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AIM: To examine how the development of cardiovascular and renal disease (CVRD) translates to hospital healthcare costs in individuals with type 2 diabetes (T2D) initially free from CVRD. METHODS: Data were obtained from the digital healthcare systems of 12 nations using a prespecified protocol. A fixed country-specific index date of 1 January was chosen to secure sufficient cohort disease history and maximal follow-up, varying between each nation from 2006 to 2017. At index, all individuals were free from any diagnoses of CVRD (including heart failure [HF], chronic kidney disease [CKD], coronary ischaemic disease, stroke, myocardial infarction [MI], or peripheral artery disease [PAD]). Outcomes during follow-up were hospital visits for CKD, HF, MI, stroke, and PAD. Hospital healthcare costs obtained from six countries, representing 68% of the total study population, were cumulatively summarized for CVRD events occurring during follow-up. RESULTS: In total, 1.2 million CVRD-free individuals with T2D were identified and followed for 4.5 years (mean), that is, 4.9 million patient-years. The proportion of individuals indexed before 2010 was 18% (n = 207 137); 2010-2015, 31% (361 175); and after 2015, 52% (609 095). Overall, 184 420 (15.7%) developed CVRD, of which cardiorenal disease was most frequently the first disease to develop (59.7%), consisting of 23.0% HF and 36.7% CKD, and more common than stroke (16.9%), MI (13.7%), and PAD (9.7%). The total cumulative cost for CVRD was US$1 billion, of which 59.0% was attributed to cardiorenal disease, 3-, 5-, and 6-fold times greater than the costs for stroke, MI, and PAD, respectively. CONCLUSION: Across all nations, HF or CKD was the most frequent CVRD manifestation to develop in a low-risk population with T2D, accounting for the highest proportion of hospital healthcare costs. These novel findings highlight the importance of cardiorenal awareness when planning healthcare.
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Diabetes Mellitus Tipo 2 , Insuficiência Cardíaca , Infarto do Miocárdio , Insuficiência Renal Crônica , Acidente Vascular Cerebral , Atenção à Saúde , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/epidemiologia , Diabetes Mellitus Tipo 2/terapia , Insuficiência Cardíaca/epidemiologia , Humanos , Hipertensão Renal , Infarto do Miocárdio/complicações , Nefrite , Aceitação pelo Paciente de Cuidados de Saúde , Insuficiência Renal Crônica/complicações , Insuficiência Renal Crônica/epidemiologia , Insuficiência Renal Crônica/terapia , Acidente Vascular Cerebral/complicações , Acidente Vascular Cerebral/epidemiologiaRESUMO
With the widespread use of electronic medical records and administrative claims databases, analytic results from so-called real-world data have become increasingly important in healthcare decision-making. Diabetes mellitus is a heterogeneous condition that involves a broad spectrum of patients. Real-world database studies have been recognised as a powerful tool to understand the impact of current practices on clinical courses and outcomes, such as long-term glucose control, development of microvascular or macro-vascular diseases, and mortality. Diabetes is also a major global health issue and poses a significant social and economic burden worldwide. Therefore, it is critical to understand the epidemiology, clinical course, treatment reality, and long-term outcomes of diabetes to determine realistic solutions to a variety of disease-related issues that we are facing. In the present review, we summarise the healthcare system and large-scale databases currently available in Japan, introduce the results from recent database studies involving Japanese patients with diabetes, and discuss future opportunities and challenges for the use of databases in the management of diabetes.
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Diabetes Mellitus Tipo 2 , Bases de Dados Factuais , Humanos , Japão/epidemiologiaRESUMO
AIMS: To examine heart failure (HF) and chronic kidney disease (CKD) risks reduction associated with sodium-glucose cotransporter-2 inhibitors (SGLT-2i) compared to other glucose-lowering drugs (oGLD) in the early stage of type 2 diabetes patients without established cardiovascular or renal diseases (CVRD-free T2D). MATERIALS AND METHODS: We performed an observational cohort study using a Japanese hospital claims registry, Medical Data Vision. CVRD-free T2D patients were identified between 1 April 2014 and 30 September 2018. SGLT-2i and oGLD new users (and dipeptidyl peptidase 4 inhibitors [DPP-4i] separately) were subjected to 1:1 propensity-score matching analysis. Hazard ratios (HRs) of cardiorenal disease (HF and/or CKD), HF, CKD, stroke, myocardial infarction (MI), and all-cause mortality, were estimated using unadjusted Cox regression. RESULTS: A total of 108 362 CVRD-free patients including 54 181 SGLT-2i and 54 181 oGLD users were matched. Baseline characteristics were well balanced (mean age 59.1 years, 63% male, and follow-up 1.50 years [162 970 patient-years]). Compared to oGLD group, SGLT-2i group had lower risk of cardiorenal disease, HF, CKD, stroke, and all-cause mortality with HRs (95% confidence intervals) 0.55 (0.49-0.61), 0.73 (0.61-0.87), 0.45 (0.39-0.52), 0.69 (0.59-0.81), and 0.52 (0.46-0.58), respectively, while no difference in MI. These were consistent in 1:1 propensity-score matching analysis between SGLT-2i and DPP-4i users (n = 17 232 in each group). CONCLUSIONS: In Japanese CVRD-free T2D patients, SGLT-2i initiation was associated with lower risk of cardiorenal diseases, stroke, and all-cause mortality compared to oGLD, suggesting preventive effect of SGLT-2i treatment in the early stage of T2D patients without CVRD manifestation.
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Doenças Cardiovasculares , Diabetes Mellitus Tipo 2 , Inibidores da Dipeptidil Peptidase IV , Insuficiência Cardíaca , Preparações Farmacêuticas , Insuficiência Renal Crônica , Inibidores do Transportador 2 de Sódio-Glicose , Doenças Cardiovasculares/epidemiologia , Doenças Cardiovasculares/prevenção & controle , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/epidemiologia , Feminino , Glucose , Insuficiência Cardíaca/epidemiologia , Humanos , Hipoglicemiantes/uso terapêutico , Japão/epidemiologia , Masculino , Pessoa de Meia-Idade , Insuficiência Renal Crônica/complicações , Insuficiência Renal Crônica/epidemiologia , Sódio , Inibidores do Transportador 2 de Sódio-Glicose/uso terapêuticoRESUMO
AIMS: We compared the new use of sodium-glucose cotransporter-2 inhibitor (SGLT2i) versus dipeptidyl peptidase-4 inhibitor (DPP4i) and the risk of cardiorenal disease, heart failure (HF) or chronic kidney disease (CKD), in patients with type 2 diabetes without a history of prevalent cardiovascular and renal disease, defined as cardiovascular and renal disease (CVRD) free, managed in routine clinical practice. MATERIALS AND METHODS: In this observational cohort study, patients were identified from electronic health records from England, Germany, Japan, Norway, South Korea and Sweden, during 2012-2018. In total, 1 006 577 CVRD-free new users of SGLT2i or DPP4i were propensity score matched 1:1. Unadjusted Cox regression was used to estimate hazard ratios (HRs) for outcomes: cardiorenal disease, HF, CKD, stroke, myocardial infarction (MI), cardiovascular and all-cause mortality. RESULTS: Baseline characteristics were well balanced between the treatment groups (n = 105 130 in each group) with total follow-up of 187 955 patient years. Patients had a mean age of 56 years, 43% were women and they were indexed between 2013 and 2018. The most commonly used agents were dapagliflozin (91.7% of exposure time) and sitagliptin/linagliptin (55.0%), in the SGLT2i and DPP4i, groups, respectively. SGLT2i was associated with lower risk of cardiorenal disease, HF, CKD, all-cause and cardiovascular mortality; HR (95% confidence interval), 0.56 (0.42-0.74), 0.71 (0.59-0.86), 0.44 (0.28-0.69), 0.67 (0.59-0.77), and 0.61 (0.44-0.85), respectively. No differences were observed for stroke [0.87 (0.69-1.09)] and MI [0.94 (0.80-1.11)]. CONCLUSION: In this multinational observational study, SGLT2i was associated with a lower risk of HF and CKD versus DPP4i in patients with type 2 diabetes otherwise free from both cardiovascular and renal disease.
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Doenças Cardiovasculares , Diabetes Mellitus Tipo 2 , Inibidores da Dipeptidil Peptidase IV , Inibidores do Transportador 2 de Sódio-Glicose , Doenças Cardiovasculares/epidemiologia , Doenças Cardiovasculares/prevenção & controle , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/epidemiologia , Inibidores da Dipeptidil Peptidase IV/uso terapêutico , Inglaterra , Feminino , Alemanha , Glucose , Humanos , Japão , Pessoa de Meia-Idade , Noruega , República da Coreia , Sódio , Inibidores do Transportador 2 de Sódio-Glicose/uso terapêutico , Suécia/epidemiologiaRESUMO
AIMS: To examine the manifestation of cardiovascular or renal disease (CVRD) in patients with type 2 diabetes (T2D) initially free from CVRD as well as the mortality risks associated with these diseases. METHODS: Patients free from CVRD were identified from healthcare records in England, Germany, Japan, the Netherlands, Norway and Sweden at a fixed date. CVRD manifestation was defined by first diagnosis of cardiorenal disease, or a stroke, myocardial infarction (MI) or peripheral artery disease (PAD) event. The mortality risk associated with single CVRD history of heart failure (HF), chronic kidney disease (CKD), MI, stroke or PAD was compared with that associated with CVRD-free status. RESULTS: Of 1 177 896 patients with T2D, 772 336 (66%) were CVRD-free and followed for a mean of 4.5 years. A total of 137 081 patients (18%) developed a first CVRD manifestation, represented by CKD (36%), HF (24%), stroke (16%), MI (14%) and PAD (10%). HF or CKD was associated with increased cardiovascular and all-cause mortality risk: hazard ratio (HR) 2.02 (95% confidence interval [CI] 1.75-2.33) and HR 2.05 (95% CI 1.82-2.32), respectively. HF and CKD were separately associated with significantly increased mortality risks, and the combination was associated with the highest cardiovascular and all-cause mortality risk: HRs 3.91 (95% CI 3.02-5.07) and 3.14 (95% CI 2.90-3.40), respectively. CONCLUSION: In a large multinational study of >750 000 CVRD-free patients with T2D, HF and CKD were consistently the most frequent first cardiovascular disease manifestations and were also associated with increased mortality risks. These novel findings show these cardiorenal diseases to be important and serious complications requiring improved preventive strategies.
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Diabetes Mellitus Tipo 2 , Insuficiência Cardíaca , Insuficiência Renal Crônica , Estudos de Coortes , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/epidemiologia , Inglaterra , Alemanha , Insuficiência Cardíaca/epidemiologia , Humanos , Japão , Países Baixos , Noruega , Insuficiência Renal Crônica/complicações , Insuficiência Renal Crônica/epidemiologia , Fatores de Risco , SuéciaRESUMO
Background: Vericiguat was developed to treat patients with heart failure (HF). Currently, limited data are available to characterize vericiguat-treated patients in real-world clinical settings. Methods: This retrospective cohort study was done using a Japanese hospital administrative database to describe the use of vericiguat in patients with HF in real-world settings. Adult patients diagnosed with HF prescribed vericiguat between 1 July 2021 and 30 September 2022 were included. Patient characteristics at the initiation of vericiguat treatment, patterns of HF medication use, and vericiguat dose titrations were assessed within the first 90 days of treatment. Results: The study included 829 patients who were initiated on vericiguat therapy. The mean age was 75.5 years and 69.0% were male. Hypertension, coronary artery disease, and diabetes mellitus were present in 91.7, 71.3, and 60.1% of patients, respectively. Most patients had previously received HF medications, with high percentages using angiotensin-receptor blocker neprilysin inhibitors (ARNI; 43.9%) and sodium-glucose cotransporter-2 inhibitors (54.4%). During the first 90 days of vericiguat treatment, 65.8% of the patients were uptitrated from their starting dose, and 32.3% had reached the maximal daily dose. The median time to reach the maximal daily dose was 34 days. The multivariable model identified that initiating vericiguat treatment in an outpatient setting and using ARNI before initiating vericiguat treatment were factors significantly associated with reaching the maximal daily dose of vericiguat at any given time, whereas older age, chronic kidney disease, hyperkalemia, and anemia were not associated. Conclusions: These findings provide early insights into the use of vericiguat, which aid in optimizing the combinations and/or sequences of HF treatment incorporating vericiguat therapy.
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Currently, the utilization patterns of medications for heart failure (HF) after worsening HF events remain unelucidated in Japan. Here, we conducted a retrospective cohort study evaluating the changes in HF drug utilization patterns in 6 months before and after hospitalizations for HF. The adherence to newly initiated HF medications was evaluated based on the proportion of days covered (PDC) and persistence as continuous treatment episodes among new users. The study included 9091 patients hospitalized for HF between January 2016 and September 2019, including 2735 (30.1%) patients who were newly prescribed at least one HF medication after hospitalization. Despite increases in the use of foundational HF therapy (beta-blockers, angiotensin-converting-enzyme inhibitors/angiotensin receptor blockers, or mineralocorticoid receptor antagonists), 35.6% and 7.6% of patients were treated with the HF foundational monotherapy or diuretics alone after hospitalization, respectively. The mean PDC of newly initiated HF medications ranged from 0.57 for thiazide diuretics to 0.77 for sodium-glucose cotransporter-2 inhibitors. Continuous use of HF medications during the first year after initiation was observed in 30-60% of patients. The mean PDC and one-year continuous HF medication use were consistently lower in patients aged ≥ 75 years and in patients with a history of HF hospitalization for all HF medication classes except for tolvaptan and digoxin. Despite the guideline recommendations of HF pharmacotherapy, both treatment and adherence were suboptimal after HF hospitalization, especially in vulnerable populations such as older patients and those with prior HF hospitalizations.
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Insuficiência Cardíaca , Inibidores do Transportador 2 de Sódio-Glicose , Humanos , Estudos Retrospectivos , Japão , Inibidores do Transportador 2 de Sódio-Glicose/uso terapêutico , Insuficiência Cardíaca/tratamento farmacológico , Inibidores da Enzima Conversora de Angiotensina/uso terapêutico , Hospitalização , Antagonistas Adrenérgicos beta/uso terapêutico , Diuréticos/uso terapêutico , Antagonistas de Receptores de Angiotensina/uso terapêutico , Antagonistas de Receptores de Mineralocorticoides/uso terapêuticoRESUMO
In the original publication [...].
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Background: Whether to continue renin−angiotensin−aldosterone system inhibitor (RAASi) therapy in patients with hyperkalemia remains a clinical challenge, particularly in patients with heart failure (HF), where RAASis remain the cornerstone of treatment. We investigated the incidence of dose reduction or the cessation of RAASis and evaluated the threshold of serum potassium at which cessation alters the risk−benefit balance. Methods: This retrospective analysis of a Japanese nationwide claims database investigated treatment patterns of RAASis over 12 months after the initial hyperkalemic episode. The incidences of the clinical outcomes of patients with RAASi (all ACEi/ARB/MRA) or MRA-only cessation (vs. non-cessation) were compared via propensity score-matched patients. A cubic spline regression analysis assessed the hazard of death resulting from treatment cessation vs. no cessation at each potassium level. Results: A total of 5059 hyperkalemic HF patients were identified; most received low to moderate doses of ACEis and ARBs (86.9% and 71.5%, respectively) and low doses of MRAs (76.2%). The RAASi and MRA cessation rates were 34.7% and 52.8% at 1 year post-diagnosis, while the dose reduction rates were 8.4% and 6.5%, respectively. During the mean follow-up of 2.8 years, patients who ceased RAASi or MRA therapies were at higher risk for adverse outcomes; cubic spline analysis found that serum potassium levels of <5.9 and <5.7 mmol/L conferred an increased mortality risk for RAASi and MRA cessation, respectively. Conclusions: Treatment cessation/dose reduction of RAASis are common among HF patients. The risks of RAASi/MRA cessation may outweigh the benefits in patients with mild to moderate hyperkalemia.
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Hyperkalemia is associated with increased risks of mortality and adverse clinical outcomes. The treatment of hyperkalemia often leads to the discontinuation or restriction of beneficial but potassium-increasing therapy such as renin-angiotensin-aldosterone inhibitors (RAASi) and high-potassium diet including fruits and vegetables. To date, limited evidence is available for personalized risk evaluation in this heterogeneous and multifactorial pathophysiological condition. We developed risk prediction models using extreme gradient boosting (XGB), multiple logistic regression (LR), and deep neural network. Models were derived from a retrospective cohort of hyperkalemic patients with either heart failure or chronic kidney disease stage ≥3a from a Japanese nationwide database (1 April 2008−30 September 2018). Studied outcomes included all-cause death, renal replacement therapy introduction (RRT), hospitalization for heart failure (HHF), and cardiovascular events within three years after hyperkalemic episodes. The best performing model was further validated using an external cohort. A total of 24,949 adult hyperkalemic patients were selected for model derivation and internal validation. A total of 1452 deaths (16.6%), 887 RRT (10.1%), 1,345 HHF (15.4%), and 621 cardiovascular events (7.1%) were observed. XGB outperformed other models. The area under receiver operator characteristic curves (AUROCs) of XGB vs. LR (95% CIs) for death, RRT, HHF, and cardiovascular events were 0.823 (0.805−0.841) vs. 0.809 (0.791−0.828), 0.957 (0.947−0.967) vs. 0.947 (0.936−0.959), 0.863 (0.846−0.880) vs. 0.838 (0.820−0.856), and 0.809 (0.784−0.834) vs. 0.798 (0.772−0.823), respectively. In the external dataset including 86,279 patients, AUROCs (95% CIs) for XGB were: death, 0.747 (0.742−0.753); RRT, 0.888 (0.882−0.894); HHF, 0.673 (0.666−0.679); and cardiovascular events, 0.585 (0.578−0.591). Kaplan−Meier curves of the high-risk predicted group showed a statistically significant difference from that of the low-risk predicted groups for all outcomes (p < 0.005; log-rank test). These findings suggest possible use of machine learning models for real-world risk assessment as a guide for observation and/or treatment decision making that may potentially lead to improved outcomes in hyperkalemic patients while retaining the benefit of life-saving therapies.
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Insuficiência Cardíaca , Hiperpotassemia , Adulto , Humanos , Hiperpotassemia/complicações , Inibidores da Enzima Conversora de Angiotensina/farmacologia , Sistema Renina-Angiotensina , Estudos Retrospectivos , Potássio/farmacologia , Insuficiência Cardíaca/complicações , Anti-Hipertensivos/farmacologia , Aprendizado de MáquinaRESUMO
OBJECTIVE: To examine the association between hyperkalemia and long-term cardiovascular and renal outcomes in patients with chronic kidney disease. PATIENTS AND METHODS: An observational retrospective cohort study was performed using a Japanese hospital claims registry, Medical Data Vision (April 1, 2008, to September 30, 2018). Of 1,208,894 patients with at least 1 potassium measurement, 167,465 patients with chronic kidney disease were selected based on International Classification of Diseases, Tenth Revision codes or estimated glomerular filtration rate (eGFR) less than 60 mL/min/1.73 m2. Hyperkalemia was defined as at least 2 potassium measurements of 5.1 mmol/L or greater within 12 months. Normokalemic controls were patients without a record of potassium levels of 5.1 mmol/L or greater and 3.5 mmol/L or less. Changes in eGFRs and hazard ratios of death, hospitalization for cardiac events, heart failure, and renal replacement therapy introduction were assessed between propensity score-matched hyperkalemic patients and normokalemic controls. RESULTS: Of 16,133 hyperkalemic patients and 11,898 normokalemic controls eligible for analyses, 5859 (36.3%) patients and 5859 (49.2%) controls were selected after propensity score matching. The mean follow-up period was 3.5 years. The 3-year eGFR change in patients and controls was -5.75 and -1.79 mL/min/1.73 m2, respectively. Overall, hyperkalemic patients had higher risks for death, hospitalization for cardiac events, heart failure, and renal replacement therapy introduction than controls, with hazard ratios of 4.40 (95% CI, 3.74 to 5.18), 1.95 (95% CI, 1.59 to 2.39), 5.09 (95% CI, 4.17 to 6.21), and 7.54 (95% CI, 5.73 to 9.91), respectively. CONCLUSION: Hyperkalemia was associated with significant risks for mortality and adverse clinical outcomes, with more rapid decline of renal function. These findings underscore the significance of hyperkalemia as a predisposition to future adverse events in patients with chronic kidney disease.
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RATIONALE & OBJECTIVE: Hyperkalemia is a common electrolyte abnormality of chronic kidney disease and heart failure associated with increased mortality and morbidity. We aimed to assess the long-term economic burden of hyperkalemia. DESIGN: Observational cohort study using a Japanese nationwide hospital claims database (April 1, 2008, to September 30, 2018). SETTING & POPULATION: : Patients 18 years or older with at least 1 serum potassium value (N = 1,208,894). EXPOSURES: Hyperkalemia defined with the presence of at least 2 serum potassium values ≥ 5.1 mmol/L. OUTCOME MEASURES: Direct health care costs and resource use in patients with hyperkalemia within and after 12 months from first hyperkalemia episodes. ANALYTICAL APPROACH: Health care costs and resource use were compared with propensity score-matched or nonmatched normokalemic controls. Multivariable regression analysis was performed to examine factors associated with health care costs. RESULTS: 27,534 patients with hyperkalemia and 233,098 normokalemic controls were studied. Mean ± SD age was 73±13 years in patients with hyperkalemia; among them, 59% and 35% had chronic kidney disease and heart failure, respectively. In the propensity score-matched cohort (n = 5,859 in each group), average numbers of hospitalizations per patient per year in patients with hyperkalemia within and after 12 months were 1.2 and 1.6 times higher, respectively, compared with those in patients with normokalemia. The total cost per patient in patients with hyperkalemia was higher than for controls, with mean differences of $8,611 (95% CI, $8,046-$9,175) within 12 months and $5,150 (95% CI, $4,733-$5,566) after 12 months. The number of repeat hyperkalemic episodes was the factor with the strongest association with long-term health care costs, whereas severity of hyperkalemia was not associated. LIMITATIONS: This study used secondary data; therefore, residual confounders may not be fully excluded. CONCLUSIONS: Hyperkalemia was associated with significant long-term economic burden with frequent hospitalizations due to recurrent episodes, indicating the importance of hyperkalemia treatment for the sake of reducing health economic burdens and clinical complications.
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INTRODUCTION: An abnormal serum potassium (S-K) level is an important electrolyte disturbance. However, its relation to clinical outcomes in real-world patients, particularly hyperkalemia burden, is not extensively studied. METHODS: An observational retrospective cohort study using a Japanese hospital claims database was done (April 2008-September 2017; N = 1,022,087). Associations between index S-K level and 3-year survival were modeled using cubic spline regression. Cox regression model was applied to estimate the time to death according to different S-K levels. Prevalence, patient characteristics, treatment patterns, and management of patients with hyperkalemia from first episode were assessed. RESULTS: Hyperkalemia prevalence was 67.9 (95% confidence interval [CI]: 67.1-68.8) per 1000 and increased in patients with chronic kidney disease (CKD) (227.9; 95% CI: 224.3-231.5), heart failure (134.0; 95% CI: 131.2-136.8), and renin-angiotensin-aldosterone system inhibitor (RAASi) use (142.2; 95% CI: 139.6-144.7). U-shaped associations between S-K level and 3-year survival were observed with nadir 4.0 mEq/l. The risk of death was increased at S-K 5.1-5.4 mEq with hazard ratio of 7.6 (95% CI: 7.2-8.0). The 3-year mortality rate in patients with CKD stages 3a, 3b, 4, and 5 with normokalemia were 1.51%, 3.93%, 10.86%, and 12.09%, whereas that in patients with CKD stage 3a at S-K 5.1-5.4, 5.5-5.9, and ≥6.0 mEq/l increased to 10.31%, 11.43%, and 22.64%, respectively. Despite treatment with loop diuretics (18.5%) and potassium binders (5.8%), >30% of patients had persistently high S-K (≥5.1 mEq/l). CONCLUSION: This study provides real-world insight on hyperkalemia based on a large number of patients with various medical backgrounds.
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Due to the associated and substantial efforts of many stakeholders involved in malaria containment, the disease burden of malaria has dramatically decreased in many malaria-endemic countries in recent years. Some decades after the past efforts of the global malaria eradication program, malaria elimination has again featured on the global health agenda. While risk distribution modeling and a mapping approach are effective tools to assist with the efficient allocation of limited health-care resources, these methods need some adjustment and reexamination in accordance with changes occurring in relation to malaria elimination. Limited available data, fine-scale data inaccessibility (for example, household or individual case data), and the lack of reliable data due to inefficiencies within the routine surveillance system, make it difficult to create reliable risk maps for decision-makers or health-care practitioners in the field. Furthermore, the risk of malaria may dynamically change due to various factors such as the progress of containment interventions and environmental changes. To address the complex and dynamic nature of situations in low-to-moderate malaria transmission settings, we built a spatiotemporal model of a standardized morbidity ratio (SMR) of malaria incidence, calculated through annual parasite incidence, using routinely reported surveillance data in combination with environmental indices such as remote sensing data, and the non-environmental regional containment status, to create fine-scale risk maps. A hierarchical Bayesian frame was employed to fit the transitioning malaria risk data onto the map. The model was set to estimate the SMRs of every study location at specific time intervals within its uncertainty range. Using the spatial interpolation of estimated SMRs at village level, we created fine-scale maps of two provinces in western Cambodia at specific time intervals. The maps presented different patterns of malaria risk distribution at specific time intervals. Moreover, the visualized weights estimated using the risk model, and the structure of the routine surveillance network, represent the transitional complexities emerging from ever-changing regional endemic situations.
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The disease burden of malaria has decreased as malaria elimination efforts progress. The mapping approach that uses spatial risk distribution modeling needs some adjustment and reinvestigation in accordance with situational changes. Here we applied a mathematical modeling approach for standardized morbidity ratio (SMR) calculated by annual parasite incidence using routinely aggregated surveillance reports, environmental data such as remote sensing data, and non-environmental anthropogenic data to create fine-scale spatial risk distribution maps of western Cambodia. Furthermore, we incorporated a combination of containment status indicators into the model to demonstrate spatial heterogeneities of the relationship between containment status and risks. The explanatory model was fitted to estimate the SMR of each area (adjusted Pearson correlation coefficient R2 = 0.774; Akaike information criterion AIC = 149.423). A Bayesian modeling framework was applied to estimate the uncertainty of the model and cross-scale predictions. Fine-scale maps were created by the spatial interpolation of estimated SMRs at each village. Compared with geocoded case data, corresponding predicted values showed conformity [Spearman's rank correlation r = 0.662 in the inverse distance weighed interpolation and 0.645 in ordinal kriging (95% confidence intervals of 0.414-0.827 and 0.368-0.813, respectively), Welch's t-test; Not significant]. The proposed approach successfully explained regional malaria risks and fine-scale risk maps were created under low-to-moderate malaria transmission settings where reinvestigations of existing risk modeling approaches were needed. Moreover, different representations of simulated outcomes of containment status indicators for respective areas provided useful insights for tailored interventional planning, considering regional malaria endemicity.