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Concept: Interval finite element

483

Both social isolation and loneliness are associated with increased mortality, but it is uncertain whether their effects are independent or whether loneliness represents the emotional pathway through which social isolation impairs health. We therefore assessed the extent to which the association between social isolation and mortality is mediated by loneliness. We assessed social isolation in terms of contact with family and friends and participation in civic organizations in 6,500 men and women aged 52 and older who took part in the English Longitudinal Study of Ageing in 2004-2005. A standard questionnaire measure of loneliness was administered also. We monitored all-cause mortality up to March 2012 (mean follow-up 7.25 y) and analyzed results using Cox proportional hazards regression. We found that mortality was higher among more socially isolated and more lonely participants. However, after adjusting statistically for demographic factors and baseline health, social isolation remained significantly associated with mortality (hazard ratio 1.26, 95% confidence interval, 1.08-1.48 for the top quintile of isolation), but loneliness did not (hazard ratio 0.92, 95% confidence interval, 0.78-1.09). The association of social isolation with mortality was unchanged when loneliness was included in the model. Both social isolation and loneliness were associated with increased mortality. However, the effect of loneliness was not independent of demographic characteristics or health problems and did not contribute to the risk associated with social isolation. Although both isolation and loneliness impair quality of life and well-being, efforts to reduce isolation are likely to be more relevant to mortality.

Concepts: Sample size, Interval finite element, Confidence interval, Demographics, Proportional hazards models, Epidemiology, Statistics, Sociology

203

Moderate-intensity exercise has attracted considerable attention because of its safety and many health benefits. Tai Chi, a form of mind-body exercise that originated in ancient China, has been gaining popularity. Practicing Tai Chi may improve overall health and well-being; however, to our knowledge, no study has evaluated its relationship with mortality. We assessed the associations of regular exercise and specifically participation in Tai Chi, walking, and jogging with total and cause-specific mortality among 61,477 Chinese men in the Shanghai Men’s Health Study (2002-2009). Information on exercise habits was obtained at baseline using a validated physical activity questionnaire. Deaths were ascertained through biennial home visits and linkage with a vital statistics registry. During a mean follow-up of 5.48 years, 2,421 deaths were identified. After adjustment for potential confounders, men who exercised regularly had a hazard ratio for total mortality of 0.80 (95% confidence interval: 0.74, 0.87) compared with men who did not exercise. The corresponding hazard ratios were 0.80 (95% confidence interval: 0.72, 0.89) for practicing Tai Chi, 0.77 (95% confidence interval: 0.69, 0.86) for walking, and 0.73 (95% confidence interval: 0.59, 0.90) for jogging. Similar inverse associations were also found for cancer and cardiovascular mortality. The present study provides the first evidence that, like walking and jogging, practicing Tai Chi is associated with reduced mortality.

Concepts: Statistics, Interval finite element, Physical fitness, Obesity, Normal distribution, Cardiovascular disease, Physical exercise, Exercise

194

The global epidemic of obesity and physical inactivity may have detrimental implications for young people’s cognitive function and academic achievement. This prospective study investigated whether childhood motor function predicts later academic achievement via physical activity, fitness, and obesity. The study sample included 8,061 children from the Northern Finland Birth Cohort 1986, which contains data about parent-reported motor function at age 8 y and self-reported physical activity, predicted cardiorespiratory fitness (cycle ergometer test), obesity (body weight and height), and academic achievement (grades) at age 16 y. Structural equation models with unstandardized (B) and standardized (β) coefficients were used to test whether, and to what extent, physical activity, cardiorespiratory fitness, and obesity at age 16 mediated the association between childhood motor function and adolescents' academic achievement. Physical activity was associated with a higher grade-point average, and obesity was associated with a lower grade-point average in adolescence. Furthermore, compromised motor function in childhood had a negative indirect effect on adolescents' academic achievement via physical inactivity (B = -0.023, 95% confidence interval = -0.031, -0.015) and obesity (B = -0.025, 95% confidence interval = -0.039, -0.011), but not via cardiorespiratory fitness. These results suggest that physical activity and obesity may mediate the association between childhood motor function and adolescents' academic achievement. Compromised motor function in childhood may represent an important factor driving the effects of obesity and physical inactivity on academic underachievement.

Concepts: Confidence interval, Physical fitness, Overweight, Adolescence, Interval finite element, Prediction interval, Structural equation modeling, Obesity

174

BACKGROUND: Systematic reviews have been challenged to consider effects on disadvantaged groups. A priori specification of subgroup analyses is recommended to increase the credibility of these analyses. This study aimed to develop and assess inter-rater agreement for an algorithm for systematic review authors to predict whether differences in effect measures are likely for disadvantaged populations relative to advantaged populations (only relative effect measures were addressed). METHODS: A health equity plausibility algorithm was developed using clinimetric methods with three items based on literature review, key informant interviews and methodology studies. The three items dealt with the plausibility of differences in relative effects across sex or socioeconomic status (SES) due to: 1) patient characteristics; 2) intervention delivery (i.e., implementation); and 3) comparators. Thirty-five respondents (consisting of clinicians, methodologists and research users) assessed the likelihood of differences across sex and SES for ten systematic reviews with these questions. We assessed inter-rater reliability using Fleiss multi-rater kappa. RESULTS: The proportion agreement was 66% for patient characteristics (95% confidence interval: 61%-71%), 67% for intervention delivery (95% confidence interval: 62% to 72%) and 55% for the comparator (95% confidence interval: 50% to 60%). Inter-rater kappa, assessed with Fleiss kappa, ranged from 0 to 0.199, representing very low agreement beyond chance. CONCLUSIONS: Users of systematic reviews rated that important differences in relative effects across sex and socioeconomic status were plausible for a range of individual and population-level interventions. However, there was very low inter-rater agreement for these assessments. There is an unmet need for discussion of plausibility of differential effects in systematic reviews. Increased consideration of external validity and applicability to different populations and settings is warranted in systematic reviews to meet this need.

Concepts: Meta-analysis, Evidence-based medicine, Contract, Assessment, Interval finite element, Cohen's kappa, Inter-rater reliability, Fleiss' kappa

173

Classic beam theory is frequently used in biomechanics to model the stress behaviour of vertebrate long bones, particularly when creating intraspecific scaling models. Although methodologically straightforward, classic beam theory requires complex irregular bones to be approximated as slender beams, and the errors associated with simplifying complex organic structures to such an extent are unknown. Alternative approaches, such as finite element analysis (FEA), while much more time-consuming to perform, require no such assumptions. This study compares the results obtained using classic beam theory with those from FEA to quantify the beam theory errors and to provide recommendations about when a full FEA is essential for reasonable biomechanical predictions. High-resolution computed tomographic scans of eight vertebrate long bones were used to calculate diaphyseal stress owing to various loading regimes. Under compression, FEA values of minimum principal stress (σ(min)) were on average 142 per cent (±28% s.e.) larger than those predicted by beam theory, with deviation between the two models correlated to shaft curvature (two-tailed p = 0.03, r(2) = 0.56). Under bending, FEA values of maximum principal stress (σ(max)) and beam theory values differed on average by 12 per cent (±4% s.e.), with deviation between the models significantly correlated to cross-sectional asymmetry at midshaft (two-tailed p = 0.02, r(2) = 0.62). In torsion, assuming maximum stress values occurred at the location of minimum cortical thickness brought beam theory and FEA values closest in line, and in this case FEA values of τ(torsion) were on average 14 per cent (±5% s.e.) higher than beam theory. Therefore, FEA is the preferred modelling solution when estimates of absolute diaphyseal stress are required, although values calculated by beam theory for bending may be acceptable in some situations.

Concepts: Torsion, Interval finite element, Model, Solid mechanics, Biomechanics, Beam, Structural analysis, Finite element method

164

The prognosis for fit patients with mantle cell lymphoma has improved with intensive strategies. Currently, the role of maintenance/consolidation approaches is being tested as relapses continue appearing. In this trial we evaluated the feasibility, safety and efficacy of R-Hyper-CVAD alternating with R-MtxAraC followed by consolidation with 90Y-Ibritumomab-Tiuxetan. Patients received 6 cycles followed by a single dose of 90Y-Ibritumomab-Tiuxetan. Thirty patients were enrolled. Median age was 59 years. Twenty four patients finished the induction treatment, 23 achieved complete remission (77%, 95% confidence interval 60-93) and one patient had progressive disease (3%). Eighteen patients (60%), all in complete remission, received consolidation. In the intent- to- treat population, failure free, progression free and overall survival at 4 years were 40 % (95% confidence interval 20.4-59.6), 52% (95% confidence interval 32.4-71.6) and 81% (95% confidence interval 67.28-94.72), respectively. For patients who received consolidation, failure free and overall survival were 55% (95% confidence interval 31.48&-78.52) and 87% (95% confidence interval 70-100), respectively. Hematological toxicity was significant during induction and responsible for one death (3.3%). After consolidation, grade 3-4 neutropenia and thrombocytopenia were observed in 72% and 83% of patients, with median duration of 5 and 12 weeks, respectively. Six (20%) patients died, 3 due to secondary malignancies (myelodisplastic syndrome and bladder and rectum carcinomas). In conclusion, our experience with R-Hyper-CVAD/R-MtxAraC followed by consolidation with 90Y-Ibritumomab-Tiuxetan is efficacious although less feasible than expected. The unacceptable toxicity observed, specially secondary malignancies, advise against the indication of this strategy. Trial registration: clinical.gov identifier: NCT2005-004400-37.

Concepts: Lung cancer, Interval finite element, Chemotherapy, Hematological malignancy, Types of cancer, Cancer, Normal distribution, Mantle cell lymphoma

95

Objective To evaluate a “telephone first” approach, in which all patients wanting to see a general practitioner (GP) are asked to speak to a GP on the phone before being given an appointment for a face to face consultation.Design Time series and cross sectional analysis of routine healthcare data, data from national surveys, and primary survey data.Participants 147 general practices adopting the telephone first approach compared with a 10% random sample of other practices in England.Intervention Management support for workload planning and introduction of the telephone first approach provided by two commercial companies.Main outcome measures Number of consultations, total time consulting (59 telephone first practices, no controls). Patient experience (GP Patient Survey, telephone first practices plus controls). Use and costs of secondary care (hospital episode statistics, telephone first practices plus controls). The main analysis was intention to treat, with sensitivity analyses restricted to practices thought to be closely following the companies' protocols.Results After the introduction of the telephone first approach, face to face consultations decreased considerably (adjusted change within practices -38%, 95% confidence interval -45% to -29%; P<0.001). An average practice experienced a 12-fold increase in telephone consultations (1204%, 633% to 2290%; P<0.001). The average duration of both telephone and face to face consultations decreased, but there was an overall increase of 8% in the mean time spent consulting by GPs, albeit with large uncertainty on this estimate (95% confidence interval -1% to 17%; P=0.088). These average workload figures mask wide variation between practices, with some practices experiencing a substantial reduction in workload and others a large increase. Compared with other English practices in the national GP Patient Survey, in practices using the telephone first approach there was a large (20.0 percentage points, 95% confidence interval 18.2 to 21.9; P<0.001) improvement in length of time to be seen. In contrast, other scores on the GP Patient Survey were slightly more negative. Introduction of the telephone first approach was followed by a small (2.0%) increase in hospital admissions (95% confidence interval 1% to 3%; P=0.006), no initial change in emergency department attendance, but a small (2% per year) decrease in the subsequent rate of rise of emergency department attendance (1% to 3%; P=0.005). There was a small net increase in secondary care costs.Conclusions The telephone first approach shows that many problems in general practice can be dealt with over the phone. The approach does not suit all patients or practices and is not a panacea for meeting demand. There was no evidence to support claims that the approach would, on average, save costs or reduce use of secondary care.

Concepts: Patient, Statistics, Primary care, Telephone, General practitioner, Physician, Hospital, Interval finite element

60

Zika virus (ZIKV) infection during pregnancy has been linked to birth defects,(1) yet the magnitude of risk remains uncertain. Investigators studying the 2013-2014 Zika outbreak in French Polynesia estimated that the risk of microcephaly due to ZIKV infection in the first trimester of pregnancy was 0.95% (95% confidence interval, 0.34 to 1.91), on the basis of eight microcephaly cases identified retrospectively in a population of approximately 270,000 people with an estimated rate of ZIKV infection of 66%.(2) In the current outbreak, thousands of cases of infants with suspected microcephaly or other developmental anomalies of the central nervous system that may . . .

Concepts: French Polynesia, Interval finite element, Pregnancy, Childbirth, Statistics, Brain, Central nervous system, Nervous system

38

Background Concerns remain about the safety of adding long-acting β2-agonists to inhaled glucocorticoids for the treatment of asthma. In a postmarketing safety study mandated by the Food and Drug Administration, we evaluated whether the addition of formoterol to budesonide maintenance therapy increased the risk of serious asthma-related events in patients with asthma. Methods In this multicenter, double-blind, 26-week study, we randomly assigned patients, 12 years of age or older, who had persistent asthma, were receiving daily asthma medication, and had had one to four asthma exacerbations in the previous year to receive budesonide-formoterol or budesonide alone. Patients with a history of life-threatening asthma were excluded. The primary end point was the first serious asthma-related event (a composite of adjudicated death, intubation, and hospitalization), as assessed in a time-to-event analysis. The noninferiority of budesonide-formoterol to budesonide was defined as an upper limit of the 95% confidence interval for the risk of the primary safety end point of less than 2.0. The primary efficacy end point was the first asthma exacerbation, as assessed in a time-to-event analysis. Results A total of 11,693 patients underwent randomization, of whom 5846 were assigned to receive budesonide-formoterol and 5847 to receive budesonide. A serious asthma-related event occurred in 43 patients who were receiving budesonide-formoterol and in 40 patients who were receiving budesonide (hazard ratio, 1.07; 95% confidence interval [CI], 0.70 to 1.65]); budesonide-formoterol was shown to be noninferior to budesonide alone. There were two asthma-related deaths, both in the budesonide-formoterol group; one of these patients had undergone an asthma-related intubation. The risk of an asthma exacerbation was 16.5% lower with budesonide-formoterol than with budesonide (hazard ratio, 0.84; 95% CI, 0.74 to 0.94; P=0.002). Conclusions Among adolescents and adults with predominantly moderate-to-severe asthma, treatment with budesonide-formoterol was associated with a lower risk of asthma exacerbations than budesonide and a similar risk of serious asthma-related events. (Funded by AstraZeneca; ClinicalTrials.gov number, NCT01444430 .).

Concepts: Randomness, Confidence interval, Formoterol, Interval finite element, Budesonide, Glucocorticoid, AstraZeneca, Asthma

29

AIM: This study examined the effects of grapefruit juice on the new P2Y(12) inhibitor ticagrelor, which is a substrate of CYP3A4 and P-glycoprotein. METHODS: In a randomized crossover study, ten healthy volunteers ingested 200 ml of grapefruit juice or water thrice daily for four days. On day three, they ingested a single 90-mg dose of ticagrelor. RESULTS: Grapefruit juice increased ticagrelor geometric mean peak plasma concentration (C(max) ) to 165% (95% confidence interval, 147-184%) and area under the concentration-time curve (AUC(0-∞) ) to 221% of control (95% confidence interval, 200-245%). The C(max) and AUC(0-34h) (P < 0.05) but not the AUC(0-∞) of the active metabolite C12490XX were decreased significantly. Grapefruit juice had a minor effect on ticagrelor elimination half-life prolonging it from 6.7 to 7.2 h (P = 0.036). In good correlation with the elevated plasma ticagrelor concentrations, grapefruit juice enhanced the antiplatelet effect of ticagrelor, assessed with VerifyNow® and Multiplate® methods, and postponed the recovery of platelet reactivity. CONCLUSIONS: Grapefruit juice increased ticagrelor exposure by more than two-fold, leading to an enhanced and prolonged ticagrelor antiplatelet effect. The grapefruit juice-ticagrelor interaction seems clinically important and indicates the significance of intestinal metabolism to ticagrelor pharmacokinetics.

Concepts: Effect, Pharmacokinetics, Grapefruit, Statistical hypothesis testing, Interval finite element, Statistics, Crossover study, Pharmacology