Time to licensure for driving among U.S. teens: Survival analysis of interval-censored survey data

Abstract

Objective

Novice drivers who delay in driving licensure may miss safety benefits of Graduate Driver Licensing (GDL) programs, potentially putting themselves at higher crash-risk. Time to licensure relates their access to independent transportation to potential future economic- and educational-related opportunities. The objective of this study was to explore time to licensure associations with teens’ race/ethnicity and GDL restrictions.

Methods

Secondary analysis using all seven annual assessments of the NEXT Generation Health Study, a nationally representative longitudinal study starting with 10th grade (N = 2785; 2009–2010 school year). Data were collected in U.S. public/private schools, colleges, workplaces, and other settings. The outcome variable was interval-censored time to licensure (event = obtained driving licensure). Independent variables included race/ethnicity and state-specific GDL restrictions. Covariates included family affluence, parent education, nativity, sex, and urbanicity. Proportional hazards (PH) models were conducted for interval-censored survival analysis based on stepwise backward elimination for fitting multivariate models with consideration of complex survey features. In the PH models, a hazard ratio (HR) estimates a greater (>1) or lesser (<1) likelihood of licensure at all timepoints.

Results

Median time to licensure after reaching legal driving age for Latinos, African Americans, and Non-Latino Whites was 3.47, 2.90, and 0.41 years, respectively. Multivariate PH models showed that Latinos were 46% less likely (HR = 0.54, 95%CI: 0.35–0.72) and African Americans were 56% less likely (HR = 0.44, 95%CI: 0.32–0.56) to have obtained licensure at any time compared to Non-Latino Whites. Only learner minimum age GDL restriction was associated with time to licensure. Living in a state with a required learner driving minimum age of ≥16 years (HR = 0.57, 95%CI: 0.16–0.98) also corresponded with 43% lower likelihood of licensure at legal eligibility compared to living in other states with a required learner driving minimum age of <16 years.

Conclusion

Latinos and African American teens obtained their license approximately three years after eligibility on average, and much later than Non-Latino Whites. Time to licensure likelihood was associated with race/ethnicity and required minimum age of learner permit, indicating important implications for teens of different racial/ethnic groups in relation to licensure, access to independent transportation, and exposure to GDL programs.

Keywords:

• Graduate driver licensing
• novice drivers
• time to licensure
• survival analysis

Acknowledgment

We thank Dr. Jimikaye Courtney at Colorado State University for her contributions in selected aspects of analysis coding and manuscript editing.

Additional information

Funding

NIAAA Funding Support: Research reported in this publication was supported by the National Institute on Alcohol Abuse and Alcoholism of the National Institutes of Health under Award Numbers R21AA026346 and R01AA026313. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. NICHD – NEXT Generation Health Study: This project (contract HHSN275201200001I) was supported in part by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development; the National Heart, Lung, and Blood Institute; the National Institute on Alcohol Abuse and Alcoholism; the National Institute on Drug Abuse; and the Maternal and Child Health Bureau of the Health Resources and Services Administration.