Fundamental behaviors emerge from simulations of a living minimal cell.

We present a whole-cell fully dynamical kinetic model (WCM) of JCVI-syn3A, a minimal cell with a reduced genome of 493 genes that has retained few regulatory proteins or small RNAs. Cryo-electron tomograms provide the cell geometry and ribosome distributions. Time-dependent behaviors of concentrations and reaction fluxes from stochastic-deterministic simulations over a cell cycle reveal how the cell balances demands of its metabolism, genetic information processes, and growth, and offer insight into the principles of life for this minimal cell. The energy economy of each process including active transport of amino acids, nucleosides, and ions is analyzed. WCM reveals how emergent imbalances lead to slowdowns in the rates of transcription and translation. Integration of experimental data is critical in building a kinetic model from which emerges a genome-wide distribution of mRNA half-lives, multiple DNA replication events that can be compared to qPCR results, and the experimentally observed doubling behavior.

Evolutionary Ecology of Wolbachia Releases for Disease Control.

Wolbachia is an endosymbiotic Alphaproteobacteria that can suppress insect-borne diseases through decreasing host virus transmission (population replacement) or through decreasing host population density (population suppression). We contrast natural Wolbachia infections in insect populations with Wolbachia transinfections in mosquitoes to gain insights into factors potentially affecting the long-term success of Wolbachia releases. Natural Wolbachia infections can spread rapidly, whereas the slow spread of transinfections is governed by deleterious effects on host fitness and demographic factors. Cytoplasmic incompatibility (CI) generated by Wolbachia is central to both population replacement and suppression programs, but CI in nature can be variable and evolve, as can Wolbachia fitness effects and virus blocking. Wolbachia spread is also influenced by environmental factors that decrease Wolbachia titer and reduce maternal Wolbachia transmission frequency. More information is needed on the interactions between Wolbachia and host nuclear/mitochondrial genomes, the interaction between invasion success and local ecological factors, and the long-term stability of Wolbachia-mediated virus blocking.

Pregnancy is linked to faster epigenetic aging in young women.

A central prediction of evolutionary theory is that energy invested into reproduction comes at the expense of somatic maintenance and repair, accelerating biological aging. Supporting this prediction are findings that high fertility among women predicts shorter lifespan and poorer health later in life. However, biological aging is thought to begin before age-related health declines, limiting the applicability of morbidity and mortality for studying the aging process earlier in life. Here, we examine the relationship between reproductive history and biological aging in a sample of young (20 to 22yo) men and women from the Cebu Longitudinal Health and Nutrition Survey, located in the Philippines (n = 1,735). We quantify biological aging using six measures, collectively known as epigenetic clocks, reflecting various facets of cellular aging, health, and mortality risk. In a subset of women, we test whether longitudinal changes in gravidity between young and early-middle adulthood (25 to 31yo) are associated with changes in epigenetic aging during that time. Cross-sectionally, gravidity was associated with all six measures of accelerated epigenetic aging in women (n = 825). Furthermore, longitudinal increases in gravidity were linked to accelerated epigenetic aging in two epigenetic clocks (n = 331). In contrast, the number of pregnancies a man reported fathering was not associated with epigenetic aging among same-aged cohort men (n = 910). These effects were robust to socioecological, environmental, and immunological factors, consistent with the hypothesis that pregnancy accelerates biological aging and that these effects can be detected in young women in a high-fertility context.

Costs of being a diet generalist for the protist predator Dictyostelium discoideum.

Consumers range from specialists that feed on few resources to generalists that feed on many. Generalism has the clear advantage of having more resources to exploit, but the costs that limit generalism are less clear. We explore two understudied costs of generalism in a generalist amoeba predator, Dictyostelium discoideum, feeding on naturally co-occurring bacterial prey. Both involve costs of combining prey that are suitable on their own. First, amoebas exhibit a reduction in growth rate when they switched to one species of prey bacteria from another compared to controls that experience only the second prey. The effect was consistent across all six tested species of bacteria. These switching costs typically disappear within a day, indicating adjustment to new prey bacteria. This suggests that these costs are physiological. Second, amoebas usually grow more slowly on mixtures of prey bacteria compared to the expectation based on their growth on single prey. There were clear mixing costs in three of the six tested prey mixtures, and none showed significant mixing benefits. These results support the idea that, although amoebas can consume a variety of prey, they must use partially different methods and thus must pay costs to handle multiple prey, either sequentially or simultaneously.

Prospective, multi-site study of healthcare utilization after actionable monogenic findings from clinical sequencing.

As large-scale genomic screening becomes increasingly prevalent, understanding the influence of actionable results on healthcare utilization is key to estimating the potential long-term clinical impact. The eMERGE network sequenced individuals for actionable genes in multiple genetic conditions and returned results to individuals, providers, and the electronic health record. Differences in recommended health services (laboratory, imaging, and procedural testing) delivered within 12 months of return were compared among individuals with pathogenic or likely pathogenic (P/LP) findings to matched individuals with negative findings before and after return of results. Of 16,218 adults, 477 unselected individuals were found to have a monogenic risk for arrhythmia (n = 95), breast cancer (n = 96), cardiomyopathy (n = 95), colorectal cancer (n = 105), or familial hypercholesterolemia (n = 86). Individuals with P/LP results more frequently received services after return (43.8%) compared to before return (25.6%) of results and compared to individuals with negative findings (24.9%; p < 0.0001). The annual cost of qualifying healthcare services increased from an average of $162 before return to $343 after return of results among the P/LP group (p < 0.0001); differences in the negative group were non-significant. The mean difference-in-differences was $149 (p < 0.0001), which describes the increased cost within the P/LP group corrected for cost changes in the negative group. When stratified by individual conditions, significant cost differences were observed for arrhythmia, breast cancer, and cardiomyopathy. In conclusion, less than half of individuals received billed health services after monogenic return, which modestly increased healthcare costs for payors in the year following return.

Developmental energetics: Energy expenditure, budgets and metabolism during animal embryogenesis.

Developing embryos are metabolically active, open systems that constantly exchange matter and energy with their environment. They function out of thermodynamic equilibrium and continuously use metabolic pathways to obtain energy from maternal nutrients, in order to fulfill the energetic requirements of growth and development. While an increasing number of studies highlight the role of metabolism in different developmental contexts, the physicochemical basis of embryogenesis, or how cellular processes use energy and matter to act together and transform a zygote into an adult organism, remains unknown. As we obtain a better understanding of metabolism, and benefit from current technology development, it is a promising time to revisit the energetic cost of development and how energetic principles may govern embryogenesis. Here, we review recent advances in methodology to measure and infer energetic parameters in developing embryos. We highlight a potential common pattern in embryonic energy expenditure and metabolic strategy across animal embryogenesis, and discuss challenges and open questions in developmental energetics.

Forecasting the Economic Burden of Cardiovascular Disease and Stroke in the United States Through 2050: A Presidential Advisory From the American Heart Association.

BACKGROUND: Quantifying the economic burden of cardiovascular disease and stroke over the coming decades may inform policy, health system, and community-level interventions for prevention and treatment. METHODS: We used nationally representative health, economic, and demographic data to project health care costs attributable to key cardiovascular risk factors (hypertension, diabetes, hypercholesterolemia) and conditions (coronary heart disease, stroke, heart failure, atrial fibrillation) through 2050. The human capital approach was used to estimate productivity losses from morbidity and premature mortality due to cardiovascular conditions. RESULTS: One in 3 US adults received care for a cardiovascular risk factor or condition in 2020. Annual inflation-adjusted (2022 US dollars) health care costs of cardiovascular risk factors are projected to triple between 2020 and 2050, from $400 billion to $1344 billion. For cardiovascular conditions, annual health care costs are projected to almost quadruple, from $393 billion to $1490 billion, and productivity losses are projected to increase by 54%, from $234 billion to $361 billion. Stroke is projected to account for the largest absolute increase in costs. Large relative increases among the Asian American population (497%) and Hispanic American population (489%) reflect the projected increases in the size of these populations. CONCLUSIONS: The economic burden of cardiovascular risk factors and overt cardiovascular disease in the United States is projected to increase substantially in the coming decades. Development and deployment of cost-effective programs and policies to promote cardiovascular health are urgently needed to rein in costs and to equitably enhance population health.

Unpredictability of the Fitness Effects of Antimicrobial Resistance Mutations Across Environments in Escherichia coli.

The evolution of antimicrobial resistance (AMR) in bacteria is a major public health concern, and antibiotic restriction is often implemented to reduce the spread of resistance. These measures rely on the existence of deleterious fitness effects (i.e. costs) imposed by AMR mutations during growth in the absence of antibiotics. According to this assumption, resistant strains will be outcompeted by susceptible strains that do not pay the cost during the period of restriction. The fitness effects of AMR mutations are generally studied in laboratory reference strains grown in standard growth environments; however, the genetic and environmental context can influence the magnitude and direction of a mutation's fitness effects. In this study, we measure how three sources of variation impact the fitness effects of Escherichia coli AMR mutations: the type of resistance mutation, the genetic background of the host, and the growth environment. We demonstrate that while AMR mutations are generally costly in antibiotic-free environments, their fitness effects vary widely and depend on complex interactions between the mutation, genetic background, and environment. We test the ability of the Rough Mount Fuji fitness landscape model to reproduce the empirical data in simulation. We identify model parameters that reasonably capture the variation in fitness effects due to genetic variation. However, the model fails to accommodate the observed variation when considering multiple growth environments. Overall, this study reveals a wealth of variation in the fitness effects of resistance mutations owing to genetic background and environmental conditions, which will ultimately impact their persistence in natural populations.

The Economic Iceberg of Celiac Disease: More Than the Cost of Gluten-Free Food.

Celiac disease (CeD) is a chronic autoimmune disorder of global relevance, with the potential for acute and long-term complications. However, the economic burden of CeD is rarely considered and largely thought of as limited to the cost of gluten-free food. Fortunately, recent research has shed light on the various societal costs of CeD across the health care continuum. This article summarizes the current evidence on the economic impacts of CeD, which suggest that the societal economic burden of CeD stretches beyond the cost of gluten-free food. This review provides ample evidence of larger but hidden costs related to excess health care use for complications and comorbidities, as well as reduced productivity. Although significant advances are expected in the management of CeD, their effect on the economic burden of CeD remain uncertain. The aim of this review was to inform stakeholders across society and contribute to improved policies to support patients with CeD.

The financial burden and distress of patients with cancer: Understanding and stepping-up action on the financial toxicity of cancer treatment.

"Financial toxicity" has now become a familiar term used in the discussion of cancer drugs, and it is gaining traction in the literature given the high price of newer classes of therapies. However, as a phenomenon in the contemporary treatment and care of people with cancer, financial toxicity is not fully understood, with the discussion on mitigation mainly geared toward interventions at the health system level. Although important, health policy prescriptions take time before their intended results manifest, if they are implemented at all. They require corresponding strategies at the individual patient level. In this review, the authors discuss the nature of financial toxicity, defined as the objective financial burden and subjective financial distress of patients with cancer, as a result of treatments using innovative drugs and concomitant health services. They discuss coping with financial toxicity by patients and how maladaptive coping leads to poor health and nonhealth outcomes. They cover management strategies for oncologists, including having the difficult and urgent conversation about the cost and value of cancer treatment, availability of and access to resources, and assessment of financial toxicity as part of supportive care in the provision of comprehensive cancer care. CA Cancer J Clin 2018;68:153-165. © 2018 American Cancer Society.

Universal healthcare as pandemic preparedness: The lives and costs that could have been saved during the COVID-19 pandemic.

The fragmented and inefficient healthcare system in the United States leads to many preventable deaths and unnecessary costs every year. During a pandemic, the lives saved and economic benefits of a single-payer universal healthcare system relative to the status quo would be even greater. For Americans who are uninsured and underinsured, financial barriers to COVID-19 care delayed diagnosis and exacerbated transmission. Concurrently, deaths beyond COVID-19 accrued from the background rate of uninsurance. Universal healthcare would alleviate the mortality caused by the confluence of these factors. To evaluate the repercussions of incomplete insurance coverage in 2020, we calculated the elevated mortality attributable to the loss of employer-sponsored insurance and to background rates of uninsurance, summing with the increased COVID-19 mortality due to low insurance coverage. Incorporating the demography of the uninsured with age-specific COVID-19 and nonpandemic mortality, we estimated that a single-payer universal healthcare system would have saved about 212,000 lives in 2020 alone. We also calculated that US$105.6 billion of medical expenses associated with COVID-19 hospitalization could have been averted by a single-payer universal healthcare system over the course of the pandemic. These economic benefits are in addition to US$438 billion expected to be saved by single-payer universal healthcare during a nonpandemic year.

Encouraging voluntary government action via a solar-friendly designation program to promote solar energy in the United States.

SignificanceDue to market and system failures, policies and programs at the local level are needed to accelerate the renewable energy transition. A voluntary environmental program (VEP), such as SolSmart, can encourage local governments to adopt solar-friendly best practices. Unlike previous research, this study uses a national sample, more recent data, and a matched control group for difference-in-differences estimation to quantify the causal impact of a VEP in the public, rather than private, sector. We offer empirical evidence that SolSmart increased installed solar capacity and, with less statistical significance, the number of solar installations. The results inform the design of sustainability-focused VEPs and future research to understand the causal pathways between local governments' voluntary actions and solar market development.

Food Is Medicine: A Presidential Advisory From the American Heart Association.

Unhealthy diets are a major impediment to achieving a healthier population in the United States. Although there is a relatively clear sense of what constitutes a healthy diet, most of the US population does not eat healthy food at rates consistent with the recommended clinical guidelines. An abundance of barriers, including food and nutrition insecurity, how food is marketed and advertised, access to and affordability of healthy foods, and behavioral challenges such as a focus on immediate versus delayed gratification, stand in the way of healthier dietary patterns for many Americans. Food Is Medicine may be defined as the provision of healthy food resources to prevent, manage, or treat specific clinical conditions in coordination with the health care sector. Although the field has promise, relatively few studies have been conducted with designs that provide strong evidence of associations between Food Is Medicine interventions and health outcomes or health costs. Much work needs to be done to create a stronger body of evidence that convincingly demonstrates the effectiveness and cost-effectiveness of different types of Food Is Medicine interventions. An estimated 90% of the $4.3 trillion annual cost of health care in the United States is spent on medical care for chronic disease. For many of these diseases, diet is a major risk factor, so even modest improvements in diet could have a significant impact. This presidential advisory offers an overview of the state of the field of Food Is Medicine and a road map for a new research initiative that strategically approaches the outstanding questions in the field while prioritizing a human-centered design approach to achieve high rates of patient engagement and sustained behavior change. This will ideally happen in the context of broader efforts to use a health equity-centered approach to enhance the ways in which our food system and related policies support improvements in health.

Out-of-pocket costs for diagnostic testing following abnormal prostate cancer screening among privately insured men.

OBJECTIVE: Prostate cancer is the most common malignancy among men and following a positive prostate-specific antigen (PSA) screening test, patients may undergo more expensive diagnostic testing. However, testing-related out-of-pocket costs (OOPCs), which may preclude patients from completing the screening process, have not been previously quantified. OOPCs for follow-up diagnostic testing (i.e., prostate biopsy and/or magnetic resonance imaging [MRI]) in patients with private insurance undergoing prostate cancer screening were estimated. METHODS: Men ages 55 to 69 years old who underwent PSA-based prostate cancer screening from 2010 to 2020 from the IBM Marketscan database were identified. The number of patients undergoing follow-up diagnostic testing within 12 months of screening was tabulated, dividing patients into three groups: (1) biopsy only, (2) MRI only, and (3) MRI + biopsy. Over the study period, patients with nonzero cost-sharing and calculated inflation-adjusted OOPCs, adding copayment, coinsurance, and deductible payments, for each group were identified. RESULTS: Among screened patients (n = 3,075,841) from 2010 through 2020, 91,850 had a second PSA test and an elevated PSA level, of which 40,329 (43.9%) underwent subsequent diagnostic testing. More than 75% of these patients experienced cost-sharing, and median OOPCs rose substantially over the study period for patients undergoing biopsy only ($79 to $214), MRI only ($81 to $490), and MRI and biopsy ($353 to $620). CONCLUSIONS: OOPCs from diagnostic testing after prostate cancer screening are common and rising. This work aligns with the recent position statement from the American Cancer Society, that payers should eliminate cost-sharing, which may undermine the screening process, for diagnostic testing following cancer screening.

Cost-of-care discussions for individuals with advanced non-small cell lung cancer and melanoma: Findings from a large, population-based pilot study.

BACKGROUND: Costs of cancer care can result in patient financial hardship; many professional organizations recommend provider discussions about treatment costs as part of high-quality care. In this pilot study, the authors examined patient-provider cost discussions documented in the medical records of individuals who were diagnosed with advanced non-small cell lung cancer (NSCLC) and melanoma-cancers with recently approved, high-cost treatment options. METHODS: Individuals who were newly diagnosed in 2017-2018 with stage III/IV NSCLC (n = 1767) and in 2018 with stage III/IV melanoma (n = 689) from 12 Surveillance, Epidemiology, and End Results regions were randomly selected for the National Cancer Institute Patterns of Care Study. Documentation of cost discussions was abstracted from the medical record. The authors examined patient, treatment, and hospital factors associated with cost discussions in multivariable logistic regression analyses. RESULTS: Cost discussions were documented in the medical records of 20.3% of patients with NSCLC and in 24.0% of those with melanoma. In adjusted analyses, privately insured (vs. publicly insured) patients were less likely to have documented cost discussions (odds ratio [OR], 0.54; 95% confidence interval [CI], 0.37-0.80). Patients who did not receive systemic therapy or did not receive any cancer-directed treatment were less likely to have documented cost discussions than those who did receive systemic therapy (OR, 0.39 [95% CI, 0.19-0.81] and 0.46 [95% CI, 0.30-0.70], respectively), as were patients who were treated at hospitals without residency programs (OR, 0.64; 95% CI, 0.42-0.98). CONCLUSIONS: Cost discussions were infrequently documented in the medical records of patients who were diagnosed with advanced NSCLC and melanoma, which may hinder identifying patient needs and tracking outcomes of associated referrals. Efforts to increase cost-of-care discussions and relevant referrals, as well as their documentation, are warranted.

The impact of outpatient supportive oncology on cancer care cost and utilization.

BACKGROUND: Supportive oncology (SO) care reduces symptom severity, admissions, and costs in patients with advanced cancer. This study examines the impact of SO care on utilization and costs. METHODS: Retrospective analysis of utilization and costs comparing patients enrolled in SO versus three comparison cohorts who did not receive SO. Using claims, the authors estimated differences in health care utilization and cost between the treatment group and comparison cohorts. The treatment group consisting of patients treated for cancer at an National Cancer Institute-designated cancer center who received SO between January 2018 and December 2019 were compared to an asynchronous cohort that received cancer care before January 2018 (n = 60), a contemporaneous cohort with palliative care receiving SO care from other providers in the Southeastern Pennsylvania region during the program period (n = 86), and a contemporaneous cohort without palliative care consisting of patients at other cancer centers who were eligible for but did not receive SO care (n = 393). RESULTS: At 30, 60, and 90 days post-enrollment into SO, the treatment group had between 27% and 70% fewer inpatient admissions and between 16% and 54% fewer emergency department visits (p < .05) compared to non-SO cohorts. At 90 days following enrollment in SO care, total medical costs were between 4.4% and 24.5% lower for the treatment group across all comparisons (p < .05). CONCLUSIONS: SO is associated with reduced admissions, emergency department visits, and total costs in advanced cancer patients. Developing innovative reimbursement models could be a cost-effective approach to improve care of patients with advanced cancer.

Oncology drug pricing: potential Medicare savings on cancer-directed and supportive care medications through the Mark Cuban cost plus drug model.

Prescription drug costs within oncology remain a challenge for many patients with cancer. The Mark Cuban Cost Plus Drug Company (MCCPDC) launched in 2022, aiming to provide transparently priced medications at reduced costs. In this study, we sought to describe the potential impact of MCCPDC on Medicare Part-D oncology spending related to cancer-directed (n = 7) and supportive care (n = 26) drugs. We extracted data for drug-specific Part-D claims and spending for 2021. Using 90-count purchases from MCCPDC, we found potential Part-D savings of $857.8 million (91% savings) across the 7 cancer-directed drugs and $28.7 million (67% savings) across 21/26 (5/26 did not demonstrate savings) supportive care drugs. Collectively, our findings support that alternative purchasing models like MCCPDC may promote substantial health care savings.

Prevalence and Costs of Esophageal Strictures in the United States.

BACKGROUND & AIMS: Esophageal strictures are a leading cause of dysphagia, but data regarding the epidemiology of esophageal strictures are limited. This study aimed to investigate the prevalence, health care utilization, and financial burden of esophageal strictures in the United States. METHODS: We performed a retrospective cohort study using 2 large national insurance claims databases (MarketScan and Medicare). Using International Classification of Diseases-9 and -10 diagnostic codes, annual prevalence was calculated for both cohorts overall, and stratified by age and sex strata. Most common diagnostic and procedural codes associated with esophageal strictures were extracted and analyzed to estimate health care utilization. Direct annual medical costs of esophageal strictures were calculated. RESULTS: The annual prevalence of esophageal strictures in MarketScan in 2021 was 203.14 cases/100,000 people, whereas the annual prevalence in Medicare cohort in 2017 was 1123.47 cases/100,000. Although rates were relatively stable over time, esophageal stricture prevalence increased with advancing age. No prevalence differences were noticed between males and females. Gastroesophageal reflux disease/erosive esophagitis was the top diagnostic code associated with esophageal strictures, although an increase in the proportion of eosinophilic esophagitis codes was noted over time. Esophageal dilation codes were present in ∼50% of stricture cases. The total health care costs associated with esophageal strictures were estimated at $1.39 billion in 2017. CONCLUSIONS: Esophageal strictures are common, affecting between 1/100 and 1/1000 patients in the United States, with the highest rates seen in patients aged 75 years and older. Accordingly, strictures have a significant financial burden on the health care system, with costs greater than $1 billion annually.

Novel Symptom Subgroups in Individuals With Irritable Bowel Syndrome Predict Disease Impact and Burden.

BACKGROUND & AIMS: Current classification systems based on bowel habit fail to capture the multidimensional nature of irritable bowel syndrome (IBS). We previously derived and validated a classification system, using latent class analysis, incorporating factors beyond bowel habit. We applied this in another cohort of people with IBS to assess its ability to capture the impact of IBS on the individual, the health care system, and society. METHODS: We collected demographic, symptom, and psychological health data from adults in the community self-identifying as having IBS, and meeting Rome IV criteria. We applied our latent class analysis model to identify the 7 subgroups (clusters) described previously, based on overall gastrointestinal symptom severity and psychological burden. We assessed quality of life, health care costs (£1 = $1.20), employment status, annual income, work productivity, and ability to perform work duties in each cluster. RESULTS: Of 1278 responders, 752 (58.8%) met Rome IV criteria. The 7-cluster model fit the data well. The patients in the 4 clusters with the highest psychological burden, and particularly those in cluster 6 with high overall gastrointestinal symptom severity and high psychological burden, showed lower educational levels, higher gastrointestinal symptom-specific anxiety, were more likely to have consulted a gastroenterologist, and used more drugs for IBS. IBS-related and generic quality of life were impaired significantly in these 4 clusters and significantly fewer individuals reported earning ≥£30,000 per year. Productivity and the ability to work, manage at home, engage in social and private leisure activities, and maintain close relationships all were impacted significantly, and IBS-related health care costs over the previous 12 months were highest in these 4 clusters. In those in cluster 6, costs were more than £1000 per person per year. CONCLUSIONS: Our clusters identify groups of individuals with significant impairments in quality of life, earning potential, and ability to work and function socially, who are high utilizers of health care.

Characterization of time toxicity in older patients with metastatic breast cancer.

PURPOSE: Recognizing that receiving healthcare can be time intensive and burdensome, time toxicity has been conceptualized as the time spent by patients seeking healthcare. This study investigates the association between age at diagnosis and time toxicity for patients with Metastatic Breast Cancer (MBC) and identifies major components of care that confer the greatest time toxicity. METHODS: We conducted a retrospective cohort study among patients with MBC aged 67 or older using the SEER-Medicare database. We assessed time toxicity using the number of encounter days patients interacted with the healthcare system per 100 days, within the first year of starting cancer treatment. We used a Poisson model to analyze the association between age and encounter days, adjusting for clinical and sociodemographic factors. We stratified the mean encounter days for each age cohort by treatment types. FINDINGS: The final sample included 2949 patients; 51.4% were between 70 and 79 years old, and 81.3% were white. Although unadjusted analysis showed an association between older age and more encounter days (Rate Ratio (RR) 1.12; 95% CI 1.02, 1.22), there was no significant association after adjusting for comorbidities and treatment type. Patients with more than three comorbidities had significantly higher encounter days compared to those without comorbidities [RR 1.36 (95% CI 1.26, 1.46)]. Receipt of radiotherapy [RR: 1.45 95% CI (1.37, 1.54)] was associated with more encounter days compared to not receiving radiotherapy, while receipt of bone-modifying agents was associated with fewer encounter days compared to not using Bone modifying agents [RR 0.75 (95% CI 0.70, 0.79)]. CONCLUSION: Our study identified comorbidities and cancer treatment modality, including radiotherapy, as the factors affecting time toxicity in older patients with MBC. Assessment of an individual's comorbid medical conditions and types of treatment planned are crucial to understanding age-related impacts on encounter days and to support shared decision making in older patients.