Education & Certifications
PhD, Johns Hopkins School of Public Health, Biostatistics (2011)
BA, St. Olaf College, Mathematics with minors in Statistics and Linguistics (2006)
Although controlled donation after circulatory determination of death (cDCDD) could increase the supply of donor lungs within the United States, the yield of lungs from cDCDD donors remains low compared with donation after neurologic determination of death (DNDD). To explore the reason for low lung yield from cDCDD donors, Scientific Registry of Transplant Recipient data were used to assess the impact of donor lung quality on cDCDD lung utilization by fitting a logistic regression model. The relationship between center volume and cDCDD use was assessed, and the distance between center and donor hospital was calculated by cDCDD status. Recipient survival was compared using a multivariable Cox regression model. Lung utilization was 2.1% for cDCDD donors and 21.4% for DNDD donors. Being a cDCDD donor decreased lung donation (adjusted odds ratio 0.101, 95% confidence interval [CI] 0.085-0.120). A minority of centers have performed cDCDD transplant, with higher volume centers generally performing more cDCDD transplants. There was no difference in center-to-donor distance or recipient survival (adjusted hazard ratio 1.03, 95% CI 0.78-1.37) between cDCDD and DNDD transplants. cDCDD lungs are underutilized compared with DNDD lungs after adjusting for lung quality. Increasing transplant center expertise and commitment to cDCDD lung procurement is needed to improve utilization.
View details for DOI 10.1111/ajt.13599
View details for Web of Science ID 000373075400021
The relationship between statin use and non-melanoma skin cancer (NMSC) is unclear with conflicting findings in literature. Data from the Women's Health Initiative (WHI) Observational Study and WHI Clinical Trial were used to investigate the prospective relationship between statin use and NMSC in non-Hispanic white (NHW) postmenopausal women.The WHI study enrolled women aged 50-79 years at 40 US centres. Among 133 541 NHW participants, 118 357 with no cancer history at baseline and complete medication/covariate data comprised the analytic cohort. The association of statin use (baseline, overall as a time-varying variable, duration, type, potency, lipophilicity) and NMSC incidence was determined using random-effects logistic regression models.Over a mean of 10.5 years of follow-up, we identified 11 555 NMSC cases. Compared with participants with no statin use, use of any statin at baseline was associated with significantly increased NMSC incidence (adjusted odds ratio (ORadj) 1.21; 95% confidence interval (CI): 1.07-1.35)). In particular, lovastatin (OR 1.52; 95% CI: 1.08-2.16), simvastatin (OR 1.38; 95% CI: 1.12-1.69), and lipophilic statins (OR 1.39; 95% CI: 1.18-1.64) were associated with higher NMSC risk. Low and high, but not medium, potency statins were associated with higher NMSC risk. No significant effect modification of the statin-NMSC relationship was found for age, BMI, smoking, solar irradiation, vitamin D use, and skin cancer history.Use of statins, particularly lipophilic statins, was associated with increased NMSC risk in postmenopausal white women in the WHI cohort. The lack of duration-effect relationship points to possible residual confounding. Additional prospective research should further investigate this relationship.
View details for DOI 10.1038/bjc.2015.376
View details for Web of Science ID 000369223600011
View details for PubMedID 26742009
Genome-wide association studies have identified polymorphisms linked to both smoking exposure and risk of lung cancer. The degree to which lung cancer risk is driven by increased smoking, genetics, or gene-environment interactions is not well understood.We analyzed associations between 28 single nucleotide polymorphisms (SNPs) previously associated with smoking quantity and lung cancer in 7156 African-American females in the Women's Health Initiative (WHI), then analyzed main effects of top nominally significant SNPs and interactions between SNPs, cigarettes per day (CPD) and pack-years for lung cancer in an independent, multi-center case-control study of African-American females and males (1078 lung cancer cases and 822 controls).Nine nominally significant SNPs for CPD in WHI were associated with incident lung cancer (corrected p-values from 0.027 to 6.09 × 10(- 5)). CPD was found to be a nominally significant effect modifier between SNP and lung cancer for six SNPs, including CHRNA5 rs2036527[A](betaSNP*CPD = - 0.017, p = 0.0061, corrected p = 0.054), which was associated with CPD in a previous genome-wide meta-analysis of African-Americans.These results suggest that chromosome 15q25.1 variants are robustly associated with CPD and lung cancer in African-Americans and that the allelic dose effect of these polymorphisms on lung cancer risk is most pronounced in lighter smokers.
View details for DOI 10.1016/j.ebiom.2016.01.002
View details for PubMedID 26981579
We examined the social and economic factors associated with nursing home (NH) admission in older women, overall and poststroke.The Women's Health Initiative (WHI) included women aged 50-79 years at enrollment (1993-1998). In the WHI Extension Study (2005-2010), participants annually reported any NH admission in the preceding year. Separate multivariate logistic regression models analyzed social and economic factors associated with long-term NH admission, defined as an admission on 2 or more questionnaires, overall and poststroke.Of 103,237 participants, 8904 (8.6%) reported NH admission (2005-2010); 534 of 2225 (24.0%) women with incident stroke reported poststroke NH admission. Decreased likelihoods of NH admission overall were demonstrated for Asian, Black, and Hispanic women (versus whites, adjusted odds ratio [aOR] = .35-.44, P < .001) and women with higher income (aOR = .75, 95% confidence interval [CI] = .63-.90), whereas increased likelihoods of NH admission overall were seen for women with lower social support (aOR = 1.34, 95% CI = 1.16-1.54) and with incident stroke (aOR = 2.59, 95% CI = 2.15-3.12). Increased odds of NH admission after stroke were demonstrated for women with moderate disability after stroke (aOR = 2.76, 95% CI = 1.73-4.42). Further adjustment for stroke severity eliminated the association found for race/ethnicity, income, and social support.The level of care needed after a disabling stroke may overwhelm social and economic structures in place that might otherwise enable avoidance of NH admission. We need to identify ways to provide care consistent with patients' preferences, even after a disabling stroke.
View details for DOI 10.1016/j.jstrokecerebrovasdis.2015.06.013
View details for Web of Science ID 000362181400029
It is unknown whether supplementation with calcium and vitamin D has an impact on menopause-related symptoms.As part of the Women's Health Initiative Calcium/Vitamin D Supplementation Trial (CaD), women were randomized at 40 clinical sites to elemental calcium carbonate 1000 mg with vitamin D 400 IU daily or placebo. At the CaD baseline visit (year 1 or year 2) and during a mean follow-up of 5.7 years, participants provided data on menopause-related symptoms via questionnaires. Generalized linear mixed effects techniques were used to address research questions.After excluding participants with missing data (N=2125), we compared menopause-related symptoms at follow-up visits of 17,101 women randomized to CaD with those of 17,056 women given the placebo. Women in the CaD arm did not have a different number of symptoms at follow-up compared to women taking the placebo (p=0.702). Similarly, there was no difference between sleep disturbance, emotional well-being, or energy/fatigue at follow-up in those who were randomized to CaD supplementation compared to those taking the placebo.Our data suggest that supplementation with 1000 mg of calcium plus 400 IU of vitamin D does not influence menopause-related symptoms over an average of 5.7 years of follow-up among postmenopausal women with an average age of 64 at the WHI baseline visit.
View details for DOI 10.1016/j.maturitas.2015.04.007
View details for Web of Science ID 000357229600009
View details for PubMedID 26044075
Insulin resistance is associated with diabetes mellitus, but it is uncertain whether it improves cardiovascular disease (CVD) risk prediction beyond traditional cardiovascular risk factors.We identified 15,288 women from the Women's Health Initiative Biomarkers studies with no history of CVD, atrial fibrillation, or diabetes mellitus at baseline (1993-1998). We assessed the prognostic value of adding fasting serum insulin, HOMA-IR (homeostasis model assessment-insulin resistance), serum-triglyceride-to-serum-high-density lipoprotein-cholesterol ratio TG/HDL-C, or impaired fasting glucose (serum glucose ≥110 mg/dL) to traditional risk factors in separate Cox multivariable analyses and assessed risk discrimination and reclassification. The study end point was major CVD events (nonfatal and fatal coronary heart disease and ischemic stroke) within 10 years, which occurred in 894 (5.8%) women. Insulin resistance was associated with CVD risk after adjusting for age and race/ethnicity with hazard ratios (95% confidence interval [CI]) per doubling in insulin of 1.21 (CI, 1.12-1.31), in HOMA-IR of 1.19 (CI, 1.11-1.28), in TG/HDL-C of 1.35 (CI, 1.26-1.45), and for impaired fasting glucose of 1.31 (CI, 1.05-1.64). Although insulin, HOMA-IR, and TG/HDL-C remained associated with increased CVD risk after adjusting for most CVD risk factors, none remained significant after adjusting for HDL-C: hazard ratios for insulin, 1.06 (CI, 0.98-1.16); for HOMA-IR, 1.06 (CI, 0.98-1.15); for TG/HDL-C, 1.11 (CI, 0.99-1.25); and for glucose, 1.20 (CI, 0.96-1.50). Insulin resistance measures did not improve CVD risk discrimination and reclassification.Measures of insulin resistance were no longer associated with CVD risk after adjustment for high-density lipoprotein-cholesterol and did not provide independent prognostic information in postmenopausal women without diabetes mellitus.URL: http://www.clinicaltrial.gov. Unique identifier: NCT00000611.
View details for DOI 10.1161/CIRCOUTCOMES.114.001563
View details for PubMedID 25944628
It is unclear whether obesity unaccompanied by metabolic abnormalities is associated with increased cardiovascular disease risk across racial and ethnic subgroups.We identified 14 364 postmenopausal women from the Women's Health Initiative who had data on fasting serum lipids and serum glucose and no history of cardiovascular disease or diabetes at baseline. We categorized women by body mass index (in kg/m(2)) as normal weight (body mass index 18.5 to <25), overweight (body mass index 25 to <30), or obese (body mass index ≥30) and by metabolic health, defined first as the metabolic syndrome (metabolically unhealthy: ≥3 metabolic abnormalities) and second as the number of metabolic abnormalities. We used Cox proportional hazards regression to assess associations between baseline characteristics and cardiovascular risk. Over 13 years of follow-up, 1101 women had a first cardiovascular disease event (coronary heart disease or ischemic stroke). Among black women without metabolic syndrome, overweight women had higher adjusted cardiovascular risk than normal weight women (hazard ratio [HR] 1.49), whereas among white women without metabolic syndrome, overweight women had similar risk to normal weight women (HR 0.92, interaction P=0.05). Obese black women without metabolic syndrome had higher adjusted risk (HR 1.95) than obese white women (HR 1.07; interaction P=0.02). Among women with only 2 metabolic abnormalities, cardiovascular risk was increased in black women who were overweight (HR 1.77) or obese (HR 2.17) but not in white women who were overweight (HR 0.98) or obese (HR 1.06). Overweight and obese women with ≤1 metabolic abnormality did not have increased cardiovascular risk, regardless of race or ethnicity.Metabolic abnormalities appeared to convey more cardiovascular risk among black women.
View details for DOI 10.1161/JAHA.114.001695
View details for PubMedID 25994446
Lung cancer is the leading cause of worldwide cancer deaths. While smoking is its leading risk factor, few prospective cohort studies have reported on the association of lung cancer with both active and passive smoking. This study aimed to determine the relationship between lung cancer incidence with both active and passive smoking (childhood, adult at home, and at work).The Women's Health Initiative Observational Study (WHI-OS) was a prospective cohort study conducted at 40 US centers that enrolled postmenopausal women from 1993 to 1999. Among 93 676 multiethnic participants aged 50-79, 76 304 women with complete smoking and covariate data comprised the analytic cohort. Lung cancer incidence was calculated by Cox proportional hazards models, stratified by smoking status.Over 10.5 mean follow-up years, 901 lung cancer cases were identified. Compared with never smokers (NS), lung cancer incidence was much higher in current [hazard ratio (HR) 13.44, 95% confidence interval (CI) 10.80-16.75] and former smokers (FS; HR 4.20, 95% CI 3.48-5.08) in a dose-dependent manner. Current and FS had significantly increased risk for all lung cancer subtypes, particularly small-cell and squamous cell carcinoma. Among NS, any passive smoking exposure did not significantly increase lung cancer risk (HR 0.88, 95% CI 0.52-1.49). However, risk tended to be increased in NS with adult home passive smoking exposure ≥30 years, compared with NS with no adult home exposure (HR 1.61, 95% CI 1.00-2.58).In this prospective cohort of postmenopausal women, active smoking significantly increased risk of all lung cancer subtypes; current smokers had significantly increased risk compared with FS. Among NS, prolonged passive adult home exposure tended to increase lung cancer risk. These data support continued need for smoking prevention and cessation interventions, passive smoking research, and further study of lung cancer risk factors in addition to smoking.NCT00000611.
View details for DOI 10.1093/annonc/mdu470
View details for Web of Science ID 000347416300034
View details for PubMedID 25316260
To measure the following three relevant outcomes of a personal preparedness curriculum for public health workers: 1) the extent of change (increase) in knowledge about personal preparedness activities and knowledge about tools for conducting personal preparedness activities; 2) the extent of change (increase) in preparedness activities performed post-training and/or confidence in conducting these tasks; and 3) an understanding of how to improve levels of personal preparedness using the Extended Parallel Process Model (EPPM) framework.Cross-sectional preinterventional and postinterventional survey using a convenience sample.During 2010, three face-to-face workshops were conducted in three locations in West Virginia.One hundred thirty-one participants (baseline survey); 69 participants (1-year resurvey)-representing West Virginia local health department (LHD) and State Health Department employees.A 3-hour interactive, public health-specific, face-to-face workshop on personal disaster preparedness.Change in 1) knowledge about, and tools for, personal preparedness activities; 2) preparedness activities performed post-training and/or confidence in conducting these activities; and 3) the relationship of EPPM categories to personal preparedness activities.One year postworkshop, 77 percent of respondents reported having personal emergency kits (40 percent at baseline) and 67 percent reported having preparedness plans (38 percent at baseline) suggesting some participants assembled supply kits and plans postworkshop. Within the context of EPPM, respondents in high-threat categories agreed more often than respondents in low-threat categories that severe personal impacts were likely to result from a moderate flood. Compared to respondents categorized as low efficacy, respondents in high-efficacy categories perceived confidence in their knowledge and an impact of their response on their job success at higher rates.Personal disaster preparedness trainings for the LHD workforce can yield gains in relevant preparedness behaviors and attitudes but may require longitudinal reinforcement. The EPPM can offer a useful threat and efficacy-based lens to understand relevant perceptions surrounding personal disaster preparedness behaviors among LHD employees.
View details for DOI 10.5055/jem.2014.0162
View details for PubMedID 24691916
Exercise use among patients with cancer has been shown to have many benefits and few notable risks. The purpose of this study was to evaluate the impact of a home-based walking intervention during cancer treatment on sleep quality, emotional distress, and fatigue. Methods. A total of 138 patients with prostate (55.6%), breast (32.5%), and other solid tumors (11.9%) were randomized to a home-based walking intervention or usual care. Exercise dose was assessed using a five-item subscale of the Cooper Aerobics Center Longitudinal Study Physical Activity Questionnaire. Primary outcomes of sleep quality, distress, and fatigue were compared between the two study arms. Results. The exercise group (n = 68) reported more vigor (p = .03) than control group participants (n = 58). In dose response models, greater participation in aerobic exercise was associated with 11% less fatigue (p < .001), 7.5% more vigor (p = .001), and 3% less emotional distress (p = .03), after controlling for intervention group assignment, age, and baseline exercise and fatigue levels. Conclusion. Patients who exercised during cancer treatment experienced less emotional distress than those who were less active. Increasing exercise was also associated with less fatigue and more vigor. Home-based walking is a simple, sustainable strategy that may be helpful in improving a number of symptoms encountered by patients undergoing active treatment for cancer.
View details for DOI 10.1634/theoncologist.2012-0278
View details for Web of Science ID 000318336200024
View details for PubMedID 23568000
Researchers often describe the collection of repeated measurements on each individual in a study design. Advanced statistical methods, namely, mixed and marginal models, are the preferred analytic choices for analyzing this type of data.The aim was to provide a conceptual understanding of these modeling techniques.An understanding of mixed models and marginal models is provided via a thorough exploration of the methods that have been used historically in the biomedical literature to summarize and make inferences about this type of data. The limitations are discussed, as is work done on expanding the classic linear regression model to account for repeated measurements taken on an individual, leading to the broader mixed-model framework.A description is provided of a variety of common types of study designs and data structures that can be analyzed using a mixed model and a marginal model.This work provides an overview of advanced statistical modeling techniques used for analyzing the many types of correlated .data collected in a research study.
View details for DOI 10.1097/NNR.0b013e31824f5f58
View details for Web of Science ID 000303604500006
View details for PubMedID 22551993
This paper reports the results of a clinical investigation to determine the sustainability of intervention effects to lower blood pressure (BP) that were obtained through a short-term education via home telemonitoring of BP and regular counseling by bilingual nurses during 1 year. A total of 359 middle-aged (40-64 years) Korean immigrants completed a 15-month intervention that consisted of 6-week behavioral education followed by home telemonitoring of BP and bilingual nurse telephone counseling for 12 months. The final analysis revealed a sharp increase in BP control rates sustained for more than 12 months. At baseline, only 30% of the sample achieved BP control (<140/90 mm Hg). After the initial education period (approximately 3 months), 73.3% of the participants had controlled BP levels. The levels of control were maintained and continuously improved during a 12-month follow-up period (83.2%, P<.001). These findings suggest that home telemonitoring of BP and tailored counseling are both useful tools to sustain or improve short-term education effects.
View details for DOI 10.1111/j.1751-7176.2011.00479.x
View details for Web of Science ID 000293349600010
View details for PubMedID 21806771
Although a variety of intervention methods have been used to promote Pap test screening among ethnic minority women in the US, the effectiveness of such interventions is unclear. We performed a meta-analysis to examine the overall effectiveness of these interventions in increasing Pap test use by ethnic minority women in the US.A search of databases (MEDLINE, Cumulative Index to Nursing and Allied Health Literature, PsycINFO, and Science Citation Index-Expanded) and review articles for articles published between 1984 and April 2009 identified 18 randomized and non-randomized controlled trials. The primary study outcome was the difference in the proportion of Pap tests between the treatment and comparison groups.The pooled mean weighted effect size (d) for the 18 studies was 0.158 (95% confidence interval [CI]=0.100, 0.215), indicating that the interventions were effective in improving Pap test use among ethnic minority women. Among the intervention types, access enhancement yielded the largest effect size (0.253 [95% CI=0.110, 0.397]), followed by community education (0.167 [95% CI=0.057, 0.278]) and individual counseling or letters (0.132 [95% CI=0.069, 0.195]). Combined intervention effects were significant for studies targeting Asian (0.177 [95% CI=0.098, 0.256]) and African American women (0.146 [95% CI=0.028, 0.265]), but not Hispanic women (0.116 [95% CI=-0.008, 0.240]).Pap test use among ethnic minority women is most likely to increase when access-enhancing strategies are combined. Further research is needed to determine whether more tightly controlled trials of such interventions might reveal an improved rate of cervical cancer screening in Hispanic women as well.
View details for DOI 10.1002/pon.1754
View details for Web of Science ID 000288860400001
View details for PubMedID 20878847
: We evaluated whether tibia lead was associated with longitudinal change in brain volumes and white matter lesions in male former lead workers and population-based controls in whom we have previously reported on the cognitive and structural consequences of cumulative lead dose.: We used linear regression to identify predictors of change in brain volumes and white matter lesion grade scores, using two magnetic resonance imaging scans an average of 5 years apart.: On average, total brain volume declined almost 30 cm, predominantly in gray matter. Increasing age at the first magnetic resonance imaging was strongly associated with larger declines in volumes and greater increases in white matter lesion scores. Tibia lead was not associated with change in brain volumes or white matter lesion scores.: In former lead workers in whom cumulative lead dose was associated with progressive declines in cognitive function decades after occupational exposure had ended, cumulative lead dose was associated with earlier persistent effects on brain structure but not with additional worsening during 5 years.
View details for DOI 10.1097/JOM.0b013e3181d5e386
View details for Web of Science ID 000276668300006
View details for PubMedID 20357679
View details for Web of Science ID 000282840000011
Although many studies have been focused on interventions designed to promote mammography screening among ethnic minority women, few summaries of the effectiveness of the interventions are available.The aim of this study was to determine the effectiveness of the interventions for improving mammography screening among asymptomatic ethnic minority women.A meta-analysis was performed on intervention studies designed to promote mammography use in samples of ethnic minority women. Random-effects estimates were calculated for interventions by measuring differences in intervention and control group screening rates postintervention.The overall mean weighted effect size for the 23 studies was 0.078 (Z = 4.414, p < .001), indicating that the interventions were effective in improving mammography use among ethnic minority women. For mammography intervention types, access-enhancing strategies had the biggest mean weighted effect size of 0.155 (Z = 4.488, p < .001), followed by 0.099 (Z = 6.552, p < .001) for individually directed approaches such as individual counseling or education. Tailored, theory-based interventions resulted in a bigger effect size compared with nontailored interventions (effect sizes = 0.101 vs. 0.076, respectively; p < .05 for all models). Of cultural strategies, ethnically matched intervention deliveries and offering culturally matched intervention materials had effect sizes of 0.067 (Z = 2.516, p = .012) and 0.051 (Z = 2.365, p = .018), respectively.Uniform improvement in mammography screening is a goal to address breast cancer disparities in ethnic minority communities in this country. The results of this meta-analysis suggest a need for increased use of a theory-based, tailored approach with enhancement of access.
View details for Web of Science ID 000268162700004
View details for PubMedID 19609176