The Health and economic effects of light rail lines: design, methods, and protocol for a natural experiment

The TROLLEY Study: assessing travel, health, and equity impacts of a new light rail transit investment during the COVID-19 pandemic

BACKGROUND

The COVID-19 pandemic disrupted life in extraordinary ways impacting health and daily mobility. Public transit provides a strategy to improve individual and population health through increased active travel and reduced vehicle dependency, while ensuring equitable access to jobs, healthcare, education, and mitigating climate change. However, health safety concerns during the COVID-19 pandemic eroded ridership, which could have longstanding negative consequences. Research is needed to understand how mobility and health change as the pandemic recedes and how transit investments impact health and equity outcomes.

METHODS

The TROLLEY (TRansit Opportunities for HeaLth, Livability, Exercise and EquitY) study will prospectively investigate a diverse cohort of university employees after the opening of a new light rail transit (LRT) line and the easing of campus COVID-19 restrictions. Participants are current staff who live either < 1 mile, 1-2 miles, or  > 2 miles from LRT, with equal distribution across economic and racial/ethnic strata. The primary aim is to assess change in physical activity, travel mode, and vehicle miles travelled using accelerometer and GPS devices. Equity outcomes include household transportation and health-related expenditures. Change in health outcomes, including depressive symptoms, stress, quality of life, body mass index and behavior change constructs related to transit use will be assessed via self-report. Pre-pandemic variables will be retrospectively collected. Participants will be measured at 3 times over 2 years of follow up. Longitudinal changes in outcomes will be assessed using multilevel mixed effects models. Analyses will evaluate whether proximity to LRT, sociodemographic, and environmental factors modify change in outcomes over time.

DISCUSSION

The TROLLEY study will utilize rigorous methods to advance our understanding of health, well-being, and equity-oriented outcomes of new LRT infrastructure through the COVID-19 recovery period, in a sample of demographically diverse adult workers whose employment location is accessed by new transit. Results will inform land use, transportation and health investments, and workplace interventions. Findings have the potential to elevate LRT as a public health priority and provide insight on how to ensure public transit meets the needs of vulnerable users and is more resilient in the face of future health pandemics.

TRIAL REGISTRATION

The TROLLEY study was registered at ClinicalTrials.gov ( NCT04940481 ) June 17, 2021, and OSF Registries ( https://doi.org/10.17605/OSF.IO/PGEHU ) June 24, 2021, prior to participant enrollment.

Transit Use and Health Care Costs: A Cross-sectional Analysis

INTRODUCTION

Greater transit use is associated with higher levels of physical activity, which is associated with lower health risks and better health outcomes. However, there is scant evidence about whether health care costs differ based on level of transit ridership.

METHODS

A sample (n=947) of members of Kaiser Permanente in the Portland, Oregon area were surveyed in 2015 about their typical use of various modes of travel including transit. Electronic medical record-derived health care costs were obtained among these members for the prior three years. Analysis examined proportional costs between High transit users (3+ days/week), Low transit users (1-2 days/week), and Non-users adjusting for age and sex, and then individually (base models) and together for demographic and health status variables.

RESULTS

In separate base models across individual covariates, High transit users had lower total health care costs (59-69% of Non-user's costs) and medication costs (31-37% of Non-users' costs) than Non-users. Low transit users also had lower total health care (69%-76% of Non-users' costs) and medication costs (43-57% transit of Non-user's costs) than Non-users. High transit users' outpatient costs were also lower (77-82% of Non-users). In fully-adjusted models, total health care and medication costs were lower among High transit users' (67% and 39%) and Low transit users' (75% and 48%) compared to Non-users, but outpatient costs did not differ by transit use.

CONCLUSIONS

Findings have implications for the potential cost benefit of encouraging and supporting more transit use, although controlled longitudinal and experimental evidence is needed to confirm findings and understand mechanisms.

Causal evaluation of the health effects of light rail line: A Natural Experiment

BACKGROUND AND OBJECTIVE

No research to date has causally linked built environment data with health care costs derived from clinically assessed health outcomes within the framework of longitudinal intervention design. This study examined the impact of light rail transit (LRT) line intervention on health care costs after controlling for mode-specific objectively assessed moderateto-vigorous physical activity (MVPA), participant-level neighborhood environmental measures, demographics, attitudinal predispositions, and residential choices.

DATA AND METHODS

Based on a natural experiment related to a new LRT line in Portland - 282 individuals divided into treatment and control groups were prospectively followed during the pre- and post-intervention periods. For each individual, we harness high-resolution data on Electronic Medical Record (EMR) based health care costs, mode-specific MVPA, survey-based travel behavior, attitudinal/perception information, and objectively assessed built environment measures. Simulation-assisted longitudinal grouped random parameter models are developed to gain more accurate insights into the effects of LRT line intervention.

RESULTS

Regarding the "average effect" of the LRT line intervention, no statistically significant reductions in health care costs were observed for the treated individuals over time. However, substantial heterogeneity was observed not only in the magnitude of effects but its direction as well after controlling for the within- and between-individual variations. For a subgroup of treated individuals, the LRT line opening decreased health care costs over time relative to the control group. Further comparative analysis based on the findings of heterogeneity-based models revealed that the effect of LRT intervention for the treated individuals differed by individual characteristics, attitudes/perceptions, and neighborhood level environmental features.

CONCLUSIONS

The study revealed the presence of significant effect modifiers and distinct subgroup structures in the data related to the effects of LRT line intervention on health care costs. Severe implications of ignoring unobserved heterogeneity are highlighted. Limitations and potential avenues for future research are discussed.

Validity of the Exercise Vital Sign Tool to Assess Physical Activity

INTRODUCTION

Assessment and counseling by healthcare providers can successfully increase physical activity; however, a valid instrument to effectively measure physical activity is needed. This study examines the validity of the Exercise Vital Sign tool by comparing Exercise Vital Sign data collected at Kaiser Permanente Northwest with accelerometry data.

METHODS

Participants (n=521) completed accelerometer monitoring and had ≥1 Exercise Vital Sign measurement in their electronic medical record. Using accelerometry as the gold standard, the association between moderate-to-vigorous physical activity minutes per week estimated through Exercise Vital Sign and that estimated through accelerometry was examined using the Spearman correlation coefficient. Comparability of moderate-to-vigorous physical activity categories (inactive, lowly active, moderately active, sufficiently active) was assessed using simple and weighted κ statistics. Sensitivity, specificity, and positive and negative predictive values were calculated. The study was conducted in 2012-2015, with analysis in 2019-2020.

RESULTS

Average accelerometry-based moderate-to-vigorous physical activity was 212 minutes per week, and 57% of the participants were considered sufficiently active. Exercise Vital Sign‒based moderate-to-vigorous physical activity averaged 170 minutes per week, and 53% of the participants were active. There was a positive correlation between the moderate-to-vigorous physical activity minutes per week reported through Exercise Vital Sign and that reported through accelerometry (r =0.38, p<0.0001). A fair agreement was observed between Exercise Vital Sign‒ and accelerometry-based moderate-to-vigorous physical activity categories (weighted κ=0.29), with the highest agreement occurring for those with physical activity level ≥150 minutes per week. The positive correlation increased when moderate-to-vigorous physical activity was examined dichotomously (<150 or ≥150 minutes per week, κ=0.34). The sensitivity, specificity, positive predictive value, and negative predictive value for Exercise Vital Sign (when compared with those of accelerometry) were 67%, 68%, 61%, and 73%, respectively.

CONCLUSIONS

The Exercise Vital Sign is a useful physical activity assessment tool that correctly identifies the majority of adults who do and do not meet physical activity guidelines.

Metro and elderly health in Hong Kong: protocol for a natural experiment study in a high-density city

INTRODUCTION

Public transport accessible to older people may offer a transformative solution to achieving healthy ageing. However, the evidence to support such transport infrastructure modifications is unclear. Previous studies on public transport use and elderly health were mostly observational studies using cross-sectional data. Few studies have examined the before-and-after effects of a new metro, for example, to see if it leads to improved elderly health.

METHODS AND ANALYSIS

We use a new metro line in Hong Kong as a natural experiment to examine the impact of the metro-led public transport intervention on elderly health. In Hong Kong, more than 90% of daily travels are made by public transport. The public transport modifications consist of the new metro line with eight stations and changes in the walking environment and bus services around the stations. We will look at the before-and-after differences in public transport use and health outcomes between elderly participants living in treatment neighbourhoods (400 m walking buffered areas of the new metro stations) and in control groups (living in comparable areas but unaffected by the new metro). Questionnaire-based baseline data were collected in 2019 before the COVID-19 pandemic, while some qualitative interviews are ongoing. Amid the pandemic, we conducted a quick telephone-based survey of COVID-19's potential impact on public transport use behaviours of our elderly cohort in September 2020. Note there is no lockdown in Hong Kong until the writing of the paper (January 2021). After the new metro opens, we will conduct a follow-up survey, tentatively in late 2022. We aim to investigate if the new metro and the associated changes in the built environment have any effects on public transport use behaviours, physical activity and wider health outcomes among the elderly (eg, social inclusion, quality of life, subjective well-being).

ETHICS AND DISSEMINATION

The Human Research Ethics Committee of the University of Hong Kong reviewed and approved the study procedures and materials (reference number: EA1710040). Results will be communicated through scientific papers and research reports.