Joint Modeling for Longitudinal Data with Missing Values: A Bayesian Perspective on Human Intelligence

2021 ◽  
Vol 13 (2) ◽  
pp. 521-536
Author(s):  
T. Gokul ◽  
M. R. Srinivasan
Keyword(s):  
Longitudinal Data ◽  
Missing Values ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Joint Modeling ◽  
Model Framework ◽  
Response Data ◽  
Count Response ◽  
Longitudinal Count Data

Joint modeling in longitudinal data is an interesting area of research since it predicts the outcome with covariates that are measured repeatedly over the time. However, there is no proper methodology available in literature to incorporate the joint modeling approach for count-count response data. In addition, there are several situations where longitudinal data might not be possible to collect the complete data and the Missingness may occur due to the absence of the subjects at the follow-up. In this paper, joint modelling for longitudinal count data is adopted using Bayesian Generalized Linear Mixed Model framework to understand the association between the variables. Further, an imputation method is used to handle the missing entries in the data and the efficiency of the methodology has been studied using Markov Chain Monte-Carlo (MCMC) technique. An application to the proposed methodology has been discussed and identified the suitable nutritional supplements in Bayesian perspective without eliminating the missing entries in the dataset.

Analyzing discontinuities in longitudinal count data: A multilevel generalized linear mixed model.

2020 ◽  
Author(s):  
James L. Peugh ◽  
Sarah J. Beal ◽  
Meghan E. McGrady ◽  
Michael D. Toland ◽  
Constance Mara
Keyword(s):  
Count Data ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Generalized Linear Mixed Model ◽  
Longitudinal Count Data

Long-term seizure outcomes after pediatric temporal lobectomy: does brain MRI lesion matter?

2019 ◽  
Vol 24 (2) ◽  
pp. 200-208
Author(s):  
Ravindra Arya ◽  
Francesco T. Mangano ◽  
Paul S. Horn ◽  
Sabrina K. Kaul ◽  
Serena K. Kaul ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Hippocampal Sclerosis ◽  
Brain Mri ◽  
Temporal Lobectomy ◽  
Seizure Freedom ◽  
Seizure Onset

OBJECTIVEThere is emerging data that adults with temporal lobe epilepsy (TLE) without a discrete lesion on brain MRI have surgical outcomes comparable to those with hippocampal sclerosis (HS). However, pediatric TLE is different from its adult counterpart. In this study, the authors investigated if the presence of a potentially epileptogenic lesion on presurgical brain MRI influences the long-term seizure outcomes after pediatric temporal lobectomy.METHODSChildren who underwent temporal lobectomy between 2007 and 2015 and had at least 1 year of seizure outcomes data were identified. These were classified into lesional and MRI-negative groups based on whether an epilepsy-protocol brain MRI showed a lesion sufficiently specific to guide surgical decisions. These patients were also categorized into pure TLE and temporal plus epilepsies based on the neurophysiological localization of the seizure-onset zone. Seizure outcomes at each follow-up visit were incorporated into a repeated-measures generalized linear mixed model (GLMM) with MRI status as a grouping variable. Clinical variables were incorporated into GLMM as covariates.RESULTSOne hundred nine patients (44 females) were included, aged 5 to 21 years, and were classified as lesional (73%), MRI negative (27%), pure TLE (56%), and temporal plus (44%). After a mean follow-up of 3.2 years (range 1.2–8.8 years), 66% of the patients were seizure free for ≥ 1 year at last follow-up. GLMM analysis revealed that lesional patients were more likely to be seizure free over the long term compared to MRI-negative patients for the overall cohort (OR 2.58, p < 0.0001) and for temporal plus epilepsies (OR 1.85, p = 0.0052). The effect of MRI lesion was not significant for pure TLE (OR 2.64, p = 0.0635). Concordance of ictal electroencephalography (OR 3.46, p < 0.0001), magnetoencephalography (OR 4.26, p < 0.0001), and later age of seizure onset (OR 1.05, p = 0.0091) were associated with a higher likelihood of seizure freedom. The most common histological findings included cortical dysplasia types 1B and 2A, HS (40% with dual pathology), and tuberous sclerosis.CONCLUSIONSA lesion on presurgical brain MRI is an important determinant of long-term seizure freedom after pediatric temporal lobectomy. Pediatric TLE is heterogeneous regarding etiologies and organization of seizure-onset zones with many patients qualifying for temporal plus nosology. The presence of an MRI lesion determined seizure outcomes in patients with temporal plus epilepsies. However, pure TLE had comparable surgical seizure outcomes for lesional and MRI-negative groups.

Identifying patients with CKD risk at the time of nephrectomy: When to initiate nephrology consult

2021 ◽  
pp. 239936932110319
Author(s):  
Yihe Yang ◽  
Zachary Kozel ◽  
Purva Sharma ◽  
Oksana Yaskiv ◽  
Jose Torres ◽  
...  
Keyword(s):  
Risk Factors ◽  
Multivariate Analysis ◽  
Radical Nephrectomy ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Interstitial Fibrosis ◽  
Kidney Neoplasm ◽  
Tubular Atrophy ◽  
Independent Risk Factors

Introduction: The prevalence of chronic kidney disease (CKD) is high among kidney neoplasm patients because of the overlapping risk factors. Our purpose is to identify kidney cancer survivors with higher CKD risk. Methods: We studied a retrospective cohort of 361 kidney tumor patients with partial or radical nephrectomy. Linear mixed model was performed. Results: Of patients with follow-up >3 months, 84% were identified retrospectively to fulfill criteria for CKD diagnosis, although CKD was documented in only 15%. Urinalysis was performed in 205 (57%) patients at the time of nephrectomy. Multivariate analysis showed interstitial fibrosis and tubular atrophy (IFTA) >25% ( p = 0.005), severe arteriolar sclerosis ( p = 0.013), female gender ( p = 0.024), older age ( p = 0.012), BMI ⩾ 25 kg/m2 ( p < 0.001), documented CKD ( p < 0.001), baseline eGFR ⩽ 60 ml/min/1.73 m2 ( p < 0.001), and radical nephrectomy ( p < 0.001) were independent risk factors of lower eGFR at baseline and during follow-up. Average eGFR decreased within 3 months post nephrectomy. However, patients with different risk levels showed different eGFR time trend pattern at longer follow-ups. Multivariate analysis of time × risk factor interaction showed BMI, radical nephrectomy and baseline eGFR had time-dependent impact. BMI ⩾ 25 kg/m2 and radical nephrectomy were associated with steeper eGFR decrease slope. In baseline eGFR > 90 ml/min/1.73 m2 group, eGFR rebounded to pre-nephrectomy levels during extended follow-up. In partial nephrectomy patients with baseline eGFR ⩾ 90 ml/min/1.73 m2 ( n = 61), proteinuria ( p < 0.001) and BMI ( p < 0.001) were independent risk factors of decreased eGFR during follow up. Conclusions: As have been suggested by others and confirmed by our study, proteinuria and CKD are greatly under-recognized. Although self-evident as a minimum workup for nephrectomy patients to include SCr, eGFR, urinalysis, and proteinuria, the need for uniform applications of this practice should be reinforced. Non-neoplastic histology evaluation is valuable and should include an estimate of global sclerosis% (GS) and IFTA%. Patients with any proteinuria and/or eGFR ⩽ 60 at the time of nephrectomy or in follow-up with urologists, and/or >25% GS or IFTA, should be referred for early nephrology consultation.

scholarly journals Joint modeling of multiple repeated measures and survival data using multidimensional latent trait linear mixed model

2018 ◽  
Vol 28 (10-11) ◽  
pp. 3392-3403 ◽  
Author(s):  
Jue Wang ◽  
Sheng Luo
Keyword(s):  
Survival Data ◽  
Repeated Measures ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Proportional Hazards Model ◽  
Latent Trait ◽  
Joint Modeling ◽  
Fine Motor ◽  
Terminal Event ◽  
Longitudinal Outcomes

Impairment caused by Amyotrophic lateral sclerosis (ALS) is multidimensional (e.g. bulbar, fine motor, gross motor) and progressive. Its multidimensional nature precludes a single outcome to measure disease progression. Clinical trials of ALS use multiple longitudinal outcomes to assess the treatment effects on overall improvement. A terminal event such as death or dropout can stop the follow-up process. Moreover, the time to the terminal event may be dependent on the multivariate longitudinal measurements. In this article, we develop a joint model consisting of a multidimensional latent trait linear mixed model (MLTLMM) for the multiple longitudinal outcomes, and a proportional hazards model with piecewise constant baseline hazard for the event time data. Shared random effects are used to link together two models. The model inference is conducted using a Bayesian framework via Markov chain Monte Carlo simulation implemented in Stan language. Our proposed model is evaluated by simulation studies and is applied to the Ceftriaxone study, a motivating clinical trial assessing the effect of ceftriaxone on ALS patients.

scholarly journals Improved cephalic index following early cranial vault remodeling in patients with isolated nonsyndromic sagittal synostosis

2021 ◽  
Vol 50 (4) ◽  
pp. E7
Author(s):  
Arvid Frostell ◽  
Maryam Haghighi ◽  
Jiri Bartek ◽  
Ulrika Sandvik ◽  
Bengt Gustavsson ◽  
...  
Keyword(s):  
Mixed Model ◽  
Linear Mixed Model ◽  
Cranial Vault ◽  
Hospital Length Of Stay ◽  
Cephalic Index ◽  
Sagittal Synostosis ◽  
The Mean ◽  
Cranial Vault Remodeling

OBJECTIVE Isolated nonsyndromic sagittal synostosis (SS) is the most common form of craniosynostosis in children, accounting for approximately 60% of all craniosynostoses. The typical cranial measurement used to define and follow SS is the cephalic index (CI). Several surgical techniques have been suggested, but agreement on type and timing of surgery is lacking. This study aimed to evaluate the authors’ institutional experience of surgically treating SS using a modified subtotal cranial vault remodeling technique in a population-based cohort. Special attention was directed toward the effect of patient age at time of surgery on long-term CI outcome. METHODS A retrospective analysis was conducted on all patients with isolated nonsyndromic SS who were surgically treated from 2003 to 2011. Data from electronic medical records were gathered. Eighty-two patients with SS were identified, 77 fulfilled inclusion criteria, and 72 had sufficient follow-up data and were included. CI during follow-up after surgery was investigated with ANOVA and a linear mixed model. RESULTS In total, 72 patients were analyzed, consisting of 16 females (22%) and 56 males (78%). The mean ± SD age at surgery was 4.1 ± 3.1 months. Blood transfusions were received by 81% of patients (26% intraoperatively, 64% postoperatively, 9% both). The mean ± SD time in the pediatric ICU was 1.1 ± 0.25 days, and the mean ± SD total hospital length of stay was 4.6 ± 2.0 days. No patient required reoperation. The mean ± SD CI increased from 69 ± 3 to 87 ± 5 for patients who underwent surgery before 45 days of age. Surgery resulted in a larger increase in CI for patients who underwent surgery at a younger age compared with older patients (p < 0.05, Tukey’s HSD test). In the comparison of patients who underwent surgery before 45 days of age with patients who underwent surgery at 45–90, 90–180, and more than 180 days of age, the linear mixed model estimated a long-term loss of CI of 3.0, 5.5, and 7.4 points, respectively. CONCLUSIONS The modified subtotal cranial vault remodeling technique used in this study significantly improved CI in patients with SS. The best results were achieved when surgery was performed early in life.

scholarly journals Thalamic white matter macrostructure and subnuclei volumes in Parkinson’s disease depression

2022 ◽  
Vol 8 (1) ◽  
Author(s):  
R. Bhome ◽  
A. Zarkali ◽  
G. E. C. Thomas ◽  
J. E. Iglesias ◽  
J. H. Cole ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
White Matter ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Neural Structure ◽  
Generalised Linear Mixed Model ◽  
Antidepressant Use ◽  
The Relationship

AbstractDepression is a common non-motor feature of Parkinson’s disease (PD) which confers significant morbidity and is challenging to treat. The thalamus is a key component in the basal ganglia-thalamocortical network critical to the pathogenesis of PD and depression but the precise thalamic subnuclei involved in PD depression have not been identified. We performed structural and diffusion-weighted imaging (DWI) on 76 participants with PD to evaluate the relationship between PD depression and grey and white matter thalamic subnuclear changes. We used a thalamic segmentation method to divide the thalamus into its 50 constituent subnuclei (25 each hemisphere). Fixel-based analysis was used to calculate mean fibre cross-section (FC) for white matter tracts connected to each subnucleus. We assessed volume and FC at baseline and 14–20 months follow-up. A generalised linear mixed model was used to evaluate the relationship between depression, subnuclei volume and mean FC for each thalamic subnucleus. We found that depression scores in PD were associated with lower right pulvinar anterior (PuA) subnucleus volume. Antidepressant use was associated with higher right PuA volume suggesting a possible protective effect of treatment. After follow-up, depression scores were associated with reduced white matter tract macrostructure across almost all tracts connected to thalamic subnuclei. In conclusion, our work implicates the right PuA as a relevant neural structure in PD depression and future work should evaluate its potential as a therapeutic target for PD depression.

scholarly journals Bi-directional prospective associations between objectively measured physical activity and fundamental motor skills in children: a two-year follow-up

2020 ◽  
Vol 17 (1) ◽  
Author(s):  
Ada Kristine Ofrim Nilsen ◽  
Sigmund Alfred Anderssen ◽  
Kjersti Johannessen ◽  
Katrine Nyvoll Aadland ◽  
Einar Ylvisaaker ◽  
...  
Keyword(s):  
Physical Activity ◽  
Young Children ◽  
Motor Skills ◽  
Motor Development ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Gross Motor ◽  
Object Control ◽  
Fundamental Motor Skills

Abstract Background The direction of the longitudinal relationship between physical activity (PA) and fundamental motor skills (FMS) remains unclear. We evaluated the bi-directional, prospective relationships between intensity-specific physical activity (PA) and domain-specific fundamental motor skills (FMS) over 2 years in children attending preschool at baseline. Methods A sample of 230 children (mean age at baseline 4.7 yr, 52% boys) from the 'Sogn og Fjordane Preschool Physical Activity Study' was measured 2 years apart. PA was assessed using ActiGraph accelerometers (GT3X+). FMS were evaluated by a test battery guided by the 'Test of Gross Motor Development 3' and the 'Preschooler Gross Motor Quality Scale'. PA outcomes were total PA (TPA [counts per minute]) and intensity specific PA and sedentary behaviour (SED) (min/day). FMS outcomes were locomotor, object control, and balance skills. Linear mixed model adjusting for potential co-variates was used to evaluate the bi-directional prospective associations between these variables, including the moderating effect of sex and age. Results Baseline total PA, moderate-to-vigorous PA (MVPA), and vigorous PA predicted higher locomotor, object control, and balance skills at follow-up (standardized regression coefficient (β): 0.17 to 0.26, p = 0.002–0.017). Baseline SED predicted lower locomotor skills at follow-up (β: − 0.27, p = 0.012). Baseline light PA did not predict FMS at follow-up. Baseline FMS were not associated with PA or SED at follow-up. Conclusions MVPA was positively associated with development of FMS in young children. In contrast, FMS were not related to future PA levels. Our results suggest promotion of MVPA is important for FMS development in young children.

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