Gary Yu

Faculty

Gary Yu headshot

Gary Yu

Associate Research Scientist
Adjunct Associate Professor

1 212 998 5486

433 First Ave
Room 745G
New York, NY 10010
United States

Gary Yu's additional information

Gary Yu, PhD, is an associate research scientist and adjunct associate professor at NYU Rory Meyers College of Nursing. He has conducted statistical analyses of data on multiple NIH-funded research projects. 

His dissertation focused on creating a new statistical technique for clustering individuals based on their patterns of responses (e.g., on a questionnaire of drug items). He extended the finite mixture model to allow for the number of repeated measures to be incorporated and contribute to the clustering of individuals. The dimension of the repeated measures can be summarized into a count of responses and can be assumed to follow a truncated Poisson distribution. This information can be included in what is called a dimension informative finite mixture model (DIMM) [NIH/NHLBI R01HL111195]. This model was originally developed and applied to continuous physical activity data, and it has been applied to binary drug items among men who have sex with men (MSM) in the United States and among male sex workers (MSW) in Vietnam.

Yu earned his PhD in biostatistics from Columbia University, MPH in epidemiology from Boston University, and BS in Bioengineering from the University of California, Berkeley.

PhD, Biostatistics - Columbia University (2014)
MPH, Epidemiology - Boston University (2006)
BS, Bioengineering - University of California, Berkeley (2004)

Substance use
HIV/AIDS
Global

Faculty Honors Awards

Bernard Challenor Spirit Prize, Mailman School of Public Health, Columbia University (2014)

Publications

Associations of Insomnia Symptoms With Cognition in Persons With Heart Failure

Gharzeddine, R., Yu, G., McCarthy, M. M., & Dickson, V. V. (2021). Western Journal of Nursing Research, 43(12), 1105-1117. 10.1177/0193945920988840
Abstract
Abstract
Although cognitive impairment is common among persons with heart failure and negatively impacts self-care, hospitalization, and mortality, the associations between cognitive impairment and insomnia symptoms are not clearly understood. The purpose of this study was to explore these associations and examine if they are maintained after adjusting for relevant sociodemographic, clinical, and lifestyle factors. Guided by the Neurocognitive model of insomnia and sleep and the self-care conceptual model, a cross-sectional data analysis using parametric testing was conducted on the Health and Retirement Study wave 2016. Difficulty initiating sleep and early morning awakening, but not difficulty maintaining sleep were significantly associated with poorer cognitive performance in the bivariate and multivariate analysis. Our results are suggestive of different phenotypes of insomnia symptoms that may have different associations with cognition in persons with heart failure. Further research using objective measurements of insomnia symptoms and detailed neuropsychiatric testing of cognition is needed to confirm this conclusion.

Characterizing Glycemic Control and Sleep in Adults with Long-Standing Type 1 Diabetes and Hypoglycemia Unawareness Initiating Hybrid Closed Loop Insulin Delivery

Malone, S. K., Peleckis, A. J., Grunin, L., Yu, G., Jang, S., Weimer, J., Lee, I., Rickels, M. R., & Goel, N. (2021). Journal of Diabetes Research, 2021. 10.1155/2021/6611064
Abstract
Abstract
Nocturnal hypoglycemia is life threatening for individuals with type 1 diabetes (T1D) due to loss of hypoglycemia symptom recognition (hypoglycemia unawareness) and impaired glucose counter regulation. These individuals also show disturbed sleep, which may result from glycemic dysregulation. Whether use of a hybrid closed loop (HCL) insulin delivery system with integrated continuous glucose monitoring (CGM) designed for improving glycemic control, relates to better sleep across time in this population remains unknown. The purpose of this study was to describe long-term changes in glycemic control and objective sleep after initiating hybrid closed loop (HCL) insulin delivery in adults with type 1 diabetes and hypoglycemia unawareness. To accomplish this, six adults (median age=58 y) participated in an 18-month ongoing trial assessing HCL effectiveness. Glycemic control and sleep were measured using continuous glucose monitoring and wrist accelerometers every 3 months. Paired sample t-tests and Cohen's d effect sizes modeled glycemic and sleep changes and the magnitude of these changes from baseline to 9 months. Reduced hypoglycemia (d=0.47-0.79), reduced basal insulin requirements (d=0.48), and a smaller glucose coefficient of variation (d=0.47) occurred with medium-large effect sizes from baseline to 9 months. Hypoglycemia awareness improved from baseline to 6 months with medium-large effect sizes (Clarke score (d=0.60), lability index (d=0.50), HYPO score (d=1.06)). Shorter sleep onset latency (d=1.53; p<0.01), shorter sleep duration (d=0.79), fewer total activity counts (d=1.32), shorter average awakening length (d=0.46), and delays in sleep onset (d=1.06) and sleep midpoint (d=0.72) occurred with medium-large effect sizes from baseline to 9 months. HCL led to clinically significant reductions in hypoglycemia and improved hypoglycemia awareness. Sleep showed a delayed onset, reduced awakening length and onset latency, and maintenance of high sleep efficiency after initiating HCL. Our findings add to the limited evidence on the relationships between diabetes therapeutic technologies and sleep health. This trial is registered with ClinicalTrials.gov (NCT03215914).

Co-Occurrence of Symptoms and Gut Microbiota Composition Before Neoadjuvant Chemotherapy and Radiation Therapy for Rectal Cancer: A Proof of Concept

González-Mercado, V. J., Lim, J., Yu, G., Penedo, F., Pedro, E., Bernabe, R., Tirado-Gómez, M., & Aouizerat, B. (2021). Biological Research for Nursing, 23(3), 513-523. 10.1177/1099800421991656
Abstract
Abstract
Purpose: To examine a) whether there are significant differences in gut microbial diversity and in the abundance of gut microbial taxa; and b) differences in predicted functional pathways of the gut microbiome between those participants with high co-occurring symptoms and those with low co-occurring symptoms, prior to neoadjuvant chemotherapy and radiation therapy (CRT) for rectal cancer. Methods: Rectal cancer patients (n = 41) provided stool samples for 16 S rRNA gene sequencing and symptom ratings for fatigue, sleep disturbance, and depressive symptoms prior to CRT. Descriptive statistics were computed for symptoms. Gut microbiome data were analyzed using QIIME2, LEfSe, and the R statistical package. Results: Participants with high co-occurring symptoms (n = 19) had significantly higher bacterial abundances of Ezakiella, Clostridium sensu stricto, Porphyromonas, Barnesiella, Coriobacteriales Incertae Sedis, Synergistiaceae, Echerichia-Shigella, and Turicibacter compared to those with low co-occurring symptoms before CRT (n = 22). Biosynthesis pathways for lipopolysaccharide, L-tryptophan, and colanic acid building blocks were enriched in participants with high co-occurring symptoms. Participants with low co-occurring symptoms showed enriched abundances of Enterococcus and Lachnospiraceae, as well as pathways for β-D-glucoronosides, hexuronide/hexuronate, and nicotinate degradation, methanogenesis, and L-lysine biosynthesis. Conclusion: A number of bacterial taxa and predicted functional pathways were differentially abundant in patients with high co-occurring symptoms compared to those with low co-occurring symptoms before CRT for rectal cancer. Detailed examination of bacterial taxa and pathways mediating co-occurring symptoms is warranted.

Comparison of social cognition using an adapted Chinese version of the Reading the Mind in the Eyes Test in drug-naive and regularly medicated individuals with chronic schizophrenia and healthy controls in rural China

Deng, F., Phillips, M. R., Cai, B., Yu, G., Qian, M., Grivel, M. M., Chen, H., Ouyang, X., Xue, F., Zhao, M., Kegeles, L. S., Susser, E. S., Keshavan, M. S., Stone, W. S., & Yang, L. H. (2021). Psychological Medicine. 10.1017/S003329172100043X
Abstract
Abstract
Background Social cognition has not previously been assessed in treatment-naive patients with chronic schizophrenia, in patients over 60 years of age, or in patients with less than 5 years of schooling. Methods We revised a commonly used measure of social cognition, the Reading the Mind in the Eyes Test (RMET), by expanding the instructions, using both self-completion and interviewer-completion versions (for illiterate respondents), and classifying each test administration as 'successfully completed' or 'incomplete'. The revised instrument (RMET-CV-R) was administered to 233 treatment-naive patients with chronic schizophrenia (UT), 154 treated controls with chronic schizophrenia (TC), and 259 healthy controls (HC) from rural communities in China. Results In bivariate and multivariate analyses, successful completion rates and RMET-CV-R scores (percent correct judgments about emotion exhibited in 70 presented slides) were highest in HC, intermediate in TC, and lowest in UT (adjusted completion rates, 97.0, 72.4, and 49.9%, respectively; adjusted RMET-CV-R scores, 45.4, 38.5, and 34.6%, respectively; all p < 0.02). Stratified analyses by the method of administration (self-completed v. interviewer-completed) and by education and age ('educated-younger' v. 'undereducated-older') show the same relationship between groups (i.e. NC>TC>UT), though not all differences remain statistically significant. Conclusions We find poorer social cognition in treatment-naive than in treated patients with chronic schizophrenia. The discriminant validity of RMET-CV-R in undereducated, older patients demonstrates the feasibility of administering revised versions of RMET to patients who may otherwise be considered ineligible due to education or age by changing the method of test administration and carefully assessing respondents' ability to complete the task successfully.

Correlates of Suicide Ideation and Resilience Among Native- and Foreign-Born Adolescents in the United States

Stark, L., Seff, I., Yu, G., Salama, M., Wessells, M., Allaf, C., & Bennouna, C. (2021). Journal of Adolescent Health. 10.1016/j.jadohealth.2021.07.012
Abstract
Abstract
Purpose: Nearly 20% of U.S. adolescents have considered suicide. Yet, gaps remain in understanding correlates of resilience and suicide risk, especially among populations born outside the United States who may face unique migration- and acculturation-related stressors. This study adds to the literature by exploring correlates of suicide ideation among a diverse population. Methods: This study analyzes quantitative data (N = 357) from the Study of Adolescent Lives after Migration to America, in Detroit and Harrisonburg. More than 40% of the sample was born outside the United States, with the majority born in the Middle East and North Africa. Path analysis was used to model dual outcomes of resilience and suicide ideation using measures of hope, school belonging, stressful life events, and being born outside the United States. Results: Suicide ideation and resilience were negatively correlated (ß = -.236[.069]; p < .001). Adolescents with greater hope (ß = .367; p < .001) and school belonging (ß = .407; p < .001) reported higher resilience, while lower levels of school belonging correlated with higher levels of suicide ideation (ß = -.248; p = .009). More stressful life events were associated with suicide ideation (ß = .243; p < .001), while fewer were correlated with resilience (ß = -.106; p = .003). Being born outside the United States was associated with suicide ideation (ß = .186; P-.015), with this finding driven by those from the Middle East and North Africa region, who faced significantly increased risk of suicide ideation (ß = .169; p = .036). Conclusions: Findings suggest that adolescents born in the Middle East and North Africa region may represent a vulnerable group needing targeted and culturally responsive interventions to destigmatize mental health and psychosocial well-being, boost existing sources of resilience, and encourage help-seeking behaviors.

Disease expression and outcomes in black and white adults with hypertrophic cardiomyopathy

Arabadjian, M. E., Yu, G., Sherrid, M. V., & Dickson, V. V. (2021). Journal of the American Heart Association, 10(17). 10.1161/JAHA.120.019978
Abstract
Abstract
BACKGROUND: There is limited research on hypertrophic cardiomyopathy (HCM), which is the most common inherited cardiac disorder, in diverse populations, including Black individuals. Current literature lacks comprehensive data on HCM disease expression, comorbidities, and outcomes in this historically disadvantaged group. The purpose of this study was to examine structural HCM characteristics, comorbidities, and outcomes in a Black and White cohort with HCM. METHODS AND RESULTS: The study was a subgroup analysis from a longitudinal, prospective study on HCM, with supplemental chart review. The sample included adults (≥18 years) with a clinical diagnosis of HCM, who self-identified as Black/African American or White. The study sample comprised 434 individuals; 57 (13.1%) were Black, and 180 (41.5%) were women. Black patients were younger than White patients, 54.6 (13.4) versus 62.5 (14.8) years, P=0.001. Black patients were more likely to have sub-basal and diffuse hypertrophy, 22 (38.6%) versus 56 (14.9%), P<0.001, 6 (10.5%) versus 15 (4%), P=0.017, mid-LV obstruction, 7 (12.3%) versus 21 (5.5%), P=0.025, and cardiac fibrosis ≥15%, 10 (22.2%) versus 19 (8.8%), P=0.009, than White patients. Black patients were more likely to experience appropriate implantable cardioverter defibrillator interventions, 5 (38.5) versus 5 (6.8), P<0.001 and were more likely to have ≥2 sudden death risk factors. Comorbidities were largely similar between groups, though more Black participants had Class II obesity, 12 (21.8) versus 30 (8.1), P<0.001. Both groups had similar rates of genetic testing usage. CONCLUSIONS: This study underscores the need for continued research of HCM in Black populations, including tailored approaches to diagnosis and precise evaluation of cardiac anatomy.

Gender-equitable caregiver attitudes and education and safety of adolescent girls in South Kivu, DRC: A secondary analysis from a randomized controlled trial

Seff, I., Falb, K., Yu, G., Landis, D., & Stark, L. (2021). PLoS Medicine, 18(9). 10.1371/journal.pmed.1003619
Abstract
Abstract
Background Adolescent girls face myriad threats to their well-being and safety : as a result of gender-inequitable attitudes and norms, and these risks are often exacerbated during humanitarian emergencies. While humanitarian actors have begun to address caregivers’ behaviors and gender attitudes as an approach to support and meet the needs of adolescent girls, best practices for working with caregivers to improve adolescent girls’ well-being in these settings have yet to be identified. Methods and findings This study uses panel data from a program evaluation to analyze associations between changes in gender-equitable attitudes among caregivers and changes in schooling and violence victimization for girls ages 10 to 14 years old in the Democratic Republic of the Congo (DRC). Participants were recruited in May 2015 for baseline (May to July 2015) and endline (August to October 2016) data collection. Baseline and endline data for both caregivers and girls were available for 732 girls. The average ages of adolescents and caregivers were 12 and 40.7, respectively, and 92% of caregivers were female. The predictor of interest was the change in caregivers’ gender-equitable attitudes between the 2 points in time, where attitudes were measured using 10 underlying survey questions. The primary outcomes of interest were dichotomous and included improvement in schooling participation and declines in physical, sexual, and emotional violence and feeling uncared for. Logistic regression was used to estimate the association between changes in caregivers’ attitudes and 5 outcomes of interest and revealed that an increase in a caregiver’s gender-equitable attitude score was associated with significantly greater odds of a girl experiencing an improvement in schooling participation (aOR = 1.08, CI [1.005, 1.154], p = 0.036) and of a girl experiencing a marginal decline in physical violence victimization (aOR = 1.07, CI [0.989, 1.158], p = 0.092). Analyses also revealed that older girls had lower odds of experiencing an improvement in schooling participation (aOR = 0.77, CI [0.686, 0.861], p < 0.001), physical violence (aOR = 0.86, CI [0.757, 0.984], p = 0.028), sexual violence (aOR = 0.86, CI [0.743, 1.003], p = 0.055), or emotional violence (aOR = 0.98, CI [0.849, 1.105], p = 0.005). Important limitations in this study include the self-reported nature of:outcomes, use of single questionnaire items to construct the outcome variables, and potential self-selection bias. Conclusions Results suggest that supporting caregivers to increase gender equitable attitudes may be associated with benefits in dual outcomes of education and safety for adolescent girls in eastern DRC. Further research is needed to better understand how to induce a shift in these attitudes in multisectoral programming.

Habitual physical activity patterns in a nationally representative sample of U.S. adults

Malone, S. K., Patterson, F., Grunin, L., Melkus, G. D., Riegel, B., Punjabi, N., Yu, G., Urbanek, J., Crainiceanu, C., & Pack, A. (2021). Translational Behavioral Medicine, 11(2), 332-341. 10.1093/tbm/ibaa002
Abstract
Abstract
Physical inactivity is a leading determinant of noncommunicable diseases. Yet, many adults remain physically inactive. Physical activity guidelines do not account for the multidimensionality of physical activity, such as the type or variety of physical activity behaviors. This study identified patterns of physical activity across multiple dimensions (e.g., frequency, duration, and variety) using a nationally representative sample of adults. Sociodemographic characteristics, health behaviors, and clinical characteristics associated with each physical activity pattern were defined. Multivariate finite mixture modeling was used to identify patterns of physical activity among 2003-2004 and 2005-2006 adult National Health and Nutrition Examination Survey participants. Chi-square tests were used to identify sociodemographic differences within each physical activity cluster and test associations between the physical activity clusters with health behaviors and clinical characteristics. Five clusters of physical activity patterns were identified: (a) low frequency, short duration (n = 730, 13%); (b) low frequency, long duration (n = 392, 7%); (c) daily frequency, short duration (n = 3,011, 55%); (d) daily frequency, long duration (n = 373, 7%); and (e) high frequency, average duration (n = 964, 18%). Walking was the most common form of activity; highly active adults engaged in more varied types of activity. High-activity clusters were comprised of a greater proportion of younger, White, nonsmoking adult men reporting moderate alcohol use without mobility problems or chronic health conditions. Active females engaged in frequent short bouts of activity. Data-driven approaches are useful for identifying clusters of physical activity that encompass multiple dimensions of activity. These activity clusters vary across sociodemographic and clinical subgroups.

Insomnia and Insomnia Symptoms in Persons with Heart Failure: An Integrative Review

Gharzeddine, R., McCarthy, M. M., Yu, G., & Vaughan Dickson, V. (2021). Journal of Cardiovascular Nursing, 36(4), 374-384. 10.1097/JCN.0000000000000719
Abstract
Abstract
Background/Objective Insomnia and insomnia symptoms are highly prevalent in persons with heart failure (HF), and they are associated with several untoward outcomes. The purpose of this integrative review is to describe the correlates, predictors, and outcomes of insomnia and insomnia symptoms in persons with HF. Methods Using integrative review methods, an extensive electronic search of 5 databases was conducted for the period of 2000-2019. Sixteen studies were identified that met the inclusion criteria for review and investigated insomnia or insomnia symptoms in HF. Results Various sociodemographic factors, chronic comorbidities, clinical factors, and cognitive-behavioral factors are correlates and predictors of insomnia and insomnia symptoms in persons with HF. Depression, fatigue, daytime sleepiness, poor self-reported physical functioning, decreased exercise capacity, cardiac events, and poor health-related quality of life are significant outcomes of insomnia and insomnia symptoms in persons with HF. The associations of insomnia and insomnia symptoms with age, sex, sleep-disordered breathing, and cognition were not consistent across all studies. Conclusion Larger studies with diverse age and race groups as well as longitudinal studies and designs that test mediation effects are needed to disentangle complex relationships between insomnia and insomnia symptoms and several of their potential predictors and correlates in HF.

Limb Volume Changes and Activities of Daily Living: A Prospective Study

Park, J. H., Merriman, J., Brody, A., Fletcher, J., Yu, G., Ko, E., Yancey, A., & Fu, M. R. (2021). Lymphatic Research and Biology, 19(3), 261-268. 10.1089/lrb.2020.0077
Abstract
Abstract
Background: Breast cancer-related lymphedema (BCRL) limits the movements of patients' limbs, which leads to a diminished ability to achieve essential activities of daily living (ADLs). The purpose of this study was to examine the associations between limb volume changes from the baseline before breast cancer surgery and self-reported difficulty in performing ADLs at 12 months following cancer surgery. We hypothesized that a positive association existed between limb volume changes from the baseline and self-reported difficulty in performing ADLs at 12 months following breast cancer surgery. Methods and Results: The data of the present study were part of a larger study with 140 breast cancer patients recruited before breast cancer surgery and followed up during their first year of treatment. Patients with more than 10% limb volume increase reported more frequent distress in performing 13 ADL items, compared with patients whose limb volume increased by 5%-10%. Regression analysis showed a significant increase in the odds ratio of reporting difficulty in ADLs compared with the group with less than 5% limb volume increase. Conclusion: Overall, patients with a greater limb volume increase underwent more difficulty performing ADLs. Patients reported more difficulty in performing ADLs even with 5%-10% limb volume increase. Currently, there is no standardized guideline to diagnose BCRL, although previous evidence suggests a limb volume increase greater than 10% as a criterion for BCRL. The findings from the present study suggest a more precise and clinically meaningful criteria for diagnosing BCRL to accommodate those with 5%-10% increase in limb volume.