Biomedical subjects

Roberto Pastor-Barriuso

Publications and source records attributed to Roberto Pastor-Barriuso.

9 recordsLinked to original sources

PubMed2006

Time trend and age-period-cohort effect on kidney cancer mortality in Europe, 1981-2000.

BACKGROUND: The incorporation of diagnostic and therapeutic improvements, as well as the different smoking patterns, may have had an influence on the observed variability in renal cancer mortality across Europe. This study examined time trends in kidney cancer mortality in fourteen European countries during the last two decades of the 20th century. METHODS: Kidney cancer deaths and population estimates for each country during the period 1981-2000 were drawn from the World Health Organization Mortality Database. Age- and period-adjusted mortality rates, as well as annual percentage changes in age-adjusted mortality rates, were calculated for each country and geographical region. Log-linear Poisson models were also fitted to study the effect of age, death period, and birth cohort on kidney cancer mortality rates within each country. RESULTS: For men, the overall standardized kidney cancer mortality rates in the eastern, western, and northern European countries were 20, 25, and 53% higher than those for the southern European countries, respectively. However, age-adjusted mortality rates showed a significant annual decrease of -0.7% in the north of Europe, a moderate rise of 0.7% in the west, and substantial increases of 1.4% in the south and 2.0% in the east. This trend was similar among women, but with lower mortality rates. Age-period-cohort models showed three different birth-cohort patterns for both men and women: a decrease in mortality trend for those generations born after 1920 in the Nordic countries, a similar but lagged decline for cohorts born after 1930 in western and southern European countries, and a continuous increase throughout all birth cohorts in eastern Europe. Similar but more heterogeneous regional patterns were observed for period effects. CONCLUSION: Kidney cancer mortality trends in Europe showed a clear north-south pattern, with high rates on a downward trend in the north, intermediate rates on a more marked rising trend in the east than in the west, and low rates on an upward trend in the south. The downward pattern observed for cohorts born after 1920-1930 in northern, western, and southern regions suggests more favourable trends in coming years, in contrast to the eastern countries where birth-cohort pattern remains upward.

Adolescent↗

PubMed2006

Selenium and coronary heart disease: a meta-analysis.

BACKGROUND: It is hypothesized that low selenium concentrations are associated with an increased risk of cardiovascular disease and that selenium supplements prevent coronary heart disease. OBJECTIVE: The objective was to perform a meta-analysis on the association of selenium biomarkers with coronary heart disease endpoints in observational studies and on the efficacy of selenium supplements in preventing coronary heart disease endpoints in randomized trials. DESIGN: The MEDLINE and the Cochrane Library databases were searched for studies conducted from 1966 through 2005. Relative risks were pooled by using an inverse-variance weighted random-effects model. RESULTS: Twenty-five observational studies (14 cohort and 11 case-control studies) that measured blood or toenail selenium concentrations and 6 randomized trials that evaluated supplements containing selenium met our inclusion criteria. The pooled relative risk in a comparison of the highest with the lowest selenium concentration categories was 0.85 (95% CI: 0.74, 0.99) in cohort studies and 0.43 (0.29, 0.66) in case-control studies. In observational studies, a 50% increase in selenium concentrations was associated with a 24% (7%, 38%) reduction in coronary heart disease risk. In randomized trials, the pooled relative risk in a comparison of supplements containing selenium with placebo was 0.89 (0.68, 1.17). CONCLUSIONS: Selenium concentrations were inversely associated with coronary heart disease risk in observational studies. Because observational studies have provided misleading evidence for other antioxidants, the validity of this association is uncertain. Few randomized trials have addressed the cardiovascular efficacy of selenium supplementation, and their findings are still inconclusive. Evidence from large ongoing trials is needed to establish low selenium concentrations as a cardiovascular disease risk factor. Currently, selenium supplements should not be recommended for cardiovascular disease prevention.

Biomarkers↗

PubMed2006

Vitamin-mineral supplementation and the progression of atherosclerosis: a meta-analysis of randomized controlled trials.

BACKGROUND: Laboratory and observational studies suggest that antioxidant and B vitamin supplementation may prevent atherosclerosis. Although trials have not shown a benefit of these supplements on clinical cardiovascular events, it is unknown whether they affect the progression of atherosclerosis as measured by imaging techniques. OBJECTIVE: The objective was to perform a meta-analysis of randomized controlled trials of the effect of vitamin-mineral supplementation on atherosclerosis progression. DESIGN: We searched the MEDLINE, EMBASE, and CENTRAL databases for relevant studies. No language restrictions were applied. We separately analyzed trials using antioxidants (vitamins E and C, beta-carotene, or selenium) and trials using B vitamins (folate, vitamin B-6, or vitamin B-12). The progression of atherosclerosis was evaluated by B-mode ultrasound, intravascular ultrasound, or angiography. Effect sizes were calculated for the difference in slope of atherosclerosis progression between participants assigned to supplements and those assigned to the control group. RESULTS: In trials not involving percutaneous transluminal coronary angioplasty, the pooled effect size was -0.06 (95% CI: -0.20, 0.09; 7 trials) for antioxidants and -0.93 (95% CI: -2.11, 0.26; 4 trials) for B vitamins. In trials involving percutaneous transluminal coronary angioplasty, the pooled relative risk of restenosis was 0.82 (95% CI: 0.54, 1.26; 3 trials) for antioxidants and 0.84 (95% CI: 0.34, 2.07; 2 trials) for B vitamins. CONCLUSION: Our meta-analysis showed no evidence of a protective effect of antioxidant or B vitamin supplements on the progression of atherosclerosis, thus providing a mechanistic explanation for their lack of effect on clinical cardiovascular events.

Adult↗

PubMed2005

Body mass index and incident ischemic heart disease in South Korean men and women.

Asian populations have a higher body fat percentage for a given body mass index (BMI) than Caucasians. However, little information is available on the association of BMI with ischemic heart disease (IHD) incidence in Asians at low BMI levels. The authors prospectively evaluated the association of BMI (weight (kg)/height m2) with IHD incidence over 9 years of follow-up (1993-2001) among 133,740 South Korean adults (89,050 men, 44,690 women) who participated in the 1990 and 1992 examinations of the Korea Medical Insurance Corporation Study. Average BMI at baseline was 23.4 (standard deviation, 2.3) in men and 22.3 (standard deviation, 2.3) in women. After multivariate adjustment, there was a 14% (95% confidence interval: 12, 16) increased risk of incident IHD per unit of increase in BMI. This trend was also observed within the range considered normal by Western standards, and a BMI of 24-<25 was associated with an IHD hazard ratio of 2.01 (95% confidence interval: 1.32, 3.05) in comparison with a BMI of 18-<19. The association of BMI with IHD in this cohort of relatively young South Korean men and women was progressive over the range of BMI values, with no threshold of change in risk and no indication of a U-shaped relation at low BMI levels.

Adult↗

PubMed2005

Reliability of portal control procedure in irradiation of breast cancer: a Bayesian analysis.

BACKGROUND AND PURPOSE: To determine whether the information gathered from a fixed number of periodic verification films accurately reflects the true imprecision in patient positioning during the whole radiation therapy of early breast cancer. PATIENTS AND METHODS: A total of 204 medial and lateral treatment fields were evaluated in 102 breast cancer patients treated with conservative surgery and radiation therapy. For each treatment field, the central lung distance was measured on portal films obtained from one simulation and four treatment controls at weekly intervals during breast irradiation. Systematic and random errors in patient positioning throughout all treatment fractions were estimated from the available controls using Bayesian methods. RESULTS: The average systematic and random errors during treatment controls were 2.7 and 1.9 mm, respectively. For these mean control values, the probabilities that the true systematic and random errors remain below 5mm during all treatment fractions were 99 and 100%, respectively. CONCLUSIONS: Reproducibility of patient positioning was supported by a virtually null probability for systematic or random errors greater than 5 mm during the whole radiation therapy. Weekly verification films seem to be sufficient to estimate patient positioning errors with high accuracy in radiotherapy of early breast cancer.

Adult↗

PubMed2005

Seasonal analyses of air pollution and mortality in 100 US cities.

Time series models relating short-term changes in air pollution levels to daily mortality counts typically assume that the effects of air pollution on the log relative rate of mortality do not vary with time. However, these short-term effects might plausibly vary by season. Changes in the sources of air pollution and meteorology can result in changes in characteristics of the air pollution mixture across seasons. The authors developed Bayesian semiparametric hierarchical models for estimating time-varying effects of pollution on mortality in multisite time series studies. The methods were applied to the database of the National Morbidity and Mortality Air Pollution Study, which includes data for 100 US cities, for the period 1987-2000. At the national level, a 10-microg/m(3) increase in particulate matter less than 10 microm in aerodynamic diameter at a 1-day lag was associated with 0.15% (95% posterior interval (PI): -0.08, 0.39), 0.14% (95% PI: -0.14, 0.42), 0.36% (95% PI: 0.11, 0.61), and 0.14% (95% PI: -0.06, 0.34) increases in mortality for winter, spring, summer, and fall, respectively. An analysis by geographic region found a strong seasonal pattern in the Northeast (with a peak in summer) and little seasonal variation in the southern regions of the country. These results provide useful information for understanding particle toxicity and guiding future analyses of particle constituent data.

Air Pollution↗

PubMed2004

Meta-analysis: high-dosage vitamin E supplementation may increase all-cause mortality.

BACKGROUND: Experimental models and observational studies suggest that vitamin E supplementation may prevent cardiovascular disease and cancer. However, several trials of high-dosage vitamin E supplementation showed non-statistically significant increases in total mortality. PURPOSE: To perform a meta-analysis of the dose-response relationship between vitamin E supplementation and total mortality by using data from randomized, controlled trials. PATIENTS: 135,967 participants in 19 clinical trials. Of these trials, 9 tested vitamin E alone and 10 tested vitamin E combined with other vitamins or minerals. The dosages of vitamin E ranged from 16.5 to 2000 IU/d (median, 400 IU/d). DATA SOURCES: PubMed search from 1966 through August 2004, complemented by a search of the Cochrane Clinical Trials Database and review of citations of published reviews and meta-analyses. No language restrictions were applied. DATA EXTRACTION: 3 investigators independently abstracted study reports. The investigators of the original publications were contacted if required information was not available. DATA SYNTHESIS: 9 of 11 trials testing high-dosage vitamin E (> or =400 IU/d) showed increased risk (risk difference > 0) for all-cause mortality in comparisons of vitamin E versus control. The pooled all-cause mortality risk difference in high-dosage vitamin E trials was 39 per 10,000 persons (95% CI, 3 to 74 per 10,000 persons; P = 0.035). For low-dosage vitamin E trials, the risk difference was -16 per 10,000 persons (CI, -41 to 10 per 10,000 persons; P > 0.2). A dose-response analysis showed a statistically significant relationship between vitamin E dosage and all-cause mortality, with increased risk of dosages greater than 150 IU/d. LIMITATIONS: High-dosage (> or =400 IU/d) trials were often small and were performed in patients with chronic diseases. The generalizability of the findings to healthy adults is uncertain. Precise estimation of the threshold at which risk increases is difficult. CONCLUSION: High-dosage (> or =400 IU/d) vitamin E supplements may increase all-cause mortality and should be avoided.

Adult↗

PubMed2003

Systolic blood pressure, diastolic blood pressure, and pulse pressure: an evaluation of their joint effect on mortality.

BACKGROUND: The relative importance of blood pressure components (systolic blood pressure, diastolic blood pressure, and pulse pressure) on cardiovascular risk is currently being debated. Many studies, however, are limited by inadequate statistical methods to separate these effects. OBJECTIVE: To evaluate the joint effect of blood pressure components on all-cause and cardiovascular mortality by using nonparametric and change point models. DESIGN: Prospective cohort study. SETTING: 15-year mortality follow-up of participants in the Second National Health and Nutrition Examination Survey. PARTICIPANTS: 7830 white and African-American men and women 30 to 74 years of age, apparently free of cardiovascular disease at baseline. MEASUREMENTS: Baseline blood pressure, corrected for measurement error. RESULTS: Of the 1588 patients who died, 582 died of cardiovascular disease. Systolic blood pressure was linearly related to all-cause and cardiovascular mortality in younger and elderly participants. The association of diastolic blood pressure with all-cause and cardiovascular mortality was hockey stick-shaped (flat then increasing) in younger participants and J-shaped in elderly participants. Increased pulse pressure was associated with increased risk, decreased risk, or no change in risk depending on age and systolic and diastolic blood pressure. CONCLUSIONS: On the basis of these and previous data, the evidence for a monotonic association of systolic blood pressure with all-cause and cardiovascular mortality is compelling, but a J-shaped association for diastolic blood pressure may develop at older age. The complexity of the association of pulse pressure with mortality discourages its use for prognostic or therapeutic decisions.

Age Factors↗

PubMed2003

Transition models for change-point estimation in logistic regression.

Although a wide variety of change-point models are available for continuous outcomes, few models are available for dichotomous outcomes. This paper introduces transition methods for logistic regression models in which the dose-response relationship follows two different straight lines, which may intersect or may present a jump at an unknown change-point. In these models, the logit includes a differentiable transition function that provides parametric control of the sharpness of the transition at the change-point, allowing for abrupt changes or more gradual transitions between the two different linear trends, as well as for estimation of the location of the change-point. Linear-linear logistic models are particular cases of the proposed transition models. We present a modified iteratively reweighted least squares algorithm to estimate model parameters, and we provide inference procedures including a test for the existence of the change-point. These transition models are explored in a simulation study, and they are used to evaluate the existence of a change-point in the association between plasma glucose after an oral glucose tolerance test and mortality using data from the Mortality Follow-up of the Second National Health and Nutrition Examination Survey.

Adult↗