Management of Resistant Hypertension.

Resistant hypertension (RH) is a severe form of hypertension associated with increased cardiovascular risk. Although true RH affects less than 10% of the patients receiving antihypertensive therapy, the absolute number is high and continues to increase. The workup of these patients requires screening for secondary hypertension and pseudoresistance, including poor adherence to prescribed medicines and the white-coat phenomenon. The treatment of RH consists of lifestyle modifications and pharmacological therapies. Lifestyle modifications include dietary adjustments, weight loss, physical activity, and limiting alcohol consumption; pharmacological therapies include diuretics, mineralocorticoid receptor antagonists, beta blockers, angiotensin receptor-neprilysin inhibitors, and others. Over the last 15 years, interventional approaches have emerged as adjunct treatment options; we highlight catheter-based renal denervation. This review summarizes the rationales and latest clinical evidence and, based thereon, proposes an updated algorithm for the management of RH.

Instrumental variables methods reconcile intention-to-screen effects across pragmatic cancer screening trials.

Pragmatic cancer screening trials mimic real-world scenarios in which patients and doctors are the ultimate arbiters of treatment. Intention-to-screen (ITS) analyses of such trials maintain randomization-based apples-to-apples comparisons, but differential adherence (the failure of subjects assigned to screening to get screened) makes ITS effects hard to compare across trials and sites. We show how instrumental variables (IV) methods address the nonadherence challenge in a comparison of estimates from 17 sites in five randomized trials measuring screening effects on colorectal cancer incidence. While adherence rates and ITS estimates vary widely across and within trials, IV estimates of per-protocol screening effects are remarkably consistent. An application of simple IV tools, including graphical analysis and formal statistical tests, shows how differential adherence explains variation in ITS impact. Screening compliers are also shown to have demographic characteristics similar to those of the full trial study sample. These findings argue for the clinical relevance of IV estimates of cancer screening effects.

Sex Disparities in Longitudinal Use and Intensification of Guideline-Directed Medical Therapy Among Patients With Newly Diagnosed Heart Failure With Reduced Ejection Fraction.

BACKGROUND: Guideline-directed medical therapies (GDMTs) are the mainstay of treatment for heart failure with reduced ejection fraction (HFrEF), but they are underused. Whether sex differences exist in the initiation and intensification of GDMT for newly diagnosed HFrEF is not well established. METHODS: Patients with incident HFrEF were identified from the 2016 to 2020 Optum deidentified Clinformatics Data Mart Database, which is derived from a database of administrative health claims for members of large commercial and Medicare Advantage health plans. The primary outcome was the use of optimal GDMT within 12 months of HFrEF diagnosis. Consistent with the guideline recommendations during the time period of the study, optimal GDMT was defined as ≥50% of the target dose of evidence-based beta-blocker plus ≥50% of the target dose of angiotensin-converting enzyme inhibitor or angiotensin receptor blocker, or any dose of angiotensin receptor neprilysin inhibitor plus any dose of mineralocorticoid receptor antagonist. The probability of achieving optimal GDMT on follow-up and predictors of optimal GDMT were evaluated with time-to-event analysis with adjusted Cox proportional hazard models. RESULTS: The study cohort included 63 759 patients (mean age, 71.3 years; 15.2% non-Hispanic Black race; 56.6% male). Optimal GDMT use was achieved by 6.2% of patients at 12 months after diagnosis. Female (compared with male) patients with HFrEF had lower use across every GDMT class and lower use of optimal GDMT at each time point at follow-up. In an adjusted Cox model, female sex was associated with a 23% lower probability of achieving optimal GDMT after diagnosis (hazard ratio [HR], 0.77 [95% CI, 0.71-0.83]; P<0.001). The sex disparities in GDMT use after HFrEF diagnosis were most pronounced among patients with commercial insurance (females compared with males; HR, 0.66 [95% CI, 0.58-0.76]) compared with Medicare (HR, 0.85 [95% CI, 0.77-0.92]); Pinteraction sex×insurance status=0.005) and for younger patients (age <65 years: HR, 0.65 [95% CI, 0.58-0.74]) compared with older patients (age ≥65 years: HR, 87 [95% CI, 80-96]) Pinteraction sex×age=0.009). CONCLUSIONS: Overall use of optimal GDMT after HFrEF diagnosis was low, with significantly lower use among female (compared with male) patients. These findings highlight the need for implementation efforts directed at improving GDMT initiation and titration.

Emerging Therapeutics, Technologies, and Drug Development Strategies to Address Patient Nonadherence and Improve Tuberculosis Treatment.

Imperfect medication adherence remains the biggest predictor of treatment failure for patients with tuberculosis. Missed doses during treatment lead to relapse, tuberculosis resistance, and further spread of disease. Understanding individual patient phenotypes, population pharmacokinetics, resistance development, drug distribution to tuberculosis lesions, and pharmacodynamics at the site of infection is necessary to fully measure the impact of adherence on patient outcomes. To decrease the impact of expected variabilityin drug intake on tuberculosis outcomes, an improvement in patient adherence and new forgiving regimens that protect against missed doses are needed. In this review, we summarize emerging technologies to improve medication adherence in clinical practice and provide suggestions on how digital adherence technologies can be incorporated in clinical trials and practice and the drug development pipeline that will lead to more forgiving regimens and benefit patients suffering from tuberculosis.

Patient Centricity Driving Formulation Innovation: Improvements in Patient Care Facilitated by Novel Therapeutics and Drug Delivery Technologies.

Innovative formulation technologies can play a crucial role in transforming a novel molecule to a medicine that significantly enhances patients' lives. Improved mechanistic understanding of diseases has inspired researchers to expand the druggable space using new therapeutic modalities such as interfering RNA, protein degraders, and novel formats of monoclonal antibodies. Sophisticated formulation strategies are needed to deliver the drugs to their sites of action and to achieve patient centricity, exemplified by messenger RNA vaccines and oral peptides. Moreover, access to medical information via digital platforms has resulted in better-informed patient groups that are requesting consideration of their needs during drug development. This request is consistent with health authority efforts to upgrade their regulations to advance age-appropriate product development for patients. This review describes formulation innovations contributingto improvements in patient care: convenience of administration, preferred route of administration, reducing dosing burden, and achieving targeted delivery of new modalities.

Past, Present, and Future of Noninvasive Tests to Assess Gluten Exposure, Celiac Disease Activity, and End-Organ Damage.

Although many biomarkers have been proposed, and several are in widespread clinical use, there is no single readout or combination of readouts that correlates tightly with gluten exposure, disease activity, or end-organ damage in treated patients with celiac disease. Challenges to developing and evaluating better biomarkers include significant interindividual variability-related to immune amplification of gluten exposure and how effects of immune activation are manifest. Furthermore, the current "gold standard" for assessment of end-organ damage, small intestinal biopsy, is itself highly imperfect, such that a marker that is a better reflection of the "ground truth" may indeed appear to perform poorly. The goal of this review was to analyze past and present efforts to establish robust noninvasive tools for monitoring treated patients with celiac disease and to highlight emerging tools that may prove to be useful in clinical practice.

Phenotype-Based Threat Assessment.

Bacterial pathogen identification, which is critical for human health, has historically relied on culturing organisms from clinical specimens. More recently, the application of machine learning (ML) to whole-genome sequences (WGSs) has facilitated pathogen identification. However, relying solely on genetic information to identify emerging or new pathogens is fundamentally constrained, especially if novel virulence factors exist. In addition, even WGSs with ML pipelines are unable to discern phenotypes associated with cryptic genetic loci linked to virulence. Here, we set out to determine if ML using phenotypic hallmarks of pathogenesis could assess potential pathogenic threat without using any sequence-based analysis. This approach successfully classified potential pathogenetic threat associated with previously machine-observed and unobserved bacteria with 99% and 85% accuracy, respectively. This work establishes a phenotype-based pipeline for potential pathogenic threat assessment, which we term PathEngine, and offers strategies for the identification of bacterial pathogens.

Food is Medicine for HIV: Improved health and hospitalizations in the Changing Health through Food Support (CHEFS-HIV) pragmatic randomized trial.

BACKGROUND: Policy support for "Food is Medicine"-medically tailored meals or groceries to improve health-is rapidly growing. No randomized trials have heretofore investigated the benefits of medically tailored food programs for people living with HIV (PLHIV). METHODS: The CHEFS-HIV pragmatic randomized trial included PLHIV who were clients of Project Open Hand (POH), a San Francisco-based nonprofit food organization. The intervention arm (n = 93) received comprehensive medically tailored meals, groceries, and nutritional education. Control participants (n = 98) received less intensive (POH "standard of care") food services. Health, nutrition, and behavioral outcomes were assessed at baseline and 6 months later. Primary outcomes measured were viral non-suppression and health related quality of life. Mixed models estimated treatment effects as differences-in-differences between arms. RESULTS: The intervention arm had lower odds of hospitalization (odds ratio [OR] = 0.11), food insecurity (OR = 0.23), depressive symptoms (OR = 0.32), antiretroviral therapy adherence <90% (OR = 0.18), and unprotected sex (OR = 0.18), and less fatty food consumption (ß= -0.170 servings/day) over 6 months, compared to the control arm. There was no difference between study arms in viral non-suppression and health-related quality of life over 6 months. CONCLUSIONS: A "Food-is-Medicine" intervention reduced hospitalizations and improved mental and physical health among PLHIV, despite no impact on viral suppression. CLINICAL TRIALS REGISTRATION: NCT03191253.

Once-weekly insulins: a promising approach to reduce the treatment burden in people with diabetes.

Despite the availability of new classes of glucose-lowering drugs that improve glycaemic levels and minimise long-term complications, at least 20-25% of people with type 2 diabetes require insulin therapy. Moreover, a substantial proportion of these individuals do not achieve adequate metabolic control following insulin initiation. This is due to several factors: therapeutic inertia, fear of hypoglycaemia and/or weight gain, poor communication, complexity of insulin titration, and the number of injections needed, with the associated reduced adherence to insulin therapy. Once-weekly insulins provide a unique opportunity to simplify basal insulin therapy and to allow good glycaemic control with a low risk of hypoglycaemia. Several approaches to developing a stable and effective once-weekly insulin have been proposed, but, to date, insulin icodec and basal insulin Fc (insulin efsitora alfa) are the only two formulations for which clinical studies have been reported. The results of Phase I and II studies emphasise both efficacy (in term of glucose levels) and potential risks and adverse events. Phase III studies involving insulin icodec are reassuring regarding the risk of hypoglycaemia compared with daily basal insulin analogues. Despite some concerns raised in ongoing clinical trials, the available data suggest that weekly insulins may also be an option for individuals with type 1 diabetes, especially when adherence is suboptimal. For the first time there is an opportunity to make an important breakthrough in basal insulin therapy, particularly in people with type 2 diabetes, and to improve not only the quality of life of people with diabetes, but also the practice of diabetologists.

Non-adherence to cardiometabolic medication as assessed by LC-MS/MS in urine and its association with kidney and cardiovascular outcomes in type 2 diabetes mellitus.

AIMS/HYPOTHESIS: Non-adherence to medication is a frequent barrier in the treatment of patients with type 2 diabetes mellitus, potentially limiting the effectiveness of evidence-based treatments. Previous studies have mostly relied on indirect adherence measures to analyse outcomes based on adherence. The aim of this study was to use LC-MS/MS in urine-a non-invasive, direct and objective measure-to assess non-adherence to cardiometabolic drugs and analyse its association with kidney and cardiovascular outcomes. METHODS: This cohort study includes 1125 participants from the PROVALID study, which follows patients with type 2 diabetes mellitus at the primary care level. Baseline urine samples were tested for 79 cardiometabolic drugs and metabolites thereof via LC-MS/MS. An individual was classified as totally adherent if markers for all drugs were detected, partially non-adherent when at least one marker for one drug was detected, and totally non-adherent if no markers for any drugs were detected. Non-adherence was then analysed in the context of cardiovascular (composite of myocardial infarction, stroke and cardiovascular death) and kidney (composite of sustained 40% decline in eGFR, sustained progression of albuminuria, kidney replacement therapy and death from kidney failure) outcomes. RESULTS: Of the participants, 56.3% were totally adherent, 42.0% were partially non-adherent, and 1.7% were totally non-adherent to screened cardiometabolic drugs. Adherence was highest to antiplatelet and glucose-lowering agents and lowest to lipid-lowering agents. Over a median (IQR) follow-up time of 5.10 (4.12-6.12) years, worse cardiovascular outcomes were observed with non-adherence to antiplatelet drugs (HR 10.13 [95% CI 3.06, 33.56]) and worse kidney outcomes were observed with non-adherence to antihypertensive drugs (HR 1.98 [95% CI 1.37, 2.86]). CONCLUSIONS/INTERPRETATION: This analysis shows that non-adherence to cardiometabolic drug regimens is common in type 2 diabetes mellitus and negatively affects kidney and cardiovascular outcomes.

miR-147a targets ZEB2 to regulate ox-LDL-induced monocyte adherence to HUVECs, atherosclerotic plaque formation, and stability in atherosclerosis.

The mechanisms underlying atherosclerosis (AS) that seriously affect human health, such as those involved in endothelial cell injury and monocyte/macrophage aggregation and infiltration, have not been fully elucidated. To investigate these processes, we established human umbilical vein endothelial cells (HUVECs) injured by oxidized low-density lipoprotein (ox-LDL) to mimic AS in vitro. Apolipoprotein E knockout (ApoE-/-) C57BL/6 mice were fed with a high-cholesterol diet to establish an AS model in vivo. We detected HUVEC apoptosis, and apoptosis-related proteins by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide and lactate dehydrogenase, flow cytometry, and Western blot assays, respectively, and we observed monocytes (THP-1 cells) adhering to HUVECs. Furthermore, miR-147a and its downstream target gene ZEB2 (zinc finger E-box binding homeobox 2) were predicted by bioinformatics analysis to be involved in AS, and their correlation was confirmed by several experiments. We determined the localization of miR-147a and ZEB2 within macrophages of AS mice by in situ hybridization and immunofluorescence. Atherosclerotic plaques in whole aortas were detected by histology observation. miR-147a attenuated adherence of monocytes to HUVECs and the upregulation of mononuclear chemotactic adhesion receptors in THP-1 cells induced by ox-LDL-injured HUVEC supernatants through directly downregulating ZEB2 levels. Moreover, miR-147a influenced M1/M2 macrophage polarization from THP-1 cells and the roles of their supernatants (THP-1 cells) in HUVEC apoptosis. miR-147a targeted ZEB2 to impact lipid accumulation and atherosclerotic plaque formation through regulating M1/M2 polarization and macrophage adhesion in AS mice. In summary, miR-147a attenuates ox-LDL-induced adherence of monocytes to HUVECs and modulates atherosclerotic plaque formation and stability through targeting ZEB2 during AS.

Two Cases of Viral Re-suppression After M184V + R263K Selection on Dolutegravir/Lamivudine Without Treatment Modification.

Dolutegravir/lamivudine (DTG/3TC) has a high genetic barrier against the development of human immunodeficiency virus drug resistance. We report 2 cases of R263K + M184V mutations during DTG/3TC failure followed by viral suppression after adherence intervention without treatment change that we attribute to residual drug activity, reduced viral fitness, and robust immune competence.

Ischemic Stroke and Reduced Left Ventricular Ejection Fraction: A Multidisciplinary Approach to Optimize Brain and Cardiac Health.

Reduced left ventricular ejection fraction ≤40%, a known risk factor for adverse cardiac outcomes and recurrent acute ischemic stroke, may be detected during an acute ischemic stroke hospitalization. A multidisciplinary care paradigm informed by neurology and cardiology expertise may facilitate the timely implementation of an array of proven heart failure-specific therapies and procedures in a nuanced manner to optimize brain and cardiac health.

Cumulative Tenofovir Exposure Among Patients With HIV/Hepatitis B Coinfection With Differential Viral Suppression.

This case-control study explored cumulative tenofovir exposure among patients with human immunodeficiency virus/hepatis B virus (HIV/HBV) coinfection with HIV viral suppression. Among patients taking tenofovir disoproxil fumarate, median TFV-DP levels in dried blood spots were ∼3-fold lower among patients with incomplete HBV viral suppression (n = 4) compared to those with complete suppression (n = 5) (516 vs 1456 fmol/punch).

Tenofovir-Diphosphate and Emtricitabine-Triphosphate Adherence Benchmarks in Dried Blood Spots for Persons with HIV Receiving Tenofovir Alafenamide and Emtricitabine-based Antiretroviral Therapy (QUANTI-TAF).

BACKGROUND: QUANTI-TAF aimed to establish tenofovir-diphosphate/emtricitabine-triphosphate (TFV-DP/FTC-TP) adherence benchmarks in dried blood spots (DBS) for persons with HIV (PWH) receiving tenofovir alafenamide/emtricitabine (TAF/FTC)-based antiretroviral therapy (ART). METHODS: During a 16-week pharmacokinetic study, PWH received TAF/FTC-based ART co-encapsulated with an ingestible sensor to directly measure cumulative (enrollment to final visit) and 10-day adherence. At monthly visits, intraerythrocytic concentrations of TAF/FTC anabolites (TFV-DP/FTC-TP) in DBS were quantified by LC-MS/MS and summarized at steady-state (week 12 or 16) as median (IQR). Linear mixed-effects models evaluated factors associated with TFV-DP/FTC-TP. RESULTS: 84 participants (86% male, 11% female, and 4% transgender), predominantly receiving bictegravir/TAF/FTC (73%) enrolled. 92% completed week 12 or 16 (94% receiving unboosted ART). TFV-DP for <85% (7/72), ≥85%-<95% (9/72), and ≥95% (56/72) cumulative adherence was 2696 (2039-4108), 3117 (2332-3339), and 3344 (2605-4293) fmol/punches. All participants with ≥85% cumulative adherence had TFV-DP ≥1800 fmol/punches. Adjusting for cumulative adherence, TFV-DP was higher with boosted ART, lower BMI, and in non-Blacks. FTC-TP for <85% (14/77), ≥85%-<95% (6/77), and ≥95% (57/77) 10-day adherence was 3.52 (2.64-4.48), 4.58 (4.39-5.06), and 4.96 (4.21-6.26) pmol/punches. All participants with ≥85% 10-day adherence had FTC-TP ≥2.5 pmol/punches. Low-level viremia (HIV-1 RNA ≥20-<200 copies/mL) occurred at 60/335 (18%) visits in 33/84 (39%) participants (range: 20-149 copies/mL), with similar TFV-DP (3177 [2494-4149] fmol/punches) compared with HIV-1 RNA <20 copies/mL visits (3279 [2580-4407] fmol/punches). CONCLUSIONS: We propose PK-based TFV-DP (≥1800 fmol/punches)/FTC-TP (≥2.5 pmol/punches) benchmarks in DBS for PWH receiving unboosted TAF/FTC-based ART with ≥85% adherence. In the setting of high adherence, low-level viremia was common.

Clinical factors associated with patterns of endocrine therapy adherence in premenopausal breast cancer patients.

INTRODUCTION: Patients with hormone receptor positive breast cancer are recommended at least five years of adjuvant endocrine therapy, but adherence to this treatment is often suboptimal. We investigated longitudinal trends in adjuvant endocrine therapy (AET) adherence among premenopausal breast cancer patients and identified clinical characteristics, including baseline comorbidities and non-cancer chronic medication use, associated with AET adherence. METHODS: We included stage I-III premenopausal breast cancer patients diagnosed during 2002-2011 and registered in the Danish Breast Cancer Group clinical database who initiated AET. We used group-based trajectory modeling to describe AET adherence patterns. We also linked patients to Danish population-based registries and fit multinomial logistic models to compute odds ratios (ORs) and 95% confidence intervals (95% CIs) associating clinical characteristics with AET adherence patterns. RESULTS: We identified three adherence patterns among 4,353 women-high adherers (57%), slow decliners (36%), and rapid decliners (6.9%). Women with stage I disease (vs. stage II; OR: 1.9, 95% CI 1.5, 2.5), without chemotherapy (vs. chemotherapy; OR: 4.3, 95% CI 3.0, 6.1), with prevalent comorbid disease (Charlson Comorbidity Index score ≥ 1 vs. 0; OR: 1.6, 95% CI 1.1, 2.3), and with a history of chronic non-cancer medication use (vs. none; OR: 1.3, 95% CI 1.0, 1.8) were more likely to be rapid decliners compared with high adherers. CONCLUSIONS: Women with stage I cancer, no chemotherapy, higher comorbidity burden, and history of chronic non-cancer medication use were less likely to adhere to AET. Taking steps to promote adherence in these groups of women may reduce their risk of recurrence.

Costs of Digital Adherence Technologies for Tuberculosis Treatment Support, 2018-2021.

Digital adherence technologies are increasingly used to support tuberculosis (TB) treatment adherence. Using microcosting, we estimated healthcare system costs (in 2022 US dollars) of 2 digital adherence technologies, 99DOTS medication sleeves and video-observed therapy (VOT), implemented in demonstration projects during 2018-2021. We also obtained cost estimates for standard directly observed therapy (DOT). Estimated per-person costs of 99DOTS for drug-sensitive TB were $98 in Bangladesh (n = 719), $119 in the Philippines (n = 396), and $174 in Tanzania (n = 976). Estimated per-person costs of VOT were $1,154 in Haiti (87 drug-sensitive), $304 in Moldova (173 drug-sensitive), $452 in Moldova (135 drug-resistant), and $661 in the Philippines (110 drug-resistant). 99DOTS costs may be similar to or less expensive than standard DOT. VOT is more expensive, although in some settings, labor cost offsets or economies of scale may yield savings. 99DOTS and VOT may yield savings to local programs if donors cover infrastructure costs.

Imatinib adherence prediction using machine learning approach in patients with gastrointestinal stromal tumor.

BACKGROUND: Nonadherence to imatinib is common in patients with gastrointestinal stromal tumor (GIST), which is associated with poor prognosis and financial burden. The primary aim of this study was to investigate the adherence rate in patients with GIST and subsequently develop a model based on machine learning (ML) and deep learning (DL) techniques to identify the associated factors and predict the risk of imatinib nonadherence. METHODS: All eligible patients completed four sections of questionnaires. After the data set was preprocessed, statistically significance variables were identified and further processed to modeling. Six ML and four DL algorithms were applied for modeling, including eXtreme gradient boosting, light gradient boosting machine (LGBM), categorical boosting, random forest, support vector machine, artificial neural network, multilayer perceptron, NaiveBayes, TabNet, and Wide&Deep. The optimal ML model was used to identify potential factors for predicting adherence. RESULTS: A total of 397 GIST patients were recruited. Nonadherence was observed in 185 patients (53.4%). LGBM exhibited superior performance, achieving a mean f1_score of 0.65 and standard deviation of 0.12. The predominant indicators for nonadherent prediction of imatinib were cognitive functioning, whether to perform therapeutic drug monitoring (if_TDM), global health status score, social support, and gender. CONCLUSIONS: This study represents the first real-world investigation using ML techniques to predict risk factors associated with imatinib nonadherence in patients with GIST. By highlighting the potential factors and identifying high-risk patients, the multidisciplinary medical team can devise targeted strategies to effectively address the daily challenges of treatment adherence.

Patient-reported symptom monitoring and adherence to therapy in patients with newly diagnosed chronic myeloid leukemia.

BACKGROUND: The authors assessed the clinical utility of patient-reported symptom monitoring in the setting of newly diagnosed chronic myeloid leukemia (CML). The primary objective was to evaluate adherence to therapy. METHODS: The authors conducted an international prospective study that included patients with newly diagnosed, chronic-phase CML. Before clinical consultation, patients were provided a tablet computer to self-rate their symptoms, and the results were available in real time to each physician during the patient's visit. Adherence was assessed by pill count and with a validated self-reported questionnaire. The proportions of optimal responders at 3 and 6 months were assessed according to the European LeukemiaNet criteria. RESULTS: Between July 2020 and August 2021, 94 patients with a median age of 57 years were enrolled. Pill count adherence analysis indicated that 86 of 93 evaluable patients (92.5%) took at least 90% of prescribed tyrosine kinase inhibitor therapy during the 6-month observation period. The online platform was well accepted by patients and physicians. An optimal response was achieved by 69 of 79 patients (87.3%) at 3 months and by 61 of 81 patients (75.3%) at 6 months. CONCLUSIONS: Patient-reported symptom monitoring from the beginning of therapy in patients with CML may be critical to improve adherence to therapy and early molecular response rates (ClinicalTrials.gov identifier NCT04384848).

Adherence, clinical benefits, and adverse effects of endocrine therapies among women with nonmetastatic breast cancer in developing countries: A systematic review and meta-analysis.

BACKGROUND: Despite significant advances in breast cancer control and survival with endocrine therapies (ETs), treatment utilization and outcomes in developing countries have not been adequately explored. This review evaluated ET adherence, potential benefits, and harms in populations across developing countries. METHODS: A literature search was conducted through August 2023 in five databases: PubMed, Cochrane Library, Web of Science, Global Health, and WHO Global Index Medicus. Retrieved records were screened to identify observational research presenting at least one outcome in women with nonmetastatic breast cancer in developing countries who received ET (tamoxifen or aromatase inhibitors). A random effects model was used to compute the rates of adherence, discontinuation, adverse events (AEs), disease progression, and death. RESULTS: A total of 104 studies met the inclusion criteria. Risk of bias was low in most studies, and a large portion of the patients involved Asians. The overall heterogeneity between studies was partially attributed to variations in study design or outcome measurement method. Results showed a pooled adherence rate of 75% (95% confidence interval [CI], 67%-81%) and a discontinuation rate of 16% (95% CI, 10%-25%). Treatment side effects and young age consistently emerged as significant predictors of nonadherence. A wide range of AEs was identified in our analysis. The estimated average rates of cancer recurrence and mortality at 5-years were 16% and 8%, respectively. CONCLUSIONS: The findings of this study underscore suboptimal ET use in developing countries and provide comprehensive insights into treatment experiences in the real-world setting. Targeted strategies are warranted to enhance adherence and subsequently optimize treatment benefits.