A groundbreaking new study sheds light on the profound health consequences of severe flooding on older adults in the United States, revealing a striking association between major flood events and hospitalizations due to a range of specific causes. Drawing upon an extensive dataset spanning 17 years of Medicare hospitalization claims paired with high-resolution satellite flood maps, researchers from leading institutions including Harvard T.H. Chan School of Public Health, Ohio State University, University of Wisconsin–Madison, and Columbia University have uncovered significant increases in hospital admission rates for skin diseases, nervous system disorders, musculoskeletal conditions, and injuries or poisonings among adults aged 65 and older following flood exposure.
This rigorous retrospective matched cohort analysis represents one of the most comprehensive examinations to date of flood-related health impacts on an especially vulnerable demographic. Unlike prior investigations limited to isolated flood incidents or narrow health outcomes, this study integrates data from over 4.5 million hospitalizations and 72 distinct major flood events across the United States between 2000 and 2016. By leveraging the Global Flood Database’s satellite-driven, fine-grained flood exposure metrics, the research team was able to meticulously match hospitalization episodes to specific flood incident windows, allowing for precise estimation of relative changes in cause-specific hospitalization rates within the critical four-week period after flooding.
The findings reveal a notable elevation in hospitalization risk post-flood: skin diseases rose by approximately 3.1%, nervous system diseases by 2.5%, musculoskeletal diseases by 1.3%, and injuries or poisonings by 1.1%. These statistics underscore the multifaceted health burden flooding places on older adults, many of whom contend with diminished physiological resilience owing to immunosenescence, mobility limitations, and chronic health conditions such as dementia. The interplay of environmental exposure and individual vulnerabilities magnifies the risk of acute medical episodes necessitating hospital care.
Intriguingly, the study highlights racial disparities in flood-related health outcomes, indicating that communities with lower percentages of Black residents experience disproportionately higher hospitalization rates for nervous system diseases—up to a 7.6% increase—whereas the incidence of skin diseases and mental health-related hospitalizations are more exacerbated in areas with higher proportions of Black residents, showing increments of 6.1% and 3.0%, respectively. These divergent patterns may reflect underlying differences in social determinants of health, pre-existing medical conditions, housing infrastructure, access to emergency services, and potential systemic biases within healthcare coding and delivery.
From a pathophysiological perspective, the surge in skin diseases following floods can be attributed to repeated and sustained contact with contaminated floodwaters laden with microbial and chemical pollutants. Additionally, overcrowded shelters during evacuations often foster suboptimal hygienic conditions, facilitating the transmission and exacerbation of dermatological infections and inflammatory conditions. Nervous system hospitalizations may result from neurological trauma—such as traumatic brain injuries incurred during flood-related accidents—or from exacerbations of chronic neurological disorders like epilepsy, where stress and sleep deprivation triggered by flooding can precipitate seizure episodes.
Musculoskeletal system hospitalizations appear linked not only to direct injuries sustained during flood events and subsequent cleanup activities but also to the exacerbation of underlying degenerative joint diseases due to delayed access to routine care and physical therapy. These cumulative stresses highlight the complex physical demands floods impose on older adults, amplifying morbidity in a population already prone to frailty.
Beyond individual-level factors, the researchers emphasize the importance of structural and systemic contributors to the observed health outcomes. Older adults’ restricted mobility and diminished capacity to evacuate or seek timely medical attention compound flood-related risks. Meanwhile, disparities in housing quality and neighborhood infrastructure may exacerbate exposure levels and hinder emergency response in marginalized communities. The authors also suggest that implicit racial biases within healthcare coding practices might skew diagnoses and hospital admission records, underscoring the necessity for equitable clinical vigilance and data collection.
The significance of this study transcends epidemiological description; it catalyzes a call for targeted public health interventions and policy adaptations to mitigate flood-induced health impacts amid the escalating threat posed by climate change. The researchers advocate for flood-specific resilience strategies prioritizing older adult populations, including enhanced evacuation planning, robust community alert systems, and tailored health communication campaigns. Ensuring hospitals and healthcare facilities maintain operational continuity during flood events is critical, achievable through infrastructural adaptations such as elevating essential equipment above flood levels.
Technological innovations present promising avenues to enhance medical access during floods. Mobile medicine units, capable of delivering onsite healthcare services, and telemedicine platforms can bridge care gaps when physical access to hospitals is compromised. Additionally, drone deployments offer a cutting-edge solution for delivering essential medical supplies to affected areas and for real-time reconnaissance to identify safe evacuation routes, thereby supporting emergency responders in dynamic flood scenarios.
At the forefront of this research, lead author Sarika Aggarwal, a PhD candidate at Harvard Chan School, alongside co-authors Jie K. Hu, Jonathan A. Sullivan, Robbie M. Parks, and Rachel C. Nethery, have collectively contributed a vital evidence base that informs both scientific understanding and practical policy development. Their work illuminates previously underappreciated health consequences of flooding and underscores the urgency of enhancing climate resilience within aging populations.
Funded by prestigious bodies including the Harvard Data Science Initiative, Harvard Graduate Prize Fellowship, the Alfred P. Sloan Foundation, and the National Institutes of Health, this study reflects a collaborative multidisciplinary effort to decipher and address environmental health hazards exacerbated by climate change. The authors declare no conflicts of interest, further emphasizing the study’s objectivity and commitment to public health advancement.
As climate models predict an intensification of severe flooding events globally, particularly in high-income nations with aging populations, the relevance of these findings is profound. Public health systems must proactively integrate flood risk assessments into healthcare planning and resource allocation to safeguard vulnerable groups. This research serves as a clarion call for enhanced surveillance, infrastructure fortification, and innovative healthcare delivery modalities to mitigate the insidious yet preventable morbidity burden imposed by flood disasters.
Ultimately, this comprehensive analysis delivers a sobering but actionable message: older adults face multifaceted health risks in the wake of flooding, risks that are amplified by social inequities and healthcare system constraints. Addressing these challenges requires coordinated, equity-focused approaches that harness technological advancement and community engagement, ensuring that increasingly frequent climate-driven disasters do not translate into disproportionate suffering among society’s most vulnerable members.
Subject of Research: People
Article Title: Severe flooding and cause-specific hospitalisation among older adults in the USA: a retrospective matched cohort analysis
News Publication Date: 30-Jul-2025
Web References: The Lancet Planetary Health article
References: DOI 10.1016/S2542-5196(25)00132-9
Keywords: Climate change, Older adults, Floods, Public health, Environmental health
