Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 11 de 11
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Stat Med ; 40(16): 3667-3681, 2021 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-33866577

RESUMO

Polytomous regression models generalize logistic models for the case of a categorical outcome variable with more than two distinct categories. These models are currently used in clinical research, and it is essential to measure their abilities to distinguish between the categories of the outcome. In 2012, van Calster et al proposed the polytomous discrimination index (PDI) as an extension of the binary discrimination c-statistic to unordered polytomous regression. The PDI is a summary of the simultaneous discrimination between all outcome categories. Previous implementations of the PDI are not capable of running on "big data." This article shows that the PDI formula can be manipulated to depend only on the distributions of the predicted probabilities evaluated for each outcome category and within each observed level of the outcome, which substantially improves the computation time. We present a SAS macro and R function that can rapidly evaluate the PDI and its components. The routines are evaluated on several simulated datasets after varying the number of categories of the outcome and size of the data and two real-world large administrative health datasets. We compare PDI with two other discrimination indices: M-index and hypervolume under the manifold (HUM) on simulated examples. We describe situations where the PDI and HUM, indices based on multiple comparisons, are superior to the M-index, an index based on pairwise comparisons, to detect predictions that are no different than random selection or erroneous due to incorrect ranking.


Assuntos
Modelos Logísticos , Humanos
2.
J Diabetes Complications ; 35(4): 107804, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33349557

RESUMO

OBJECTIVES: The antepartum oral glucose tolerance test (OGTT) has re-emerged as associated with risk of diabetes among women with gestational diabetes (GDM). This systematic review summarized evidence on associations between antepartum OGTT and risk of diabetes in GDM (PROSPERO CRD42018100316). METHODS: MEDLINE, EMBASE, Web of Science, and CENTRAL were searched from January 1, 1982 to February 2020. Studies assessing associations between antepartum OGTT and risk of diabetes among women with GDM were included. Data on study characteristics, participants, OGTT values, and diabetes outcomes were extracted. Estimates on the association between antepartum OGTT and diabetes at follow-up were recorded. Pooled odds ratios for developing diabetes were calculated by study design. FINDINGS AND CONCLUSIONS: Of 6423 citations, 17 studies were included. Both elevated fasting blood glucose (FBG; OR: 3.62 ([95% CI 1.30, 10.12], I2 = 36%, p < 0.05)) and 2 h OGTT (OR: 3.96 [1.17, 13.40], I2 = 87%, p < 0.05) were associated with diabetes. These associations were attenuated (FBG: OR: 1.91 ([95% CI 0.80, 24.54], I2 = 83%, p = NS) and 1.58 ([95% CI 0.92, 2.74] I2 = 83%, p = NS) for prospective and retrospective data, respectively; 2 h OGTT: ORa: 1.95 ([95% CI 0.43, 8.93], I2 = 94%, p = NS)) after adjustments for common confounders. Further research is needed before clinical recommendations can be made.

3.
Respir Med ; 155: 133-140, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31349187

RESUMO

BACKGROUND: Asthmatics are at increased cardiovascular disease risk, which has been linked to beta2(ß2)-agonist use. Inhalation of ß2-agonists increases sympathetic nerve activity (SNA) in healthy individuals, however the systemic impact of salbutamol in asthmatics using ß2-agonists regularly is unknown. OBJECTIVES: This study compared the systemic vascular responses to a clinical dose of salbutamol (Phase I) and following an acute increase in SNA (Phase II) in asthmatics and controls. METHODS: Fourteen controls and 14 asthmatics were recruited for Phase I. On separate days, flow-mediated dilation (FMD) and peripheral arterial stiffness (pPWV) were evaluated at baseline and following either 400 µg inhaled salbutamol or a placebo inhaler. For Phase II, heart rate, blood pressure, vascular conductance, pPWV, and central (c)PWV were evaluated in response to a large increase in SNA brought on by cold-water hand immersion (i.e. cold-pressor test) or body-temperature water hand immersion (i.e. control) in 10 controls and 10 asthmatics. RESULTS: Following salbutamol, asthmatics demonstrated reduced FMD (-3.0%, p < 0.05) and increased pPWV (+0.7 m/s, p < 0.05); however, salbutamol had no effect in controls. The cold-pressor test resulted in similar increases in blood pressure, vascular flow rates and conductance, pPWV, and cPWV in both asthmatics and controls, suggesting similar neurovascular transduction in asthmatics and controls. CONCLUSION: Inhaled Salbutamol leads to increased arterial stiffness and reduced FMD in asthmatics. As asthmatics and controls had similar vascular responses to an increase in SNA, these findings suggest asthmatics have heightened sympathetic responses to ß2-agonists which may contribute to the increased cardiovascular risk in asthma.


Assuntos
Agonistas de Receptores Adrenérgicos beta 2/administração & dosagem , Albuterol/administração & dosagem , Asma/tratamento farmacológico , Asma/fisiopatologia , Administração por Inalação , Agonistas de Receptores Adrenérgicos beta 2/efeitos adversos , Adulto , Albuterol/efeitos adversos , Pressão Sanguínea , Doenças Cardiovasculares/etiologia , Feminino , Humanos , Masculino , Risco , Rigidez Vascular , Adulto Jovem
4.
J Appl Physiol (1985) ; 127(5): 1278-1287, 2019 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-31295067

RESUMO

Recent work demonstrates that carotid chemoreceptor (CC) activity/sensitivity is elevated in patients with chronic obstructive pulmonary disease (COPD) compared with healthy controls, and this elevated chemoreception appears to contribute to increased cardiovascular risk. Exercise training has been shown to normalize CC activity/sensitivity in other populations, and therefore, the purpose of this study was to determine whether pulmonary rehabilitation (PR) can reduce CC activity/sensitivity in COPD. Forty-five COPD patients [mean FEV1 (forced expiratory volume in 1 s) = 56.6% predicted] completed PR, while 15 COPD patients (mean FEV1 = 74.6% predicted) served as non-PR controls. CC activity was determined by the reduction in ventilation while breathing transient hyperoxia ([Formula: see text] = 1.0); CC sensitivity was evaluated by the increase in ventilation relative to the drop in arterial saturation while breathing hypoxia. Dyspnea, six-minute walk and autonomic function data were also obtained. PR improved 6-minute walk distance (P < 0.001) and dyspnea (P = 0.04); however, there was no effect on CC activity (P = 0.60), sensitivity (P = 0.69), or autonomic function (P > 0.05 for all). Subgroup analyses indicated that PR reduced CC activity in those with elevated baseline CC activity, independent of changes in autonomic function. No change in dyspnea (P = 0.24), CC activity (P = 0.19), sensitivity (P = 0.80), or autonomic function (P > 0.05 for all) was observed in the control group. Despite improvements in exercise tolerance and dyspnea, PR appears to be generally ineffective at reducing CC sensitivity in stable COPD patients; while PR reduced CC activity in those with elevated basal CC activity, the physiological significance of this is unclear. Further investigations aimed at improving CC function in COPD are needed.NEW & NOTEWORTHY While work in other chronic diseases has shown that exercise training may help normalize carotid chemoreceptor (CC) activity/sensitivity, the current study found that exercise training through pulmonary rehabilitation did not consistently reduce CC activity/sensitivity in patients with chronic obstructive pulmonary disease (COPD). These results suggest that other interventions are needed to normalize CC activity/sensitivity in COPD.


Assuntos
Corpo Carotídeo/fisiopatologia , Doença Pulmonar Obstrutiva Crônica/reabilitação , Idoso , Estudos de Casos e Controles , Dispneia/fisiopatologia , Humanos , Pessoa de Meia-Idade , Doença Pulmonar Obstrutiva Crônica/fisiopatologia
5.
J Am Heart Assoc ; 8(10): e011608, 2019 05 21.
Artigo em Inglês | MEDLINE | ID: mdl-31088190

RESUMO

Background We examined temporal trends, timing, and frequency, as well as adverse neonatal and maternal outcomes occurring in the first year postpartum among women experiencing syncope during pregnancy. Methods and Results This was a retrospective study of pregnancies between January 1, 2005, and December 31, 2014, in the province of Alberta, Canada. Of 481 930 pregnancies, 4667 had an episode of syncope. Poisson regression analysis found a 5% increase/year (rate ratio, 1.05; 95% CI, 1.04-1.06) in the age-adjusted incidence of syncope. Overall, 1506 (32.3%) of the syncope episodes first occurred in the first trimester, 2058 (44.1%) in the second trimester, and 1103 (23.6%) in the third trimester; and 8% (n=377) of pregnancies had >1 episode of syncope. Compared with women without syncope, women who experienced syncope were younger (age <25 years; 34.7% versus 20.8%; P<0.001), and primiparous (52.1% versus 42.4%; P<0.001). The rate of preterm birth was higher in pregnancies with syncope during the first trimester (18.3%), compared with the second (15.8%) and third trimesters (14.2%) and pregnancies without syncope (15.0%; P<0.01). The incidence of congenital anomalies among children born of pregnancies with multiple syncope episodes was significantly higher (4.9%) compared with children of pregnancies without syncope (2.9%; P<0.01). Within 1 year after delivery, women with syncope during pregnancy had higher rates of cardiac arrhythmias and syncope episodes than women with no syncope during pregnancy. Conclusions Pregnant women with syncope, especially when the syncopal event occurs during the first trimester, may be at a higher risk of adverse pregnancy outcomes as well as an increased incidence of cardiac arrhythmia and syncope postpartum.


Assuntos
Complicações na Gravidez/epidemiologia , Síncope/epidemiologia , Adulto , Fatores Etários , Alberta/epidemiologia , Arritmias Cardíacas/epidemiologia , Anormalidades Congênitas/epidemiologia , Feminino , Humanos , Incidência , Período Pós-Parto , Gravidez , Complicações na Gravidez/diagnóstico , Trimestres da Gravidez , Estudos Retrospectivos , Medição de Risco , Fatores de Risco , Síncope/diagnóstico , Fatores de Tempo , Adulto Jovem
6.
J Appl Physiol (1985) ; 125(3): 870-877, 2018 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-29878869

RESUMO

Dyspnea has been reported to be a main contributor to exercise avoidance in asthma. While traditional markers of ventilation do not explain the heightened dyspnea during exercise in patients with asthma, this study proposed that exertional dyspnea in asthma was due to high-operating lung volumes, which may be improved with a short-acting ß2-agonist. On two separate days, 16 patients with asthma and 16 controls completed a lung function test and incremental exercise tests to exhaustion. On one of the days (order randomized), 400 µg salbutamol was administered before exercise. Inspiratory capacity (IC), inspiratory reserve volume (IRV), and dyspnea (modified Borg scale) were evaluated throughout exercise. Compared with controls, patients with asthma reported greater dyspnea at the same absolute submaximal workloads. Furthermore, patients with asthma demonstrated altered breathing responses to exercise, characterized by reduced IC and IRV throughout exercise compared with controls. The reduced IRV was associated with increased dyspnea in patients with asthma. Salbutamol did not affect dyspnea or operating lung volumes in either group. The increased perception of dyspnea during incremental exercise in patients with asthma appears to be secondary to a reduction in IRV, which is unaffected by an inhaled ß2-agonist. NEW & NOTEWORTHY Increased exertional dyspnea in asthma appears to be due to high operating lung volumes and is not affected by salbutamol.


Assuntos
Asma/patologia , Dispneia/patologia , Pulmão/patologia , Agonistas Adrenérgicos beta/uso terapêutico , Adulto , Resistência das Vias Respiratórias , Albuterol/uso terapêutico , Antiasmáticos/uso terapêutico , Asma/tratamento farmacológico , Dispneia/tratamento farmacológico , Teste de Esforço , Tolerância ao Exercício , Feminino , Humanos , Volume de Reserva Inspiratória , Medidas de Volume Pulmonar , Masculino , Testes de Função Respiratória , Adulto Jovem
7.
J Cardiopulm Rehabil Prev ; 38(5): 320-326, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29652760

RESUMO

PURPOSE: Some patients with chronic obstructive pulmonary disease (COPD) fail to achieve health benefits with pulmonary rehabilitation (PR). Exercise intensity and load represent stimulus for adaptation but it is unclear whether inappropriate exercise intensity and/or load are affected by severity of COPD, which may affect health benefits. The purpose was to determine whether COPD severity and/or the severity of pulmonary limitation to exercise (PLE) impacted exercising intensity or load and whether resultant intensity/load affected health outcomes derived from PR. METHODS: Patients with COPD (n = 58, age = 67 ± 7 y, forced expiratory volume in the first second of expiration [FEV1] % predicted = 52 ± 21%) were recruited upon referral to PR. Primary health outcomes evaluated were 6-min walk distance and St George's Respiratory Questionnaire. Patients were stratified for disease severity using Global Initiative for Obstructive Lung Disease (GOLD) staging and PLE severity by change in inspiratory capacity during exercise. Exercise intensity and load were calculated from daily exercise records. RESULTS: Participants achieved comparable training duration and load regardless of GOLD severity. Patients with more severe PLE achieved greater training duration (more severe: 546 ± 143 min., less severe: 451 ± 109 min., P = .036), and relative training load (more severe: 2200.8 ± 595.3 kcal, less severe: 1648.3 ± 597.8 kcal, P = .007). Greater overall training load was associated with greater improvements in 6-min walk distance (r = 0.24, P = .035). No significant relationships were observed between PLE, GOLD severity, training parameters, and St George's Respiratory Questionnaire response. CONCLUSIONS: Improvements in exercise tolerance can be explained by achieving greater training loads, demonstrating the importance of appropriate training load to maximize health outcomes in PR.


Assuntos
Terapia por Exercício/métodos , Exercício Físico/fisiologia , Esforço Físico/fisiologia , Doença Pulmonar Obstrutiva Crônica/fisiopatologia , Doença Pulmonar Obstrutiva Crônica/reabilitação , Idoso , Volume Expiratório Forçado , Humanos , Pessoa de Meia-Idade , Índice de Gravidade de Doença , Inquéritos e Questionários , Teste de Caminhada
8.
Respir Med ; 132: 56-61, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29229106

RESUMO

BACKGROUND: Heightened arterial stiffness is a marker of cardiovascular risk and is elevated in chronic obstructive pulmonary disease (COPD). Physical activity has been shown to reduce arterial stiffness, and our previous work has shown that arterial stiffness is related to physical activity and exercise tolerance in COPD. The purpose of this study was to evaluate whether baseline physical activity and exercise tolerance influence the cardiovascular benefits associated with standard COPD outpatient pulmonary rehabilitation (PR). METHODS: A total of 66 patients with COPD were recruited from the G.F. MacDonald Centre for Lung Health, Edmonton, Alberta, prior to entering PR. Another 23 COPD patients not attending the PR program were recruited as time controls (TC). Arterial stiffness (carotid-radial pulse wave velocity, PWV), physical activity (steps taken over three days), and 6-min walk distance (6MWD) were assessed before and after PR, or before and after six weeks of standard care. RESULTS: Thirty-nine PR and 11 TC completed all parts of the study. Following PR, there was no overall change in PWV. However, changes in arterial stiffness with PR were dependent on baseline exercise tolerance, with those patients with a 6MWD <350 m showing a significant reduction in PWV following PR (6MWD >350 m: 8.2 ± 1.6 to 8.5 ± 1.7 versus 6MWD <350 m: 9.2 ± 0.6 to 7.3 ± 2.0 m/s, p < 0.05). The PWV response to PR was not influenced by baseline physical activity levels. CONCLUSION: COPD patients with low exercise tolerance appear to derive the greatest cardiovascular benefits from PR.


Assuntos
Doenças Cardiovasculares/fisiopatologia , Tolerância ao Exercício/fisiologia , Exercício Físico , Doença Pulmonar Obstrutiva Crônica/reabilitação , Rigidez Vascular/fisiologia , Idoso , Doenças Cardiovasculares/epidemiologia , Estudos de Casos e Controles , Terapia por Exercício/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Doença Pulmonar Obstrutiva Crônica/fisiopatologia , Análise de Onda de Pulso , Terapia Respiratória/métodos , Teste de Caminhada
9.
Respir Physiol Neurobiol ; 231: 14-20, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27236040

RESUMO

Asthma independently increases the risk of developing cardiovascular disease. As inhaled ß-agonists have systemic cardiovascular effects, and elevations in arterial stiffness and sympathetic nerve activity are associated with increased cardiovascular morbidity/mortality, this study examines the effect of salbutamol use on pulse wave velocity (PWV) and muscle sympathetic nervous activity (MSNA). Healthy men and women (26.2±1.5years) were recruited for: Day 1: 4 inhalations of placebo followed by 4 inhalations of salbutamol (4×100µg); Day 2: placebo only; Day 3: carotid-femoral PWV measurements before/after placebo/salbutamol. Heart rate (HR), mean arterial pressure (MAP), and carotid-radial PWV were obtained on Day 1 and 2. MSNA was obtained on Day 1. Salbutamol increased HR and total MSNA (Baseline1: 2.8±2.8au; Placebo: 2.4±2.1au; Baseline2: 2.7±3.0au; Salbutamol: 3.3±2.9au; p=0.05), with no changes in MAP or PWV. There were no effects of placebo on HR, MSNA, or PWV. Acute salbutamol use increases sympathetic activity suggesting that salbutamol could contribute to cardiovascular morbidity/mortality in individuals using inhaled ß-agonists.


Assuntos
Agonistas de Receptores Adrenérgicos beta 2/administração & dosagem , Albuterol/administração & dosagem , Sistema Nervoso Simpático/efeitos dos fármacos , Rigidez Vascular/efeitos dos fármacos , Administração por Inalação , Agonistas de Receptores Adrenérgicos beta 2/efeitos adversos , Adulto , Albuterol/efeitos adversos , Pressão Arterial/efeitos dos fármacos , Doenças Cardiovasculares/epidemiologia , Feminino , Frequência Cardíaca/efeitos dos fármacos , Humanos , Masculino , Análise de Onda de Pulso , Risco , Adulto Jovem
10.
J Physiol ; 593(14): 3147-57, 2015 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-25952760

RESUMO

Pulmonary gas exchange, as evaluated by the alveolar-arterial oxygen difference (A-aDO2), is impaired during intense exercise, and has been correlated with recruitment of intrapulmonary arteriovenous anastomoses (IPAVA) as measured by agitated saline contrast echocardiography. Previous work has shown that dopamine (DA) recruits IPAVA and increases venous admixture (Q̇s/Q̇t) at rest. As circulating DA increases during exercise, we hypothesized that A-aDO2 and IPAVA recruitment would be decreased with DA receptor blockade. Twelve healthy males (age: 25 ± 6 years, V̇O2 max : 58.6 ± 6.5 ml kg(-1) min(-1) ) performed two incremental staged cycling exercise sessions after ingestion of either placebo or a DA receptor blocker (metoclopramide 20 mg). Arterial blood gas, cardiorespiratory and IPAVA recruitment (evaluated by agitated saline contrast echocardiography) data were obtained at rest and during exercise up to 85% of V̇O2 max . On different days, participants also completed incremental exercise tests and exercise tolerance (time-to-exhaustion (TTE) at 85% of V̇O2 max ) with or without dopamine blockade. Compared to placebo, DA blockade did not change O2 consumption, CO2 production, or respiratory exchange ratio at any intensity. At 85% V̇O2 max , DA blockade decreased A-aDO2, increased arterial O2 saturation and minute ventilation, but did not reduce IPAVA recruitment, suggesting that positive saline contrast is unrelated to A-aDO2. Compared to placebo, DA blockade decreased maximal cardiac output, V̇O2 max and TTE. Despite improving pulmonary gas exchange, blocking dopamine receptors appears to be detrimental to exercise performance. These findings suggest that endogenous dopamine is important to the normal cardiopulmonary response to exercise and is necessary for optimal high-intensity exercise performance.


Assuntos
Antagonistas dos Receptores de Dopamina D2/farmacologia , Tolerância ao Exercício/efeitos dos fármacos , Metoclopramida/farmacologia , Troca Gasosa Pulmonar/efeitos dos fármacos , Adulto , Anastomose Arteriovenosa/efeitos dos fármacos , Anastomose Arteriovenosa/fisiologia , Débito Cardíaco/efeitos dos fármacos , Humanos , Masculino
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...