Use of online social networks for smoking cessation has been associated with abstinence. Little i... more Use of online social networks for smoking cessation has been associated with abstinence. Little is known about the mechanisms through which the formation of social ties in an online network may influence smoking behavior. Using dynamic social network analysis, we investigated how temporal changes of an individual's number of social network ties are prospectively related to abstinence in an online social network for cessation. In a network where quitting is normative and is the focus of communications among members, we predicted that an increasing number of ties would be positively associated with abstinence. Participants were N = 2,657 adult smokers recruited to a randomized cessation treatment trial following enrollment on BecomeAnEX.org, a longstanding Internet cessation program with a large and mature online social network. At 3-months post-randomization, 30-day point prevalence abstinence was assessed and website engagement metrics were extracted. The social network was cons...
Prenatal chemical exposures may adversely affect neurodevelopment, but few studies have examined ... more Prenatal chemical exposures may adversely affect neurodevelopment, but few studies have examined the persistence of these associations. We examined whether associations between prenatal bisphenol A (BPA) or polybrominated diphenyl ether (PBDE) exposures persist or resolve as children age. We followed 346 mother-child pairs (enrolled 2003-2006) from Cincinnati, OH from pregnancy until children were 8 years old. We measured BPA in urine collected at 16 and 26 weeks gestation and PBDE-47 in serum collected at 16 weeks gestation. We administered repeated measures of children's behavior, mental/psychomotor development, and IQ from ages 1-8 years. We determined if associations of BPA or PBDE-47 with child neurobehavior persisted or resolved as children aged using linear mixed models and estimated neurobehavioral measure reproducibility using intraclass correlation coefficients (ICCs). Higher BPA in girls and higher PBDE-47 in both boys and girls were associated with more externalizing...
Annals of behavioral medicine : a publication of the Society of Behavioral Medicine, Jan 15, 2018
Partial adherence in Internet smoking cessation interventions presents treatment and evaluation c... more Partial adherence in Internet smoking cessation interventions presents treatment and evaluation challenges. Increasing adherence may improve outcomes. To present smoking outcomes from an Internet randomized trial of two strategies to encourage adherence to tobacco dependence treatment components: (i) a social network (SN) strategy to integrate smokers into an online community and (ii) free nicotine replacement therapy (NRT). In addition to intent-to-treat analyses, we used novel statistical methods to distinguish the impact of treatment assignment from treatment utilization. A total of 5,290 current smokers on a cessation website (WEB) were randomized to WEB, WEB + SN, WEB + NRT, or WEB + SN + NRT. The main outcome was 30-day point prevalence abstinence at 3 and 9 months post-randomization. Adherence measures included self-reported medication use (meds), and website metrics of skills training (sk) and community use (comm). Inverse Probability of Retention Weighting and Inverse Proba...
Overweight/obese individuals with Type 2 diabetes have low adiponectin levels, which may improve ... more Overweight/obese individuals with Type 2 diabetes have low adiponectin levels, which may improve with lifestyle changes. We investigated whether genetic variants associated with adiponectin levels in genome-wide association studies (GWAS) would also be related with adiponectin changes in response to an intensive lifestyle intervention (ILI), potentially through mechanisms altering the adipose microenvironment via weight loss and/or improved cardiorespiratory fitness. Look AHEAD was a randomized trial comparing the cardiovascular benefits of ILI-induced weight loss and physical activity compared with diabetes support and education among overweight/obese individuals with Type 2 diabetes. In a subsample of Look AHEAD with adiponectin data and genetic consent ( n = 1,351), we evaluated the effects of 24 genetic variants, demonstrated by GWAS to be cross-sectionally associated with adiponectin, on adiponectin change 1-yr postintervention. We explored via mediational analyses whether any ...
In this thesis, a mixture-model cluster analysis technique under different covariance structures ... more In this thesis, a mixture-model cluster analysis technique under different covariance structures of the component densities is developed and presented, to capture the compactness, orientation, shape, and the volume of component clusters in one expert system to handle Gaussian high dimensional heterogeneous data sets to achieve flexibility in currently practiced cluster analysis techniques. Two approaches to parameter estimation are considered and compared; one using the Expectation-Maximization (EM) algorithm and another following a Bayesian framework using the Gibbs sampler. We develop and score several forms of the ICOMP criterion of Bozdogan (1994, 2004) as our fitness function; to choose the number of component clusters, to choose the correct component covariance matrix structure among nine candidate covariance structures, and to select the optimal parameters and the best fitting mixture-model. We demonstrate our approach on simulated datasets and a real large data set, focusing...
Little is known about the influence of online peer interactions on health behavior change. This s... more Little is known about the influence of online peer interactions on health behavior change. This study examined the relationship between exposure to peer sentiment about nicotine replacement therapy (NRT) in an online social network for smoking cessation and NRT use. Participants were 3297 current smokers who enrolled in an Internet smoking cessation program, participated in a randomized trial, and completed a 3-month follow-up. Half received free NRT as part of the trial. Automated text classification identified 27,038 posts about NRT that one or more participants were exposed to in the social network. Sentiment towards NRT was rated on Amazon Mechanical Turk. Participants' exposure to peer sentiment about NRT was determined by analysis of clickstream data. Modified Poisson regression examined self-reported use of NRT at 3-months as a function of exposure to NRT sentiment, controlling for study arm and post exposure. One in five participants (19.3%, n = 639) were exposed to any ...
To assess the effect of the FTO genotype on weight loss after dietary, physical activity, or dru... more To assess the effect of the FTO genotype on weight loss after dietary, physical activity, or drug based interventions in randomised controlled trials. Systematic review and random effects meta-analysis of individual participant data from randomised controlled trials. Ovid Medline, Scopus, Embase, and Cochrane from inception to November 2015. Randomised controlled trials in overweight or obese adults reporting reduction in body mass index, body weight, or waist circumference by FTO genotype (rs9939609 or a proxy) after dietary, physical activity, or drug based interventions. Gene by treatment interaction models were fitted to individual participant data from all studies included in this review, using allele dose coding for genetic effects and a common set of covariates. Study level interactions were combined using random effect models. Metaregression and subgroup analysis were used to assess sources of study heterogeneity. We identified eight eligible randomised controlled trials for the systematic review and meta-analysis (n=9563). Overall, differential changes in body mass index, body weight, and waist circumference in response to weight loss intervention were not significantly different between FTO genotypes. Sensitivity analyses indicated that differential changes in body mass index, body weight, and waist circumference by FTO genotype did not differ by intervention type, intervention length, ethnicity, sample size, sex, and baseline body mass index and age category. We have observed that carriage of the FTO minor allele was not associated with differential change in adiposity after weight loss interventions. These findings show that individuals carrying the minor allele respond equally well to dietary, physical activity, or drug based weight loss interventions and thus genetic predisposition to obesity associated with the FTO minor allele can be at least partly counteracted through such interventions. PROSPERO CRD42015015969.
Journal of consulting and clinical psychology, 2016
To estimate the causal effects of online community use on 30-day point prevalence abstinence at 3... more To estimate the causal effects of online community use on 30-day point prevalence abstinence at 3 months among smokers that received a combined Internet/phone intervention for smoking cessation. Participants were 399 adult smokers selected from the combined Internet/phone arm of The iQUITT Study (Graham et al., 2011), a randomized trial of Internet and proactive telephone counseling for smoking cessation. All selected participants had accessed a web-based smoking-cessation program with an established online community and received at least one telephone counseling call. Automated tracking metrics of passive (e.g., reading posts, viewing profiles) and active (e.g., writing posts, sending messages) community use were extracted at 3 months. Self-selected community use defined the groups of interest as None, Passive, and Both (passive and active). Inverse probability of treatment weighting corrected for baseline imbalances on demographic, smoking, and psychosocial variables. Propensity w...
Annals of behavioral medicine : a publication of the Society of Behavioral Medicine, Jan 9, 2016
The potential for sampling bias in Internet smoking cessation studies is widely recognized. Howev... more The potential for sampling bias in Internet smoking cessation studies is widely recognized. However, few studies have explicitly addressed the issue of sample representativeness in the context of an Internet smoking cessation treatment trial. The purpose of the present study is to examine the generalizability of participants enrolled in a randomized controlled trial of an Internet smoking cessation intervention using weighted data from the National Health Interview Survey (NHIS). A total of 5290 new users on a smoking cessation website enrolled in the trial between March 2012 and January 2015. Descriptive statistics summarized baseline characteristics of screened and enrolled participants, and multivariate analysis examined predictors of enrollment. Generalizability analyses compared demographic and smoking characteristics of trial participants to current smokers in the 2012-2014 waves of NHIS (n = 19,043) and to an NHIS subgroup based on Internet use and cessation behavior (n = 366...
We estimated the causal effects of use of an online smoking cessation community on 30-day point p... more We estimated the causal effects of use of an online smoking cessation community on 30-day point prevalence abstinence at 3 months. Participants (N = 492) were adult current smokers in the enhanced Internet arm of The iQUITT Study, a randomized trial of Internet and telephone treatment for smoking cessation. All participants accessed a Web-based smoking-cessation program that included a large, established online community. Automated tracking metrics of passive (e.g., reading forum posts, viewing member profiles) and active (e.g., writing forum posts, sending private messages) community use were extracted from the site at 3 months. Self-selected community use defines the groups of interest: "None," "Passive," and "Both" (passive + active). Inverse probability of treatment weighting corrected for baseline imbalances on demographic, smoking, psychosocial, and medical history variables. Propensity weights estimated via generalized boosted models were used to calculate Average Treatment Effects (ATE) and Average Treatment effects on the Treated (ATT). Patterns of community use were: None = 198 (40.2%), Passive = 110 (22.4%), and Both = 184 (37.4%). ATE-weighted abstinence rates were: None = 4.2% (95% CI = 1.5-6.9); Passive = 15.1% (95% CI = 8.4-21.9); Both = 20.4% (95% CI = 13.9-26.8). ATT-weighted abstinence rates indicated even greater benefits of community use. Community users were more likely to quit smoking at 3 months than nonusers. The estimated benefit from use of online community resources was even larger among subjects with high propensity to use them. No differences in abstinence emerged between passive and passive/active users. Results suggest that lurking in online communities confers specific abstinence benefits. Implications of these findings for online cessation communities are discussed. (PsycINFO Database Record
-Glucokinase regulatory protein (GCKR) inhibitors offer a novel treatment approach for glucose co... more -Glucokinase regulatory protein (GCKR) inhibitors offer a novel treatment approach for glucose control in diabetes; however their cardiometabolic effects, particularly in relation to increased triglycerides and C-reactive protein (CRP) levels are of concern. GCKR Leu446Pro is a common variant associated with reduced GCKR function, increased triglycerides and CRP. -We investigated whether a 1-year intensive lifestyle intervention for weight loss (ILI) would avert the unfavorable cardiometabolic effects associated with GCKR Leu446Pro when compared to a diabetes support and education arm (DSE) in overweight/obese individuals with type 2 diabetes with triglyceride (n=3,214) and CRP (n=1,411) data participating in a randomized lifestyle intervention study for weight loss, Look AHEAD (Action for Health in Diabetes). Once demographics, medication use and baseline adiposity and fitness were accounted for, ILI did not modify the baseline association of GCKR-Leu446Pro with elevated triglycerides (β± SE= 0.067 ± 0.013, p= 1.5×10(-7) and β± SE= 0.052 ± 0.015, p=5×10(-4)) or with elevated CRP (β± SE= 0.136 ± 0.034, p=5.1×10(-5) and β± SE= 0.903 ± 0.038, p=0.015) in the overall sample and Non-Hispanic Whites, respectively. The lack of a protective effect from ILI at 1-year when compared to DSE (ILI versus DSE interaction for triglyceride and CRP change, respectively: p= 0.64 and 0.37 in the overall sample; p= 0.27 and 0.05 in Non-Hispanic Whites) persisted after additional adjustment for changes in adiposity and fitness. -Moderate improvements in adiposity and fitness with ILI did not mitigate the adverse cardiometabolic effects of GCKR inhibition in overweight/obese individuals with diabetes.
Numerous studies have found elevated depressive symptoms among individuals with Type 2 diabetes, ... more Numerous studies have found elevated depressive symptoms among individuals with Type 2 diabetes, yet the mechanisms remain unclear. We examined whether genetic loci previously associated with depressive symptoms predict depressive symptoms among overweight/obese individuals with Type 2 diabetes or change in depressive symptoms during behavioral weight loss. The Illumina CARe iSelect (IBC) chip and Cardiometabochip were characterized in 2118 overweight or obese participants with Type 2 diabetes from Look AHEAD (Action for Health in Diabetes), a randomized trial to determine the effects of intensive life-style intervention and diabetes support and education on cardiovascular morbidity and mortality. Primary analyses focused on baseline Beck Depression Inventory (BDI) scores and depressive symptom change at 1 year. Of eight single nucleotide polymorphisms (SNPs) in six loci, three a priori SNPs in two loci (chromosome 5: rs60271; LBR: rs2230419, rs1011319) were associated with baseline...
Numerous studies have found elevated depressive symptoms among individuals with Type 2 diabetes, ... more Numerous studies have found elevated depressive symptoms among individuals with Type 2 diabetes, yet the mechanisms remain unclear. We examined whether genetic loci previously associated with depressive symptoms predict depressive symptoms among overweight/obese individuals with Type 2 diabetes or change in depressive symptoms during behavioral weight loss. The Illumina CARe iSelect (IBC) chip and Cardiometabochip were characterized in 2118 overweight or obese participants with Type 2 diabetes from Look AHEAD (Action for Health in Diabetes), a randomized trial to determine the effects of intensive life-style intervention and diabetes support and education on cardiovascular morbidity and mortality. Primary analyses focused on baseline Beck Depression Inventory (BDI) scores and depressive symptom change at 1 year. Of eight single nucleotide polymorphisms (SNPs) in six loci, three a priori SNPs in two loci (chromosome 5: rs60271; LBR: rs2230419, rs1011319) were associated with baseline BDI scores, but in the opposite direction of prior research. In joint analysis of 90,003 IBC and Cardiometabochip SNPs, rs1543654 in the region of KCNE1 predicted change in BDI scores at Year 1 in diabetes support and education (β = -1.05, standard error [SE] = 0.21, p = 6.9 × 10) at the level of chip-wide significance, while also showing a nominal association with baseline BDI (β = 0.35, SE = 0.16, p = .026). Adjustment for antidepressant medication and/or limiting analyses to non-Hispanic white individuals did not meaningfully alter results. Previously reported genetic associations with depressive symptoms did not replicate in this cohort of overweight/obese individuals with Type 2 diabetes. We identified KCNE1 as a potential novel locus associated with depressive symptoms.
Clinically relevant weight loss is achievable through lifestyle modification, but unintentional w... more Clinically relevant weight loss is achievable through lifestyle modification, but unintentional weight regain is common. We investigated whether recently discovered genetic variants affect weight loss and/or weight regain during behavioral intervention. Participants at high-risk of (Diabetes Prevention Program [DPP]; N=917/907 intervention/comparison) or with (Look AHEAD; N=2,014/1,892 intervention/comparison) type 2 diabetes were from two parallel arm (lifestyle vs. comparison) randomized controlled trials. The associations of 91 established obesity-predisposing loci with weight loss across 4 years, and with weight regain across years-2-4 after a minimum of 3% weight loss, were tested. Each copy of the minor G allele of MTIF3 rs1885988 was consistently associated with greater weight loss following lifestyle intervention over 4-years across DPP and LA. No such effect was observed across comparison arms, leading to a nominally significant SNP × treatment interaction (P=4.3×10(-3)). However, this effect was not significant at a study-wise significance level (Bonferroni threshold P<5·8×10(-4)). Most obesity-predisposing gene variants were not associated with weight loss or regain within the DPP and Look AHEAD trials, directly or via interactions with lifestyle.
In this thesis, a mixture-model cluster analysis technique under different covariance structures ... more In this thesis, a mixture-model cluster analysis technique under different covariance structures of the component densities is developed and presented, to capture the compactness, orientation, shape, and the volume of component clusters in one expert system to handle Gaussian high dimensional heterogeneous data sets to achieve flexibility in currently practiced cluster analysis techniques. Two approaches to parameter estimation are considered and compared; one using the Expectation-Maximization (EM) algorithm and another following a Bayesian framework using the Gibbs sampler. We develop and score several forms of the ICOMP criterion of Bozdogan (1994, 2004) as our fitness function; to choose the number of component clusters, to choose the correct component covariance matrix structure among nine candidate covariance structures, and to select the optimal parameters and the best fitting mixture-model. We demonstrate our approach on simulated datasets and a real large data set, focusing...
Use of online social networks for smoking cessation has been associated with abstinence. Little i... more Use of online social networks for smoking cessation has been associated with abstinence. Little is known about the mechanisms through which the formation of social ties in an online network may influence smoking behavior. Using dynamic social network analysis, we investigated how temporal changes of an individual's number of social network ties are prospectively related to abstinence in an online social network for cessation. In a network where quitting is normative and is the focus of communications among members, we predicted that an increasing number of ties would be positively associated with abstinence. Participants were N = 2,657 adult smokers recruited to a randomized cessation treatment trial following enrollment on BecomeAnEX.org, a longstanding Internet cessation program with a large and mature online social network. At 3-months post-randomization, 30-day point prevalence abstinence was assessed and website engagement metrics were extracted. The social network was cons...
Prenatal chemical exposures may adversely affect neurodevelopment, but few studies have examined ... more Prenatal chemical exposures may adversely affect neurodevelopment, but few studies have examined the persistence of these associations. We examined whether associations between prenatal bisphenol A (BPA) or polybrominated diphenyl ether (PBDE) exposures persist or resolve as children age. We followed 346 mother-child pairs (enrolled 2003-2006) from Cincinnati, OH from pregnancy until children were 8 years old. We measured BPA in urine collected at 16 and 26 weeks gestation and PBDE-47 in serum collected at 16 weeks gestation. We administered repeated measures of children's behavior, mental/psychomotor development, and IQ from ages 1-8 years. We determined if associations of BPA or PBDE-47 with child neurobehavior persisted or resolved as children aged using linear mixed models and estimated neurobehavioral measure reproducibility using intraclass correlation coefficients (ICCs). Higher BPA in girls and higher PBDE-47 in both boys and girls were associated with more externalizing...
Annals of behavioral medicine : a publication of the Society of Behavioral Medicine, Jan 15, 2018
Partial adherence in Internet smoking cessation interventions presents treatment and evaluation c... more Partial adherence in Internet smoking cessation interventions presents treatment and evaluation challenges. Increasing adherence may improve outcomes. To present smoking outcomes from an Internet randomized trial of two strategies to encourage adherence to tobacco dependence treatment components: (i) a social network (SN) strategy to integrate smokers into an online community and (ii) free nicotine replacement therapy (NRT). In addition to intent-to-treat analyses, we used novel statistical methods to distinguish the impact of treatment assignment from treatment utilization. A total of 5,290 current smokers on a cessation website (WEB) were randomized to WEB, WEB + SN, WEB + NRT, or WEB + SN + NRT. The main outcome was 30-day point prevalence abstinence at 3 and 9 months post-randomization. Adherence measures included self-reported medication use (meds), and website metrics of skills training (sk) and community use (comm). Inverse Probability of Retention Weighting and Inverse Proba...
Overweight/obese individuals with Type 2 diabetes have low adiponectin levels, which may improve ... more Overweight/obese individuals with Type 2 diabetes have low adiponectin levels, which may improve with lifestyle changes. We investigated whether genetic variants associated with adiponectin levels in genome-wide association studies (GWAS) would also be related with adiponectin changes in response to an intensive lifestyle intervention (ILI), potentially through mechanisms altering the adipose microenvironment via weight loss and/or improved cardiorespiratory fitness. Look AHEAD was a randomized trial comparing the cardiovascular benefits of ILI-induced weight loss and physical activity compared with diabetes support and education among overweight/obese individuals with Type 2 diabetes. In a subsample of Look AHEAD with adiponectin data and genetic consent ( n = 1,351), we evaluated the effects of 24 genetic variants, demonstrated by GWAS to be cross-sectionally associated with adiponectin, on adiponectin change 1-yr postintervention. We explored via mediational analyses whether any ...
In this thesis, a mixture-model cluster analysis technique under different covariance structures ... more In this thesis, a mixture-model cluster analysis technique under different covariance structures of the component densities is developed and presented, to capture the compactness, orientation, shape, and the volume of component clusters in one expert system to handle Gaussian high dimensional heterogeneous data sets to achieve flexibility in currently practiced cluster analysis techniques. Two approaches to parameter estimation are considered and compared; one using the Expectation-Maximization (EM) algorithm and another following a Bayesian framework using the Gibbs sampler. We develop and score several forms of the ICOMP criterion of Bozdogan (1994, 2004) as our fitness function; to choose the number of component clusters, to choose the correct component covariance matrix structure among nine candidate covariance structures, and to select the optimal parameters and the best fitting mixture-model. We demonstrate our approach on simulated datasets and a real large data set, focusing...
Little is known about the influence of online peer interactions on health behavior change. This s... more Little is known about the influence of online peer interactions on health behavior change. This study examined the relationship between exposure to peer sentiment about nicotine replacement therapy (NRT) in an online social network for smoking cessation and NRT use. Participants were 3297 current smokers who enrolled in an Internet smoking cessation program, participated in a randomized trial, and completed a 3-month follow-up. Half received free NRT as part of the trial. Automated text classification identified 27,038 posts about NRT that one or more participants were exposed to in the social network. Sentiment towards NRT was rated on Amazon Mechanical Turk. Participants' exposure to peer sentiment about NRT was determined by analysis of clickstream data. Modified Poisson regression examined self-reported use of NRT at 3-months as a function of exposure to NRT sentiment, controlling for study arm and post exposure. One in five participants (19.3%, n = 639) were exposed to any ...
To assess the effect of the FTO genotype on weight loss after dietary, physical activity, or dru... more To assess the effect of the FTO genotype on weight loss after dietary, physical activity, or drug based interventions in randomised controlled trials. Systematic review and random effects meta-analysis of individual participant data from randomised controlled trials. Ovid Medline, Scopus, Embase, and Cochrane from inception to November 2015. Randomised controlled trials in overweight or obese adults reporting reduction in body mass index, body weight, or waist circumference by FTO genotype (rs9939609 or a proxy) after dietary, physical activity, or drug based interventions. Gene by treatment interaction models were fitted to individual participant data from all studies included in this review, using allele dose coding for genetic effects and a common set of covariates. Study level interactions were combined using random effect models. Metaregression and subgroup analysis were used to assess sources of study heterogeneity. We identified eight eligible randomised controlled trials for the systematic review and meta-analysis (n=9563). Overall, differential changes in body mass index, body weight, and waist circumference in response to weight loss intervention were not significantly different between FTO genotypes. Sensitivity analyses indicated that differential changes in body mass index, body weight, and waist circumference by FTO genotype did not differ by intervention type, intervention length, ethnicity, sample size, sex, and baseline body mass index and age category. We have observed that carriage of the FTO minor allele was not associated with differential change in adiposity after weight loss interventions. These findings show that individuals carrying the minor allele respond equally well to dietary, physical activity, or drug based weight loss interventions and thus genetic predisposition to obesity associated with the FTO minor allele can be at least partly counteracted through such interventions. PROSPERO CRD42015015969.
Journal of consulting and clinical psychology, 2016
To estimate the causal effects of online community use on 30-day point prevalence abstinence at 3... more To estimate the causal effects of online community use on 30-day point prevalence abstinence at 3 months among smokers that received a combined Internet/phone intervention for smoking cessation. Participants were 399 adult smokers selected from the combined Internet/phone arm of The iQUITT Study (Graham et al., 2011), a randomized trial of Internet and proactive telephone counseling for smoking cessation. All selected participants had accessed a web-based smoking-cessation program with an established online community and received at least one telephone counseling call. Automated tracking metrics of passive (e.g., reading posts, viewing profiles) and active (e.g., writing posts, sending messages) community use were extracted at 3 months. Self-selected community use defined the groups of interest as None, Passive, and Both (passive and active). Inverse probability of treatment weighting corrected for baseline imbalances on demographic, smoking, and psychosocial variables. Propensity w...
Annals of behavioral medicine : a publication of the Society of Behavioral Medicine, Jan 9, 2016
The potential for sampling bias in Internet smoking cessation studies is widely recognized. Howev... more The potential for sampling bias in Internet smoking cessation studies is widely recognized. However, few studies have explicitly addressed the issue of sample representativeness in the context of an Internet smoking cessation treatment trial. The purpose of the present study is to examine the generalizability of participants enrolled in a randomized controlled trial of an Internet smoking cessation intervention using weighted data from the National Health Interview Survey (NHIS). A total of 5290 new users on a smoking cessation website enrolled in the trial between March 2012 and January 2015. Descriptive statistics summarized baseline characteristics of screened and enrolled participants, and multivariate analysis examined predictors of enrollment. Generalizability analyses compared demographic and smoking characteristics of trial participants to current smokers in the 2012-2014 waves of NHIS (n = 19,043) and to an NHIS subgroup based on Internet use and cessation behavior (n = 366...
We estimated the causal effects of use of an online smoking cessation community on 30-day point p... more We estimated the causal effects of use of an online smoking cessation community on 30-day point prevalence abstinence at 3 months. Participants (N = 492) were adult current smokers in the enhanced Internet arm of The iQUITT Study, a randomized trial of Internet and telephone treatment for smoking cessation. All participants accessed a Web-based smoking-cessation program that included a large, established online community. Automated tracking metrics of passive (e.g., reading forum posts, viewing member profiles) and active (e.g., writing forum posts, sending private messages) community use were extracted from the site at 3 months. Self-selected community use defines the groups of interest: "None," "Passive," and "Both" (passive + active). Inverse probability of treatment weighting corrected for baseline imbalances on demographic, smoking, psychosocial, and medical history variables. Propensity weights estimated via generalized boosted models were used to calculate Average Treatment Effects (ATE) and Average Treatment effects on the Treated (ATT). Patterns of community use were: None = 198 (40.2%), Passive = 110 (22.4%), and Both = 184 (37.4%). ATE-weighted abstinence rates were: None = 4.2% (95% CI = 1.5-6.9); Passive = 15.1% (95% CI = 8.4-21.9); Both = 20.4% (95% CI = 13.9-26.8). ATT-weighted abstinence rates indicated even greater benefits of community use. Community users were more likely to quit smoking at 3 months than nonusers. The estimated benefit from use of online community resources was even larger among subjects with high propensity to use them. No differences in abstinence emerged between passive and passive/active users. Results suggest that lurking in online communities confers specific abstinence benefits. Implications of these findings for online cessation communities are discussed. (PsycINFO Database Record
-Glucokinase regulatory protein (GCKR) inhibitors offer a novel treatment approach for glucose co... more -Glucokinase regulatory protein (GCKR) inhibitors offer a novel treatment approach for glucose control in diabetes; however their cardiometabolic effects, particularly in relation to increased triglycerides and C-reactive protein (CRP) levels are of concern. GCKR Leu446Pro is a common variant associated with reduced GCKR function, increased triglycerides and CRP. -We investigated whether a 1-year intensive lifestyle intervention for weight loss (ILI) would avert the unfavorable cardiometabolic effects associated with GCKR Leu446Pro when compared to a diabetes support and education arm (DSE) in overweight/obese individuals with type 2 diabetes with triglyceride (n=3,214) and CRP (n=1,411) data participating in a randomized lifestyle intervention study for weight loss, Look AHEAD (Action for Health in Diabetes). Once demographics, medication use and baseline adiposity and fitness were accounted for, ILI did not modify the baseline association of GCKR-Leu446Pro with elevated triglycerides (β± SE= 0.067 ± 0.013, p= 1.5×10(-7) and β± SE= 0.052 ± 0.015, p=5×10(-4)) or with elevated CRP (β± SE= 0.136 ± 0.034, p=5.1×10(-5) and β± SE= 0.903 ± 0.038, p=0.015) in the overall sample and Non-Hispanic Whites, respectively. The lack of a protective effect from ILI at 1-year when compared to DSE (ILI versus DSE interaction for triglyceride and CRP change, respectively: p= 0.64 and 0.37 in the overall sample; p= 0.27 and 0.05 in Non-Hispanic Whites) persisted after additional adjustment for changes in adiposity and fitness. -Moderate improvements in adiposity and fitness with ILI did not mitigate the adverse cardiometabolic effects of GCKR inhibition in overweight/obese individuals with diabetes.
Numerous studies have found elevated depressive symptoms among individuals with Type 2 diabetes, ... more Numerous studies have found elevated depressive symptoms among individuals with Type 2 diabetes, yet the mechanisms remain unclear. We examined whether genetic loci previously associated with depressive symptoms predict depressive symptoms among overweight/obese individuals with Type 2 diabetes or change in depressive symptoms during behavioral weight loss. The Illumina CARe iSelect (IBC) chip and Cardiometabochip were characterized in 2118 overweight or obese participants with Type 2 diabetes from Look AHEAD (Action for Health in Diabetes), a randomized trial to determine the effects of intensive life-style intervention and diabetes support and education on cardiovascular morbidity and mortality. Primary analyses focused on baseline Beck Depression Inventory (BDI) scores and depressive symptom change at 1 year. Of eight single nucleotide polymorphisms (SNPs) in six loci, three a priori SNPs in two loci (chromosome 5: rs60271; LBR: rs2230419, rs1011319) were associated with baseline...
Numerous studies have found elevated depressive symptoms among individuals with Type 2 diabetes, ... more Numerous studies have found elevated depressive symptoms among individuals with Type 2 diabetes, yet the mechanisms remain unclear. We examined whether genetic loci previously associated with depressive symptoms predict depressive symptoms among overweight/obese individuals with Type 2 diabetes or change in depressive symptoms during behavioral weight loss. The Illumina CARe iSelect (IBC) chip and Cardiometabochip were characterized in 2118 overweight or obese participants with Type 2 diabetes from Look AHEAD (Action for Health in Diabetes), a randomized trial to determine the effects of intensive life-style intervention and diabetes support and education on cardiovascular morbidity and mortality. Primary analyses focused on baseline Beck Depression Inventory (BDI) scores and depressive symptom change at 1 year. Of eight single nucleotide polymorphisms (SNPs) in six loci, three a priori SNPs in two loci (chromosome 5: rs60271; LBR: rs2230419, rs1011319) were associated with baseline BDI scores, but in the opposite direction of prior research. In joint analysis of 90,003 IBC and Cardiometabochip SNPs, rs1543654 in the region of KCNE1 predicted change in BDI scores at Year 1 in diabetes support and education (β = -1.05, standard error [SE] = 0.21, p = 6.9 × 10) at the level of chip-wide significance, while also showing a nominal association with baseline BDI (β = 0.35, SE = 0.16, p = .026). Adjustment for antidepressant medication and/or limiting analyses to non-Hispanic white individuals did not meaningfully alter results. Previously reported genetic associations with depressive symptoms did not replicate in this cohort of overweight/obese individuals with Type 2 diabetes. We identified KCNE1 as a potential novel locus associated with depressive symptoms.
Clinically relevant weight loss is achievable through lifestyle modification, but unintentional w... more Clinically relevant weight loss is achievable through lifestyle modification, but unintentional weight regain is common. We investigated whether recently discovered genetic variants affect weight loss and/or weight regain during behavioral intervention. Participants at high-risk of (Diabetes Prevention Program [DPP]; N=917/907 intervention/comparison) or with (Look AHEAD; N=2,014/1,892 intervention/comparison) type 2 diabetes were from two parallel arm (lifestyle vs. comparison) randomized controlled trials. The associations of 91 established obesity-predisposing loci with weight loss across 4 years, and with weight regain across years-2-4 after a minimum of 3% weight loss, were tested. Each copy of the minor G allele of MTIF3 rs1885988 was consistently associated with greater weight loss following lifestyle intervention over 4-years across DPP and LA. No such effect was observed across comparison arms, leading to a nominally significant SNP × treatment interaction (P=4.3×10(-3)). However, this effect was not significant at a study-wise significance level (Bonferroni threshold P<5·8×10(-4)). Most obesity-predisposing gene variants were not associated with weight loss or regain within the DPP and Look AHEAD trials, directly or via interactions with lifestyle.
In this thesis, a mixture-model cluster analysis technique under different covariance structures ... more In this thesis, a mixture-model cluster analysis technique under different covariance structures of the component densities is developed and presented, to capture the compactness, orientation, shape, and the volume of component clusters in one expert system to handle Gaussian high dimensional heterogeneous data sets to achieve flexibility in currently practiced cluster analysis techniques. Two approaches to parameter estimation are considered and compared; one using the Expectation-Maximization (EM) algorithm and another following a Bayesian framework using the Gibbs sampler. We develop and score several forms of the ICOMP criterion of Bozdogan (1994, 2004) as our fitness function; to choose the number of component clusters, to choose the correct component covariance matrix structure among nine candidate covariance structures, and to select the optimal parameters and the best fitting mixture-model. We demonstrate our approach on simulated datasets and a real large data set, focusing...
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