Specification of Variance-Covariance Structure in Bivariate Mixed Model for Unequally Time-Spaced Longitudinal Data

In medical studies, the longitudinal data sets obtained from more than one response variables and covariates are mostly analyzed to investigate the change in repeated measurements of each subject at different time points. In this study, the usability of multivariate models in the analysis of these kind of data sets is investigated, because it provides the joint analysis of multiple response variables over time and enables researchers to examine both the correlations of response variables and autocorrelation between measurements from each response variable over time. It has been shown that different parameter estimation methods affect the results in the analysis of multivariate unbalanced longitudinal data. We investigated that autocorrelation structure over time between measurements from same response variable should be truly specified. We also illustrated and compared the simpler, more standard models for fixed effects with multivariate models provided by SAS on a real-life data set in the joint analysis of two response variables. Results show that misspecification of autocorrelation structures has a negative impact on the parameter estimates and parameter estimation method should become of interest

Longitudinal age-and cohort trends in body mass index in Sweden - a 24-year follow-up study

Background: The aim of this longitudinal study was to analyze whether mean Body Mass Index (BMI), assessed at four occasions, changed within different age groups and birth cohorts over time, i.e., between 1980/81 and 2004/05, after adjustment for possible confounders. Methods: A sample of 2728 men and 2770 women aged 16-71 years at study start were randomly drawn from the Swedish Total Population Register and followed from 1980/81 to 2004/05. The same sample was assessed on four occasions during the 24-year study period (i.e., every eighth year). The outcome variable, BMI, was based on self-reported height and weight. A mixed model, with random intercept and random slope, was used to estimate annual changes in BMI within the different age groups and birth cohorts. Results: Mean BMI increased from 24.1 to 25.5 for men and from 23.1 to 24.3 for women during the 24-year study period. The annual change by age group was highest in the ages of 32-39, 40-47 and 48-55 years among men, and in the ages of 24-31, 32-39, and 40-47 years among women. The highest annual changes were found in the youngest birth cohorts for both men and women, i.e., those born 1958-65, 1966-73, and 1974-81. For each birth cohort, the annual change in BMI increased compared to the previous, i.e., older, birth cohort. In addition, age-by-cohort interaction tests revealed that the increase in BMI by increasing age was higher in the younger birth cohorts (1966-1989) than in the older ones. Conclusions: Public health policies should target those age groups and birth cohorts with the highest increases in BMI. For example, younger birth cohorts had higher annual increases in BMI than older birth cohorts, which means that younger cohorts increased their BMI more than older ones during the study period

Using next-generation DNA sequence data for genetic association tests based on allele counts with and without consideration of zero inflation

The relationship between genetic variability and individual phenotypes is usually investigated by testing for association relying on called genotypes. Allele counts obtained from next-generation sequence data could be used for this purpose too. Genetic association can be examined by treating alternative allele counts (AACs) as the response variable in negative binomial regression. AACs from sequence data often contain an excess of zeros, thus motivating the use of Hurdle and zero-inflated models. Here we examine rough type I error rates and the ability to pick out variants with small probability values for 7 different testing approaches that incorporate AACs as an explanatory or as a response variable. Model comparisons relied on chromosome 3 DNA sequence data from 407 Hispanic participants in the Type 2 Diabetes Genetic Exploration by Next-generation sequencing in Ethnic Samples (T2D-GENES) project 1 with complete information on diastolic blood pressure and related medication. Our results suggest that in the investigation of the relationship between AAC as response variable and individual phenotypes as explanatory variable, Hurdle-negative binomial regression has some advantages. This model showed a good ability to discriminate strongly associated variants and controlled overall type I error rates. However, probability values from Hurdle-negative binomial regression were not obtained for approximately 25 % of the investigated variants because of convergence problems, and the mass of the probability value distribution was concentrated around 1

Bleeding frequency of patients taking ticagrelor, aspirin, clopidogrel, and dual antiplatelet therapy after tooth extraction and minor oral surgery

Background. Perioperative bleeding complications of ticagrelor, a newer oral antiplatelet, has not been studied in dentistry. Studies about bleeding status after oral surgical procedures in patients receiving continued antiplatelet therapy are also limited. We investigated the effects of continuing aspirin, clopidogrel, ticagrelor, or dual antiplatelet therapy on the frequency of bleeding events in patients undergoing tooth extractions or minor oral surgery

682. The Changing Epidemiology Of Bacterial Meningitis During 2015–2017 In Turkey: A Hospital-Based Prospective Surveillance Study

Background The etiology of bacterial meningitis in Turkey has been changed after the implementation of conjugated vaccines against Streptococcus pneumonia and Haemophilus influenzae type b (Hib) in Turkish national immunization schedule. Methods. This prospective study was conducted in 25 hospitals located seven regions of Turkey (representing 30% of Turkey population) and children aged between 1 month and 18 years with suspected meningitis and hospitalized were included. Cerebrospinal fluid samples were collected and bacterial identification was made according to the multiplex PCR assay results. Results. During the study period, 927 children were hospitalized for suspected meningitis and Hib (n:1), S. pneumonia (n:17) and Neisseria meningitidis (n:59) were detected in 77 samples (Figure 1, Table 1). During 2015–2016, N. meningitidis serogroup W, B, A, Y, X frequencies were as 5 (13.9%), 16 (44.4%), 1 (2.8%), 1 (2.8%), 1 (2.8%), respectively. There were 12 nongroupable N. meningitidis samples and serogroup C was not detected. In 2017, of meningococcal meningitis serogroup B, W, A, Y and X were identified in two (8.7%), 15 (65.2%), two (8.7%), 1 (4.3%) and 1 (4.3%) cases, respectively (Figure 2). There were four deaths in this study period, all of them were caused by N. meningitidis serogroup B and three of them were under 1 year old. Conclusion. The epidemiology of meningococcal diseases has been varied in time with or without any apparent reasons. Hajj is a well-known cause for serogroup W epidemics and serogorup W was the most common cause of meningitis in Turkey during 2009–2014 as in other Middle East countries. After the impact of serogroup W epidemics related to Hajj seen in 2010’s was diminished, serogroup B has been leading cause of childhood meningitis since 2015. In countries affected from Hajj like Turkey, vaccination of children with serogroup B meningococcal vaccine as well as quadrivalentconjugated vaccine seems to be very important. It should be kept in mind that meningococcal epidemiology is dynamic and needed to be closely monitored to detect changes in years Disclosures All authors: No reported disclosures.PubMe

Antibiotic associated diarrhea in outpatient pediatric antibiotic therapy

Background: Antibiotic-associated diarrhea is one of the most frequent side effects of antimicrobial therapy. We assessed the epidemiological data of antibiotic-associated diarrhea in pediatric patients in our region. Methods: The prospective multi-center study included pediatric patients who were initiated an oral antibiotic course in outpatient clinics and followed in a well-established surveillance system. This follow-up system constituded inclusion of patient by the primary physician, supply of family follow-up charts to the family, passing the demographics and clinical information of patient to the Primary Investigator Centre, and a close telephone follow-up of patients for a period of eight weeks by the Primary Investigator Centre. Results: A result of 758 cases were recruited in the analysis which had a frequency of 10.4% antibiotic-associated diarrhea. Among the cases treated with amoxicillin-clavulanate 10.4%, and cephalosporins 14.4% presented with antibiotic-associated diarrhea. In the analysis of antibiotic-associated diarrhea occurrence according to different geographical regions of Turkey, antibiotic-associated diarrhea episodes differed significantly (p = 0.014), particularly higher in The Eastern Anatolia and Southeastern Anatolia. Though most commonly encountered with cephalosporin use, antibiotic-associated diarrhea is not a frequent side effect. Conclusion: This study on pediatric antibiotic-associated diarrhea displayed epidemiological data and the differences geographically in our region

Differences and similarities of multisystem inflammatory syndrome in children, Kawasaki disease and macrophage activating syndrome due to systemic juvenile idiopathic arthritis: a comparative study

To compare the clinical and laboratory findings of multisystem inflammatory syndrome in children (MIS-C), patients with Kawasaki disease (KD) and with macrophage activating syndrome due to systemic juvenile idiopathic arthritis (sJIA-MAS) on real-life data. Patients diagnosed with MIS-C, KD, and sJIA-MAS from 12 different centers in Turkey who were followed for at least 6 months were included in the study. Demographic, clinical, and laboratory findings of all patients were analyzed. A total of 154 MIS-C, 59 KD, and 31 sJIA-MAS patients were included. The median age of patients with MIS-C were higher than those with KD while lower than those with sJIA-MAS (8.2, 3, 12 years, respectively). Myalgia (39.6%), cardiac (50.6%), gastrointestinal (72.7%), and neurological (22.1%) involvements were more common in patients with MIS-C compared to others. MIS-C patients had lower levels of lymphocyte (950 vs 1700 cells/mu l) and thrombocyte (173,000 vs 355,000 cells/mu l) counts and higher pro-BNP (1108 vs 55 pg/ml) levels than KD. Ferritin levels were higher in patients with MIS-C compared to patients with KD while they were lower than patients with sJIA-MAS (440, 170, 10,442 ng/ml, respectively). Patients with MIS-C had a shorter duration of hospitalization than sJIA-MAS (p = 0.02) while they required intensive care unit admission more frequently (55 vs 8 patients, p < 0.001). The median MAS/sJIA score of MIS-C patients was - 1.64 (- 5.23 to 9.68) and the median MAS/sJIA score of sJIA-MAS patients was -2.81 ([- 3.79] to [- 1.27]). MIS-C patients displayed certain differences in clinical and laboratory features when compared to KD and sJIA-MAS. Definition of the differences and similarities between MIS-C and the other intense inflammatory syndromes of childhood such as KD and MAS will help the clinicians while making timely diagnosis

COVID-19 associated multisystemic inflammatory syndrome in 614 children with and without overlap with Kawasaki disease-Turk MIS-C study group.

Multisystemic inflammatory syndrome (MIS-C) diagnosis remains difficult because the clinical features overlap with Kawasaki disease (KD). The study aims to highlight the clinical and laboratory features and outcomes of patients with MISC whose clinical manifestations overlap with or without KD. This study is a retrospective analysis of a case series designed for patients aged 1 month to 18 years in 28 hospitals between November 1, 2020, and June 9, 2021. Patient demographics, complaints, laboratory results, echocardiographic results, system involvement, and outcomes were recorded. A total of 614 patients were enrolled; the median age was 7.4 years (interquartile range (IQR) 3.9-12 years). A total of 277 (45.1%) patients with MIS-C had manifestations that overlapped with KD, including 92 (33.3%) patients with complete KD and 185 (66.7%) with incomplete KD. Lymphocyte and platelet counts were significantly lower in patients with MISC, overlapped with KD (lymphocyte count 1080 vs. 1280 cells x mu L, p = 0.028; platelet count 166 vs. 216 cells x 10(3)/mu L, p 12 years reduced the risk of overlap with KD by 66% (p < 0.001, 95% CI 0.217-0.550), lethargy increased the risk of overlap with KD by 2.6-fold (p = 0.011, 95% CI 1.244-5.439), and each unit more albumin (g/dl) reduced the risk of overlap with KD by 60% (p < 0.001, 95% CI 0.298-0.559)