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Ronald Gangnon

Professor of Biostatistics

University of Wisconsin-Madison

Biography

I am a Professor in the Department of Biostatistics and Medical Informatics and the Department of Population Health Sciences in the School of Medicine and Public Health at the University of Wisconsin-Madison. I have an affiliate appointment in the Department of Statistics.

I grew up in Duluth, Minnesota. I graduated from East High School in 1988. I received a BA in Mathematics and Economics in 1992 from the University of Minnesota-Duluth and an MS in Statistics in 1994 and a PhD in Statistics with emphasis in Biostatistics in 1998 from the University of Wisconsin-Madison. My PhD advisor was Murray Clayton.

I was a research scientist in the Statistical Data Analysis Center(SDAC) in the Department of Biostatistics and Medical Informatics at the University of Wisconsin-Madison, 1998-2005. I joined the faculty with a joint appointment in the Department of Biostatistics and Medical Informatics and the Department of Population Health Sciences in 2005.

I am an applied biostatistician focusing on problems in clinical and epidemiologic research. Current methodologic areas of interest include (1) multi-state models for incidence, progression and regression of ocular (and other) diseases, (2) small area estimation problems, particularly ranking, (3) spatial and spatio-temporal modeling, particularly cluster detection and high-dimensional variable selection and (4) age-period-cohort modeling.

Outside of the office, I’m an avid cyclist. You can check out my recent rides on Strava. I’m also a big movie fan. You’ll definitely see me at the Wisconsin Film Festival, one of my favorite events every year, and you can see lists of my favorite films and what I’ve been watching recently on Letterboxd.

Interests

  • Spatial and Spatio-Temporal Modeling
  • Age-Period-Cohort Models
  • Ranking
  • Multi-State Models

Education

  • PhD in Statistics (emphasis in Biostatistics), 1998

    University of Wisconsin-Madison

  • MS in Statistics, 1994

    University of Wisconsin-Madison

  • BA in Mathematics and Economics, 1992

    University of Minnesota-Duluth

Publications

Lower Neighborhood-level Socioeconomic Status is Associated with Lower Colorectal Cancer Screening Uptake in the Southern Community Cohort Study

Colorectal cancer (CRC) is highly preventable with timely screening, but screening modalities are widely underused, especially among those of low individual-level socioeconomic status (SES). In addition to individual-level SES, neighborhood-level SES may also play a role in CRC screening completion through less geographic access to health care, transportation, and community knowledge of and support for screenings. We investigated the associations between neighborhood SES using a census tract-level measure of social and economic conditions with the uptake of colonoscopy and stool-based testing. We utilized data from the Southern Community Cohort Study, a large, prospective study of English-speaking adults aged 40-79 from the southeastern United States with 65% of participants identifying as non-Hispanic Black and 53% having annual household income <$15,000. Neighborhood SES was measured via a Neighborhood Deprivation Index compiled from principal component analysis of 11 census tract variables in the domains of education, employment, occupation, and poverty; screening was self-reported at the baseline interview (2002-2009) and follow-up interview (2008-2012). We found that participants residing in the lowest SES areas had lower odds of ever undergoing colonoscopy (ORQ5vsQ1=0.75; 95%CI=[0.68, 0.82]) or stool-based CRC testing (ORQ5vsQ1=0.71; 95%CI=[0.63, 0.80]), while adjusting for individual-level SES factors. Associations were consistent between neighborhood SES and screening in subgroups defined by race, sex, household income, insurance, or education (p>0.20 for all interaction tests). Our findings suggest that barriers to screening exist at the neighborhood level and that residents of lower SES neighborhoods may experience more barriers to screening using colonoscopy and stool-based modalities.

Physical Activity and Supportive Care Intervention Preferences: A Cross-Sectional Study of Barriers in Advanced Cancer

Purpose Physical activity may greatly benefit adults living with advanced cancer; however, barriers to physical activity and preferences for supportive care interventions are not well understood. This study investigates barriers to physical activity and differences in intervention preferences by demographic and clinical characteristics among adults with advanced cancer. Methods Data came from a cross-sectional study of 247 adults with advanced cancer who visited the University of Wisconsin Carbone Cancer Centre from January 2021 to January 2023. The Godin–Shepard Leisure Score Index (insufficiently active, moderately active and active) was used to assess physical activity. Physical activity barriers were reported as mean scores (1–5: ‘not at all’ to ‘a great deal’). Differences in intervention preferences were assessed using X2 tests. Results Adults living with advanced cancer were insufficiently active (53%), moderately active (21%) or active (26%). Respondents identified several barriers to physical activity spanning tiredness (x̄=3.2), winter weather concerns (x̄=3.2) and lack of motivation (x̄=2.7). Respondents were most interested in a supportive care intervention designed to increase energy (88%) and improve physical health (86%) with physical therapy (73%), walking (72%) and resistance exercises (72%). Differences in preferences emerged by demographic characteristics and to a lesser extent by clinical characteristics. Conclusions Adults with advanced cancer reported several barriers to physical activity. Future interventions should emphasise increasing energy and physical health and include strategies to manage tiredness and winter weather concerns.

Intrapartum Care Experiences Associated with Postpartum Visit Attendance

Introduction: The postpartum visit is an important opportunity to prevent pregnancy-related morbidity and mortality; however, about 1 in 10 birthing people fail to attend this visit. Intrapartum care experiences are an understudied factor that may contribute to postpartum healthcare engagement. Materials and Methods: We analyze data from a novel survey supplement on intrapartum care experiences administered to a probability-based population sample of people who have recently given birth through the Wisconsin Pregnancy Risk Assessment Monitoring System. Results: In regression models adjusting for a robust set of individual characteristics and birth hospital clustering, we find that lower provider responsiveness during intrapartum care is associated with increased odds of forgoing the postpartum visit (aOR 1.4, 95% CI 1.0-2.0). Discussion: The quality of care received during the birth hospitalization may shape how birthing people feel about health care providers and their willingness to attend future visits. Experiences of care during the intrapartum period may contribute to postpartum mental health outcomes and future health care utilization. Improving these experiences is an opportunity to promote long-term health.

Prevalence of Motor Milestone Delays in Autistic Children: A Population-based Cross-sectional Study

Importance: Prior literature has explored the prevalence of motor impairments in autistic individuals, but estimates come from clinical samples, convenience samples, or small sample sizes, which limits their generalizability. Better understanding of the frequency of motor milestone delays in autistic individuals could lead to improved early identification and subsequently earlier intervention and better developmental outcomes. Objectives: To determine the prevalence of motor milestone delays in a population-based sample of 8-year-old autistic children and to evaluate if having motor milestone delays is associated with an earlier age of autism evaluation or diagnosis. Design: Cross-sectional study of Autism and Developmental Disabilities Monitoring (ADDM) Network data between surveillance years 2000 and 2016. Data were analyzed from October 2023 to AugustMay 2024. Setting: ADDM Network data are population-based and come from 17 sites across the United States. Participants: Population-based sample of autistic 8-year-old children. Exposures: Binary indicator of motor milestone delays. Main Outcomes and Measures: The prevalence of motor milestone delays among autistic 8-year-old children was calculated. Associations between motor milestone delays and age of autism evaluation or diagnosis were evaluated using linear regression. Covariates included study site, surveillance year, the sum of autism discriminators, intellectual disability, child sex, race, and ethnicity. Results: Among 32,850 children aged 8 years identified with autism by active surveillance, 71.4% met criteria for motor milestone delays. In adjusted regression models, children with motor milestone delays (44.2 months of age; 95% CI, 43.5-44.9) were evaluated for autism significantly earlier (44.2 months of age; 95% CI, 43.5-44.9) than children without motor milestone delays (50.5 months of age; 95% CI, 49.7-51.2). After stratifying by the co-occurrence of intellectual disability (ID), children with motor milestone delays were evaluated for autism earlier than those without motor milestone delays, regardless of having ID. Conclusions and Relevance: This study estimates the prevalence of motor milestone delays among autistic youth and highlights the association between these delays and an earlier autism evaluation, even in children without co-occurring ID. Early identification of autism is a public health priority and examining motor milestone delays may facilitate an earlier autism evaluation, leading to more timely interventions and better developmental outcomes.

Racial disparities in intrapartum care experiences and birth hospital characteristics

Policymakers and researchers have posited intrapartum care as a potential mediator of racial inequities in perinatal outcomes. However, few studies have measured patient-centered quality of intrapartum care or explored differences by race. To address this gap, we developed a survey supplement using cognitive interviewing and administered it to a probability-based race-stratified random sample of people who recently gave birth in Wisconsin in 2020, including oversamples of non-Hispanic Black and Indigenous birthing people. We estimate overall and race-specific prevalences of intrapartum care experiences and use survey-weighted mixed effects ordinal and logistic regression to estimate differences in intrapartum care experiences by race/ethnicity and hospital characteristics. We find significant racial differences in the population prevalence of negative experiences of intrapartum care providers, including disrespect, lack of responsiveness, inclusion in decision-making about care, and pressure to use epidural analgesia. In unadjusted models, both non-Hispanic Indigenous (American Indian/Alaska Native) and non-Hispanic Black respondents had higher odds (than non-Hispanic White birthing people) of reporting several negative intrapartum experiences, including feeling disrespected by providers and experiencing a lower level of care team responsiveness. In adjusted models, Indigenous respondents had significantly higher odds of reporting that intrapartum care providers withheld information, showed disrespect, and were less responsive. Giving birth at a low birth-volume hospital was associated with higher odds of reporting greater participation in decision-making.