Sample size calculations for evaluating mediation

A social media game to increase physical activity among older adult women: protocol of a randomized controlled trial to evaluate CHALLENGE

BACKGROUND

Older adult women often do not engage in sufficient physical activity (PA) and can encounter biological changes that exacerbate the negative effects of inadequate activity. Wearable activity monitors can facilitate PA initiation, but evidence of sustained behavior change is lacking. Supplementing wearable technologies with intervention content that evokes enjoyment, interest, meaning, and personal values associated with PA may support long term adherence. In this paper, we present the protocol of an NIA-funded study designed to evaluate the efficacy of CHALLENGE for increasing step count and motivation for PA in insufficiently active older women (Challenges for Healthy Aging: Leveraging Limits for Engaging Networked Game-based Exercise). CHALLENGE uses social media to supplement wearable activity monitors with the autonomy-supportive frame of a game. We hypothesize that CHALLENGE will engender playful experiences that will improve motivation for exercise and lead to sustained increases in step count.

METHODS

We will recruit 300 healthy, community dwelling older adult women on a rolling basis and randomize them to receive either the CHALLENGE intervention (experimental arm) or an activity monitor-only intervention (comparison arm). Participants in both groups will receive a wearable activity monitor and personalized weekly feedback emails. In the experimental group, participants will also be added to a private Facebook group, where study staff will post weekly challenges that are designed to elicit playful experiences while walking. Assessments at baseline and 6, 12, and 18 months will measure PA and motivation-related constructs. We will fit linear mixed-effects models to evaluate differences in step count and motivational constructs, and longitudinal mediation models to evaluate if interventional effects are mediated by changes in motivation. We will also conduct thematic content analysis of text and photos posted to Facebook and transcripts from individual interviews.

DISCUSSION

By taking part in a year-long intervention centered on imbuing walking behaviors with playful and celebratory experiences, participating older adult women may internalize changes to their identity and relationship with PA that facilitate sustained behavior change. Study results will have implications for how we can harness powerful and increasingly ubiquitous technologies for health promotion to the vast and growing population of older adults in the U.S. and abroad.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT04095923. Registered September 17th, 2019.

Increasing pre-exposure prophylaxis (PrEP) in primary care: A study protocol for a multi-level intervention using the multiphase optimization strategy (MOST) framework

BACKGROUND

In the United States, over 1.2 million people are living with HIV. This disease disproportionately affects men who have sex with men (MSM), people of color, youth and young adults, and transgender individuals. Pre-exposure prophylaxis (PrEP) is an effective HIV prevention method. Barriers exist for both primary care providers (PCPs) to prescribe PrEP and prevent patients from initiating PrEP.

METHODS

This study, MOST: PrEP, follows the multiphase optimization strategy (MOST) framework. The purpose is to identify a multi-level intervention among patients and PCPs to increase PrEP prescriptions in primary care. First, feedback will be obtained from providers and patients via focus groups, then, suggestions related to the context-specific (provider and individual level) factors of intervention component delivery will be incorporated. Subsequently, a rigorous experiment will be conducted using a 24 factorial design focusing on priority populations for PrEP initiation. Provider components include computer-based simulation training and a best practice alert. Patient components include a tailored PrEP educational video and HIV risk assessment. Finally, the facilitators and barriers to implementing the intervention components will be qualitatively examined.

CONCLUSION

In this protocol paper, we describe the one of the first known multilevel MOST optimization trial in healthcare. Intervention components are to be delivered to patients and providers in a large healthcare system, based in an HIV Ending the Epidemic priority jurisdiction. If effective, this multi-level approach could be disseminated to providers and patients in other large healthcare systems to make a significant impact on HIV prevention.

Effect of dorsolateral prefrontal cortex structural measures on neuroplasticity and response to paired-associative stimulation in Alzheimer's dementia

Long-term potentiation (LTP)-like activity can be induced by stimulation protocols such as paired associative stimulation (PAS). We aimed to determine whether PAS-induced LTP-like activity (PAS-LTP) of the dorsolateral prefrontal cortex (DLPFC) is associated with cortical thickness and other structural measures impaired in Alzheimer's dementia (AD). We also explored longitudinal relationships between these brain structures and PAS-LTP response after a repetitive PAS (rPAS) intervention. Mediation and regression analyses were conducted using data from randomized controlled trials with AD and healthy control participants. PAS-electroencephalography assessed DLPFC PAS-LTP. DLPFC thickness and surface area were acquired from T1-weighted magnetic resonance imaging. Fractional anisotropy and mean diffusivity (MD) of the superior longitudinal fasciculus (SLF)-a tract important to induce PAS-LTP-were measured with diffusion-weighted imaging. AD participants exhibited reduced DLPFC thickness and increased SLF MD. There was also some evidence that reduction in DLPFC thickness mediates DLPFC PAS-LTP impairment. Longitudinal analyses showed preliminary evidence that SLF MD, and to a lesser extent DLPFC thickness, is associated with DLPFC PAS-LTP response to active rPAS. This study expands our understanding of the relationships between brain structural changes and neuroplasticity. It provides promising evidence for a structural predictor to improving neuroplasticity in AD with neurostimulation. This article is part of a discussion meeting issue 'Long-term potentiation: 50 years on'.

Impact of prenatal maternal depression on gestational length: post hoc analysis of a randomized clinical trial

Background

Shortened gestation is a leading cause of childhood morbidity and mortality with lifelong consequences for health. There is a need for public health initiatives on increasing gestational age at birth. Prenatal maternal depression is a pervasive health problem robustly linked via correlational and epidemiological studies to shortened gestational length. This proof-of-concept study tests the impact of reducing prenatal maternal depression on gestational length with analysis of a randomized clinical trial (RCT).

Methods

Participants included 226 pregnant individuals enrolled into an RCT and assigned to receive either interpersonal psychotherapy (IPT) or enhanced usual care (EUC). Recruitment began in July 2017 and participants were enrolled August 10, 2017 to September, 8 2021. Depression diagnosis (Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition; DSM 5) and symptoms (Edinburgh Postnatal Depression Scale and Symptom Checklist) were evaluated at baseline and longitudinally throughout gestation to characterize depression trajectories. Gestational dating was collected based on current guidelines via medical records. The primary outcome was gestational age at birth measured dichotomously (≥39 gestational weeks) and the secondary outcome was gestational age at birth measured continuously. Posthoc analyses were performed to test the effect of reducing prenatal maternal depression on gestational length. This trial is registered with ClinicalTrials.gov (NCT03011801).

Findings

Steeper decreases in depression trajectories across gestation predicted later gestational age at birth, specifically an increase in the number of full-term babies born ≥39 gestational weeks (EPDS linear slopes: OR = 1.54, 95% CI 1.10-2.16; and SCL-20 linear slopes: OR = 1.67, 95% CI 1.16-2.42). Causal mediation analyses supported the hypothesis that participants assigned to IPT experienced greater reductions in depression symptom trajectories, which in turn, contributed to longer gestation. Supporting mediation, the natural indirect effect (NIE) showed that reduced depression trajectories resulting from intervention were associated with birth ≥39 gestational weeks (EPDS, OR = 1.65, 95% CI 1.02-2.66; SCL-20, OR = 1.85, 95% CI 1.16-2.97).

Interpretation

We used a RCT design and found that reducing maternal depression across pregnancy was associated with lengthened gestation.

Funding

This research was supported by the NIH (R01 HL155744, R01 MH109662, R21 MH124026, P50 MH096889).

Development and validation of a nomogram for predicting cognitive frailty in patients on maintenance haemodialysis

AIMS

This study aimed to construct a nomogram for predicting the risk of cognitive frailty in patients on maintenance haemodialysis.

DESIGN

An explorative cross-sectional design was adopted.

METHODS

From April 2022 to July 2022, 496 participants were recruited from five haemodialysis centres in Qingdao, Shandong Province, China. Participants with cognitive frailty were screened by Frailty Phenotype scale and Mini-Mental State Examination. Least Absolute Shrinkage and Selection Operator (LASSO) regression and multivariate logistic regression were utilized to determine predictors. The predictive performance of the nomogram was validated by calibration and discrimination. Decision curve analysis was used to assess clinical utility. Internal validation was implemented using 1000 bootstrap samples to mitigate overfitting.

RESULTS

The prevalence of cognitive frailty was 17.5% (n = 87). Six risk predictors, namely health empowerment, alexithymia, age, educational level, marital status and dialysis vintage, were screened and used to develop a nomogram model. The nomogram had satisfactory discrimination and calibration, and decision curve analysis revealed considerable clinical utility.

CONCLUSIONS

A nomogram incorporated with the six risk predictors was developed, and it exhibited excellent prediction performance. The nomogram may strengthen the effective screening of patients at high risk of cognitive frailty.

IMPACT

This study established a tool for healthcare staff to predict cognitive frailty probability and identify risk factors in patients on maintenance haemodialysis. The nomogram can meet the needs of personalized care and precision medicine simultaneously.

PATIENT OR PUBLIC CONTRIBUTION

Data were collected from patients on maintenance haemodialysis by using questionnaire survey.

REPORTING METHOD

STROBE checklist was used.

Social interactions offset the detrimental effects of digital media use on children's vocabulary

Young children's rapid vocabulary growth during the first few years is supported by input during social interactions with caregivers and, increasingly, from digital media. However, the amount of exposure to both sources can vary substantially across socioeconomic classes, and little is known about how social interactions and digital media use together predict vocabulary in the first few years of life. The current study takes a first step toward examining whether increased social interactions with other individuals may buffer the potentially detrimental effects of digital media use on language among a socioeconomically diverse sample. 305 caregivers of children between 17 and 30-months completed questionnaires about their family demographics, their child's technology use, and the child's daily routines and social interactions. Findings suggest children who experience fewer human interactions and greater technology exposure have smaller vocabularies than their peers who socialize more and use less technology, and this disparity becomes greater as children get older. Moreover, the number of social interactions moderates the link between SES, digital media, and vocabulary such that the negative impact of digital media on vocabulary for children from low SES households can be offset with increased social interactions. Together, this suggests that increasing the amount of human interactions may serve as a protective factor for vocabulary outcomes in a world where digital media use is prominent.

Sample size and power calculations for causal mediation analysis: A Tutorial and Shiny App

When designing a study for causal mediation analysis, it is crucial to conduct a power analysis to determine the sample size required to detect the causal mediation effects with sufficient power. However, the development of power analysis methods for causal mediation analysis has lagged far behind. To fill the knowledge gap, I proposed a simulation-based method and an easy-to-use web application ( https://xuqin.shinyapps.io/CausalMediationPowerAnalysis/ ) for power and sample size calculations for regression-based causal mediation analysis. By repeatedly drawing samples of a specific size from a population predefined with hypothesized models and parameter values, the method calculates the power to detect a causal mediation effect based on the proportion of the replications with a significant test result. The Monte Carlo confidence interval method is used for testing so that the sampling distributions of causal effect estimates are allowed to be asymmetric, and the power analysis runs faster than if the bootstrapping method is adopted. This also guarantees that the proposed power analysis tool is compatible with the widely used R package for causal mediation analysis, mediation, which is built upon the same estimation and inference method. In addition, users can determine the sample size required for achieving sufficient power based on power values calculated from a range of sample sizes. The method is applicable to a randomized or nonrandomized treatment, a mediator, and an outcome that can be either binary or continuous. I also provided sample size suggestions under various scenarios and a detailed guideline of app implementation to facilitate study designs.

Awareness with paralysis and symptoms of post-traumatic stress disorder among mechanically ventilated emergency department survivors (ED-AWARENESS-2 Trial): study protocol for a pragmatic, multicenter, stepped wedge cluster randomized trial

BACKGROUND

Awareness with paralysis (AWP) is memory recall during neuromuscular blockade (NMB) and can cause significant psychological harm. Decades of effort and rigorous trials have been conducted to prevent AWP in the operating room, where prevalence is 0.1-0.2%. By contrast, AWP in mechanically ventilated emergency department (ED) patients is common, with estimated prevalence of 3.3-7.4% among survivors given NMB. Longer-acting NMB use is a critical risk for AWP, and we have shown an association between ED rocuronium use and increased AWP prevalence. As NMB are given to more than 90% of ED patients during tracheal intubation, this trial provides a platform to test an intervention aimed at reducing AWP. The overall objective is to test the hypothesis that limiting ED rocuronium exposure will significantly reduce the proportion of patients experiencing AWP.

METHODS

This is a pragmatic, stepped wedge cluster randomized trial conducted in five academic EDs, and will enroll 3090 patients. Per the design, all sites begin in a control phase, under observational conditions. At 6-month intervals, sites sequentially enter a 2-month transition phase, during which we will implement the multifaceted intervention, which will rely on use of nudges and defaults to change clinician decisions regarding ED NMB use. During the intervention phase, succinylcholine will be the default NMB over rocuronium. The primary outcome is AWP, assessed with the modified Brice questionnaire, adjudicated by three independent, blinded experts. The secondary outcome is the proportion of patients developing clinically significant symptoms of post-traumatic stress disorder at 30 and 180 days after hospital discharge. We will also assess for symptoms of depression and anxiety, and health-related quality of life. A generalized linear model, adjusted for time and cluster interactions, will be used to compare AWP in control versus intervention phases, analyzed by intention-to-treat.

DISCUSSION

The ED-AWARENESS-2 Trial will be the first ED-based trial aimed at preventing AWP, a critical threat to patient safety. Results could shape clinical use of NMB in the ED and prevent more than 10,000 annual cases of AWP related to ED care.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT05534243 . Registered 06, September 2022.

Anticipatory postural adjustments mediate the changes in fear-related behaviors in individuals with chronic low back pain

OBJECTIVES

The role(s) of anticipatory postural adjustments (APAs) in changes in subsequent motor and postural controls in response to movement perturbations are unclear in individuals with chronic low back pain (CLBP). This study aimed to clarify the relationships among kinesiophobia, APAs, lumbar kinematic output, and postural control associated with lumbar movement in individuals with CLBP.

METHODS

CLBP participants (n=48) and healthy controls (HCs) without CLBP (n=22) performed a bend-forward task using their lumbar region on a force platform and returned upright. Each participant's lumbar movements were recorded using an electrogoniometer. We calculated the APA duration, the duration of lumbar direction changes from forward to backward, and the center of pressure (COP) position after lumbar movement tasks completion.

RESULTS

Compared with the HCs, the duration of direction changes in lumbar movement and the APA duration in CLBP participants were prolonged, and the COP position was shifted forward. The mediation analysis revealed that the duration of lumbar direction changes in the CLBP group was subjected to a significant indirect effect of APAs and a direct effect of kinesiophobia, and the COP position was subjected to a significant indirect effect of kinesiophobia through APAs.

CONCLUSIONS

APAs partially mediate the relationship between kinesiophobia and changes in lumbar motor control and mediate the relationship between kinesiophobia and postural control in response to movement perturbations. These findings expand our understanding of APAs in altered subsequent movement and postural controls due to kinesiophobia in individuals with CLBP.

Reduction in sugar drink valuation and consumption with gamified executive control training

The overvaluation of high-energy, palatable food cues contributes to unhealthy eating and being overweight. Reducing the valuation of unhealthy food may thus constitute a powerful lever to improve eating habits and conditions characterized by unhealthy eating. We conducted a double-blind, placebo-controlled, randomized intervention trial assessing the efficacy of a five to twenty days online cognitive training intervention to reduce sugary drink perceived palatability and consumption. Our intervention involved a recently identified action-to-valuation mechanism of action, in which the repeated inhibition of prepotent motor responses to hedonic food cues in a Go/NoGo (GNG) and an attentional bias modification (ABM) task eventually reduces their valuation and intake. Confirming our hypotheses, the experimental intervention with consistent (100%) mapping between motor inhibition and the targeted unhealthy sugary drinks cues induced a larger decrease in their valuation than the control intervention with inconsistent (50%) mapping (- 27.6% vs. - 19%), and a larger increase of the (water) items associated with response execution (+ 11% vs + 4.2%). Exploratory analyses suggest that the effect of training on unhealthy items valuation may persist for at least one month. Against our hypothesis, we observed equivalent reductions in self-reported consumption of sugary drinks following the two interventions (exp: - 27% vs. ctrl: - 19%, BF01 = 4.7), suggesting a dose-independent effect of motor inhibition on self-reported consumption. Our collective results corroborate the robustness and large size of the devaluation effects induced by response inhibition on palatable items, but challenge the assumption of a linear relationship between such effects and the actual consumption of the target items. PROTOCOL REGISTRATION: The stage 1 protocol for this Registered Report was accepted in principle on 30/03/2021. The protocol, as accepted by the journal, can be found at: https://doi.org/10.17605/OSF.IO/5ESMP .

Effects of drug and hazardous alcohol use on having a detectable HIV viral load: An adherence mediation analysis

Objectives

People living with HIV (PWH) with substance or alcohol use often have unsuppressed plasma HIV viral loads (pVL). The degree to which substance and alcohol use effects on HIV viral suppression are mediated through medication nonadherence is incompletely understood.

Methods

We included PWH prescribed antiretroviral therapy and receiving care at an academic HIV clinic between 2014 and 2018 who completed both patient-reported outcomes (PRO) questionnaires and had subsequent pVL measurements. Measures included assessments of alcohol use (AUDIT-C), drug use (NIDA-ASSIST), and self-reported adherence measured using four different methods. Substances found in bivariate analysis to predict detectable pVL were modeled separately for mediation effects through adherence. We report natural direct (NDE) and indirect effect (NIE), marginal total effect (MTE), and percentage mediated.

Results

Among 3125 PWH who met eligibility criteria, 25.8% reported hazardous alcohol use, 27.1% cannabis, 13.1% amphetamines, 1.9% inhalants, 5.3% cocaine, 4.5% sedative-hypnotics, 2.9% opioids, and 2.3% hallucinogens. Excellent adherence was reported by 58% of PWH, and 10% had detectable pVL. Except for sedatives, using other substances was significantly associated with worse adherence. Bivariate predictors of detectable pVL were [OR (95% CI)]: amphetamine use 2.4 (1.8-3.2) and opioid use 2.3 (1.3-4.0). The percent of marginal total effect mediated by nonadherence varied by substance: 36% for amphetamine use, 27% for opioid use, and 39% for polysubstance use.

Conclusion

Use of amphetamines, opioids, and multiple substances predicted detectable pVL. Up to 40% of their effects were mediated by self-reported nonadherence. Confirmation using longitudinal measurement models will strengthen causal inference from this cross-sectional analysis.

Investing to gain others' trust: Cognitive abstraction increases prosocial behavior and trust received from others

Being trusted has many positive implications for one's wellbeing (e.g., a better career, more satisfying interpersonal relationships). Scholars have suggested that people actively attempt to earn trust. However, it is not clear what makes people invest in actions that may earn them trust. We propose that cognitive abstraction (more than concreteness) facilitates seeing the long-term benefits of performing behaviors (i.e., prosocial behaviors) for gaining trust. We conducted a survey among employees and their supervisors and two yoked experiments-total N = 1098 or 549 pairs. In support of our claim, we find that cognitive abstraction leads to more prosocial behavior, which subsequently increases trust received. Furthermore, the effect of abstraction on the performance of prosocial behavior is limited to situations where such behavior can be observed by others (and thus be a basis for gaining observers' trust). Our research shows when and why people decide to act in ways that may gain them trust and clarifies how cognitive abstraction influences the display of prosocial behavior and the subsequent trust received from fellow organization members.

The mediating effect of achievement motivation on mindfulness and procrastination behavior of nursing students: A correlational study

Procrastination behavior is prevalent among nursing students in China. However, little research has examined how mindfulness is associated with procrastination behavior, via achievement motivation among nursing students. The aims of this study were to investigate the relationship between procrastination behavior, mindfulness and achievement motivation, and explore the mediating effect of achievement motivation on mindfulness and procrastination behavior of nursing students. A correlational cross-sectional study was performed using an online questionnaire. The study was conducted from January to March 2022 among 632 students from 1 university. A general information questionnaire, Achievement Motivation Scale, Five Facet Mindfulness Questionnaire and General Procrastination Scale (GPS) were used for investigation. Calculations were performed using SPSS Statistics, version 25. Descriptive statistics, correlation, and process plug-in mediation effect analyses were used to analyze the data. A total of 640 questionnaires were issued and 632 valid questionnaires were finally recovered, with an effective recovery rate of 98.75%. The GPS score of 632 nursing undergraduates was (55.80 ± 6.57), achievement motivation scale score was (-2.49 ± 8.73), Five Facet Mindfulness Questionnaire score was (118.21 ± 18.39). Achievement motivation and psychological capital were all negatively correlated with procrastination behavior (r = -0.291, -0.483; P < .01). Achievement motivation played a partial mediating role between mindfulness and procrastination behavior, and the mediating effect accounted for 59.82% of the total effect. The procrastination behavior of nursing undergraduates is at the middle level. Mindfulness can influence procrastination behavior through achievement motivation. Measures are needed to decrease the procrastination behavior by developing mindfulness programs to increase their achievement motivation.

The role of mothers' involvement in their daughters' self-esteem and dieting behaviors

This study presents an initial effort to develop disordered eating pathology (DEP) prevention program with an emphasis on maternal involvement. Disordered eating pathology representing a range of behaviors and attitudes, from negative body image to full-blown eating disorder. It appears mainly in adolescent females and related to psychological and familial factors, including maternal modeling of thinness. A sample of 118 Israeli girls (11-12) was divided into three groups: participants in the program in parallel with their mothers, participants without their mothers, and control. Participants completed self-report questionnaires. Groups were tested three times: pre-intervention, post-intervention, and follow-up. For those girls who participated in parallel with their mothers, higher self-esteem was associated with fewer pathological diet behaviors. Findings deepen understanding of the risk factors involved in the development of DEP. The main study contribution is the important role mothers play in preventing DEP among their daughters.

The mediating effect of mindfulness on demoralization syndrome and quality of life of thyroid cancer patients: A correlational study

Demoralization syndrome is prevalence among cancer patients in China. However, little research has examined how demoralization syndrome is associated with quality of life (QOL). The aims of this study were to investigate the relationship between mindfulness state, demoralization syndrome and QOL of thyroid cancer patients, and explore the mediating effect of mindfulness on demoralization syndrome and QOL. A correlational cross-sectional study was performed using an online questionnaire. The study was conducted from July to October 2022 among 310 thyroid cancer patients. General information questionnaire, the Demoralization Scale, Five Facet Mindfulness Questionnaire, short form health survey questionnaire were used for investigation. Calculations were performed using SPSS Statistics, version 25. Descriptive statistics, correlation, and process plug-in mediation effect analyses were used to analyze the data. A total of 310 valid questionnaires were finally recovered. The Five Facet Mindfulness Questionnaire score of 310 patients was (120.80 ± 16.57), Demoralization Scale score was (12.49 ± 4.73), short form health survey questionnaire score was (146.15 ± 28.46). Mindfulness played a partial mediating role between demoralization syndrome and QOL of thyroid cancer patients, and the mediating effect accounted for 68.57% of the total effect. Demoralization syndrome can influence QOL through mindfulness state. Measures are needed to increase the QOL of thyroid cancer patients by developing mindfulness programs to decrease their demoralization syndrome.

Contribution of intraoperative electroencephalogram suppression to frailty-associated postoperative delirium: mediation analysis of a prospective surgical cohort

BACKGROUND

Frailty is a risk factor for postoperative delirium (POD), and has led to preoperative interventions that have reduced, but not eliminated, the risk. We hypothesised that EEG suppression, another risk factor for POD, mediates some of the frailty risk for POD.

METHODS

A prospective cohort study enrolled patients aged 65 yr or older, scheduled for noncardiac surgery under total intravenous anaesthesia. Frailty was assessed using the FRAIL scale. Cumulative duration of EEG suppression, defined as an amplitude between -5 and 5 μV for >0.5 s during anaesthesia, was measured. POD was diagnosed by either confusion assessment method (CAM), CAM-ICU, or medical records. The severity of POD was assessed using the Delirium Rating Scale - Revised-98 (DRS). Mediation analysis was used to estimate the relationships between frailty, EEG suppression, and severity of POD.

RESULTS

Among 252 enrolled patients, 51 were robust, 129 were prefrail, and 72 were frail. Patients classified as frail had higher duration of EEG suppression than either the robust (19 vs 0.57 s, P<0.001) or prefrail groups (19 vs 3.22 s, P<0.001). Peak delirium score was higher in the frail group than either the robust (17 vs 15, P<0.001) or prefrail groups (17 vs 16, P=0.007). EEG suppression time mediated 24.2% of the frailty-DRS scores association.

CONCLUSION

EEG suppression time mediated a statistically significant portion of the frailty-POD association in older noncardiac surgery patients. Trials directed at reducing EEG suppression time could result in intraoperative interventions to reduce POD in frail patients.

CLINICAL TRIAL REGISTRATION

ChiCTR2000041092 (Chinese Clinical Trial Registry).

Effect of acute pain on the association between preoperative cognitive impairment and postoperative delirium: a secondary analysis of three trials

BACKGROUND

The association between preoperative cognitive impairment, postoperative pain, and postoperative delirium in older patients after noncardiac surgery is not known.

METHODS

This was a secondary analysis of datasets from three previous studies. Patients aged ≥55 yr who underwent elective noncardiac surgery were enrolled. Preoperative cognitive impairment was defined as Mini-Mental State Examination <27. Pain intensity with movement was assessed using an 11-point numeric rating scale at 12-h intervals during the first 72 h after surgery; time-weighted average (TWA) pain score was calculated. Primary outcome was the occurrence of delirium within the first 5 postoperative days. Mediation analysis was used to investigate the relationships between cognitive impairment, pain score, and delirium.

RESULTS

A total of 1497 patients were included. Prevalence of preoperative cognitive impairment was 40.3% (603/1497). Patients with cognitive impairment suffered higher TWA pain score within 72 h (4 [3-5] vs 3 [2-5], P=0.004) and more delirium within 5 days (12.9% [78/603] vs 4.9% [44/894], P<0.001) when compared with those without. Total and direct associations between cognitive impairment and delirium were (adjusted β) 8.3% (95% confidence interval [CI], 4.8-12.0%; P<0.001) and 7.8% (95% CI, 4.4-12.0%; P<0.001), respectively. A significant indirect association with acute pain was observed between cognitive impairment and delirium (adjusted β=0.4%; 95% CI, 0.1-1.0%; P=0.006), accounting for 4.9% of the total effect.

CONCLUSIONS

The association between preoperative cognitive impairment and delirium is significantly mediated by acute pain in patients after noncardiac surgery. Considering the small effect size, clinical significance of this mediation effect requires further investigation.

AIM2ACT: Randomized controlled trial protocol for a mobile health intervention for early adolescents with asthma

Early adolescents diagnosed with asthma have difficulties consistently performing disease self-management behaviors, placing them at-risk for poor asthma control, morbidity, and reduced quality of life. Helpful caregiver support is pivotal in determining whether early adolescents develop and master asthma self-management behaviors. We developed Applying Interactive Mobile health to Asthma Care in Teens (AIM2ACT), a mobile health intervention to facilitate helpful caregiver support in early adolescents (12-15 year-olds) with poorly controlled asthma. AIM2ACT is a dyadic smartphone intervention that contains three components: 1) ecological momentary assessment to identify personalized strengths and weaknesses in asthma self-management behaviors; 2) collaborative identification and tracking of goals that help early adolescents to become increasingly independent in managing their asthma; and 3) a suite of skills training videos. This paper describes our plans to test the efficacy of AIM2ACT and evaluate long-term maintenance of treatment effects in a fully powered randomized controlled trial with 160 early adolescents with poorly controlled persistent asthma, ages 12-15 years, and a caregiver. Families will be randomly assigned to receive AIM2ACT (n = 80) or a mHealth attention control condition (n = 80) that accounts for attention and novelty of a technology-based intervention for 6 months. Assessments will occur at baseline, post-intervention, and 3-, 6-, and 12-month follow-up time points. We will collect patient-reported and objectively monitored (e.g., spirometry, adherence) outcomes. Given the timing of the trial, a secondary exploratory goal is to evaluate the perceived impact of COVID-19 on family functioning and parental control of their adolescent's asthma in the context of our intervention.

Risky Early Family Environment and Genetic Associations with Adult Metabolic Dysregulation

Growing up in a family environment characterized by neglectful parenting, overt conflict, and unsupportive relationships is associated with poor health in adulthood. A risky early family environment may also be associated with obesity in adulthood, likely through the activation of the HPA axis. Likewise, the GABAergic (gamma-aminobutyric acid) T>C single nucleotide polymorphism in the 1519 nucleotide position of the GABAAα6 receptor subunit gene has been associated with a predisposition to a higher body mass index and a larger waist circumference. Participants (n = 213, Mage = 30.13 years, SD = 10.85; 57.7% men) from the Pittsburgh Cold Study 3 completed a demographic questionnaire, the Risky Families Questionnaire (RFQ) and had their height, weight, and waist circumference measured during a physical exam. Participant DNA was recovered from buccal swabs and genotyped for the various allelic types of the SNP according to published protocols. In secondary data analyses, we tested the hypothesis that early family environment and GABRA6 would be positively associated with body mass index and waist circumference. We also examined diurnal cortisol as a mechanism linking both early risky family environment and GABRA6 to metabolic outcomes. The findings provide evidence that a risky early family environment may exert more influence than genetic predisposition when determining the indices of metabolic health in adulthood.

The effect of combat exposure on sexually transmitted diseases

Traumatic exposures can affect beliefs and behaviors related to the spread of sexually transmitted diseases (STDs), a persistent public health problem. I leverage a natural experiment created by variation in US military deployment location assignments to estimate how combat exposure changes a surviving deployed male veteran's probability of acquiring a sexually transmitted disease. I analyze longitudinal data from 1994 to 2008 on 485 deployed veterans with information theoretic methods to reduce the sensitivity of estimates to small samples, an infrequently observed outcome, and highly correlated covariates. For veterans assigned to a combat zone, I estimate combat exposure results in a 5.4 percentage point increase in the probability of acquiring an STD. Additional estimations provide evidence suggesting risky behaviors involving substance use or multiple sexual partners may serve as pathways from combat exposure to STDs. My results are relevant to discussions regarding STD screening and care needs for trauma exposed individuals.

Relationship with the Father of the Baby and Pregnancy-Related Anxiety among Pregnant Black Women

PURPOSE

Pregnancy-related anxiety may increase the risk of preterm birth. Effective coping strategies and social support may help minimize pregnancy-related anxiety.

STUDY DESIGN

Secondary analysis of cross-sectional data.

METHODS

A sample of 408 pregnant non-Hispanic Black women completed questionnaires between 19 and 31 weeks gestation. Mediation analysis with structural equation modeling was used to explore effects of the relationship with the father of the baby on pregnancy-related anxiety.

RESULTS

Support from the father of the baby was negatively associated with avoidance coping ( r = -.22, p < .001) and pregnancy-related anxiety ( r = - .17, p < .001), whereas conflict with the father of the baby was positively associated with avoidance coping ( r = .37, p < .001) and pregnancy-related anxiety ( r = .29, p < .001). Avoidance coping was positively associated with pregnancy-related anxiety ( r = .34, p < .001). After adjustment, avoidance coping partially mediated the effect of conflict with the father of the baby on pregnancy-related anxiety.

CLINICAL IMPLICATIONS

Discussions with women about management of pregnancy-related anxiety should consider her current social support and coping mechanisms. Providers should offer support and resources on adaptive coping strategies.

Using the multiphase optimization strategy (MOST) framework to optimize an intervention to increase COVID-19 testing for Black and Latino/Hispanic frontline essential workers: A study protocol

BACKGROUND

Among those at highest risk for COVID-19 exposure is the large population of frontline essential workers in occupations such food service, retail, personal care, and in-home health services, among whom Black and Latino/Hispanic persons are over-represented. For those not vaccinated and at risk for exposure to COVID-19, including frontline essential workers, regular (approximately weekly) COVID-19 testing is recommended. However, Black and Latino/Hispanic frontline essential workers in these occupations experience serious impediments to COVID-19 testing at individual/attitudinal- (e.g., lack of knowledge of guidelines), social- (e.g., social norms), and structural-levels of influence (e.g., poor access), and rates of testing for COVID-19 are insufficient.

METHODS/DESIGN

The proposed community-engaged study uses the multiphase optimization strategy (MOST) framework and an efficient factorial design to test four candidate behavioral intervention components informed by an integrated conceptual model that combines critical race theory, harm reduction, and self-determination theory. They are A) motivational interview counseling, B) text messaging grounded in behavioral economics, C) peer education, and D) access to testing (via navigation to an appointment vs. a self-test kit). All participants receive health education on COVID-19. The specific aims are to: identify which components contribute meaningfully to improvement in the primary outcome, COVID-19 testing confirmed with documentary evidence, with the most effective combination of components comprising an "optimized" intervention that strategically balances effectiveness against affordability, scalability, and efficiency (Aim 1); identify mediators and moderators of the effects of components (Aim 2); and use a mixed-methods approach to explore relationships among COVID-19 testing and vaccination (Aim 3). Participants will be N = 448 Black and Latino/Hispanic frontline essential workers not tested for COVID-19 in the past six months and not fully vaccinated for COVID-19, randomly assigned to one of 16 intervention conditions, and assessed at 6- and 12-weeks post-baseline. Last, N = 50 participants will engage in qualitative in-depth interviews.

DISCUSSION

This optimization trial is designed to yield an effective, affordable, and efficient behavioral intervention that can be rapidly scaled in community settings. Further, it will advance the literature on intervention approaches for social inequities such as those evident in the COVID-19 pandemic.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT05139927 ; Registered on 11/29/2021. Protocol version 1.0. May 2, 2022, Version 1.0.

Vocabulary knowledge and reading comprehension account for SES-differences in how school-aged children infer word meanings from sentences

Socioeconomic status (SES)-related language gaps are known to widen throughout the course of the school years; however, not all children from lower SES homes perform worse than their higher SES peers on measures of language. The current study uses mediation and moderated mediation to examine how cognitive and language abilities (vocabulary, reading, phonological processing, working memory) account for individual differences in a children's ability to infer a novel word's meaning, a key component in word learning, in school-aged children from varying SES backgrounds. Vocabulary and reading comprehension mediated the relationship between SES and accuracy when inferring word meanings. The relationship between SES, vocabulary, and inferring word meaning was moderated by age, such that the influence of vocabulary on task performance was strongest in young children. The reading pathway did not interact with age effects, indicating reading is an important contributor to SES-related differences in how children infer a word's meaning throughout grade school. These findings highlight different paths by which children's trajectories for inferring word meanings may be impacted.

Impacts of two behavior change interventions on determinants of medication adherence: process evaluation applying the health action process approach and habit theory alongside a randomized controlled trial

Investigating the mechanisms of behavior change interventions provides a more fulsome understanding of how and why interventions work (or don't work). We assessed mechanisms of two interventions (mailouts alone, and mailouts plus telephone support, informed by the Health Action Process Approach (HAPA) and Habit Theory), designed to increase medication adherence after myocardial infarction. We conducted a process evaluation alongside a pragmatic trial. Medication adherence was assessed via self-report at 12-months in the trial, and participants in all trial groups were invited to contemporaneously complete an additional questionnaire assessing targeted mechanisms (HAPA constructs and automaticity). We used multiple regression-based mediation models to investigate indirect effects. Of 589 respondents, 497 were analyzed (92 excluded due to missing data). Mailouts plus telephone support had statistically significant but small effects on intention, social support, action planning, coping planning, and automaticity. There were no indirect effects of interventions on medication adherence via these constructs. Therefore, while this intervention led to changes in proposed mechanisms, these changes were not great enough to lead to behavior change. Refinements (and subsequent evaluation) of the interventions are warranted, and our findings indicate that this could involve offering more intensive support to form plans and identify cues for taking medications, in addition to providing physical supports to encourage self-monitoring, feedback, and habit formation. Trial registration: ClinicalTrials.gov: NCT02382731.

Mobile Subthreshold Exercise Program (MSTEP) for concussion: study protocol for a randomized controlled trial

BACKGROUND

Subthreshold exercise, defined as aerobic exercise below the level that causes symptoms, has been utilized as a treatment for youth with persistent postconcussive symptoms (PPCS), but there is currently little evidence to guide use. In addition, prior studies of exercise for PPCS have all required multiple in-person visits. We developed a virtual approach for delivering subthreshold exercise to youth with PPCS called the Mobile Subthreshold Exercise Program (MSTEP), and we have now been funded to conduct a large national randomized controlled trial (RCT) to test its efficacy for reducing concussive symptoms and improving health-related quality of life.

METHODS

This investigation is an RCT comparing MSTEP to an active control. We will recruit 200 adolescents 11-18 years old with postconcussive symptoms persisting for at least 1 week but less than 1 year. Youth will be randomized to receive either 6 weeks of subthreshold exercise (MSTEP) or a stretching condition (control). Youth and parents will complete surveys of concussive symptoms at baseline, weekly during the intervention, and at 3 and 6 months. The primary outcomes will be trajectory of concussive symptoms and health-related quality of life over the 6 months of the study. Secondary outcomes will include depression, anxiety, and sleep quality. We will also assess potential mediators of treatment effects including moderate-vigorous physical activity and fear avoidance of concussive symptoms.

DISCUSSION

This multisite RCT of MSTEP will provide vital information regarding the efficacy of a virtually delivered subthreshold exercise program for youth with PPCS, and insight regarding potential mediators of treatment effects, including objectively measured physical activity and fear avoidance of concussive symptoms.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04688255. Registered on December 29, 2020.

Shortened Infant Telomere Length Is Associated with Attention Deficit/Hyperactivity Disorder Symptoms in Children at Age Two Years: A Birth Cohort Study

Environmental factors can accelerate telomere length (TL) attrition. Shortened TL is linked to attention deficit/hyperactivity disorder (ADHD) symptoms in school-aged children. The onset of ADHD occurs as early as preschool-age, but the TL-ADHD association in younger children is unknown. We investigated associations between infant TL and ADHD symptoms in children and assessed environmental factors as potential confounders and/or mediators of this association. Relative TL was measured by quantitative polymerase chain reaction in cord and 12-month blood in the birth cohort study, the Barwon Infant Study. Early life environmental factors collected antenatally to two years were used to measure confounding. ADHD symptoms at age two years were evaluated by the Child Behavior Checklist Attention Problems (AP) and the Attention Deficit/Hyperactivity Problems (ADHP). Associations between early life environmental factors on TL or ADHD symptoms were assessed using multivariable regression models adjusted for relevant factors. Telomere length at 12 months (TL12), but not at birth, was inversely associated with AP (β = −0.56; 95% CI (−1.13, 0.006); p = 0.05) and ADHP (β = −0.66; 95% CI (−1.11, −0.21); p = 0.004). Infant secondhand smoke exposure at one month was independently associated with shorter TL12 and also higher ADHD symptoms. Further work is needed to elucidate the mechanisms that influence TL attrition and early neurodevelopment.

A principled approach to mediation analysis in perinatal epidemiology

For many research questions in perinatal epidemiology, gestational age is a mediator that features the causal pathway between exposure and outcome. A mediator is an intermediate variable between an exposure and outcome, which is influenced by the exposure on the causal pathway to the outcome. Therefore, conventional analyses that adjust, stratify, or match for gestational age or its proxy (eg, preterm vs term deliveries) are problematic. This practice, which is entrenched in perinatal research, induces an overadjustment bias. Depending on the causal question, it may be inappropriate to adjust (or condition) for a mediator, such as gestational age, by either design or statistical analysis, but its effect can be quantified through causal mediation analysis. In an exposition of such methods, we demonstrated the relationship between the exposure and outcome and provided a formal analytical framework to quantify the extent to which a causal effect is influenced by a mediator. We reviewed concepts of confounding and causal inference, introduced the concept of a mediator and illustrated the perils of adjusting for a mediator in an exposure-outcome paradigm for a given causal question, adopted causal methods that call for an evaluation of a mediator in a causal exposure effect on the outcome, and discussed unmeasured confounding assumptions in mediation analysis. Furthermore, we reviewed other developments in the causal mediation analysis literature, including decomposition of a total effect when the mediator interacts with the exposure (4-way decomposition), methods for multiple mediators, mediation methods for case-control studies, mediation methods for time-to-event outcomes, sample size and power analysis for mediation analysis, and available software to apply these methods. To illustrate these methods, we provided a clinical example to estimate the risk of perinatal mortality (outcome) concerning placental abruption (exposure) and to determine the extent to which preterm delivery (mediator; a proxy for gestational age) plays a role in this causal effect. We hoped that the adoption of mediation methods described in this review will move research in perinatal epidemiology away from biased adjustments of mediators toward a more nuanced quantification of effects that pose unique challenges and provide unique insights in our field.

Aerobic exercise in older people with subclinical sporadic cerebral small vessel disease: A randomized clinical trial

INTRODUCTION

The benefit and risk of aerobic exercise among older people harboring advanced cerebral small vessel disease (CSVD) upon cognition, mood, and motor functions are unknown.

METHODS

This rater-blind randomized trial examined effects of a 24-week aerobic exercise training (60 min/session, twice/week) upon clinical (cognition, mood, motor functions) and hemodynamic (pulse pressure [PP], blood pressure [BP], pulsatility index) measures in older people harboring moderate to severe CSVD, as evidenced by confluent white matter hyperintensity and/or ≥2 lacunes on magnetic resonance imaging. We further investigated interactions between treatment conditions and hemodynamics measures.

RESULTS

Fifty-three and 54 subjects were randomized into the active and control group, respectively. There was no between-group difference in any of the clinical outcomes. The active group had a greater between-group reduction in systolic BP and PP than the control group. Within-group comparison showed that global cognition of the active group remained similar at end of the study compared to baseline, whereas it declined significantly in the control group. We observed "diverging" interaction effects in that greater reduction in systolic BP/PP was associated with greater improvement in memory functions and global cognition but worsening in processing speed in the active group. Side effects were comparable between the two groups.

DISCUSSION

Future study should investigate the mechanisms of the diverging impacts of aerobic exercise upon different cognitive domains so that the benefit-risk ratio of aerobic exercise in older people harboring more advanced CSVD can be better defined.

The role of body mass index in the association between dietary sodium intake and blood pressure: A mediation analysis with NHANES

BACKGROUND AND AIMS

Recent research demonstrated that obesity and high dietary sodium intake, the two established risk factors for hypertension, were associated with each other. The objective was to investigate the potential indirect effect of sodium intake on blood pressure via body mass index (BMI).

METHODS AND RESULTS

Using ten years data from US NHANES (2007-2016), the study included adult participants (>20 years old) who were not taking antihypertensive medications and without baseline diseases (n = 12,262). BMI was modelled as the mediator of sodium intake on systolic and diastolic blood pressure, adjusted for age, sex, socioeconomic status, smoking, drinking, physical activity, calorie intake, fluid intake and potassium intake. Mediation analysis was performed to evaluate total effect, direct effect and indirect effect via BMI. Subgroup analyses based on three age subgroups (20-40, 41-60 and ≥61 years old) were performed. The mean age was 39.29 (13.4) years and 53.1 (0.45) % were males. The mean BMI was 27.8 (6.20) kg/m². Overall, 1 g/d increase in sodium intake was associated with an increased systolic blood pressure by 0.36 (95% confidence interval 0.14 to 0.58) mmHg, with a direct effect (0.14 (0.09-0.19)) and an indirect effect via BMI (0.23 (0.02-0.44)). The indirect effect was mainly observed in participants ≤60 years old.

CONCLUSION

Sodium intake showed both direct effect and indirect effect (via BMI) on systolic blood pressure in US NHANES. The findings provide evidence for combining sodium restriction and weight reduction measures for prevention of hypertension. Cautions should be taken when generalizing the findings to other populations with lower average BMI.

An Intervention by and for Transgender Women Living With HIV: Study Protocol for a Two-Arm Randomized Controlled Trial Testing the Efficacy of “Healthy Divas” to Improve HIV Care Outcomes

Introduction: Transgender women (assigned “male” at birth but who do not identify as male) are disproportionately impacted by HIV and experience unique barriers and facilitators to HIV care engagement. In formative work, we identified culturally specific and modifiable barriers to HIV treatment engagement among transgender women living with HIV (TWH), including prioritizing transition-related healthcare over HIV treatment, avoiding HIV care settings due to gender-related and HIV stigma, concerns about potential drug interactions with hormones, and inadequate social support. Grounded in the investigators' Models of Gender Affirmation and Health Care Empowerment, we developed the Healthy Divas intervention to optimize engagement in HIV care among TWH at risk for treatment failure and consequential morbidity, mortality, and onward transmission of HIV.

Methods and Analysis: We conducted a 2-arm randomized controlled trial (RCT) of the intervention's efficacy in Los Angeles and San Francisco to improve engagement in care among TWH (N = 278). The primary outcome was virologic control indicated by undetectable HIV-1 level (undetectability = < 20 copies/mL), at baseline and follow-up assessment for 12 months at 3-month intervals.

Ethics and Dissemination: This study was approved by University of California, San Francisco Institutional Review Board (15-17910) and Western Institutional Review Board (20181370). Participants provided informed consent before enrolment in the study. We are committed to collaboration with National Institutes of Health officials, other researchers, and health and social services communities for rapid dissemination of data and sharing of materials. The results will be published in peer-reviewed academic journals and scientific presentations. We will make our results available to researchers interested in transgender health to avoid unintentional duplication of research, as well as to others in health and social services communities, including HIV clinics, LGBT community-based organizations, and AIDS service organizations.

Clinical Trial Registration:Clinicaltrials.gov, identifier NCT03081559.

Modifying food items valuation and weight with gamified executive control training

Recent lines of research suggest that repeated executive control of motor responses to food items modifies their perceived value and in turn their consumption. Cognitive interventions involving the practice of motor control and attentional tasks have thus been advanced as potential approach to improve eating habits. Yet, their efficacy remains debated, notably due to a lack of proper control for the effects of expectations. We examined whether a one-month intervention combining the practice of Go/NoGo and Cue approach training modified the perceived palatability of food items (i.e. decrease in unhealthy and increase in healthy food items' palatability ratings), and in turn participants' weights. We assessed our hypotheses with a parallel, double-blind, randomized controlled trial. Motivation and adherence to the intervention were maximized by a professional-level gamification of the training tasks. The control intervention differed from the experimental intervention only in the biasing of the stimulus-response mapping rules, enabling to balance expectations between the two groups and thus to conclude on the causal influence of motoric control on items valuation. We found a larger decrease of the unhealthy items' palatability ratings in the experimental (20.6%) than control group (13.1%). However, we did not find any increase of the healthy items' ratings or weight loss. Overall, the present registered report confirms that the repeated inhibition of motor responses to food cues, together with the development of attentional biases away from these cues, reduces their perceived value.

The association of childhood trauma with sleep disturbances and risk of suicide in US veterans

BACKGROUND

Sleep dysregulation is prevalent among veterans and is associated with increased risk of suicidal ideation and behaviors. A confluence of risk factors have been identified to date that contribute to increase risk for suicidal behavior. How these risk factors including childhood trauma, comorbid psychopathology, impulsivity, and hostility together with sleep disturbance contribute to suicide risk remains an open question. These factors have never been examined simultaneously in a unified mediation model, as investigated in the present study, to determine their relative contribution to suicide risk.

METHODS

Veterans (N = 105) were recruited across 3-groups, including Major Depressive Disorder (MDD) with/without a history of a suicide attempt (n = 35 and n = 37, respectively), and non-psychiatric controls, who had no history of mental illness or suicidal behavior (n = 33). The participants were assessed using validated self-report assessments with in-depth phenotyping for relevant risk factors associated with suicidal behavior including childhood adversity, depression severity, impulsivity, hostility, and sleep quality. These factors were included in mediation models using path analysis.

RESULTS

Across all subjects including those with MDD and non-psychiatric controls, mediation analysis showed that higher levels of childhood trauma had an indirect effect on poor sleep quality (p = 0.001). This effect was orthogonal, being independently mediated by both MDD psychopathology (p = 0.003), and higher traits of impulsivity (p = 0.001) and hostility (p = 0.015). Amongst MDD veterans, childhood trauma was directly associated with increased suicide risk (p = 0.034), irrespective of their severity of depression, or their degree of hostility and impulsivity.

LIMITATIONS

include use of self-report data, and the inability to establish causal inferences with cross-sectional design.

CONCLUSION

Childhood adversity as a significant pre-deployment risk factor for disturbed sleep and elevated suicide risk, potentially important for incorporation in clinical practice for suicide.

Study of emotional distress in a comparative effectiveness trial of diabetes treatments: Rationale and design

Emotional distress, including depression and diabetes-specific distress (e.g., feeling overwhelmed by living with diabetes, feelings of failure related to diabetes self-care), is a significant and prevalent problem for patients with type 2 diabetes. Both depression and diabetes distress have been associated with metabolic/glycemic control, diabetes complications, mortality, and quality of life. Recent findings further suggest that risk for emotional distress is influenced by diabetes treatment. The GRADE Study (Glycemia Reduction Approaches in Diabetes: A Comparative Effectiveness Study) is generating prospective data that will provide a unique opportunity to examine the relationships between emotional distress, diabetes treatment, and outcomes in an experimental design. The GRADE study is a randomized clinical trial that will compare the metabolic effects of four common anti-hyperglycemic drugs when combined with metformin. This sub-study recruited a subset (n = 1739) of GRADE participants and will examine patient-level variation in baseline emotional distress as a predictor of glycemic control and other health outcomes, independent of treatment effects. The study will also provide an experimental examination of treatment regimen effects on emotional distress over time as part of the overall evaluation of comparative effectiveness. Evaluation of emotional distress using validated measures will allow us to disentangle the roles of depressive symptoms and diabetes distress, factors that share significant overlap but require distinct approaches to screening and treatment. Study findings may directly influence practice decisions regarding screening and treatment for emotional distress as part of diabetes care. ClinicalTrials.gov Identifier: NCT01794143.

Invited Commentary: Frontiers of Power Assessment in Mediation Analysis

The development of tools for power and sample-size calculations for mediation analysis has lagged far behind the development of methods. The accompanying paper by Rudolph et al. (Am J Epidemiol. 2020;189(12):1559-1567) is a helpful contribution in using simulations as a tool for power calculations for more complex methods and settings. Much work remains to be done in the development of easy-to-use packages and simple online websites for carrying out power and sample-size calculations for mediation analysis. Much remains to be learned with respect to the relative power of different methods in different settings. There will likely be feedback between these 2 important frontiers of the tools we have available and of our understanding of power when conducting mediation analysis.

The Peril of Power: A Tutorial on Using Simulation to Better Understand When and How We Can Estimate Mediating Effects

Mediation analyses are valuable for examining mechanisms underlying an association, investigating possible explanations for nonintuitive results, or identifying interventions that can improve health in the context of nonmanipulable exposures. However, designing a study for the purpose of answering a mediation-related research question remains challenging because sample size and power calculations for mediation analyses are typically not conducted or are crude approximations. Consequently, many studies are probably conducted without first establishing that they have the statistical power required to detect a meaningful effect, potentially resulting in wasted resources. In an effort to advance more accurate power calculations for estimating direct and indirect effects, we present a tutorial demonstrating how to conduct a flexible, simulation-based power analysis. In this tutorial, we compare power to estimate direct and indirect effects across various estimators (the Baron and Kenny estimator (J Pers Soc Psychol. 1986;51(6):1173-1182), inverse odds ratio weighting, and targeted maximum likelihood estimation) using various data structures designed to mimic important features of real data. We include step-by-step commented R code (R Foundation for Statistical Computing, Vienna, Austria) in an effort to lower implementation barriers to ultimately improving power assessment in mediation studies.

Do Gestational Obesity and Gestational Diabetes Have an Independent Effect on Neonatal Adiposity? Results of Mediation Analysis from a Cohort Study in South India

Purpose

Neonates born to mothers with obesity or gestational diabetes mellitus (GDM) have an increased chance of various metabolic disorders later in life. In India, it is unclear whether maternal obesity or GDM is related to offspring adiposity. We aimed to understand the independent effect of maternal obesity and GDM with neonatal adiposity and whether GDM has a mediating effect between maternal obesity and neonatal adiposity.

Methods

We recruited a cohort of 1120 women (between April 2016 and February 2019) from the public hospitals in Bangalore, India, who voluntarily agreed to participate and provided written informed consent. The primary outcome was neonatal adiposity, defined as the sum of skinfold thickness >85^th percentile. Exposure included maternal obesity, defined as >90^th percentile of skinfold thickness. GDM, the potential mediator, was classified using the World Health Organization criteria by oral glucose tolerance test. Binary logistic regression was applied to test the effect of maternal obesity and GDM on neonatal adiposity, adjusting for potential confounders. We used Paramed command in STATA version 14 for analyzing mediating effects.

Results

We found that maternal obesity (odds ratio (OR)=2.16, 95% CI 1.46, 3.18) and GDM (OR=2.21, 95% CI1.38, 3.52) have an independent effect on neonatal adiposity. GDM significantly mediates 25.2% of the total effect between maternal obesity and neonatal adiposity, (natural direct effect OR = 1.16 95% CI 1.04, 1.30) with significant direct effect of maternal obesity (natural direct effect OR = 1.90 95% CI 1.16, 3.10) and significant total effect (OR=2.20 95% CI 1.35, 3.58).

Conclusion

We showed that maternal obesity and GDM are independently associated with offspring adiposity. Also, GDM mediates the association of maternal obesity on adiposity in children. Interventions focused on obesity prevention in women, and effective screening and management of GDM may contribute to reducing childhood obesity in India.

Association of Psychache and Alexithymia With Suicide in Patients With Schizophrenia

Suicide is a leading cause of death in patients with schizophrenia. Previous studies have mostly investigated the association between suicide and sociodemographics, positive and negative symptoms, and depressive symptoms. This study evaluated psychache and alexithymia in patients with schizophrenia, which have both been associated with suicide attempts and thoughts in patients with other psychiatric disorders. Positive and Negative Syndrome Scale (PANSS), Psychache Scale (PAS), Beck Scale for Suicidal Ideation (BSSI), Calgary Depression Scale for Schizophrenia (CDSS), and Toronto Alexithymia Scale (TAS) scores were obtained in 113 patients with schizophrenia, including 50 with suicide attempts. PANSS positive symptoms and general psychopathology subscale, CDSS, BSSI, TAS, and PAS scores were significantly higher in patients with suicide attempts. In multivariate logistic regression analysis, only the PAS score was an independent predictor of attempted suicide. Mediation analysis demonstrated that psychache (both directly and indirectly) and alexithymia (indirectly) might be associated with the risk of suicide in these patients.

The role of weight gain in explaining the effects of antipsychotic drugs on positive and negative symptoms: An analysis of the CATIE schizophrenia trial

Second-generation antipsychotics are associated with moderate benefits in terms of improved schizophrenia symptoms, but also with higher rates of side-effects such as excessive weight gain (WG); a consensus on their efficacy has not been reached. To date, no study has evaluated the interplay of treatments and side-effects in a single framework, which is a critical step to clarify the role of side-effects in explaining the efficacy of these antipsychotics. We used recent methods for mediation and interaction to clarify the role of WG in explaining the effects of second-generation drugs on schizophrenia symptoms. We used data from 1460 participants in the CATIE trial, assigned to either perphenazine (first-generation comparison drug), olanzapine, quetiapine, risperidone, or ziprasidone. The primary outcome was an individual's score on the Positive and Negative Syndrome Scale (PANSS) for symptoms of schizophrenia after 9 months, separately evaluated as positive (PANSS+), negative (PANSS-), and total PANSS score. WG after 6 months was investigated as a potential mediator and effect modifier. Results showed that, by limiting WG, patients would benefit of a considerably better improvement in terms of PANSS symptoms. In the scenario of weight change being controlled between -2% and 1% for all participants, patients assigned to olanzapine would experience the highest significant improvements in both PANSS+ (-2.66 points; 95% CI: -4.98, -0.35), PANSS- (-1.59; 95% CI: -4.31, 1.14), and total PANSS (-6.11; 95% CI: -13.13, 0.92). In conclusion, occurrence of excessive WG hampers the potentially beneficial effects of second-generation antipsychotics, thus suggesting future directions for treatment and interventions.

Rationale and design for eHealth Familias Unidas Primary Care: A drug use, sexual risk behavior, and STI preventive intervention for hispanic youth in pediatric primary care clinics

Family-based behavioral interventions are efficacious and effective in preventing drug use and sexual risk behaviors; unfortunately, they have not been evaluated and disseminated in pediatric primary care practice, where they can have a significant impact. There is an increased focus on integrating parenting interventions into primary care to reduce health disparities among ethnic minorities such as Hispanics. Although Hispanic youth demonstrate higher levels of drug use and sexual risk behaviors than their non-Hispanic counterparts, few parenting interventions are available for Hispanic youth, and none have been delivered specifically to Hispanic adolescents in primary care. Therefore, this manuscript describes the rationale and design of an Internet-based, family-centered, Hispanic-specific, evidence-based prevention intervention, eHealth Familias Unidas Primary Care. Hispanic adolescents (n = 456) and their care givers will be recruited from pediatric primary care clinics in South Florida and randomized to: eHealth Familias Unidas Primary Care or prevention as usual. The intervention will be delivered by trained interns, clinic volunteers, social workers, mental health counselors, students, and nurses. Outcomes will be measured at baseline and 6, 12, 24, and 36 months post-baseline. This study will determine whether the intervention, compared to prevention as usual, is effective in reducing drug use, unprotected sex, and STI incidence in Hispanic youth through the improvement of family functioning. Additionally, we will determine the cost effectiveness of delivering eHealth Familias Unidas within primary care settings. The effectiveness of eHealth Familias Unidas Primary Care will further inform the need to integrate effective behavioral health interventions into primary care settings.

Mediation analysis with a time-to-event outcome: a review of use and reporting in healthcare research

BACKGROUND

Mediation analysis tests whether the relationship between two variables is explained by a third intermediate variable. We sought to describe the usage and reporting of mediation analysis with time-to-event outcomes in published healthcare research.

METHODS

A systematic search of Medline, Embase, and Web of Science was executed in December 2016 to identify applications of mediation analysis to healthcare research involving a clinically relevant time-to-event outcome. We summarized usage over time and reporting of important methodological characteristics.

RESULTS

We included 149 primary studies, published from 1997 to 2016. Most studies were published after 2011 (n = 110, 74%), and the annual number of studies nearly doubled in the last year (from n = 21 to n = 40). A traditional approach (causal steps or change in coefficient) was most commonly taken (n = 87, 58%), and the majority of studies (n = 114, 77%) used a Cox Proportional Hazards regression for the outcome. Few studies (n = 52, 35%) mentioned any of the assumptions or limitations fundamental to a causal interpretation of mediation analysis.

CONCLUSION

There is increasing use of mediation analysis with time-to-event outcomes. Current usage is limited by reliance on traditional methods and the Cox Proportional Hazards model, as well as low rates of reporting of underlying assumptions. There is a need for formal criteria to aid authors, reviewers, and readers reporting or appraising such studies.

The role of PANSS symptoms and adverse events in explaining the effects of paliperidone on social functioning: a causal mediation analysis approach

To date, no study has evaluated the joint role of symptoms and adverse events as mediators of the effect of second-generation antipsychotics on patients' social functioning. We used recently developed methods for mediation analysis with multiple mediators to clarify the interplay of adverse events and symptoms in explaining the effects of paliperidone (R code for implementing the mediation analysis for multiple mediators is provided). We used data from 490 participants in a 6-week randomized dose-response trial that assigned three fixed dosages of ER OROS paliperidone (3, 9, and 15 mg/day). The primary outcome was an individual's score on the social performance scale assessed after 6 weeks. The sum of Positive and Negative Syndrome Scale (PANSS), weight gain, and extrapyramidal symptoms measured via the Simpson-Angus Scale after 5 weeks were investigated as potential mediators and effect modifiers of treatment effects. Results from mediation analyses showed that the improvements in social functioning are partly explained by reduction in PANSS symptoms. Suggestive evidence that adverse events could play a role as mediators was found. In particular, weight gain displayed a non-linear relationship with social functioning, whereby beneficial effects observed at small levels of weight gain were reduced in the presence of excessive weight gain. In conclusion, we found that the short-term effects of paliperidone on social functioning were dependent on the successful reduction in PANSS symptoms and possibly the occurrence of excessive weight gain, thus suggesting future directions for treatment and interventions.

The VITamin D and OmegA-3 TriaL-Depression Endpoint Prevention (VITAL-DEP): Rationale and design of a large-scale ancillary study evaluating vitamin D and marine omega-3 fatty acid supplements for prevention of late-life depression

RATIONALE

Depression is a leading cause of disease burden and disability for older adults; thus, prevention is a priority. Biologic and observational data support potential mental health benefits of vitamin D and omega-3 fatty acids; however, it is unclear whether these supplements can prevent late-life depression.

DESIGN

We describe the novel methodology of a large-scale study: VITAL-DEP (VITamin D and OmegA-3 TriaL-Depression Endpoint Prevention), an ancillary to the VITAL trial. Primary Aims of VITAL-DEP are to determine effects on prevention of depression and on trajectory of mood symptoms of long-term (mean=5years) supplementation with vitamin D (vitamin D3 [cholecalciferol], 2000IU/day) and marine omega-3 fatty-acids (eicosapentaenoic acid + docosahexaenoic acid, 1g/day), in a 2×2 factorial design, among 25,874 older adults. Secondary Aims will evaluate: vitamin D's effects among African-Americans (an at-risk group for vitamin D deficiency); both agents' effects among those with high-risk factors or sub-syndromal depression in a sub-set of ~1000 participants with detailed examinations at baseline and 2-year follow-up; whether baseline nutrient levels influence depression risk and/or modify agents' effects. Additional planned analyses will use pre-randomization blood samples available in ~17,000 participants to address whether key biomarkers and factors influence long-term mood and depression risk and/or the agents' effects.

CONCLUSION

VITAL-DEP applies all modalities of state-of-the-art prevention research - universal, selective and indicated. VITAL-DEP will clarify effects of supplemental vitamin D and/or omega-3 on mood, and inform clinical care and public health guidelines on the use of these agents for prevention of depression in mid-life and older adults.

Are There Prognostic Factors for One-Year Outcome After Total Knee Arthroplasty? A Systematic Review

BACKGROUND

Preoperative factors predicting outcome for pain, physical function and quality of life after total knee arthroplasty (TKA) have not been clearly identified.

METHODS

Embase and MEDLINE were searched for relevant studies. A study was considered for inclusion if the study aimed to identify preoperative prognostic factors for pain, physical function, and/or quality of life after a follow-up period of at least 1 year; included at least 200 adults suffering from osteoarthritis and undergoing TKA; and analyzed data using multivariable modeling. The quality of the evidence per prognostic factor was determined using the Grading of Recommendations, Assessment, Development and Evaluation framework for prognosis studies.

RESULTS

A total of 18 studies were included. There is very low-quality evidence that preoperative more pain, presence of social support, absence of anxiety, and presence of more radiographic damage are prognostic factors for lower pain levels after TKA. There is very low-quality evidence that low preoperative physical function, less comorbidity, absence of anxiety, presence of social support, higher income, normal body mass index, and more radiographic damage are prognostic factors for better physical function. There is very low-quality evidence that female sex and less comorbidity are prognostic factors for better quality of life.

CONCLUSION

Only very low-quality evidence was found for a number of prognostic factors of long-term outcome after TKA. More studies that seek to generate understanding of the underlying process for the prognosis of outcome in TKA are needed to understand and test prognostic pathways, and it might be more valuable to look at recovery curves rather than at recovery points. Systematic review registration number: CRD42015026814.

Sample Size for Joint Testing of Indirect Effects

This paper presents methods to calculate sample size for evaluating mediation by joint testing of both links in an indirect pathway from exposure to mediator to outcome. Calculations rely on simulations of the underlying data structure, with testing of the two links performed under the simplifying assumption that the two test statistics are asymptotically independent. Simulations show that the proposed methods are accurate. Continuous and binary exposures and mediators, as well as continuous, binary, count, and survival outcomes are accommodated, along with over-dispersion of count outcomes, design effects, and confounding of the exposure-mediator and mediator-outcome relationships. An illustrative example is provided, and a documented R program implementing the calculations is available online.

Periodontal therapy and glycaemic control among individuals with type 2 diabetes: reflections from the PerioCardio study

OBJECTIVES

Diabetes mellitus and periodontal disease are highly prevalent among Indigenous Australian adults. Untreated periodontitis impacts glycaemic control in people with diabetes. The aim of this study was to report on the effect of periodontal therapy on glycaemic control among people with obesity.

METHODS

This subgroup analysis is limited to 62 participants with diabetes from the original 273 Aboriginal Australian adults enrolled into the PerioCardio study. Intervention participants received full-mouth non-surgical periodontal scaling during a single, untimed session while controls were untreated. Endpoints of interest included change in glycated haemoglobin (HbA1c), C-reactive protein (CRP) and periodontal status at 3 months post-intervention.

RESULTS

There were more females randomized to the treatment group (n = 17) than control (n = 10) while the control group had a higher overall body mass index (BMI) [mean (SD)] 33.1 (9.7 kg m^-2 ) versus 29.9 (6.0 kg m^-2 ). A greater proportion of males were followed up at 3 months compared to females, P = 0.05. Periodontal therapy did not significantly reduce HbA1c: ancova difference in means 0.22 mmol mol^-1 (95% CI -6.25 to 6.69), CRP: ancova difference in means 0.64 (95% CI -1.08, 2.37) or periodontal status at 3 months.

CONCLUSIONS

Non-surgical periodontal therapy did not significantly reduce glycated haemoglobin in participants with type 2 diabetes. Reasons are likely to be multifactorial and may be influenced by persistent periodontal inflammation at the follow-up appointments. Alternatively, the BMI of study participants may impact glycaemic control via alternative mechanisms involving the interplay between inflammation and adiposity meaning HbA1c may not be amenable to periodontal therapy in these individuals.

The Potential Role of Mycotoxins as a Contributor to Stunting in the SHINE Trial

Children in developing countries experience multiple exposures that are harmful to their growth and development. An emerging concern is frequent exposure to mycotoxins that contaminate a wide range of staple foods, including maize and groundnuts. Three mycotoxins are suspected to contribute to poor child health and development: aflatoxin, fumonisin, and deoxynivalenol. We summarize the evidence that mycotoxin exposure is associated with stunting, and propose that the causal pathway may be through environmental enteric dysfunction (EED) and disturbance of the insulin-like growth factor 1 (IGF-1) axis. The objectives of this substudy are to assess the relationship between agricultural and harvest practices and mycotoxin exposure; to evaluate associations between mycotoxin exposure and child stunting; and to investigate EED as a potential pathway linking mycotoxin exposure to child stunting, to inform potential areas for intervention.

Functional limitations as potential mediators of the effects of self-reported vision status on fall risk of older adults

OBJECTIVE

To test whether limitations in mobility and large-muscle functioning mediate self-reported vision status to increase fall risk among respondents age 65 and above.

METHOD

This study used two waves from the Health and Retirement Study. We conducted binary logistic and negative binomial regression analyses to test indirect paths leading from self-reported vision status to falls, via indices of mobility and large-muscle functioning.

RESULTS

Limited evidence was found for a mediating effect among women; however, large-muscle groups were implicated as partially mediating risk factors for falls among men with fair self-reported vision status.

DISCUSSION

Implications of these findings are discussed including the need for prioritizing improved muscle strength of older men and women with poor vision as a preventive measure against falls.