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Time Trends (time + trend)
Kinds of Time Trends Selected AbstractsTime Trends in Incidence, Mortality, and Case-Fatality after First Episode of Status EpilepticusEPILEPSIA, Issue 8 2001Giancarlo Logroscino Summary: ,Purpose: Status epilepticus (SE) is a medical emergency associated with a high mortality. Clinical series have suggested that mortality after SE has decreased. No studies have systematically examined trends in incidence, mortality, and case fatality after SE in a well-defined population. Methods: All first episodes of SE receiving medical attention between January 1, 1935, and December 31, 1984, were ascertained through the Rochester Epidemiology Project Records-Linkage System and followed up until death or study termination (February 1, 1996). We calculated incidence rates in the 50-year period (1935,1984), while we considered mortality and case-fatality in the last 30-year period (1955,1984). Results: Incidence of SE increased over time to 18.1/100,000 (1975 through 1984). The increase was related to an increased incidence in the elderly and to the advent of myoclonic SE after cardiac arrest, a condition not seen in the early decades. In the last decade, ,16% of the incidence was due to myoclonic SE. The mortality rates increased from 3.6 per year in the decade 1955,1965 to 4.0/100,000 per year between 1975 and 1984. The 30-day case-fatality (CF) was unchanged, although a trend toward improvement was shown after excluding myoclonic SE. Conclusions: Incidence and mortality rates of SE have increased in the last 30 years. Case fatality remained the same. The increased incidence and mortality are due to the occurrence in the last decade of myoclonic SE after cardiac arrest. The mortality in the elderly was twice that of the youngest age group, across all study periods. Changes in the age and cause distribution of SE over time are responsible for the stable survivorship. There is improvement in survivorship in the last decade when myoclonic SE is excluded. [source] The Effect of Linear Time Trends on the KPSS Test for CointegrationJOURNAL OF TIME SERIES ANALYSIS, Issue 3 2001Uwe Hassler The so-called KPSS test for the null hypothesis of cointegration builds on residuals from single equation regressions. Critical values have been provided for regressions with and without detrending. Here it is shown that the latter are not appropriate if the series display linear trends, although this does not mean that detrending is required. In this paper adequate percentiles are suggested for series that follow linear time trends, and tests are based on regressions without detrending. These percentiles are readily available from the literature. [source] Cigarettes and social differentiation in France: is tobacco use increasingly concentrated among the poor?ADDICTION, Issue 10 2009Patrick Peretti-Watel ABSTRACT Aims This paper aimed to assess whether the increase of social differentiation of smoking is observed in France. Design and setting Five cross-sectional telephone surveys conducted in France between 2000 and 2007. Participants The surveys were conducted among national representative samples of French subjects aged 18,75 years (n = 12 256, n = 2906, n = 27 499, n = 2887, n = 6007 in 2000, 2003, 2005, 2006 and 2007, respectively). We focused on three groups: executives, manual workers and the unemployed. Measurements Time trends of smoking prevalence were assessed, and socio-economic factors (especially occupation and job status) associated with smoking were identified and compared in 2000 and 2005. We also computed respondents' equivalized household consumption (EHI) and their cigarette budget to assess the financial burden of smoking. Findings Between 2000 and 2007, smoking prevalence decreased by 22% among executive managers and professionals and by 11% among manual workers, and did not decrease among the unemployed. Indicators of an underprivileged social situation were associated more markedly with smoking in 2005 than in 2000. In addition, the falling-off of smoking initiation occurred later and was less marked among manual workers than it was among executive managers and professionals. Finally, in 2005 15% of French smokers devoted at least 20% of their EHI to the purchase of cigarettes, versus only 5% in 2000, and smoking weighted increasingly heavily on the poorest smokers' budgets. Conclusions While these results point out an increased social differentiation in tobacco use, they underline the need to design and implement other forms of action to encourage people to quit, in particular targeting individuals belonging to underprivileged groups. [source] Prevalence of risk factors for cardiovascular disease in HIV-infected patients over time: the Swiss HIV Cohort StudyHIV MEDICINE, Issue 6 2006TR Glass Objective Metabolic changes caused by antiretroviral therapy (ART) may increase the risk of coronary heart disease (CHD). We evaluated changes in the prevalence of cardiovascular risk factors (CVRFs) and 10-year risk of CHD in a large cohort of HIV-infected individuals. Methods All individuals from the Swiss HIV Cohort Study (SHCS) who completed at least one CVRF questionnaire and for whom laboratory data were available for the period February 2000 to February 2006 were included in the analysis. The presence of a risk factor was determined using cut-offs based on the guidelines of the National Cholesterol Education Program (NCEP ATP III), the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC7), the American Diabetes Association, and the Swiss Society for Cardiology. Results Overall, 8033 individuals completed at least one CVRF questionnaire. The most common CVRFs in the first completed questionnaire were smoking (57.0%), low high-density lipoprotein (HDL) cholesterol (37.2%), high triglycerides (35.7%), and high blood pressure (26.1%). In total, 2.7 and 13.8% of patients were categorized as being at high (>20%) and moderate (10,20%) 10-year risk for CHD, respectively. Over 6 years the percentage of smokers decreased from 61.4 to 47.6% and the percentage of individuals with total cholesterol >6.2 mmol/L decreased from 21.1 to 12.3%. The prevalence of CVRFs and CHD risk was higher in patients currently on ART than in either pretreated or ART-naive patients. Conclusion During the 6-year observation period, the prevalence of CVRFs remains high in the SHCS. Time trends indicate a decrease in the percentage of smokers and individuals with high cholesterol. [source] Population Trends in BMD Testing, Treatment, and Hip and Wrist Fracture Rates: Are the Hip Fracture Projections Wrong?JOURNAL OF BONE AND MINERAL RESEARCH, Issue 6 2005Susan B Jaglal PhD Abstract A worldwide epidemic of hip fractures has been predicted. Time trends in BMD testing, bone-sparing medications and hip and wrist fractures in the province of Ontario, Canada, were examined. From 1996 to 2001, BMD testing and use of bone-sparing medications increased each year, whereas despite the aging of the population, wrist and hip fracture rates decreased. Introduction: If patients with osteoporosis are being diagnosed and effective treatments used with increasing frequency in the population, rates of hip and wrist fractures will remain stable or possibly decrease. We report here time trends in BMD testing, prescriptions for bone-sparing medications, hip and wrist fracture rates, and population projections of fracture rates to 2005 in the province of Ontario, Canada. Materials and Methods: Ontario residents have universal access to Medicare. To examine time trends in BMD testing, all physician claims for DXA from 1992 to 2001 were selected from the Ontario Health Insurance Plan (OHIP) database. Trends in prescribing were examined from 1996 to 2003 using data from the Ontario Drug Benefit plan, which provides coverage to persons ,65 years of age. Actual numbers of hip and wrist fractures were determined for 1992-2000 and population projections for 2001-2005 using time-series analysis. Wrist fractures were identified in the OHIP database and hip fractures through hospital discharge abstracts. Results: From 1992 to 2001, the number of BMD tests increased 10-fold. There has been a steady increase in the number of persons filling prescriptions for antiresorptives (12,298 in 1996 to 225,580 in 2003) and the majority were for etidronate. For women, the rate of decline for wrist fractures is greater than that for hip fractures. The rate of hip fracture was fairly constant around 41 per 10,000 women ,50 years between 1992 and 1996. In 1997, the hip fracture rate began to decrease, and the population projections suggest that this downward trend will continue to a rate of 33.1 per 10,000 in 2005. Conclusions: Our findings suggest that fracture rates may be on the decline, despite the aging of the population, because of increased patterns of diagnosis and treatment for osteoporosis. [source] Time trends in peptic ulcer, erosive reflux oesophagitis, gastric and oesophageal cancers in a multiracial Asian populationALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 7 2009K.-L. GOH Summary Background, Dramatic changes in the prevalence and pattern of gastrointestinal disease has taken place in Asia in recent years. Aim, To compare the prevalence of duodenal (DU) and gastric ulcers (GU), erosive oesophagitis (EO), gastric cancer (GCA) and oesophageal cancer (OCA) and Helicobacter pylori infection over a 10-year interval of time in a multiracial South-East Asian population. Methods, Endoscopy records of first time gastroscopy in the University of Malaya Medical Centre, Kuala Lumpur, Malaysia were reviewed for 1989/1990 and 1999/2000. Results, In the period of 1989,1990, 3252 records and in 1999,2000, 4615 records were analysed. Both DU (21.1,9.5%) and GU (11.9,9.4%) had decreased significantly (P < 0.001). EO had increased significantly from 2.0% to 8.4% (P < 0.001). Both GCA and OCA had declined in the 10-year interval. Helicobacter pylori prevalence had decreased from 51.7% to 30.3% (P < 0.001). The decrease in DU and GU was seen in all racial groups. The increase in EO was most marked in Indians and the decrease in GCA in Chinese. The proportion of H. pylori- associated DU and GU had also decreased with time. Conclusions, Peptic ulcers and H. pylori infection had declined over a 10-year period of time and showed an opposing time trend with EO, which had increased dramatically. Both GCA and OCA had declined in prevalence. [source] Time trends in first-diagnosis rates of colorectal adenomas: a 24-year population-based studyALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 10 2008V. COTTET Summary Background, Little is known about the descriptive epidemiology of colorectal adenomas diagnosed in the population. Aim, To describe time trends in the rate of first diagnosis of colorectal adenomas and estimate the proportion of adenoma-bearing individuals detected over a 24-year period. Methods, A total of 11 027 patients were first-diagnosed with colorectal adenomas among Côte-d'Or residents (France) between 1976 and 1999. Annual percentage changes were estimated using a Poisson regression model. The proportion of diagnosed adenoma-bearing individuals was estimated using the prevalence of adenomas in an autopsy study performed in the area. Results, Standardized diagnosis rates were 89.6/100 000 men and 50.3/100 000 women. During the period 1976,1993, diagnosis rates significantly increased with annual percentage changes in men and women of respectively +17.1% and +22.3% for proximal adenomas, +7.5% and +9.1% for distal adenomas and +7.2% and +8.0% for advanced adenomas. Changes were less marked during the period 1994,1999. The estimated proportion of adenoma-bearing individuals diagnosed during the 24-year period was 20.0% in men and 16.0% in women. Conclusion, Despite a marked increase in the rate of first adenoma diagnosis, the proportion of diagnosed adenoma-bearing individuals seems too low to induce a significant decrease in colorectal cancer incidence. [source] Time trends in asthma and wheeze in Swedish children 1996,2006: prevalence and risk factors by sexALLERGY, Issue 1 2010A. Bjerg Abstract Background:, Recent data suggest that the previously rising trend in childhood wheezing symptoms has plateaued in some regions. We sought to investigate sex-specific trends in wheeze, asthma, allergic conditions, allergic sensitization and risk factors for wheeze. Methods:, We compared two population-based cohorts of 7 to 8-year olds from the same Swedish towns in 1996 and 2006 using parental expanded ISAAC questionnaires. In 1996, 3430 (97%) and in 2006, 2585 (96%) questionnaires were completed. A subset was skin prick tested: in 1996, 2148 (88%) and in 2006, 1700 (90%) children participated. Results:, No significant change in the prevalence of current wheeze (P = 0.13), allergic rhinitis (P = 0.18) or eczema (P = 0.22) was found despite an increase in allergic sensitization (20.6,29.9%, P < 0.01). In boys, however, the prevalence of current wheeze (12.9,16.4%, P < 0.01), physician-diagnosed asthma (7.1,9.3%, P = 0.03) and asthma medication use increased. In girls the prevalence of current symptoms and conditions tended to decrease. The prevalence of all studied risk factors for wheeze and asthma increased in boys relative to girls from 1996 to 2006, thus increasing the boy-to-girl prevalence ratio in risk factors. Conclusions:, The previously reported increase in current wheezing indices has plateaued in Sweden. Due to increased diagnostic activity, physician diagnoses continue to increase. Time trends in wheezing symptoms differed between boys and girls, and current wheeze increased in boys. This was seemingly explained by the observed increases in the prevalence of risk factors for asthma in boys compared with girls. In contrast to the current symptoms of wheeze, rhinitis or eczema, the prevalence of allergic sensitization increased considerably. [source] Time trends in the prevalence of peanut allergy: three cohorts of children from the same geographical location in the UKALLERGY, Issue 1 2010C. Venter Abstract Background:, This article investigated the prevalence of peanut allergy in three cohorts of children born in the same geographical location, Isle of Wight, UK and seeks to determine whether the prevalence of peanut allergy has changed between 1994 and 2004. Methods:, Three cohorts of children (age 3,4 years) born on the Isle of Wight, were assessed for peanut allergy and the outcomes compared: Cohort A: Born in 1989; reviewed at 4 years of age (n = 2181). Cohort B: Born between 1994 and 1996; reviewed between 3 and 4 years of age (n = 1273). Cohort C: Born between 2001 and 2002; reviewed at 3 years of age (n = 891). Results:, Peanut sensitization increased significantly from 1.3% in Cohort A to 3.3% (P = 0.003) in Cohort B before falling back to 2.0% in Cohort C (P = 0.145). Similarly, clinical peanut allergy increased significantly from 0.5% in Cohort A to 1.4% (P = 0.023) in Cohort B, with a subsequent fall to 1.2% in Cohort C (P = 0.850). Conclusions:, Our data from three cohorts of 3- to 4-year-old children born in the same geographical area shows that peanut allergy prevalence has changed over time. Peanut sensitization and reported allergy in children born in 1994,1996 increased from 1989 but seems to have stabilized or slightly decreased since the late 1990s, although not significant. [source] Time trends in prevalence and severity of childhood asthma and allergies from 1995 to 2002 in FranceALLERGY, Issue 5 2009I. Annesi-Maesano Objective:, To assess time trends in symptoms of asthma, allergic rhinitis and atopic eczema among adolescents in Languedoc Roussillon, France. Methods:, Two cross-sectional surveys were conducted 7 years apart using the same protocol. School-based samples of 3383 participants in the 1995 survey and 1642 participants in the 2002 survey respectively were recruited. Results:, There was a tendency towards stagnation in current symptoms of asthma, rhinoconjunctivitis and eczema. Indices related to lifetime diagnosis of asthma, hay fever and eczema increased. For all the conditions, indices of severity also showed a decrease in the 7-year study period. Conclusions:, Our study shows that symptoms of asthma, allergic rhinitis and eczema were stable, supporting the effectiveness of national asthma prevention and management guidelines for such diseases. The increase in indices related to lifetime diagnosis could be the result of increased public and professional awareness of the diseases and changes in diagnostic labelling in recent years. [source] Developing epidemic of melanoma in the hispanic population of California,,CANCER, Issue 5 2006Myles G. Cockburn Ph.D. Abstract BACKGROUND Hispanics comprise almost one-third of the population of California, are the most rapidly increasing racial/ethnic group in the state, and represent almost one-third of all Hispanics in the U.S. California has among the highest rates of melanoma in the world, yet little is known about trends in melanoma in its Hispanic population. METHODS Trends in invasive and in situ melanoma incidence data and melanoma mortality data, between 1988 and 2001, from the California Cancer Registry were analyzed. Trends in the Hispanic population were compared with those in the non-Hispanic white population. Time trends in tumors of differing thicknesses and histology were assessed. RESULTS There was a statistically significant 1.8% per year increase in incidence of invasive melanomas among Hispanic males and a similar but nonstatistically significant increase in invasive melanoma among Hispanic females between 1988 and 2001. Among Hispanic males and females tumors thicker than 1.5 mm at presentation increased at 11.6% per year (95% confidence interval [CI], 8.1, 15.2) and 8.9% per year (95% CI, 4.7, 13.3), respectively. CONCLUSION Rates of invasive melanoma have increased markedly among Hispanics in California since 1988. In contrast to trends in the non-Hispanic white population, increases in melanoma in Hispanics have been confined to thicker tumors, whose prognosis is poor. We recommend that efforts be undertaken immediately to target both primary and secondary melanoma prevention messages to Hispanic communities. Cancer 2006. © 2006 American Cancer Society. [source] Trends in outcomes for very preterm infants in the southern region of Sweden over a 10-year periodACTA PAEDIATRICA, Issue 4 2009Pia Lundqvist Abstract Aim: To investigate trends in mortality and morbidity in very preterm infants. Methods: Population-based perinatal register; liveborn infants 22 + 0 to 31 + 6 gestational weeks were investigated (time period 1995,2004). Time trends for mortality and common morbidities were explored using logistic regression analyses. Results: Data from 1614 liveborn infants were included. There was an increase in live born infants below 25 gestational weeks, annual odds ratio (OR) 1.15 (95% CI: 1.08,1.23) and a decrease in mortality annual OR 0.82 (95% CI: 0.69,0.98). The rates of bronchopulmonary dysplasia (BPD) and sepsis increased during the study period, annual ORs of 1.10 (95% CI: 1.04,1.17) and 1.09 (95% CI: 1.03,1.16). The duration of mechanical ventilation increased for surviving infants <25 gestational weeks (p = 0.003), while the duration of continuous positive airway pressure (CPAP) increased for infants <28 gestational weeks (p = <0.001). There were no changes in the rates of intraventricular haemorrhages (IVH, 3,4), retinopathy of prematurity (ROP, 3,5), seizures or necrotizing enterocolitis (NEC). Conclusion: During the 10-year period changes in mortality and morbidity were most pronounced for infants with GA <28 gestational weeks. The increasing rate of sepsis was present in infants <28 gestational weeks, whereas the increase in BPD was demonstrated in the whole study population <32 gestational weeks. [source] Prospective study of 5-year caries increment among children receiving comprehensive dental care in the New England children's amalgam trialCOMMUNITY DENTISTRY AND ORAL EPIDEMIOLOGY, Issue 1 2009Nancy Nairi Maserejian Abstract,,, Objective:, To measure the 5-year caries increment among high-risk children during their participation in the New England Children's Amalgam Trial (NECAT), and to evaluate sociodemographic factors that may account for any observed disparities. Methods:, NECAT recruited 534 children aged 6,10 with at least two decayed posterior occlusal surfaces from urban Boston and rural Maine. After restoration of baseline caries and application of sealants to sound surfaces, NECAT continued to provide free comprehensive semiannual dental care to participants. The net caries increment of children who completed the 5-year follow-up (n = 429) was calculated and predictors of caries increment were investigated using multivariate negative binomial models. Results:, The majority of children (89%) experienced new caries by the end of the 5-year follow-up. Almost half (45%) had at least one newly decayed surface by the first annual visit. At year 5, the mean number of new decayed teeth was 4.5 ± 3.6 (range 0,25) and surfaces was 6.9 ± 6.5 (range 0,48). Time trends showed a noticeably higher increment rate among older children and young teenagers. Multivariate models showed that age (P < 0.001), number of baseline carious surfaces (P < 0.001), and toothbrushing frequency (<1/day versus ,2/day, P = 0.04) were associated with caries increment. Only 48 children (11%) did not develop new caries. Conclusions:, Despite the receipt of comprehensive semiannual dental care, the vast majority of these high-risk children continued to develop new caries within 5 years. While disparities were observed by age, extent of prior decay, and toothbrushing frequency, no other sociodemographic factors were associated with caries increment, suggesting that the dental care provided during the trial reduced sociodemographic disparities in prior caries experience that were observed at baseline. [source] Is the dementia rate increasing in Beijing?ACTA PSYCHIATRICA SCANDINAVICA, Issue 1 2007Prevalence, incidence of dementia 10 years later in an urban elderly population Objective:, To examine the time trend of dementia morbidity over the past decade in Beijing, China. Method:, In 1997, 1593 community-dwelling elderly aged 60+ years were examined and followed-up over 2-years to identify incident dementia. A similar cohort study of dementia conducted in the same district 10 years prior was used as historical comparison to examine the time trend of dementia incidence. Results:, Forty prevalent dementia cases were identified at the initial examination for a prevalence of 2.51% (95% CI: 1.74,3.28) and 25 incident cases were identified at the follow-up visit for an incidence of 0.90% (0.55,1.25) among residents aged 60+ years. Alzheimer's dementia (AD) was the most common type of dementia in both prevalent and incident cases. Conclusion:, The prevalence and incidence rates of dementia in Beijing were slightly higher than those 10 years ago, which was partly because of population aging. AD became the most common subtype of dementia. [source] Linear and non-linear optimization models for allocation of a limited water supply,IRRIGATION AND DRAINAGE, Issue 1 2004Bijan Ghahraman optimisation de l'irrigation; déficit d'irrigation; Iran Abstract One partial solution to the problem of ever-increasing demands on our water resources is optimal allocation of available water. A non-linear programming (NLP) optimization model with an integrated soil water balance was developed. This model is the advanced form of a previously developed one in which soil water balance was not included. The model also has the advantage of low computer run-time, as compared to commonly used dynamic programming (DP) models that suffer from dimensionality. The model can perform over different crop growth stages while taking into account an irrigation time interval in each stage. Therefore, the results are directly applicable to real-world conditions. However, the time trend of actual evapotranspiration (AET) for individual time intervals fluctuates more than that for growth-stage AETs. The proposed model was run for the Ardak area (45,km NW of the city of Mashhad, Iran) under a single cropping cultivation (corn) as well as a multiple cropping pattern (wheat, barley, corn, and sugar beet). The water balance equation was manipulated with net applied irrigation water to overcome the difficulty encountered with incorrect deep percolation. The outputs of the model, under the imposed seasonal irrigation water shortages, were compared with the results obtained from a simple NLP model. The differences between these two models (simple and integrated) became more significant as irrigation water shortage increased. Oversimplified assumptions in the previous simple model were the main causes of these differences. Copyright © 2004 John Wiley & Sons, Ltd. L'allocation optimale des ressources d'eau disponibles est une réponse partielle au problème de la demande sans cesse croissante de consommation d'eau. Un modèle d'optimisation à programmation non linéaire (NLP) qui intègre un bilan hydrique a été développé. Ce modèle est une version avancée d'un modéle précédent qui n'intégrait pas ce bilan hydrique. Il présente l'avantage de nécessiter moins de puissance informatique en comparaison des modèles à programmation dynamique (DP) généralement utilisés. Le modèle peut s'appliquer à différentes étapes de la croissance des cultures et prend en compte des fréquences d'irrigation variables. Ainsi, les résultats sont directement applicables aux conditions réelles. Le modèle proposé a été utilisé sur une seule culture (maïs) dans la région d'Ardak à 45,km nord-ouest de Mashad, Iran, et sur de multiples cultures (blé, orge, maïs, betterave sucrière). L'équation de bilan hydrique a été calibrée pour maîtriser les difficultés rencontrées avec des mesures d'infiltration incorrectes. Les résultats du modèle, dans le cadre de restrictions d'irrigation saisonnière imposées, ont été comparés avec ceux obtenus par un modèle simple NLP. Les différences entre ces deux modèles (simple et intégré) deviennent plus significatives à mesure que les restrictions d'irrigation augmentent. Les hypothèses trop simplistes du modèle simple sont la cause de ces différences. Copyright © 2004 John Wiley & Sons, Ltd. [source] Uncertainty, Real Options, and Cost Behavior: Evidence from Washington State HospitalsJOURNAL OF ACCOUNTING RESEARCH, Issue 5 2005SANJAY KALLAPUR ABSTRACT This study tests an implication of the real-options theory of investment, that uncertainty leads firms to prefer technologies with low fixed and high variable costs. In 1983, a change in Medicare reimbursement increased the uncertainty of revenues for hospitals. Using a sample of 831 departments in 59 Washington State hospitals over the 1977,1994 period, we find that the ratio of variable to total costs increased after 1983. This increase is not attributable to a gradual increase in the ratio over time: We estimate a significant increase after 1983 even after controlling for a time trend. Further, we find a greater increase in the variable-to-total cost ratio for hospitals that had higher percentages of Medicare patients, increasing our confidence in the conclusion that the change in cost behavior is attributable to Medicare's change in reimbursement. [source] Population parameters in Brazilian ThoroughbredJOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 6 2004R. Z. Taveira Summary The information in this study has been provided by the Brazilian Association of Racehorse Breeders [Associação Brasileira dos Criadores do Cavalo de Corrida (ABCCC)]. It can be found in the files on the CD-ROM developed by the ABCCC in 1999. A total of 5008 finishing time records related to 2545 winning horses that ran in the classical calendar on Brazilian hippodromes during 25 years (1974,98) were analysed. There were a total of 9949 horses on the relationship matrix. The variance components were estimated using the multiple-trait derivate-free restricted maximum likelihood (MTDFREML) program, for an animal model. Generation intervals were higher in the maternal side (10.91 years) than in the paternal one (10.41 years). The estimates for genetic, permanent environmental and phenotypic variances and heritability were 0.291, 0.161, 3.486 and 0.08, respectively. The phenotypic standard deviation for time in races was 1.86729 s. Genetic time trend on Thoroughbred races in Brazil was small and could be accelerated if selection considered the trait time effectively. With respect to the animal's country of birth, the results show that there has been an intense participation of foreign animals in breeding Brazilian Thoroughbreds. Zusammenfassung Die Angaben für die vorliegende Studie wurden von der Vereinigung brasilianischer Rennpferdezüchter (ABCCC) bereitgestellt und können auf der vom brasilianischen Stutbuch 1999 entwickelten CD-ROM nachgelesen werden. Es wurden insgesamt 5.008 Rennleistungen bezogen auf 2.545 Siegerpferde, die im klassischen Rennkalender des brasilianischen Hippodroms während 25 Jahren (1974 bis 1998) liefen, berücksichtigt. Die Gesamtzahl an Tieren in der Verwandtschaftsmatrix betrug 9.949. Die Varianzkomponenten wurden mittels des MTDFREML-Programms mit einem Tiermodell geschätzt. Das Generationsintervall war auf der maternalen Seite mit 10,91 Jahren höher als auf der paternalen mit 10,41 Jahren. Die Schätzwerte für genetische, permanente Umwelt- und phänotypische Varianzen lagen bei 0,291, 0,161 und 3,486, die Heritabilität betrug 0,08. Die phänotypische Standardabweichung für die Rennzeit war 1,86729 Sekunden. Der genetische Trend bei den Vollblütern in Brasilien war gering und könnte durch die effektive Selektion auf das Merkmal Zeit beschleunigt werden. Unter Berücksichtigung der Geburtsländer der Tiere zeigen die Ergebnisse, dass eine starke Beteiligung fremder Tiere in der Zucht des brasilianischen Vollbluts stattgefunden hat. [source] Evaluating effects of a prenatal web-based breastfeeding education programme in TaiwanJOURNAL OF CLINICAL NURSING, Issue 8 2007Mei Zen Huang MS Aims., The objectives of this study were to evaluate a web-based breastfeeding education programme provided to primigravida in the third trimester of pregnancy with the aim of deepening breastfeeding knowledge and enhancing skills. The study was conducted at a hospital in Taiwan. Background., Education is the cornerstone supporting the framework of lactation and breastfeeding. Web-based instruction is an efficient way to provide education. Design., A quasi-experimental design was used. Methods., The target population was women at 29,36 weeks gestation using the Internet on regular basis. The primigravida were assigned to either the control group (n = 60) or the experimental group (n = 60) according to time sequence. Results., Women who received web-based breastfeeding education had a higher mean breastfeeding knowledge score and more positive attitude about breastfeeding. In addition, generalized estimating equations (GEE) model was used to examine the breastfeeding rate at different time points. After adjusting for the time trend and infant birth weight, there was a significant effect in exclusive breastfeeding for the experimental group. On the other hand, the web-based breastfeeding education programme also had a significant effect on mixed feeding rate for the experimental group. Conclusion., Results suggest that web-based breastfeeding education may contribute to breastfeeding knowledge and attitude and improved breastfeeding rate. Relevance to clinical practice., Web-based breastfeeding education programme can achieve success in promoting breastfeeding and provide health professionals with an evidence-based intervention. [source] A patent analysis of global food and beverage firms: The persistence of innovationAGRIBUSINESS : AN INTERNATIONAL JOURNAL, Issue 3 2002Oscar Alfranca We explore whether current innovation has an enduring effect on future innovative activity in large, global food and beverage (F&B) companies. We analyze a sample of 16,698 patents granted in the United States over the period 1977 to 1994 to 103 F&B firms selected from the world's largest F&B multinationals. We test whether patent time series are trend stationary or difference stationary in order to detect how large the autoregressive parameter is and how enduring the impact of past innovation in these companies is. We conclude that the patent series are not consistent with the random walk model. The null hypothesis of a unit root can be rejected at the 5% level when a constant and a time trend are considered. Both utility and design patent series are stationary around a constant and a time trend. Moreover, there is a permanent component in the patent time series. Thus, global F&B firms show a stable pattern of technological accumulation in which "success breeds success." "Old" innovators are the ones to foster both important changes and new ways of packaging products among F&B multinationals. The effect of past innovation is almost permanent. By contrast, other potential stimuli to technological change have only transitory effects on innovation. Patterns of technological accumulation vary in specific F&B industries. Past experience in design is important in highly processed foods and beverages, but not in agribusinesses and basic foodstuffs. Patterns of technological accumulation are similar in both smaller multinationals/newcomers and large, established multinationals. [EconLit citations : O330, F230, L660] © 2002 Wiley Periodicals, Inc. [source] Prevalence and time trend of intestinal metaplasia in Hong KongJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 5 2009Yuk Kei Yee Abstract Background and Methods:, Upper endoscopy records from 1998 to 2003 were reviewed. The demographic data, endoscopic diagnosis, results of rapid urease test and the absence or presence of intestinal metaplasia (IM) in histology were reviewed, to evaluate the prevalence of IM and Helicobacter pylori (Hp) infection over time in Hong Kong. Results:, Among 1805 endoscopies performed, 1751 had both rapid urease test and histology available. A significant drop in the prevalence of duodenal ulcers from 17.9% in 1998 to 9.8% in 2003 was found (P = 0.015). Prevalence of IM was 13.9%, 5.9% and 9.4% in Hp positive, Hp negative and overall respectively (P < 0.05). The prevalence of IM increased with age, and the patterns were similar amongst subjects in 1998,2000 and those in 2001,2003. There was progressive decrease in Hp prevalence from 58% in 1998 to 40% in 2001 (P = 0.014), but no further decrease was seen in 2002,3. There was no corresponding decrease in IM prevalence. Instead IM prevalence in 2002,2003 was significantly higher than the prevalence in previous few years (P = 0.04). Conclusion:, The prevalence of IM did not change in the period from 1998 to 2003 despite a drop in the prevalence of Hp infection since 1994. [source] Estimating the variance of estimated trends in proportions when there is no unique subject identifierJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES A (STATISTICS IN SOCIETY), Issue 1 2007William K. Mountford Summary., Longitudinal population-based surveys are widely used in the health sciences to study patterns of change over time. In many of these data sets unique patient identifiers are not publicly available, making it impossible to link the repeated measures from the same individual directly. This poses a statistical challenge for making inferences about time trends because repeated measures from the same individual are likely to be positively correlated, i.e., although the time trend that is estimated under the naïve assumption of independence is unbiased, an unbiased estimate of the variance cannot be obtained without knowledge of the subject identifiers linking repeated measures over time. We propose a simple method for obtaining a conservative estimate of variability for making inferences about trends in proportions over time, ensuring that the type I error is no greater than the specified level. The method proposed is illustrated by using longitudinal data on diabetes hospitalization proportions in South Carolina. [source] Reducing size distortions of parametric stationarity testsJOURNAL OF TIME SERIES ANALYSIS, Issue 4 2003MARKKU LANNE The use of asymptotic critical values in stationarity tests against the alternative of a unit root process is known to lead to over-rejections in finite samples when the considered process is stationary but highly persistent. We claim that, in recent parametric tests, this is caused by estimation errors which result when the autoregressive parameters used to describe the short-run dynamics of the process are replaced by estimators. We suggest a modification that corrects for these errors. Simulation results show that the modified test works reasonably well when the persistence is moderate and there is no time trend in the model but it is less effective when the model contains a time trend. An empirical illustration with inflation rate data is provided. [source] Latex-induced occupational asthma: time trend in incidence and relationship with hospital glove policiesALLERGY, Issue 3 2009O. Vandenplas Background:, Natural rubber latex (NRL) has become as a major cause of occupational asthma (OA) in workers using NRL gloves. Few population-based studies have assessed the impact of changes in the patterns of glove usage on the incidence of NRL-induced OA. Objective:, To characterize the time trends in incident cases of NRL-induced OA in Belgium and examine whether incidence rates were related to the types of gloves used in hospitals. Methods:, Incident cases of NRL-induced OA were identified through a retrospective review of all claims submitted to the Workers' Compensation Board up to December 2004. Based on the results of diagnostic procedures, the diagnosis of NRL-induced OA was categorized as definite, probable, unlikely, or indeterminate. The patterns of glove usage were characterized through a questionnaire survey of Belgian hospitals. Results:, A total of 298 claims for NRL-induced OA were identified, including 127 subjects with definite OA and 68 with probable OA. Categorized by the year of asthma onset, the incident cases of definite and probable NRL-induced OA markedly decreased from 1999 onwards. The use of powdered NRL gloves fell from 80.9% in 1989 to 17.9% in 2004. Powdered NRL gloves were predominantly substituted with NRL-free gloves, especially in the case of non-sterile procedures. Conclusion:, These national compensation-based data confirm that a persistent decline in the incidence of NRL-induced OA has occurred since late 1990s. This downward trend has temporally been associated with a decreasing usage of powdered NRL, further supporting a beneficial role of changes in glove policies. [source] The Euro Effect on Trade is not as Large as Commonly Thought,OXFORD BULLETIN OF ECONOMICS & STATISTICS, Issue 4 2007Maurice J. G. Bun Abstract Existing studies on the impact of the euro on goods trade report increments between 5% and 40%. These estimates are based on standard panel gravity models for the level of trade. We show that the residuals from these models exhibit upward trends over time for the euro countries, and that this leads to an upward bias in the estimated euro effect. To correct for that, we extend the standard model by including a time trend that may have different effects across country-pairs. This results in an estimated euro impact of only 3%. [source] Prevalence of Epstein,Barr virus in Japan: Trends and future predictionPATHOLOGY INTERNATIONAL, Issue 3 2006Kengo Takeuchi Epstein,Barr virus (EBV) is the causative agent of infectious mononucleosis and some malignancies including EBV-associated-lymphomas. A large portion of adults all over the world are infected with EBV. In children, however, there are geographic variations. Most of the children in Asia and in other developing countries are infected in their early life, before 1 year of age (>90% of 5,9-year-old children are infected), while the age of primary infection is delayed in Western countries (approx. 50% of 5,9-year-old children are infected). The purpose of the present paper was to investigate the recent time trend of the EBV seropositivity among 5,7-year-old children living in Tokyo and its neighboring prefectures. Indirect immunofluorescein study for IgG antibody to viral capsid antigen was performed on 442 archival sera. Before the early 1990s, >80% of 5,7-year-old children were found to be seropositive, while the positivity rate decreased to 59% (P < 0.001) for the years 1995,1999. These results also showed that the delay in the age of primary infection is continuing and that the rate is estimated to be <50% in 2006. This result suggests that the delay will affect the incidence of EBV-associated disorders in Japan. [source] Effectiveness of the training program for workers at construction sites of the high-speed railway line between Torino and Novara: Impact on injury ratesAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 12 2009A. Bena MD Abstract Background There are very few published studies evaluating the impact of safety and health training on injury outcomes in the construction industry. The aim of this study was to assess the impact of the training program on injury rates at a major railway construction project. Methods The population consisted of 2,795 workers involved in a safety training program at the construction sites of the high-speed railway line Torino,Novara. Two types of analyses were carried out in order to assess the effectiveness of the training program in reducing the number of injuries: (i) a pre,post analysis, which took into account the fact that workers were enrolled at different times and the training intervention did not occur at the same time for all subjects; (ii) an interrupted time-series model, which corrected for the time trend and considered the autocorrelation between individual observations. Results Twenty-nine percent of workers who spent at least 1 day at the construction sites attended at least one training module. Pre,post analysis: At the end of the training program, the incidence of occupational injuries had fallen by 16% after the basic training module and by 25% following the specific modules. Time-series model: Training led to a 6% reduction in injury rates, which was not statistically significant. Conclusions The training program that was implemented had a moderately positive impact on the health of workers. Further studies are being conducted to obtain a more complete assessment of the actual effectiveness of the program in reducing the incidence of injuries. Am. J. Ind. Med. 52:965,972, 2009. © 2009 Wiley-Liss, Inc. [source] Optimal Valuation of Noisy Real AssetsREAL ESTATE ECONOMICS, Issue 3 2002Paul D. Childs We study the optimal valuation of real assets when true asset values are unobservable. In our model, the observed value cointegrates with the unobserved true asset value to cause serial correlation in the time series of observed values. Autocorrelation as well as total variance in the observed value are used to calculate an efficient unbiased estimate of the true asset value (the time,filtered value). The optimal value estimate is shown to have three time,weighted terms: a deterministic forward value, a comparison of observed values with previously determined time,filtered values, and a convexity correction for incomplete information. The residual variance measures the precision of the value estimate, which can increase or decrease monotonically over time as well as display a linear or nonlinear time trend. We also show how to revise time,filtered estimates based on the arrival of new information. Our results relate to work on illiquid asset markets, including appraisal smoothing, tests of market efficiency, and the valuation of options on real assets. [source] Nonlinear econometric models with cointegrated and deterministically trending regressorsTHE ECONOMETRICS JOURNAL, Issue 1 2001Yoosoon Chang This paper develops an asymptotic theory for a general class of nonlinear non-stationary regressions, extending earlier work by Phillips and Hansen (1990) on linear cointegrating regressions. The model considered accommodates a linear time trend and stationary regressors, as well as multiple I(1) regressors. We establish consistency and derive the limit distribution of the nonlinear least squares estimator. The estimator is consistent under fairly general conditions but the convergence rate and the limiting distribution are critically dependent upon the type of the regression function. For integrable regression functions, the parameter estimates converge at a reduced n1/4 rate and have mixed normal limit distributions. On the other hand, if the regression functions are homogeneous at infinity, the convergence rates are determined by the degree of the asymptotic homogeneity and the limit distributions are non-Gaussian. It is shown that nonlinear least squares generally yields inefficient estimators and invalid tests, just as in linear nonstationary regressions. The paper proposes a methodology to overcome such difficulties. The approach is simple to implement, produces efficient estimates and leads to tests that are asymptotically chi-square. It is implemented in empirical applications in much the same way as the fully modified estimator of Phillips and Hansen. [source] An update on the first decade of the European centralized procedure: how many innovative drugs?BRITISH JOURNAL OF CLINICAL PHARMACOLOGY, Issue 5 2006Domenico Motola What is already known about this subject ,,We recently proposed an algorithm to assess the degree of therapeutic innovation of new therapeutic agents. It was based on the disease seriousness, the availability of previous treatments and the extent of the therapeutic effect, and was applied to all therapeutic agents approved by the EMEA in the period 1995,2003. ,,A low percentage (32%) of important therapeutic innovation was found. This figure may be an underestimate of the actual level of innovation, because common biotechnological products, such as recombinant human insulins, must follow the centralized procedure. What this study adds ,,Details for each agent, focusing on the comparison of the degree of therapeutic innovation between biotechnological and nonbiotechnological therapeutic agents approved by EMEA during the its first decade of activity (1995,2004). The underlying hypothesis was that the latter have a higher degree of innovation because they followed the centralized procedure on the assumption that they are innovative. ,,The percentage of important therapeutic innovation was low not only for biotechnological products (25%), as expected because they include many already known products such as insulins, but also for nonbiotechnological therapeutic agents (29%). Aims In a previous paper, we proposed an algorithm to assess the degree of therapeutic innovation of the agents approved by the European centralized procedure, which must be followed by biotechnological products and is optional for drugs claimed as innovative. A low overall degree of therapeutic innovation (about 30%) was found. This figure may be an underestimate of the actual level of innovation, because common biotechnological products, such as recombinant human insulins, must follow this procedure. To test the hypothesis that therapeutic innovation prevails among nonbiotechnological products, we evaluated separately the degree of therapeutic innovation of biotechnological vs. nonbiotechnological agents in the first decade of European Medicines Agency activity, also studying a possible time trend. Methods We assessed, for each drug: (i) the seriousness of the target disease, (ii) the availability of previous treatments, and (iii) the extent of therapeutic effect according to the previously proposed algorithm. Results Our analysis considered 251 medicinal products corresponding to 198 active substances, classified according to four main areas as therapeutic agents (88.9%), diagnostics (5.5%), vaccines (5.1%) and life-style drugs (0.5%). Among all therapeutic agents, 49 out of 176 agents (28%) were classified as having an important degree of therapeutic innovation. Fifteen out of 60 biotechnological therapeutic agents were considered important therapeutic innovations (25%), whereas this figure was 29% for nonbiotechnological agents. Conclusions Among active substances claimed as innovative by the manufacturers, only a minority deserve this definition according to our algorithm. [source] Increased occurrence of asthma and allergy: critical appraisal of studies using allergic sensitization, bronchial hyper-responsiveness and lung function measurementsCLINICAL & EXPERIMENTAL ALLERGY, Issue 10 2001M. H. Wieringa Background Many studies have reported an increase in the occurrence of asthma and respiratory allergies in recent decades, but this increase is mostly based on studies using rather subjective measurements of asthma and allergies, such as questionnaires and doctor's diagnosis. None of the reviews specifically focused on studies using more ,objective' measurements, such as sensitization (specific IgE or skin prick testing (SPT)), bronchial hyper-responsiveness (BHR) or lung function (LF). Objective To review articles studying a time trend of occurrence of these ,more objective' measurements. Methods A MEDLINE-search (1966,February 2000) was performed. The following criteria were used: population-based, using IgE, SPT, BHR or LF measurements in the same age-group at least twice, with at least 2 years between and using similar methods. Results The MEDLINE-search resulted in only 16 articles, performed in 13 populations in seven different countries. Nine articles used the same objective measurements twice in the whole population. Three of these reported a non-significant increase or decrease. The other six articles found a significant increase in at least one objective measurement and of these only three reported a consistent significant increase. Conclusions The increase in the occurrence of reported asthma and allergy is supported by only a few articles confirming these results with ,more objective measurements'. [source] | ||||||||||||||||||||||||||||||||||||||||||||||