Network in Brain Aging

INTRODUCTION

The default mode network (DMN) is selectively vulnerable in brain aging. Little is known about the effect of multimorbidity as a whole onto the brain structural integrity.

OBJECTIVE

We aimed to investigate the association between multimorbidity and the structural integrity of DMN.

METHODS

We enrolled senior volunteers aged between 60 and 80 years in Hualien County during 2014-2018 and conducted in-person interview to collect information on chronic diseases. Fasting blood glucose and glycated hemoglobin (HbA1c) were tested. We assessed multimorbidity burden by the cumulative illness rating scale-geriatric (CIRS-G). MRI brain scans were standardized to measure the regional volume within the DMN. In a cross-sectional design, we employed stepwise regression models to evaluate the effects of age, sex, hyperglycemia, and multimorbidity on the DMN.

RESULTS

A total of 170 volunteers were enrolled with a mean age of 66.9 years, female preponderance (71%), an average mini-mental state examination score of 27.6, a mean HbA1c of 6.0, and a mean CIRS-G total score (TS) of 7.2. We found that older age was associated with reduced volumes in the hippocampus, left rostral anterior cingulate cortex, right posterior cingulate, right isthmus, precuneus, and right supramarginal. Higher levels of HbA1c and fasting glucose were associated with a reduced volume in the hippocampus only. A higher CIRS-G-TS was associated with reduced volumes in the left posterior cingulate cortex and right supramarginal gyrus; while a higher CIRS-G severity index was associated with a smaller right precuneus and right supramarginal.

CONCLUSIONS

In the DMN, hippocampal volume shows vulnerability to aging and hyperglycemia, whereas the posterior cingulate, supramarginal, and precuneus cortices may be the key sites to reflect the total effects of multimorbidity.

The role of C-reactive protein as a prognostic marker in COVID-19

Background

C-reactive protein (CRP) is a non-specific acute phase reactant elevated in infection or inflammation. Higher levels indicate more severe infection and have been used as an indicator of COVID-19 disease severity. However, the evidence for CRP as a prognostic marker is yet to be determined. The aim of this study is to examine the CRP response in patients hospitalized with COVID-19 and to determine the utility of CRP on admission for predicting inpatient mortality.

Methods

Data were collected between 27 February and 10 June 2020, incorporating two cohorts: the COPE (COVID-19 in Older People) study of 1564 adult patients with a diagnosis of COVID-19 admitted to 11 hospital sites (test cohort) and a later validation cohort of 271 patients. Admission CRP was investigated, and finite mixture models were fit to assess the likely underlying distribution. Further, different prognostic thresholds of CRP were analysed in a time-to-mortality Cox regression to determine a cut-off. Bootstrapping was used to compare model performance [Harrell’s C statistic and Akaike information criterion (AIC)].

Results

The test and validation cohort distribution of CRP was not affected by age, and mixture models indicated a bimodal distribution. A threshold cut-off of CRP ≥40 mg/L performed well to predict mortality (and performed similarly to treating CRP as a linear variable).

Conclusions

The distributional characteristics of CRP indicated an optimal cut-off of ≥40 mg/L was associated with mortality. This threshold may assist clinicians in using CRP as an early trigger for enhanced observation, treatment decisions and advanced care planning.

Importance of Dehydroepiandrosterone Sulfate Assessment with Special Attention for Adrenal Tumours and Arterial Hypertension

OBJECTIVE

To investigate the significance of DHEAS assessment in males of different ages.

METHODS

Retrospective cohort study of patients investigated in two large academic centres.

RESULTS

The data of DHEAS assessment of 3533 patients (3013 females and 520 males) was analysed. DHEAS was 1.6 - 13.5 times more frequently investigated in women than in men. A peak of DHEAS evaluation test for women was at 25 years old and distribution was uniform in males over decades, excepting being lower in 0-9 and 75+ages. In the age group 10-24 years, DHEAS levels were higher in females. After 45 years, DHEAS was higher in men than in women. Analysis of 510 case records showed low DHEAS levels in boys (0-9 years) and in men aged 65 - 84+. Higher DHEAS levels were detected as a peak at 30 years old, but never after 55 years. In individuals with low DHEAS levels prevailed congenital adrenal hyperplasia (32%), adrenal tumours (30%) and primary or secondary adrenal insufficiency (19%). High DHEAS levels prevailed in patients with arterial hypertension (26%), overweight-obesity -(19%), non-toxic goiter (17%) and alopecia (9%). In the normal DHEAS miscellaneous diagnoses were met most frequently - 40%. Disorders exceeding 5% were non-toxic goiter (19%), adrenal tumours - 17%, overweight/obesity - 16% and arterial hypertension- 8%. In 71 women and 124 men adrenal neoplasms were detected. Higher frequency of these was observed in women in their 30s. A peak of adrenal neoplasms in men was at their 70s. This gender difference was not conditioned by earlier attempts to seek medical care by women. A significant correlation of DHEAS, weight, body mass index and systolic blood pressure with diastolic blood pressure was found.

CONCLUSION

Our study permits to determine which DHEAS secretion and clinical pattern might be associated in males of different ages.

Blood Dehydroepiandrosterone and Dehydroepiandrosterone Sulfate as Pathophysiological Correlates of Chronic Pain: Analyses Using a National Sample of Midlife Adults in the United States

OBJECTIVE

Identifying biomarkers is a priority in translational chronic pain research. Dehydroepiandrosterone (DHEA) and its sulfated form, DHEA-S, are adrenocortical steroids in the blood with neuroprotective properties that also produce sex hormones. They may capture key sex-specific neuroendocrine mechanisms of chronic pain.

DESIGN

Cross-sectional study.

METHODS

Using data from 1,216 community-dwelling adults aged 34-84 from the Midlife in the United States (MIDUS) cohort, we examined blood DHEA and DHEA-S levels in association with chronic pain in men and women, adjusting for demographics, chronic diseases, medications including opioids, and psychosocial factors. If an association was found, we further explored dose-response relationships by the number of pain locations and the degree of pain interference.

RESULTS

In women, chronic pain was associated with 0.072 lower (95% confidence interval [CI], -0.127 to -0.017) log10 DHEA-S µg/dL, with pain in one to two locations associated with 0.068 lower (95% CI, -0.131 to -0.006) and in three or more locations 0.071 lower (95% CI, -0.148 to 0.007) log10 DHEA-S (P for trend = 0.074). Furthermore for women, low-interference pain was associated with 0.062 lower (95% CI, -0.125 to -0.000), whereas high-interference pain was associated with 0.138 lower (95% CI, -0.233 to -0.043) log10 DHEA-S (P for trend = 0.004). Chronic pain was not associated with DHEA or DHEA-S levels in men or DHEA levels in women.

CONCLUSIONS

Chronic pain and its functional interference correspond to lower blood DHEA-S levels in women.

Multimorbidity and population at risk for severe COVID-19 in the Brazilian Longitudinal Study of Aging

This study aimed to measure the occurrence of multimorbidity and to estimate the number of individuals in the Brazilian population 50 years or older at risk for severe COVID-19. This was a cross-sectional nationwide study based on data from the Brazilian Longitudinal Study of Aging (ELSI-Brazil), conducted in 2015-2016, with 9,412 individuals 50 years or older. Multimorbidity was defined as ≥ 2 chronic conditions based on a list of 15 diseases considered risk conditions for severe COVID-19. The analyses included calculation of prevalence and estimation of the absolute number of persons in the population at risk. Self-rated health status, frailty, and basic activities of daily living were used as markers of health status. Sex, age, region of the country, and schooling were used as covariables. Some 80% of the sample had at least one of the target conditions, which represents some 34 million individuals. Multimorbidity was reported by 52% of the study population, with higher proportions in the Central, Southeast, and South of Brazil. Cardiovascular diseases and obesity were the most frequent chronic conditions. An estimated 2.4 million Brazilians are at serious health risk. The results revealed inequalities according to schooling. The number of persons 50 years or older who presented risk conditions for severe COVID-19 is high both in absolute and relative terms. The estimate is important for planning strategies to monitor persons with chronic conditions and for preventive strategies to deal with the novel coronavirus.