897 resultados para multivariable regression


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BACKGROUND Access to care may be implicated in disparities between men and women in death after acute coronary syndrome, especially among younger adults. We aimed to assess sex-related differences in access to care among patients with premature acute coronary syndrome and to identify clinical and gender-related determinants of access to care. METHODS We studied 1123 patients (18-55 yr) admitted to hospital for acute coronary syndrome and enrolled in the GENESIS-PRAXY cohort study. Outcome measures were door-to-electrocardiography, door-to-needle and door-to-balloon times, as well as proportions of patients undergoing cardiac catheterization, reperfusion or nonprimary percutaneous coronary intervention. We performed univariable and multivariable logistic regression analyses to identify clinical and gender-related determinants of timely procedures and use of invasive procedures. RESULTS Women were less likely than men to receive care within benchmark times for electrocardiography (≤ 10 min: 29% v. 38%, p = 0.02) or fibrinolysis (≤ 30 min: 32% v. 57%, p = 0.01). Women with ST-segment elevation myocardial infarction (MI) were less likely than men to undergo reperfusion therapy (primary percutaneous coronary intervention or fibrinolysis) (83% v. 91%, p = 0.01), and women with non-ST-segment elevation MI or unstable angina were less likely to undergo nonprimary percutaneous coronary intervention (48% v. 66%, p < 0.001). Clinical determinants of poorer access to care included anxiety, increased number of risk factors and absence of chest pain. Gender-related determinants included feminine traits of personality and responsibility for housework. INTERPRETATION Among younger adults with acute coronary syndrome, women and men had different access to care. Moreover, fewer than half of men and women with ST-segment elevation MI received timely primary coronary intervention. Our results also highlight that men and women with no chest pain and those with anxiety, several traditional risk factors and feminine personality traits were at particularly increased risk of poorer access to care.

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BACKGROUND The association between combination antiretroviral therapy (cART) and cancer risk, especially regimens containing protease inhibitors (PIs) or nonnucleoside reverse transcriptase inhibitors (NNRTIs), is unclear. METHODS Participants were followed from the latest of D:A:D study entry or January 1, 2004, until the earliest of a first cancer diagnosis, February 1, 2012, death, or 6 months after the last visit. Multivariable Poisson regression models assessed associations between cumulative (per year) use of either any cART or PI/NNRTI, and the incidence of any cancer, non-AIDS-defining cancers (NADC), AIDS-defining cancers (ADC), and the most frequently occurring ADC (Kaposi sarcoma, non-Hodgkin lymphoma) and NADC (lung, invasive anal, head/neck cancers, and Hodgkin lymphoma). RESULTS A total of 41,762 persons contributed 241,556 person-years (PY). A total of 1832 cancers were diagnosed [incidence rate: 0.76/100 PY (95% confidence interval: 0.72 to 0.79)], 718 ADC [0.30/100 PY (0.28-0.32)], and 1114 NADC [0.46/100 PY (0.43-0.49)]. Longer exposure to cART was associated with a lower ADC risk [adjusted rate ratio: 0.88/year (0.85-0.92)] but a higher NADC risk [1.02/year (1.00-1.03)]. Both PI and NNRTI use were associated with a lower ADC risk [PI: 0.96/year (0.92-1.00); NNRTI: 0.86/year (0.81-0.91)]. PI use was associated with a higher NADC risk [1.03/year (1.01-1.05)]. Although this was largely driven by an association with anal cancer [1.08/year (1.04-1.13)], the association remained after excluding anal cancers from the end point [1.02/year (1.01-1.04)]. No association was seen between NNRTI use and NADC [1.00/year (0.98-1.02)]. CONCLUSIONS Cumulative use of PIs may be associated with a higher risk of anal cancer and possibly other NADC. Further investigation of biological mechanisms is warranted.

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The aim of this study was to associate changes in dairy farmers' self-reported attitude, knowledge, and behavior with the decrease in incidence rate of clinical mastitis (IRCM). Farmer-diagnosed clinical mastitis cases were obtained from two surveys conducted before (July 2004-June 2005) and at the end (2009) of a mastitis control program in the Netherlands. Information on farmers' attitude, knowledge, and behavior was also obtained by sending the farmers the same questionnaire during both surveys. Multivariable linear regression models identified that the herd level 2004 IRCM explained 28% of the variation in the decrease of IRCM. Changes in farmers' attitude and knowledge, and changes in farmers' behavior additionally explained 24% and 5%, respectively. These results suggest that the way management measures are executed may be at least as important as the fact that they are executed. No control group was available for this study because the intervention was applied at the national level. We therefore do not claim any causal relationships.

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Arginine vasopressin (AVP) has a key role in osmoregulation by facilitating water transport in the collecting duct. Recent evidence suggests that AVP may have additional effects on renal function and favor cyst growth in polycystic kidney disease. Whether AVP also affects kidney structure in the general population is unknown. We analyzed the association of copeptin, an established surrogate for AVP, with parameters of renal function and morphology in a multicentric population-based cohort. Participants from families of European ancestry were randomly selected in three Swiss cities. We used linear multilevel regression analysis to explore the association of copeptin with renal function parameters as well as kidney length and the presence of simple renal cysts assessed by ultrasound examination. Copeptin levels were log-transformed. The 529 women and 481 men had median copeptin levels of 3.0 and 5.2 pmol/L, respectively (P<0.001). In multivariable analyses, the copeptin level was associated inversely with eGFR (β=-2.1; 95% confidence interval [95% CI], -3.3 to -0.8; P=0.002) and kidney length (β=-1.2; 95% CI, -1.9 to -0.4; P=0.003) but positively with 24-hour urinary albumin excretion (β=0.11; 95% CI, 0.01 to 0.20; P=0.03) and urine osmolality (β=0.08; 95% CI, 0.05 to 0.10; P<0.001). A positive association was found between the copeptin level and the presence of renal cysts (odds ratio, 1.6; 95% CI, 1.1 to 2.4; P=0.02). These results suggest that AVP has a pleiotropic role in renal function and may favor the development of simple renal cysts.

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BACKGROUND AND AIMS: Selective serotonin reuptake inhibitors (SSRIs) are commonly prescribed for patients with chronic hepatitis C virus (HCV) infection. Research suggests that serotonin promotes the development and growth of hepatocellular carcinoma (HCC). We tested the hypothesis whether exposure to SSRIs is associated with an increased risk of HCC in HCV patients. METHOD: Patients who entered the United States Veterans Affairs (VA) Hepatitis C Clinical Case Registry in 2000 to 2009 were analyzed. During the 8 years of follow-up, 36,192 patients filled at least 1 SSRI prescription. Cases of HCC were identified by diagnosis codes (ICD-9 155.0). Multivariable Cox regression analyses estimated adjusted HCC hazard ratios (HRs) for SSRI-exposed versus SSRI-unexposed subjects and categories of average SSRI doses. RESULTS: The annual incidence of HCC in the VA registry cohort of 109,736 patients was 0.5% and significantly greater in the 8% with cirrhosis at baseline (HR = 5.2; 95% CI, 4.7-5.7). There was no evidence for significant interactions between the effect of SSRI-exposure and cirrhosis. Baseline characteristics of the exposed (n = 36,192) and unexposed (n = 73,544) subjects were similar. The median (interquartile range [IQR]) follow-up period after SSRI-exposure began was 44 (20-74) months with 18 (3-49) months between the first and last prescription. The median average SSRI dose during follow-up expressed as a fraction of initial recommended doses for depression was 0.94 (IQR, 0.5 to 1.3). The risk of HCC was not significantly increased after SSRI exposure (HR = 0.96; 95% CI, 0.87-1.05) or with increasing SSRI doses. CONCLUSIONS: Analysis of a large cohort of HCV patients did not support the hypothesis that SSRIs increase the risk of developing HCC.

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PURPOSE Rapid assessment and intervention is important for the prognosis of acutely ill patients admitted to the emergency department (ED). The aim of this study was to prospectively develop and validate a model predicting the risk of in-hospital death based on all available information available at the time of ED admission and to compare its discriminative performance with a non-systematic risk estimate by the triaging first health-care provider. METHODS Prospective cohort analysis based on a multivariable logistic regression for the probability of death. RESULTS A total of 8,607 consecutive admissions of 7,680 patients admitted to the ED of a tertiary care hospital were analysed. Most frequent APACHE II diagnostic categories at the time of admission were neurological (2,052, 24 %), trauma (1,522, 18 %), infection categories [1,328, 15 %; including sepsis (357, 4.1 %), severe sepsis (249, 2.9 %), septic shock (27, 0.3 %)], cardiovascular (1,022, 12 %), gastrointestinal (848, 10 %) and respiratory (449, 5 %). The predictors of the final model were age, prolonged capillary refill time, blood pressure, mechanical ventilation, oxygen saturation index, Glasgow coma score and APACHE II diagnostic category. The model showed good discriminative ability, with an area under the receiver operating characteristic curve of 0.92 and good internal validity. The model performed significantly better than non-systematic triaging of the patient. CONCLUSIONS The use of the prediction model can facilitate the identification of ED patients with higher mortality risk. The model performs better than a non-systematic assessment and may facilitate more rapid identification and commencement of treatment of patients at risk of an unfavourable outcome.

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OBJECTIVE: To investigate the prevalence of discontinuation and nonpublication of surgical versus medical randomized controlled trials (RCTs) and to explore risk factors for discontinuation and nonpublication of surgical RCTs. BACKGROUND: Trial discontinuation has significant scientific, ethical, and economic implications. To date, the prevalence of discontinuation of surgical RCTs is unknown. METHODS: All RCT protocols approved between 2000 and 2003 by 6 ethics committees in Canada, Germany, and Switzerland were screened. Baseline characteristics were collected and, if published, full reports retrieved. Risk factors for early discontinuation for slow recruitment and nonpublication were explored using multivariable logistic regression analyses. RESULTS: In total, 863 RCT protocols involving adult patients were identified, 127 in surgery (15%) and 736 in medicine (85%). Surgical trials were discontinued for any reason more often than medical trials [43% vs 27%, risk difference 16% (95% confidence interval [CI]: 5%-26%); P = 0.001] and more often discontinued for slow recruitment [18% vs 11%, risk difference 8% (95% CI: 0.1%-16%); P = 0.020]. The percentage of trials not published as full journal article was similar in surgical and medical trials (44% vs 40%, risk difference 4% (95% CI: -5% to 14%); P = 0.373). Discontinuation of surgical trials was a strong risk factor for nonpublication (odds ratio = 4.18, 95% CI: 1.45-12.06; P = 0.008). CONCLUSIONS: Discontinuation and nonpublication rates were substantial in surgical RCTs and trial discontinuation was strongly associated with nonpublication. These findings need to be taken into account when interpreting surgical literature. Surgical trialists should consider feasibility studies before embarking on full-scale trials.

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We aimed to explore the effects of (90)Y-DOTATOC and (90)Y-DOTATOC plus (177)Lu-DOTATOC on survival of patients with metastasized gastrinoma. Patients with progressive metastasized gastrinoma were treated with repeated cycles of (90)Y-DOTATOC or with cycles alternating between (90)Y-DOTATOC and (177)Lu-DOTATOC until tumor progression or permanent toxicity. Multivariable Cox regression analyses were used to study predictors of survival. A total of 36 patients were enrolled; 30 patients received (90)Y-DOTATOC (median activity per patient 11.8GBq; range: 6.1-62.2GBq) and 6 patients received (90)Y-DOTATOC plus (177)Lu-DOTATOC (median activity per patient: 14.8GBq; range: 7.4-14.8GBq). Response was found in 26 patients (72.2%), including morphological (n=12, 33.3%), biochemical (n=14, 38.9%) and/or clinical response (n=6, 16.2%). A total of 21 patients (58.3%) experienced hematotoxicity grade 1/2, while 1 patient (2.8%) experienced hematotoxicity grade 3; no grade 4 hematotoxicity occurred. Furthermore, 2 patients (5.6%) developed grade 4 renal toxicity; no grade 5 renal toxicity occurred. Responders had a significantly longer median survival from time of enrollment than non-responders (45.1 months, range: 37.1-53.1 months vs. 12.6 months, range: 11.0-14.2, hazard ratio: 0.12 (0.027-0.52), p=0.005). Additionally, there was a trend towards longer median survival with (90)Y-DOTATOC plus (177)Lu-DOTATOC as compared to (90)Y-DOTATOC alone (60.2 months, range: 19.8-100.6 months vs. 27.0 months, range: 4.0-50.0, hazard ratio: 0.21 (0.01-3.98), p=0.16). Response to (90)Y-DOTATOC and (90)Y-DOTATOC plus (177)Lu-DOTATOC therapy is associated with a longer survival in patients with metastasized gastrinoma. Both treatment regimens are promising tools for management of progressive gastrinoma.

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BACKGROUND The Quality and Outcomes Framework in the United Kingdom (UK) National Health Service previously highlighted case finding of depression amongst patients with diabetes or coronary heart disease. However, depression in older people remains under-recognized. Comprehensive data for analyses of the association of depression in older age with other health and functional measures, and demographic factors from community populations within England, are lacking. METHODS Secondary analyses of cross-sectional baseline survey data from the England arm of a randomised controlled trial of health risk appraisal for older people in Europe; PRO-AGE study. Data from 1085 community-dwelling non-disabled people aged 65 years or more from three group practices in suburban London contributed to this study. Depressed mood was ascertained from the 5-item Mental Health Inventory Screening test. Exploratory multivariable logistic regression was used to identify the strongest associations of depressed mood with a previous diagnosis of a specified physical/mental health condition, health and functional measures, and demographic factors. RESULTS Depressed mood occurred in 14% (155/1085) of participants. A previous diagnoses of depression (OR 3.39; P < 0.001) and poor vision as determined from a Visual Function Questionnaire (OR 2.37; P = 0.001) were amongst the strongest factors associated with depressed mood that were independent of functional impairment, other co-morbidities, and demographic factors. A subgroup analyses on those without a previous diagnosis of depression also indicated that within this group, poor vision (OR 2.51; P = 0.002) was amongst the strongest independent factors associated with depressed mood. CONCLUSIONS Previous case-finding strategies in primary care focussed on heart disease and diabetes but health-related conditions other than coronary heart disease and diabetes are also associated with an increased risk for depression. Complex issues of multi-morbidity occur within aging populations. 'Risk' factors that appeared stronger than those, such as, diabetes and coronary heart disease that until recently prompted for screening in the UK due to the QOF, were identified, and independent of other morbidities associated with depressed mood. From the health and functional factors investigated, amongst the strongest factors associated with depressed mood was poor vision. Consideration to case finding for depressed mood among older people with visual impairment might be justified.

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The counterfactual decomposition technique popularized by Blinder (1973, Journal of Human Resources, 436–455) and Oaxaca (1973, International Economic Review, 693–709) is widely used to study mean outcome differences between groups. For example, the technique is often used to analyze wage gaps by sex or race. This article summarizes the technique and addresses several complications, such as the identification of effects of categorical predictors in the detailed decomposition or the estimation of standard errors. A new command called oaxaca is introduced, and examples illustrating its usage are given.

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estout, introduced by Jann (Stata Journal 5: 288–308), is a useful tool for producing regression tables from stored estimates. However, its syntax is relatively complex and commands may turn out long even for simple tables. Furthermore, having to store the estimates beforehand can be cumbersome. To facilitate the production of regression tables, I therefore present here two new commands called eststo and esttab. eststo is a wrapper for offcial Stata’s estimates store and simplifies the storing of estimation results for tabulation. esttab, on the other hand, is a wrapper for estout and simplifies compiling nice-looking tables from the stored estimates without much typing. I also provide updates to estout and estadd.

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Organizing and archiving statistical results and processing a subset of those results for publication are important and often underestimated issues in conducting statistical analyses. Because automation of these tasks is often poor, processing results produced by statistical packages is quite laborious and vulnerable to error. I will therefore present a new package called estout that facilitates and automates some of these tasks. This new command can be used to produce regression tables for use with spreadsheets, LaTeX, HTML, or word processors. For example, the results for multiple models can be organized in spreadsheets and can thus be archived in an orderly manner. Alternatively, the results can be directly saved as a publication-ready table for inclusion in, for example, a LaTeX document. estout is implemented as a wrapper for estimates table but has many additional features, such as support for mfx. However, despite its flexibility, estout is—I believe—still very straightforward and easy to use. Furthermore, estout can be customized via so-called defaults files. A tool to make available supplementary statistics called estadd is also provided.

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In this paper we propose a new fully-automatic method for localizing and segmenting 3D intervertebral discs from MR images, where the two problems are solved in a unified data-driven regression and classification framework. We estimate the output (image displacements for localization, or fg/bg labels for segmentation) of image points by exploiting both training data and geometric constraints simultaneously. The problem is formulated in a unified objective function which is then solved globally and efficiently. We validate our method on MR images of 25 patients. Taking manually labeled data as the ground truth, our method achieves a mean localization error of 1.3 mm, a mean Dice metric of 87%, and a mean surface distance of 1.3 mm. Our method can be applied to other localization and segmentation tasks.

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In clinical practice, traditional X-ray radiography is widely used, and knowledge of landmarks and contours in anteroposterior (AP) pelvis X-rays is invaluable for computer aided diagnosis, hip surgery planning and image-guided interventions. This paper presents a fully automatic approach for landmark detection and shape segmentation of both pelvis and femur in conventional AP X-ray images. Our approach is based on the framework of landmark detection via Random Forest (RF) regression and shape regularization via hierarchical sparse shape composition. We propose a visual feature FL-HoG (Flexible- Level Histogram of Oriented Gradients) and a feature selection algorithm based on trace radio optimization to improve the robustness and the efficacy of RF-based landmark detection. The landmark detection result is then used in a hierarchical sparse shape composition framework for shape regularization. Finally, the extracted shape contour is fine-tuned by a post-processing step based on low level image features. The experimental results demonstrate that our feature selection algorithm reduces the feature dimension in a factor of 40 and improves both training and test efficiency. Further experiments conducted on 436 clinical AP pelvis X-rays show that our approach achieves an average point-to-curve error around 1.2 mm for femur and 1.9 mm for pelvis.