linear mixed effects models
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2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Dorothy C. Nyemba ◽  
Emma Kalk ◽  
Michael J. Vinikoor ◽  
Hlengiwe P. Madlala ◽  
Mwangelwa Mubiana-Mbewe ◽  
...  

Abstract Background Infants born HIV-exposed yet remain uninfected (HEU) are at increased risk of poorer growth and health compared to infants born HIV-unexposed (HU). Whether maternal antiretroviral treatment (ART) in pregnancy ameliorates this risk of poorer growth is not well understood. Furthermore, whether risks are similar across high burden HIV settings has not been extensively explored. Methods We harmonized data from two prospective observational studies conducted in Cape Town, South Africa, and Lusaka, Zambia, to compare weight-for-age (WAZ), length-for-age (LAZ) and weight-for-length (WLZ) Z-scores between infants who were HEU and HU, converting infant anthropometric measures using World Health Organisation Growth Standards adjusted for age and sex. Linear mixed effects models were fit to identify risk factors for differences in anthropometrics at 6–10 weeks and 6 months by infant HIV exposures status and by timing of exposure to maternal ART, either from conception or later in gestation. Results Overall 773 mother-infant pairs were included across two countries: women living with HIV (WLHIV), 51% (n = 395) with 65% on ART at conception and 35% initiating treatment in pregnancy. In linear mixed effects models, WAZ and WLZ at 6–10 weeks were lower among infants who were HEU vs HU [β = − 0.29 (95% CI: − 0.46, − 0.12) and [β = − 0.42 (95% CI: − 0.68, − 0.16)] respectively after adjusting for maternal characteristics and infant feeding with a random intercept for country. At 6 months, LAZ was lower [β = − 0.28 CI: − 0.50, − 0.06)] among infants who were HEU, adjusting for the same variables, with no differences in WAZ and WLZ. Within cohort evaluations identified different results with higher LAZ among infants who were HEU from Zambia at 6–10 weeks, [β = + 0.34 CI: + 0.01, + 0.68)] and lower LAZ among infants who were HEU from South Africa [β = − 0.30 CI: − 0.59, − 0.01)] at 6 months, without other anthropometric differences at either site. Conclusion Infant growth trajectories differed by country, highlighting the importance of studying contextual influences on outcomes of infants who were HEU.


2021 ◽  
Vol 12 ◽  
Author(s):  
Andrea Aguglia ◽  
Laura Fusar-Poli ◽  
Andrea Amerio ◽  
Valeria Placenti ◽  
Carmen Concerto ◽  
...  

Background: Long-acting injectable (LAI) antipsychotics are efficacious in managing psychotic symptoms in people affected by severe mental disorders, such as schizophrenia and bipolar disorder. The present study aimed to investigate whether attitude toward treatment and treatment adherence represent predictors of symptoms changes over time.Methods: The STAR Network “Depot Study” was a naturalistic, multicenter, observational, prospective study that enrolled people initiating a LAI without restrictions on diagnosis, clinical severity or setting. Participants from 32 Italian centers were assessed at three time points: baseline, 6-month, and 12-month follow-up. Psychopathological symptoms, attitude toward medication and treatment adherence were measured using the Brief Psychiatric Rating Scale (BPRS), the Drug Attitude Inventory (DAI-10) and the Kemp's 7-point scale, respectively. Linear mixed-effects models were used to evaluate whether attitude toward medication and treatment adherence independently predicted symptoms changes over time. Analyses were conducted on the overall sample and then stratified according to the baseline severity (BPRS < 41 or BPRS ≥ 41).Results: We included 461 participants of which 276 were males. The majority of participants had received a primary diagnosis of a schizophrenia spectrum disorder (71.80%) and initiated a treatment with a second-generation LAI (69.63%). BPRS, DAI-10, and Kemp's scale scores improved over time. Six linear regressions—conducted considering the outcome and predictors at baseline, 6-month, and 12-month follow-up independently—showed that both DAI-10 and Kemp's scale negatively associated with BPRS scores at the three considered time points. Linear mixed-effects models conducted on the overall sample did not show any significant association between attitude toward medication or treatment adherence and changes in psychiatric symptoms over time. However, after stratification according to baseline severity, we found that both DAI-10 and Kemp's scale negatively predicted changes in BPRS scores at 12-month follow-up regardless of baseline severity. The association at 6-month follow-up was confirmed only in the group with moderate or severe symptoms at baseline.Conclusion: Our findings corroborate the importance of improving the quality of relationship between clinicians and patients. Shared decision making and thorough discussions about benefits and side effects may improve the outcome in patients with severe mental disorders.


2021 ◽  
pp. 1622-1631
Author(s):  
Ricardo Perera ◽  
Antonio Ruiz ◽  
Lluis Torres ◽  
Cristina Barris ◽  
Marta Baena

2021 ◽  
Author(s):  
Ottavia M. Epifania ◽  
Pasquale Anselmi ◽  
Egidio Robusto

<div>The indirect investigation of psychological constructs has become prominent in social sciences thanks to the so-called implicit measures. Different implicit measures can be administered concurrently to the same respondents for obtaining detailed and multifaceted information on the constructs of interest. In this study, a Rasch analysis of accuracy and time responses of two commonly used implicit measures is presented. The focus in on the concurrent administration of the Implicit Association Test (IAT; Greenwald et al., 1998) and the Single Category IAT (SC-IAT; Karpinski & Steinman, 2006). Linear Mixed-Effects Models are used to address the within– and between–measures sources of variability and to obtain a Rasch parametrization of the data. By disentangling the respondent’s contribution from the stimulus contribution to the observed responses, these models allow for delving deeper on the functioning of the IAT and the SC-IAT, as well as for grasping a better understanding of the processes driving a behavioral decision. Implications of the results for social sciences and future research directions are discussed.</div>


2021 ◽  
Author(s):  
Ottavia M. Epifania ◽  
Pasquale Anselmi ◽  
Egidio Robusto

<div>The indirect investigation of psychological constructs has become prominent in social sciences thanks to the so-called implicit measures. Different implicit measures can be administered concurrently to the same respondents for obtaining detailed and multifaceted information on the constructs of interest. In this study, a Rasch analysis of accuracy and time responses of two commonly used implicit measures is presented. The focus in on the concurrent administration of the Implicit Association Test (IAT; Greenwald et al., 1998) and the Single Category IAT (SC-IAT; Karpinski & Steinman, 2006). Linear Mixed-Effects Models are used to address the within– and between–measures sources of variability and to obtain a Rasch parametrization of the data. By disentangling the respondent’s contribution from the stimulus contribution to the observed responses, these models allow for delving deeper on the functioning of the IAT and the SC-IAT, as well as for grasping a better understanding of the processes driving a behavioral decision. Implications of the results for social sciences and future research directions are discussed.</div>


2021 ◽  
Author(s):  
Joseph William Shaw ◽  
Adam Mattiussi ◽  
Derrick Dewayne Brown ◽  
Sean Williams ◽  
Matthew Springham ◽  
...  

Periodizing rehearsal and performance schedules in professional ballet is difficult given a lack of published longitudinal data. We aimed to describe the structure of a professional ballet season, and identify factors associated with inter-dancer and inter-production variation in dance hours. Scheduling data were collected from 123 dancers over five seasons at The Royal Ballet. Linear mixed effects models were used to evaluate differences in weekly dance hours and performance counts across sexes, company ranks, and months. Random forest regressions were used to investigate factors associated with the variation in rehearsal hours across different productions. Performance congestion was observed in December, whereas total dance hours peaked between January and April. Differences in weekly dance hours were observed between company ranks (p &lt; .001, range in means: 19.1–27.5 h·week-1). Seasonal performance counts varied across company ranks (p &lt; .001), ranging from 28, 95% CI [22, 35] in principals, to 113, 95% CI [108, 118] in artists. Rehearsal durations were greatest in preparation for newly choreographed and longer ballets. Dancers creating roles in new ballets completed considerably more rehearsal hours than for existing ballet. These results provide a basis for the implementation of rehearsal and repertoireperiodization in professional ballet.


2021 ◽  
pp. 027112142110303
Author(s):  
LeAnne D. Johnson ◽  
Andrea L. B. Ford ◽  
Danielle Dupuis ◽  
Maria L. Hugh

Adopting an “act-in-context” approach is helpful to researchers investigating situational variability in children’s active engagement in preschool classrooms. Aligned with this approach, we propose an empirical pathway and a conceptual model to support examinations of contextual factors hypothesized to impact active engagement as well as the means by which adults promote it. We defined two overarching factors—cognitive and organizational—and explored the predictive nature of seven features within them. With video recordings from 31 classrooms (inclusive and self-contained) of three instructional routines on three different occasions, we derived averages for classwide active engagement during each observation. A series of linear mixed effects models revealed that instructional routines significantly predicted variability in classwide active engagement as did interactions of other contextual features with instructional routines. These findings provide a foundation for continued, systematic examinations of situational factors and conceptualizations of engagement within carefully specified pathways for improving active engagement.


Author(s):  
Lisa Vork ◽  
John Penders ◽  
Jonna Jalanka ◽  
Svetlana Bojic ◽  
Sander M. J. van Kuijk ◽  
...  

IntroductionStool consistency has been associated with fecal microbial composition. Stool consistency often varies over time, in subjects with and without gastrointestinal disorders, raising the question whether variability in the microbial composition should be considered in microbiota studies. We evaluated within-subject day-to-day variability in stool consistency and the association with the fecal microbiota in irritable bowel syndrome (IBS) and healthy subjects, over seven days.MethodsTwelve IBS patients and 12 healthy subjects collected fecal samples during seven consecutive days. Stool consistency was determined by the patient-reported Bristol Stool Scale (BSS) and fecal dry weight percentage. 16S rRNA V4 gene sequencing was performed and microbial richness (alpha diversity; Chao1 index, observed number of species, effective Shannon index) and microbial community structure (beta diversity; Bray-Curtis distance, generalized UniFrac, and taxa abundance on family level) were determined.ResultsLinear mixed-effects models showed significant associations between stool consistency and microbial richness, but no time effect. This implies that between-subject but not within-subject variation in microbiota over time can partially be explained by variation in stool consistency. Redundancy analysis showed a significant association between stool consistency and microbial community structure, but additional linear mixed-effects models did not demonstrate a time effect on this.ConclusionThis study supports an association between stool consistency and fecal microbiota, but no effect of day-to-day fluctuations in stool consistency within seven days. This consolidates the importance of considering stool consistency in gut microbiota research, though confirms the validity of single fecal sampling to represent an individual’s microbiota at a given time point. NCT00775060.


2021 ◽  
Vol 8 ◽  
Author(s):  
Catia Morelli ◽  
Ennio Avolio ◽  
Angelo Galluccio ◽  
Giovanna Caparello ◽  
Emanuele Manes ◽  
...  

Adherence to Mediterranean diet (MD) and physical activity (PA) in adolescence represent powerful indicators of healthy lifestyles in adulthood. The aim of this longitudinal study was to investigate the impact of nutrition education program (NEP) on the adherence to the MD and on the inflammatory status in healthy adolescents, categorized into three groups according to their level of PA (inactivity, moderate intensity, and vigorous intensity). As a part of the DIMENU (Dieta Mediterranea &amp; Nuoto) study, 85 adolescents (aged 14–17 years) participated in the nutrition education sessions provided by a team of nutritionists and endocrinologists at T0. All participants underwent anthropometric measurements, bio-impedentiometric analysis (BIA), and measurements of inflammatory biomarkers such as ferritin, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) levels. Data were collected at baseline (T0) and 6 months after NEP (T1). To assess the adherence to the MD, we used KIDMED score. In our adolescents, we found an average MD adherence, which was increased at T1 compared with T0 (T0: 6.03 ± 2.33 vs. T1: 6.96 ± 2.03, p = 0.002), with an enhanced percentage of adolescents with optimal (≥8 score) MD adherence over the study period (T0: 24.71% vs. T1: 43.52%, p = 0.001). Interestingly, in linear mixed-effects models, we found that NEP and vigorous-intensity PA levels independently influenced KIDMED score (β = 0.868, p &lt; 0.0001 and β = 1.567, p = 0.009, respectively). Using ANOVA, NEP had significant effects on serum ferritin levels (p &lt; 0.001), while either NEP or PA influenced ESR (p = 0.035 and 0.002, respectively). We also observed in linear mixed-effects models that NEP had a negative effect on ferritin and CRP (β = −14.763, p &lt; 0.001 and β = −0.714, p = 0.02, respectively). Our results suggest the usefulness to promote healthy lifestyle, including either nutrition education interventions, or PA to improve MD adherence and to impact the inflammatory status in adolescence as a strategy for the prevention of chronic non-communicable diseases over the entire lifespan.


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