Lindsay Satterwhite Mayberry - Academia.edu (original) (raw)

Papers by Lindsay Satterwhite Mayberry

JMIR formative research, May 4, 2023

Statistics in Medicine, Jul 13, 2023

Covariate‐adjusted randomization (CAR) can reduce the risk of covariate imbalance and, when accou... more Covariate‐adjusted randomization (CAR) can reduce the risk of covariate imbalance and, when accounted for in analysis, increase the power of a trial. Despite CAR advances, stratified randomization remains the most common CAR method. Matched randomization (MR) randomizes treatment assignment within optimally identified matched pairs based on covariates and a distance matrix. When participants enroll sequentially, sequentially matched randomization (SMR) randomizes within matches found “on‐the‐fly” to meet a pre‐specified matching threshold. However, pre‐specifying the ideal threshold can be challenging and SMR yields less‐optimal matches than MR. We extend SMR to allow multiple participants to be randomized simultaneously, to use a dynamic threshold, and to allow matches to break and rematch if a better match later enrolls (sequential rematched randomization; SRR). In simplified settings and a real‐world application, we assess whether these extensions improve covariate balance, estimator/study efficiency, and optimality of matches. We investigate whether adjusting for more covariates can be detrimental upon covariate balance and efficiency as is the case of traditional stratified randomization. As secondary objectives, we use the case study to assess how SMR schemes compare side‐by‐side with common and related CAR schemes and whether adjusting for covariates in the design can be as powerful as adjusting for covariates in a parametric model. We find each SMR extension, individually and collectively, to improve covariate balance, estimator efficiency, study power, and quality of matches. We provide a case‐study where CAR schemes with randomization‐based inference can be as and more powerful than non‐CAR schemes with parametric adjustment for covariates.

arXiv (Cornell University), Apr 22, 2022

Many adaptive monitoring schemes adjust the required evidence toward a hypothesis to control Type... more Many adaptive monitoring schemes adjust the required evidence toward a hypothesis to control Type I error. This shifts focus away from determining scientific relevance with an uncompromised degree of evidence. We propose sequentially monitoring the Second Generation P-Value (SGPV) on repeated intervals until establishing evidence for scientific relevance (SeqSGPV). SeqSGPV encompasses existing strategies to monitor Region of Practical Equivalence (ROPE) or Region of Equivalence (ROE) hypotheses. Hence, our focus is to formalize sequential SGPV monitoring; establish a novel set of scientific hypotheses, called PRISM, which is a ROE with a ROPE surrounding the null hypothesis; and use monitoring frequency and a novel affirmation step to control Type I error. Under immediate and delayed outcomes, we assess finite and limiting SeqSGPV operating characteristics when monitoring

Journal of Diabetes and Its Complications, Nov 1, 2021

AIMS Elevated depressive symptoms are common among adults with type 2 diabetes (T2D). In a second... more AIMS Elevated depressive symptoms are common among adults with type 2 diabetes (T2D). In a secondary analysis from an RCT of a diabetes self-management support intervention that did not target depressive symptoms, we sought to determine if depressive symptoms were reduced by the intervention (i.e., depressive symptoms an outcome) or, alternatively, if intervention effects on hemoglobin A1c were lesser among persons with clinically elevated depressive symptoms (i.e., depressive symptoms an effect modifier). METHODS We evaluated a text messaging intervention, REACH, in a diverse (half non-white, half underinsured) sample of N = 506 adults with T2D. Participants completed the Patient Health Questionnaire-8 (PHQ) and A1c tests at baseline and 6 months. We conducted a factor analysis to identify somatic- and cognitive-affective symptoms on the PHQ. We tested our hypotheses with regression models, using interaction terms and subgroup analyses. RESULTS REACH improved depressive symptoms among participants with lower baseline A1c (<8.5%; β = -0.133, p = .007; cognitive β = -0.107, p = .038; somatic β = -0.131, p = .014) but not among participants with higher baseline A1c (≥8.5%; β = 0.040, p = .468). Baseline depressive symptoms did not modify the effect on A1c. CONCLUSIONS We found support for the hypothesis that depressive symptoms - both somatic- and cognitive-affective - may be an outcome, rather than an effect modifier, of effective diabetes self-management support interventions.

The Annals of Applied Statistics, Mar 1, 2022

Estimation of local average treatment effects in randomized trials typically relies upon the excl... more Estimation of local average treatment effects in randomized trials typically relies upon the exclusion restriction assumption in cases where we are unwilling to rule out the possibility of unmeasured confounding. Under this assumption, treatment effects are mediated through the post-randomization variable being conditioned upon, and directly attributable to neither the randomization itself nor its latent descendants. Recently, there has been interest in mobile health interventions to provide healthcare support. Mobile health interventions such as the Rapid Encouragement/Education and Communications for Health (REACH), designed to support self-management for adults with type 2 diabetes, often involve both one-way and interactive messages. In practice, it is highly likely that any benefit from the intervention is achieved both through receipt of the intervention content and through engagement with/response to it. Application of an instrumental variable analysis in order to understand the role of engagement with REACH (or a similar intervention) requires the traditional exclusion restriction assumption to be relaxed. We propose a conceptually intuitive sensitivity analysis procedure for the REACH randomized trial that places bounds on local average treatment effects. Simulation studies reveal this approach to have desirable finite-sample behavior and to recover local average treatment effects under correct specification of sensitivity parameters.

Journal of General Internal Medicine, Dec 18, 2018

Obesity science & practice, Dec 8, 2021

Author Contributions: W.H. formulated the study question, interpreted results, and drafted the in... more Author Contributions: W.H. formulated the study question, interpreted results, and drafted the initial manuscript. L.S. conducted the statistical analysis and created data representations. T.G., C.W., L.M., J.T, and N.M. all contributed to refining the study question, conceptualizing the analysis plan, interpreting results, and situating the current study within the existing literature. All authors contributed to critical revisions of the manuscript and approved the final version of the manuscript.

Jmir mhealth and uhealth, Jul 21, 2020

Background: Text message-delivered interventions are a feasible and scalable approach for improvi... more Background: Text message-delivered interventions are a feasible and scalable approach for improving chronic disease self-care and reducing health disparities; however, information on long-term user engagement with these interventions is limited. Objective: The aim of this study is to examine user engagement in a 12-month text message-delivered intervention supporting diabetes self-care, called REACH (Rapid Education/Encouragement And Communications for Health), among racially and socioeconomically diverse patients with type 2 diabetes (T2D). We explored time trends in engagement, associations between patient characteristics and engagement, and whether the addition of a human component or allowing patients to change their text frequency affected engagement. Qualitative data informed patients' subjective experience of their engagement. Methods: We recruited patients with T2D for a randomized trial evaluating mobile phone support relative to enhanced treatment as usual. This analysis was limited to participants assigned to the intervention. Participants completed a survey and hemoglobin A1c (HbA1c) test and received REACH text messages, including self-care promotion texts, interactive texts asking about medication adherence, and adherence feedback texts. For the first 6 months, texts were sent daily, and half of the participants also received monthly phone coaching. After 6 months, coaching stopped, and participants had the option to receive fewer texts for the subsequent 6 months. We defined engagement via responses to the interactive texts and responses to a follow-up interview. We used regression models to analyze associations with response rate and thematic and structural analysis to understand participants' reasons for responding to the texts and their preferred text frequency. Results: The participants were, on average, aged 55.8 (SD 9.8) years, 55.2% (137/248) female, and 52.0% (129/248) non-White; 40.7% (101/248) had ≤ a high school education, and 40.7% (101/248) had an annual household income <US $25,000. The median response rate to interactive texts was 91% (IQR 75%-97%) over 12 months. Engagement gradually declined throughout the intervention but remained high. Engagement did not differ by age, gender, education, income, diabetes duration, insulin status, health literacy, or numeracy. Black race and worse baseline medication adherence and HbA1c were each associated with lower engagement, although the effects were small. Nearly half of the participants chose to continue receiving daily texts for the last 6 months of the intervention. Participants who continued daily text messages said they wanted to continue experiencing benefits

Patient Education and Counseling, Jul 1, 2019

Journal of Cardiopulmonary Rehabilitation and Prevention, Nov 24, 2022

Background: Cardiac rehabilitation (CR) is underutilized. Psychological factors such as perceived... more Background: Cardiac rehabilitation (CR) is underutilized. Psychological factors such as perceived health competence, or one's belief in his or her ability to achieve health-related goals, may play a role in CR enrollment. We evaluated the association of perceived health competence with CR enrollment in the Vanderbilt Inpatient Cohort Study (VICS). Methods: The VICS evaluated the effect of psychosocial characteristics on post-discharge outcomes in patients hospitalized with acute coronary syndrome (ACS) from 2012-2014. The primary outcome was enrollment in an outpatient CR program. The primary predictor was the two-item perceived health competence scale (PHCS-2), which yields a score from 2-10 (higher scores indicate greater perceived health competence). We used multivariable logistic regression to evaluate the relationship between the PHCS-2 and CR enrollment. Results: A total of 2,028 VICS participants (median age 61 years, 38% female) with ACS were studied, of which 339 (17%) enrolled in CR. The PHCS-2 was associated with CR enrollment (odds ratio 1.15 per point increase, 95% confidence interval 1.06-1.26, p<0.01) after multivariable adjustment (Table). Participants with heart failure had a lower odds of CR enrollment, as did current smokers. Conclusion: Perceived health competence is associated with outpatient CR enrollment in patients hospitalized with ACS. Interventions designed to support perceived health competence may be useful for improving CR enrollment.

BMC Nephrology, Aug 10, 2022

Journal of Clinical Pharmacy and Therapeutics, Mar 4, 2016

What is known-Patients with type 2 diabetes mellitus (T2DM) are required to perform multiple self... more What is known-Patients with type 2 diabetes mellitus (T2DM) are required to perform multiple self-care behaviours to achieve and maintain optimal glycaemic control (HbA1c), which prevents complications and premature mortality. Patients with T2DM and low socioeconomic status (SES) are more likely to have suboptimal HbA1c, often due to being less adherent to recommended self-care activities than their higher-SES counterparts. Objective-Although studies support performing certain diabetes self-care behaviours for optimizing glycaemic control, there is limited research on the relative importance of each behaviour for this purpose. Identifying what behaviours are most important for HbA1c among low-SES patients with T2DM would be particularly useful for informing policy and intervention efforts for this high-risk group. Methods-In a cross-sectional study of 314 adults with T2DM and low SES, we used the Summary of Diabetes Self-Care Activities to assess self-care behaviours and multivariate models to test which behaviours were associated with lower HbA1c. Results and discussion-Only medication adherence was significantly associated with lower HbA1c after adjusting for the other self-care behaviours (β = −0 14, P = 0 028) and further adjusting for demographic and diabetes characteristics (β = −0 16, P = 0 024). What is new-Medication adherence may be the most important self-care behaviour for glycaemic control among adults with T2DM and low SES. Conclusion-Focused efforts to improve medication adherence among low-SES patient populations may improve glycaemic control.

American Journal of Preventive Medicine, Jul 1, 2019

Introduction: Among patients with type 2 diabetes, racial disparities are prevalent across a vari... more Introduction: Among patients with type 2 diabetes, racial disparities are prevalent across a variety of outcomes; however, inconsistent disparities in determinants of outcomes warrants exploring the impact of other, related factors. This study sought to examine whether disparities in health literacy, numeracy, self-care behaviors, and HbA1c persisted between non-Hispanic blacks and non-Hispanic whites after applying a robust adjustment for socioeconomic status (SES). Methods: From 2016 to 2018, adult patients with type 2 diabetes (N=444) were recruited from primary care clinics. Participants self-reported demographics, indicators of SES (i.e., income, education, health insurance, housing status, and financial strain), subjective health literacy and numeracy, and self-care behaviors. Participants also completed an HbA1c test. In 2018, differences were examined between non-Hispanic blacks and non-Hispanic whites in health literacy, numeracy, self-care, and HbA1c, first unadjusted and then adjusted using propensity score weighting. Results: In unadjusted analyses, compared with non-Hispanic whites, non-Hispanic blacks had lower health literacy (p=0.039) and numeracy (p<0.001), less medication adherence (p=0.009), use of information for dietary decisions (p=0.013), and problem eating behaviors (p<0.001; i.e., non-Hispanic blacks reported fewer problems), and higher HbA1c levels (p=0.005

Journal of Speech Language and Hearing Research, Nov 17, 2022

Purpose: The dual goals of this tutorial are (a) to increase awareness and use of mediation and m... more Purpose: The dual goals of this tutorial are (a) to increase awareness and use of mediation and moderation models in cognitive-communication rehabilitation research by describing options, benefits, and attainable analytic approaches for researchers with limited resources and sample sizes and (b) to describe how these findings may be interpreted for clinicians consuming research to inform clinical care. Method: We highlight key insights from the social sciences literature pointing to the risks of common approaches to linear modeling, which may slow progress in clinical–translational research and reduce the clinical utility of our work. We discuss the potential of mediation and moderation analyses to reduce the research-to-practice gap and describe how researchers may begin to implement these models, even in smaller sample sizes. We discuss how these preliminary analyses can help focus resources for larger trials to fully encapsulate the heterogeneity of individuals with cognitive-communication disorders. Results: In rehabilitation research, we study groups, but we use the findings from those studies to treat individuals. The most functional clinical research is about more than establishing only whether a given effect exists for an “average person” in the group of interest. It is critical to understand the active ingredients and mechanisms of action by which a given treatment works (mediation) and to know which circumstances, contexts, or individual characteristics might make that treatment most beneficial (moderation). Conclusions: Increased adoption of mediation and moderation approaches, executed in appropriate steps, could accelerate progress in cognitive-communication rehabilitation research and lead to the development of targeted treatments that work for more clients. In a field that has made limited progress in developing successful interventions for the last several decades, it is critical that we harness new approaches to advance clinical–translational research results for complex, heterogeneous groups with cognitive-communication disorders.

Elsevier eBooks, 2020

Abstract The agile method is a specific approach to project management for developing products ra... more Abstract The agile method is a specific approach to project management for developing products rapidly and iteratively. Teams using an agile approach use principles and tools that involve inputs from end users, iterations on an idea, and frequent structured communication among all team members. Work is delivered more quickly with more appeal to end users and, ultimately, more value. In this chapter, we discuss how to apply an agile methodology to research involving digital health interventions and present examples from our work in diabetes self-management support interventions. In traditional models of scientific research, processes are often slow and outcomes evaluation can be hindered by ineffective products or solutions. We highlight the benefits of applying agile methods to research such that teams can operate efficiently and learn quickly about the best course of action to maximize the likelihood of a successful project.

Journal of Behavioral Medicine, May 25, 2018

Objectives-Examine cross-sectional relationships between dispositional mindfulness and diabetes s... more Objectives-Examine cross-sectional relationships between dispositional mindfulness and diabetes self-care behaviors (i.e., medication adherence, diet and exercise behavior, and selfmonitoring of blood glucose; SMBG), hemoglobin A1c (HbA1c, %), and body mass index (BMI; continuously and obese vs. not). Method-Adults with type 2 diabetes (N=148, M age =55.7±10.1) who were recruited to participate in a web-based diabetes medication adherence intervention completed all assessments at enrollment. Results-In unadjusted analyses, mindfulness was associated with better dietary habits and worse HbA1c (p<.05). After controlling for a priori covariates (demographics, years since diabetes diagnosis, and insulin status), mindfulness remained associated with better dietary behavior (p<. 01) but not HbA1c. Mindfulness was not associated with medication adherence, exercise behavior, SMBG, or body mass index. Discussion-We found evidence that dispositional mindfulness plays an important role in dietary behaviors, supporting the use of mindful eating techniques in diabetes self-management interventions. Fostering mindfulness may be one of several behavioral tools needed to support key self-care behaviors and improve HbA1c.