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Statistical analysis of longitudinal data often involves modeling treatment effects on clinically relevant longitudinal biomarkers since an initial event (the time origin). In some studies including preventive HIV vaccine efficacy trials, some participants have biomarkers measured starting at the time origin, whereas others have biomarkers measured starting later with the time origin unknown. The semiparametric additive time‐varying coefficient model is investigated where the effects of some covariates vary nonparametrically with time while the effects of others remain constant. Weighted profile least squares estimators coupled with kernel smoothing are developed. The method uses the expectation maximization approach to deal with the censored time origin. The Kaplan–Meier estimator and other failure time regression models such as the Cox model can be utilized to estimate the distribution and the conditional distribution of left censored event time related to the censored time origin. Asymptotic properties of the parametric and nonparametric estimators and consistent asymptotic variance estimators are derived. A two‐stage estimation procedure for choosing weight is proposed to improve estimation efficiency. Numerical simulations are conducted to examine finite sample properties of the proposed estimators. The simulation results show that the theory and methods work well. The efficiency gain of the two‐stage estimation procedure depends on the distribution of the longitudinal error processes. The method is applied to analyze data from the Merck 023/HVTN 502 Step HIV vaccine study. [ABSTRACT FROM AUTHOR]

This study compared personality risk factors and readiness to change drinking behavior among mandated and volunteer college students. The sample ( N = 583) completed three measures of motivation to change and personality risk factors at baseline, 3 months, and 6 months between 2011 and 2012. Linear mixed models were used to determine an association of continuous outcome variable(s) with covariates over time. Participants in the action stage had lower impulsivity scores. Gender was significant, with females showing the highest anxiety and lowest sensation seeking. The findings indicate a number of future directions to advance innovative alcohol intervention and treatment programs on college campuses. [ABSTRACT FROM AUTHOR]

Introduction: Alcohol consumption and illicit drug use among college students are national public health concerns. Mandated students who have violated campus alcohol policies often are at higher risk for heavy drinking and illicit drug use. Purpose: This longitudinal study compared the effectiveness of the Brief Motivational Intervention (BMI) in decreasing alcohol consumption and illicit drug use, as well as the associated negative consequences among mandated students (Group 1) and voluntary students (Group 2). Methods: Eligible participants (436 voluntary, 147 mandated, N = 583) who agreed to be in the study received the BMI at baseline and again at 2 weeks, with boosters at 3 months and 6 months. Descriptive statistics, frequency tables and summary graphs were used to summarize the study variables in both groups. Results: Alcohol and drug use in both groups decreased between baseline and 6 months, with drug use in the mandated group declining to 10% by 6 months. The consequences, including blackouts, decreased significantly for both groups at baseline and 3 months, and then plateaued at 6 months. Conclusions: The results from this study showed that the BMI was effective in decreasing alcohol consumption and illegal drug use, along with the associated negative consequences, among freshman students and voluntary students who were mandated to attend the program. [ABSTRACT FROM AUTHOR]

This open-label, randomized, phase 3 study in China (V260-074; NCT04481191) evaluated the immunogenicity and safety of concomitant and staggered administration of three doses of an oral, live, pentavalent rotavirus vaccine (RV5) and three doses of an intramuscular, inactivated poliomyelitis vaccine (IPV) in 400 healthy infants. The primary objective was the non-inferiority of neutralizing antibody (nAb) responses in the concomitant- versus the staggered-use groups. Antibody responses were measured at baseline and 1-month post-dose 3 (PD3). Parents/legal guardians recorded adverse events for 30 or 15 d after study vaccinations in the concomitant-use or staggered-use groups, respectively. At PD3, >98% of participants seroconverted to all three poliovirus types, and the primary objective was met as lower bounds of the two-sided 95% CI for between-group difference in nAb seroconversion percentages ranged from - 4.3% to - 1.6%, for all poliovirus types, p  < .001. At PD3, geometric mean titers (GMTs) of nAb responses to poliovirus types 1, 2, and 3 in the concomitant-use group and the staggered-use group were comparable; 100% of participants had nAb titers ≥1:8 and ≥1:64 for all poliovirus types. Anti-rotavirus serotype-specific IgA GMTs and participants with ≥3-fold rise in postvaccination titers from baseline were comparable between groups. Administration of RV5 and IPV was well tolerated with comparable safety profiles in both groups. The immunogenicity of IPV in the concomitant-use group was non-inferior to the staggered-use group and RV5 was immunogenic in both groups. No safety concerns were identified. These data support the concomitant use of RV5 and IPV in healthy Chinese infants.