Non-significant Predictors Research Articles

Abstract 19: Using the Heckman Selection Model to Assess Selection Bias in Ischemic Stroke Patients with Documented NIHSS

Objective: Complete documentation in large scale datasets such as administrative data or disease registries is often difficult. Given that the subset of patients with complete data documentation are most likely not a random sample of patients, selection bias threatens the validity of results if a complete case analysis is used. To demonstrate, we will assess the presence and magnitude of selection bias in ischemic stroke patients with documented National Institute of Health Stroke Scale (NIHSS) [[Unable to Display Character: –]] which is often incomplete [[Unable to Display Character: –]] using the Heckman Selection Model. Methods: Patient level variables including demographics, comorbidities, clinical EMS and admission variables, and medical history/comorbidities were obtained from 10,717 ischemic stroke patients aged 65 and older in the Michigan Stroke Registry in 2009-2012. The Heckman Selection Model assesses the presence and magnitude of selection bias by estimating a correlation coefficient between error components of a linear regression model predicting patient NIHSS score [[Unable to Display Character: –]] the outcome model [[Unable to Display Character: –]] and a binary probit model predicting NIHSS documentation [[Unable to Display Character: –]] the selection model [[Unable to Display Character: –]] conditional on patient and hospital predictors. The outcome model predicting NIHSS score was specified using a backward selection process with stepwise deletion of non-significant predictors. The selection model included all variables in the outcome model, plus additional significant predictors of NIHHS documentation. Quasi-maximum likelihood estimation was used to produce robust standard errors. All analyses were done using PROC QLIM procedure in SAS. Results: 7,956 cases (74.2%) of cases had NIHSS documented. Significant predictors in the outcome and selection models are shown in the Table. The Heckman Selection Model found a statistically significant but modest correlation coefficient of ρ =0.1089 (SE=0.0119, p<0.0001). The positive correlation indicates that NIHSS was more likely to be documented in patients with higher NIHSS scores, i.e., more severe strokes. Conclusions: We found statistically significant albeit weak selection bias in the documentation of NIHSS in stroke patients. The Heckman Selection Model is a novel method that can be used to assess the presence and magnitude of selection bias when missing data is common.

Predictors of short- and long-term avoidance in completers of inpatient group interventions for agoraphobia

BackgroundLittle is currently known about predictors of follow-up outcome of psychological treatment of agoraphobia. In this study, we wished to examine predictors of short- and long-term avoidance after inpatient group interventions for agoraphobia. MethodsNinety-six (68%) of 141 agoraphobic patients (74% women) who had completed treatment in two open and one randomized controlled trial (RCT) were followed up 13 to 21 years after start of treatment. ResultsMajor depression at pre-treatment predicted less short-term (up to one year after end of treatment) improvement in agoraphobic avoidance. Working and being married/cohabiting at pre-treatment predicted greater long-term (across one-year, two-year, and 13–21 years follow-up) improvement. In contrast, the duration of agoraphobia, amount of Axis I and II co-morbidity, being diagnosed with avoidant, dependent, and obsessive-compulsive personality disorder, and the use of antidepressants and benzodiazepines the month before intake to treatment, were unrelated to short-term as well as long-term outcome. LimitationsAs many as 31.9% of the included patients did not attend long-term follow-up and the power of the study was limited. The long time period between the two and 13–21 year follow-ups is a limitation, in which it is difficult to assess what actually happened. Although all the patients received some form of CBT, there was variability among the treatments. ConclusionsThe only short-term predictor identified represented a clinical feature, whereas the long-term predictors represented features of the patients׳ life situation. The limited power of the study precludes the inference that non-significant predictors are unrelated to follow-up outcome.

Long-term outcome in men and women after CABG; results from the IMAGINE trial

BackgroundThe aim of this study is to determine sex differences in long-term outcome after coronary artery bypass grafting (CABG). MethodsThe international randomized controlled IMAGINE study included 2553 consecutive patients with a left ventricular ejection fraction of >40% who underwent isolated CABG. Median follow-up was 32 months (IQR 17–42 months). The composite endpoint comprised of death, myocardial infarction (MI), cerebrovascular event, angina, revascularization and congestive heart failure. Cox regression analysis was used to examine sex differences in outcome post-CABG. ResultsOf the 2553 patients, 2229 were men and 324 (13%) were women. Women were older and more often reported diabetes and hypertension. Smoking and impaired renal function were more prevalent in men. Women experienced a higher event rate during follow-up (composite endpoint 18% vs 12%; P = 0.007). Cox regression showed an increased risk of the composite endpoint in women after adjustment for age (HR 1.48 (95% CI: 1.11–1.97)) which was non-significant after additional adjustment for other confounders (HR 1.26 (95% CI: 0.92–1.72)). ConclusionWomen have a worse long-term outcome after CABG than men in univariate analysis. However, after adjusting for potential confounders female sex became a non-significant predictor for prognosis, possibly due to the small sample size of women. Definite answers regarding sex-differences in long-term outcome after CABG should come from future pooling of studies comprising a larger number of women.

Extending the Theory of Planned Behavior in the context of recycling: The role of moral norms and of demographic predictors

This paper examines how an individual's moral norms and demographic characteristics interact with the standard ‘Theory of Planned Behavior’ predictors (Attitude; Subjective Norms; and Perceived Behavioral Control (PBC)) in explaining the intention to recycle (RI). Our data originate from an empirical research of Greek citizens conducted in Autumn 2013 (N=293). Through structural equation modeling, we find that PBC is consistently the most important predictor of RI. Moral norms have a larger effect on RI than Attitude while their influence is primarily direct. On the contrary, demographic characteristics were found to be statistically non-significant predictors of RI, similarly to Subjective Norms.

Premature termination from psychotherapy and internalizing psychopathology: The role of demoralization

BackgroundSome research suggests that higher levels of depression and anxiety-related symptoms at intake are associated with premature termination from psychotherapy, but findings are mixed. However, theoretical and measurement considerations – introduced by a common mood factor – might complicate literature synthesis. Tellegen (1985) demonstrated that demoralization causes multicollinearity between measures of depression and anxiety, and other lines of research have converged to indicate that this construct is an important non-specific factor to consider when assessing mood pathology. MethodsWe utilized a sample of 557 community mental health center outpatients (188 males, 265 females; 80% Caucasian) with an average age of 32.2 years (SD=10.2). We used self-report indicators to model latent low positive emotionality and negative emotionality constructs, which are temperament markers of core depressive and anxiety symptoms. We further specified a latent demoralization bifactor from these indicators. ResultsAs hypothesized, the bifactor model yielded significantly better fit than competing one-factor and two-factor models. Furthermore, the bifactor was substantially correlated with a demoralization measure (r=.96). As expected, low positive emotionality and negative emotionality were significant predictors of therapist ratings of premature termination. Though demoralization was a non-significant predictor, the structural paths from the other two internalizing constructs markedly increased in the bifactor model relative to the two-factor model. LimitationsReplications with other, more diverse clinical populations using multi-method indicators of premature termination are needed. ConclusionsThis research indicates that after accounting for demoralization patients presenting with core mood disorder symptoms are at substantially increased risk for premature termination.

The legitimation of wife abuse among women: The impact of belief in a just world and gender identification

Past research has found that when victims are ingroup members, observers’ social identification interacts with general belief in a just world (GBJW) to predict judgments about those victims. In this correlational study (N=284 women, ages from 18 to 80) we aimed to test whether and how women’s explicit endorsement of BJW, both personal belief in a just world (PBJW) and GBJW, interacts with their identification as women to predict wife abuse legitimization.We predicted and found that the interaction between PBJW and social identification predicted legitimization of wife abuse. Specifically, for highly identified women, PBJW was positively associated with wife abuse legitimization, for less identified women, PBJW was not associated with wife abuse legitimization. This interaction was significant above and beyond other variables associated with this phenomenon: hostile and benevolent sexism, empathy (cognitive and emotional), and social desirability. On the contrary, the interaction between GBJW and social identification was a nonsignificant predictor of legitimization of wife abuse. These results contribute to reconceptualize the role of PBJW and GBJW on judgments about victims and to highlight the importance of considering the victimization situations in the social context and the social groups in which they actually occur.

Characterizing recent and projecting future potential patterns of mountain pine beetle outbreaks in the Southern Rocky Mountains

The recent widespread mountain pine beetle (MPB) outbreak in the Southern Rocky Mountains presents an opportunity to investigate the relative influence of anthropogenic, biologic, and physical drivers that have shaped the spatiotemporal patterns of the outbreak. The aim of this study was to quantify the landscape-level drivers that explained the dynamic patterns of MPB mortality, and simulate areas with future potential MPB mortality under projected climate-change scenarios in Grand County, Colorado, USA. The outbreak patterns of MPB were characterized by analysis of a decade-long Landsat time-series stack, aided by automatic attribution of change detected by the Landsat-based Detection of Trends in Disturbance and Recovery algorithm (LandTrendr). The annual area of new MPB mortality was then related to a suite of anthropogenic, biologic, and physical predictor variables under a general linear model (GLM) framework. Data from years 2001–2005 were used to train the model and data from years 2006–2011 were retained for validation. After stepwise removal of non-significant predictors, the remaining predictors in the GLM indicated that neighborhood mortality, winter mean temperature anomaly, and residential housing density were positively associated with MPB mortality, whereas summer precipitation was negatively related. The final model had an average area under the curve (AUC) of a receiver operating characteristic plot value of 0.72 in predicting the annual area of new mortality for the independent validation years, and the mean deviation from the base maps in the MPB mortality areal estimates was around 5%. The extent of MPB mortality will likely expand under two climate-change scenarios (RCP 4.5 and 8.5) in Grand County, which implies that the impacts of MPB outbreaks on vegetation composition and structure, and ecosystem functioning are likely to increase in the future.

Conservative management and female gender are associated with increased cancer-specific death in patients with isolated primary urothelial carcinoma in situ.

Our goal was to investigate the effect of patient and disease characteristics on the probability of cancer-specific death (CSD) in cases of isolated urothelial carcinoma in situ (CIS). We performed a retrospective analysis of patients diagnosed with isolated CIS between 1990 and 2010 identified from the Surveillance, Epidemiology, and End Results (SEER) database. Competing risk analysis using Cox proportional hazard model was used to examine the probability of CSD controlling for possible covariates. Overall (n = 1432), patients were mainly male (75%), mean age at diagnosis was 71 years, median survival 47 months, and 65% of the patients had CIS in their upper urinary tract. Caucasians were the predominant race (90%). CIS was the cause of death in 87/1432(6%) of the total cohort; 69/1239 (6%) of patients who underwent surgery, and 18/193 (9%) of the patients who were managed conservatively (CM). On multivariate analysis, CM [hazard ration (HR) = 2.019, CI: 1.189-3.429, P = 0.009] and female gender (HR = 1.690, CI: 1.041-2.741, P = 0.033) were associated with CSD, while age, site, race and year of diagnosis were non-significant predictors. Female gender and conservative management were positively associated with CSD. Multi-institutional collaboration is needed to validate markers for poor prognosis in cases of isolated CIS.

Social status, facial structure, and assertiveness in brown capuchin monkeys

Social status, facial structure, and assertiveness in brown capuchin monkeys

AB0086 IL - 17 Levels with Vitamin D Repletion in Rheuamtoid Arthritis

BackgroundIncreasing scientific evidence implicates a pathogenic role of Th17 cells and associated cytokines in rheumatoid arthritis (RA). Vitamin D may have suppressive effect on Th17 cells. In vitro studies show...

What Students Feel in School Influences the Strategies They Use for Learning: Academic Emotions and Cognitive/Meta-Cognitive Strategies

The aim of this study was to investigate how academic emotions were related to cognitive and metacognitive strategy use. Secondary school students ( N = 1,147) participated in this study and answered relevant questionnaires on academic emotions (enjoyment, hope, pride, anger, anxiety, shame, hopelessness, and boredom) and the use of various cognitive (elaboration, organisation, and rehearsal) and metacognitive strategies (planning, monitoring, regulating). Results of the analyses indicated that students who experienced positive emotions were more likely to use different types of cognitive and metacognitive strategies. Negative academic emotions were found to be non-significant predictors of strategy use. Implications are discussed.

A Two-Wave Longitudinal Study of Career Calling Among Undergraduates

This two-wave longitudinal study investigated the reciprocal relations between five possible predictors of career calling (presence of life meaning, search for life meaning, career decision self-efficacy, personal growth initiative, and intrinsic religiousness) among a sample of undergraduate college students over a 6-month period. Using structural equation modeling, two models were tested. The first model included all five predictor variables and was a poor fit for the data; the second model included only search for life meaning and personal growth and displayed improved model fit. Results from the second model indicated that search for life meaning and personal growth at Time 1 significantly predicted calling at Time 2, whereas calling at Time 1 was a nonsignificant predictor of either Time 2 outcomes. These findings suggest the more one is searching for his or her meaning in life and intentionally engaging in self-improvement, the more likely she or he is to later experience a calling.

The Role of Physically Active Leisure for Enhancing Quality of Life

Drawing upon bottom-up theory of life satisfaction, this study develops and tests a model that links physically active leisure to people's quality of life. Results from a sample of 827 running event participants revealed that satisfaction with event participation and psychological involvement in running were significant predictors of participants’ life domain satisfaction and overall life satisfaction, both of which are common subjective indicators of quality of life. Conversely, behavioral involvement in running was a non-significant predictor of life domain satisfaction and overall life satisfaction. These findings suggest that physically active leisure may enhance participants’ quality of life by providing positive experiences through event participation and contributing to psychological involvement in physical activity.

Differences in baseline characteristics, practice patterns and clinical outcomes in contemporary coronary artery bypass grafting in the United States and Europe: insights from the SYNTAX randomized trial and registry.

To investigate the until now undefined extent of differences in baseline characteristics, practice patterns and clinical outcomes of patients undergoing coronary artery bypass grafting (CABG) for complex coronary artery disease in the USA versus Europe. The impact of geographic enrollment on clinical outcomes was explored using the as-treated population of 1510 patients with de novo left main and/or three-vessel disease who underwent CABG in either the SYNTAX randomized trial or registries, and who were followed up for 5 years. There were 259 (17%) patients enrolled in the USA. Patients in the USA had more comorbidities. Off-pump procedures were more frequent in the USA (32 vs 13% in Europe; P < 0.001), and crystalloid cardioplegia was used less often (17 vs 38% in Europe; P < 0.001). In the USA, more grafts per patient were used (3.1 ± 0.8 vs 2.7 ± 0.7 in Europe; P < 0.001), with less complete arterial grafting (5 vs 18% in Europe; P < 0.001) but more complete revascularization (80 vs 66% in Europe; P < 0.001). At 5-year follow-up, patients treated in the USA versus Europe had comparable rates of major adverse cardiac and cerebrovascular events (MACCEs: 28.7 vs 24.3%, respectively; P = 0.11) and the composite safety endpoint of death, stroke and myocardial infarction (MI; 15.3 vs 17.5%, respectively; P = 0.43), but a significantly higher rate of repeat revascularization (15.0 vs 9.8%, respectively; P = 0.011) driven by repeat percutaneous coronary intervention (14.6 vs 9.2%; P = 0.005) and not repeat CABG (0.4 vs 0.8%; P = 0.48). Rates of graft occlusion were significantly higher in the USA versus Europe (8.7 vs 3.2%; P < 0.001). In multivariate analysis, enrollment in the USA was a non-significant predictor of MACCE [hazard ratio (HR) = 1.31, 95% confidence interval (95% CI) 1.00-1.73; P = 0.053], but independently predicted repeat revascularization (HR = 1.66, 95% CI 1.12-2.46; P = 0.011) and graft occlusion (HR = 2.65, 95% CI 1.52-4.62; P = 0.001). It was also a non-significant predictor of reduced rates of MI (HR = 0.38, 95% CI 0.14-1.06; P = 0.064). Differences between the USA and Europe were most pronounced among patients who underwent off-pump CABG. Repeat revascularization rates following CABG in the USA versus Europe were increased at 5 years, particularly in off-pump patients. There was no significant difference in the rate of death, stroke and MI.

Is parenting style a predictor of suicide attempts in a representative sample of adolescents?

BackgroundSuicidal ideation and suicide attempts are serious but not rare conditions in adolescents. However, there are several research and practical suicide-prevention initiatives that discuss the possibility of preventing serious self-harm. Profound knowledge about risk and protective factors is therefore necessary. The aim of this study is a) to clarify the role of parenting behavior and parenting styles in adolescents’ suicide attempts and b) to identify other statistically significant and clinically relevant risk and protective factors for suicide attempts in a representative sample of German adolescents.MethodsIn the years 2007/2008, a representative written survey of N = 44,610 students in the 9th grade of different school types in Germany was conducted. In this survey, the lifetime prevalence of suicide attempts was investigated as well as potential predictors including parenting behavior. A three-step statistical analysis was carried out: I) As basic model, the association between parenting and suicide attempts was explored via binary logistic regression controlled for age and sex. II) The predictive values of 13 additional potential risk/protective factors were analyzed with single binary logistic regression analyses for each predictor alone. Non-significant predictors were excluded in Step III. III) In a multivariate binary logistic regression analysis, all significant predictor variables from Step II and the parenting styles were included after testing for multicollinearity.ResultsThree parental variables showed a relevant association with suicide attempts in adolescents – (all protective): mother’s warmth and father’s warmth in childhood and mother’s control in adolescence (Step I). In the full model (Step III), Authoritative parenting (protective: OR: .79) and Rejecting-Neglecting parenting (risk: OR: 1.63) were identified as significant predictors (p < .001) for suicidal attempts. Seven further variables were interpreted to be statistically significant and clinically relevant: ADHD, female sex, smoking, Binge Drinking, absenteeism/truancy, migration background, and parental separation events.ConclusionsParenting style does matter. While children of Authoritative parents profit, children of Rejecting-Neglecting parents are put at risk – as we were able to show for suicide attempts in adolescence. Some of the identified risk factors contribute new knowledge and potential areas of intervention for special groups such as migrants or children diagnosed with ADHD.

Religion, Religiosity, Sex, and Willingness to Express Political Opinions: A Spiral of Silence Analysis of the 2008 U.S. Presidential Election

This study analyzes the extent to which an individual's sex, religion, and religiosity influence their willingness to voice an opinion about Barack Obama's ethnicity in the 2008 election. Results from 569 college students surveyed reveal sex to be a nonsignificant predictor, whereas religion and religiosity significantly influence willingness to voice an opinion about Obama's ethnicity. More religious individuals were more likely to voice an opinion about Obama's ethnicity as a voting issue in the campaign. There were significant differences among religious groups and their willingness to voice an opinion on this issue.

Seasonal Climate Variability and Change in the Pacific Northwest of the United States

Abstract Observed changes in climate of the U.S. Pacific Northwest since the early twentieth century were examined using four different datasets. Annual mean temperature increased by approximately 0.6°–0.8°C from 1901 to 2012, with corroborating indicators including a lengthened freeze-free season, increased temperature of the coldest night of the year, and increased growing-season potential evapotranspiration. Seasonal temperature trends over shorter time scales (&amp;lt;50 yr) were variable. Despite increased warming rates in most seasons over the last half century, nonsignificant cooling was observed during spring from 1980 to 2012. Observations show a long-term increase in spring precipitation; however, decreased summer and autumn precipitation and increased potential evapotranspiration have resulted in larger climatic water deficits over the past four decades. A bootstrapped multiple linear regression model was used to better resolve the temporal heterogeneity of seasonal temperature and precipitation trends and to apportion trends to internal climate variability, solar variability, volcanic aerosols, and anthropogenic forcing. The El Niño–Southern Oscillation and the Pacific–North American pattern were the primary modulators of seasonal temperature trends on multidecadal time scales: solar and volcanic forcing were nonsignificant predictors and contributed weakly to observed trends. Anthropogenic forcing was a significant predictor of, and the leading contributor to, long-term warming; natural factors alone fail to explain the observed warming. Conversely, poor model skill for seasonal precipitation suggests that other factors need to be considered to understand the sources of seasonal precipitation trends.

Cognitive components of a mathematical processing network in 9-year-old children.

We determined how various cognitive abilities, including several measures of a proposed domain-specific number sense, relate to mathematical competence in nearly 100 9-year-old children with normal reading skill. Results are consistent with an extended number processing network and suggest that important processing nodes of this network are phonological processing, verbal knowledge, visuo-spatial short-term and working memory, spatial ability and general executive functioning. The model was highly specific to predicting arithmetic performance. There were no strong relations between mathematical achievement and verbal short-term and working memory, sustained attention, response inhibition, finger knowledge and symbolic number comparison performance. Non-verbal intelligence measures were also non-significant predictors when added to our model. Number sense variables were non-significant predictors in the model and they were also non-significant predictors when entered into regression analysis with only a single visuo-spatial WM measure. Number sense variables were predicted by sustained attention. Results support a network theory of mathematical competence in primary school children and falsify the importance of a proposed modular ‘number sense’. We suggest an ‘executive memory function centric’ model of mathematical processing. Mapping a complex processing network requires that studies consider the complex predictor space of mathematics rather than just focusing on a single or a few explanatory factors.

Elderly visitors of an urban park, health anxiety and individual awareness of nature experiences

There is increasing evidence of a positive relation between green spaces in people's living environment and self-reported indicators of physical and mental health. However, to this moment health anxiety has not been contextualized in the light of the restorative and anxiolytic experiences of urban nature nor has it been studied in reference to the awareness of nature experiences. We aimed to determine whether “awareness of nature experiences” was a significant modifier of the beneficial effects of interaction of older citizens with urban green spaces. This construct represents the purposeful and conscious interaction with nature, a specific behaviour pre-formed as a cognitive representation of the “self” in a natural context, providing an internal replica of the previously experienced external natural world which guides people when they choose to visit an urban park. A cross-sectional interview study was conducted amongst 97 elderly visitors of “Tzar Simeon Garden” Park in Plovdiv, Bulgaria. After controlling for “awareness of nature experiences”, hierarchical multiple regression model accounted for 94% of the variance in health anxiety. The independent variables “appreciation of bird songs”, “appreciation of vegetation”, “weekly visits to the park” and “years of visiting the park” remained significant, but their power decreased, and “age” became non-significant predictor. The overall predictive capacity of the model rose significantly after “awareness of nature experiences” was added. In conclusion, health anxiety among Bulgarian elderly adults is somewhat higher than in other similar populations but still does not exceed acceptable levels. The actual interaction and experiences of the park were predictors of health anxiety independent from confounding factors. Their power, however, was to some extent dependent on individual “awareness of nature experiences”, which had unique contribution to the model.

S134 Activity monitoring in intensive care unit survivors: Assessing daily physical activity with objective outcome measures

Introduction and ObjectivesIntensive care unit (ICU) survivors commonly report long-term functional disability and reduced daily physical activity (PA). This adversely impacts on their health-related quality of life (HRQL). We aimed...