B56-14 Greenspace Exposure, Disease Severity, and Mortality in the Pulmonary Hypertension Association Registry

Rationale

Greenspace exposure has been increasingly recognized as a potential protective factor for respiratory health, potentially through reduced air pollution and heat exposure, and mitigation of psychosocial stress. However, its role in pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) remains poorly understood. We evaluated cross-sectional associations between residential greenspace exposure and disease severity, as well as longitudinal associations with transplant-free survival among patients with PAH and CTEPH.

Methods

We studied adults enrolled between September 2015 and September 2025 in the Pulmonary Hypertension Association Registry, a multicenter prospective cohort of patients with PAH and CTEPH across the United States. Residential greenspace exposure was assessed using the Normalized Difference Vegetation Index (NDVI) derived from Landsat satellite imagery, with higher NDVI indicating greater surrounding vegetative greenness. Annual average NDVI in 2015 was linked to participants’ baseline residential addresses using circular buffers with radii of 60 m, 300 m, and 1200 m. Enrollment outcomes included hemodynamics, six-minute walk distance, brain natriuretic peptide z-scores, functional class, emPHasis-10, and Short Form-12 scores. Cross-sectional associations were examined using multivariable linear and logistic regression, and transplant-free survival was evaluated using Cox proportional hazards models. Primary models adjusted for demographics, individual- and neighborhood-level socioeconomic status, disease characteristics, treatment variables, and spatial confounders. Sensitivity analyses used summer-season NDVI (June-September) and further adjusted for fine particulate matter (PM2.5) as co-exposure.

Results

Our sample included 3,371 adults for cross-sectional analyses, and 3,155 adults with at least one follow-up visit for survival analyses. Mean baseline age was 56 years (standard deviation: 15.8 years), and 72% were female. Over a 10-year follow-up (median: 2.1 years), there were 558 deaths and 69 lung transplants. At enrollment, higher annual NDVI with a 1200-m buffer was associated with lower pulmonary vascular resistance, with an decrease of 0.40 [95% confidence interval (CI): -0.76 to -0.03] Wood units per interquartile range (IQR) increase in NDVI (0.2 unit), and an increase in Cardiac Index of 0.07 [95% CI: 0.02-0.13] L/min/m2 (Figure 1.A). Higher NDVI was not associated with the risk of death or lung transplant, (Figure 1.B). Results were consistent in sensitivity analyses using summer NDVI and after additional adjustment for PM2.5.

Conclusion

Greater residential greenspace exposure was associated with less severe pulmonary hemodynamics on enrollment among patients with PAH and CTEPH. No evidence supports improved survival with higher greenspace exposure. Further studies are needed to elucidate potential mechanisms linking greenspace to PAH and CTEPH.

This abstract is funded by: NIEHS (National Institute of Environmental Health Sciences)