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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

Walking, public transit, and transitions to non-driving among US Medicare enrollees

Background Many older adults rely on private vehicles for their mobility and may continue to drive when they are advised to stop. Walking and public transit can fulfill mobility needs in some contexts, but in the U.S. these options may not adequately substitute for driving when older adults reduce or stop driving. We examined whether baseline walking or taking public transit was associated with reductions in older adults’ driving after a three-year period in the United States. Methods We analyzed National Health and Aging Trends Study data from community-dwelling older drivers in 2015 (n = 4574). We used weighted logistic regression to estimate associations between older drivers’ walking and use of public transit in 2015 and changes in their driving behavior three years later—avoiding more driving conditions, driving less often, or not driving at all. We also examined associations between neighborhood walkability and driving behavior change three years later. Results There were no statistically significant associations between walking or taking public transit in 2015 and the adjusted odds of driving behavior change three years later. However, older drivers living in the most walkable neighborhoods in 2015 had greater adjusted odds of avoiding more driving conditions compared to those in the least walkable neighborhoods (adjusted Odds Ratio (aOR) = 1.66; 95 % Confidence Interval (95 % CI): 1.23-2.25). Living in the most walkable neighborhoods compared to the least walkable neighborhoods was also associated with an increased odds of no longer driving in 2018 (aOR = 1.56; 95 % CI: 1.04–2.36). Discussion The walkability of one’s neighborhood area—shorter distances between blocks, diverse land uses, and proximity to transit stops—is associated with driving behavior changes over time for older drivers. This work can inform programs and policies designed to connect older adults with alternative transportation options to driving.

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

Importance Prior literature has explored the prevalence of motor impairments in autistic individuals, but estimates come from clinical, convenience, or small samples, limiting generalizability. Better understanding of the frequency of motor milestone delays in autistic individuals could improve early identification and subsequently lead to earlier intervention and better developmental outcomes. Objective 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 at autism evaluation or diagnosis. Design, Setting, and Participants This cross-sectional study of autistic 8-year-old children was conducted using Autism and Developmental Disabilities Monitoring (ADDM) Network data between surveillance years 2000 and 2016. ADDM Network data are population based and are drawn from 17 sites across the US. Data were analyzed from October 2023 to August 2024. Exposure Binary indicator of motor milestone delays documented in health or educational records. Main Outcomes and Measures The primary outcome was the prevalence of motor milestone delays among autistic 8-year-old children. Associations between motor milestone delays and age at autism evaluation or diagnosis were evaluated using linear regression. Covariates included study site, surveillance year, the number of autism discriminators, intellectual disability, child sex, and child race and ethnicity. Results Among 32 850 children aged 8 years identified with autism by active surveillance, 23 481 children (71.5%) met criteria for motor milestone delays. A total of 5973 children (18.2%) were female. In linear regression models, children with motor milestone delays were evaluated for autism significantly earlier (mean age, 43.65 months; 95% CI, 43.38-43.91) than children without motor milestone delays (mean age, 51.64 months; 95% CI, 51.22-52.06). 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 ID. Conclusions and Relevance This cross-sectional study estimates the prevalence of motor milestone delays among autistic 8-year-old children 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 assessing motor milestone delays, particularly in children with an increased likelihood of being autistic, may facilitate an earlier autism evaluation, leading to more timely interventions and better developmental outcomes.