Flooding increases hospitalization risks in older adults
Floods are the most frequently occurring climate hazard and are projected to become more frequent and intense in the coming decades due to climate change, urbanization, and more people living in floodplains. Older adults are especially at risk from flooding because they may have weakened immune systems, limited mobility, and pre-existing conditions such as dementia, all of which can reduce their ability to cope with climate hazards. Flooding can also interrupt their access to medical services for routine appointments.
A new study by researchers at Harvard T.H. Chan School of Public Health, Ohio State University, University of Wisconsin–Madison, and Columbia University found that in older adults, flooding was associated with increased hospitalization rates for injuries and diseases of the skin, nervous system (such as epilepsy), and musculoskeletal system (such as osteoarthritis), both during the flood and over the following month.
It’s easy to understand how floods can be dangerous while they’re happening, but now we have a better understanding of how floods can harm our health for weeks after the waters recede.
Rachel Nethery, senior author and Harvard Chan C-CHANGE core faculty member
While prior studies have examined the impact of individual flood events on a limited set of health outcomes, this is the first large-scale investigation to assess how flood exposure affects hospitalization risks for a wide spectrum of diseases in older adults using a nationwide multi-decade study design. Hospitals and health care systems can use these findings to better prepare for possible increases in hospitalizations during and after floods.
Key takeaways
Researchers looked at over 4.5 million hospitalizations over a 17-year period (2000-2016), capturing 72 major flood events in the contiguous U.S. Flooding was most common in the Mississippi and Ohio River Valleys and along the Gulf and Southeastern Atlantic coasts.
As flood severity increased, adverse health impacts also increased.
Flooding (both during the flood event and in the following 4 weeks) was associated with increases in hospitalizations of older adults in the U.S. for:
- Skin diseases (up by 3.1% on average). During the flood event, skin disease hospitalization went up by as high as 4.5%.
- Nervous system diseases (up by 2.5% on average). Hospitalizations for nervous system diseases increased the most (up by 4.0%) in the third week after a flood event.
- Musculoskeletal system diseases (up by 1.3% on average). Hospitalizations for musculoskeletal system diseases increased the most (up by 5.6%) in the fourth week after a flood event.
- Injuries (up by 1.1% on average). Hospitalizations for injuries increased the most (up by 1.7%) in the fourth week after a flood event.
Hospitalizations for respiratory diseases went down in the first 1-4 weeks after a flood event. Respiratory diseases were the only cause of hospitalization to decrease, which may be because heavy rainfall can settle dust, a respiratory irritant. However, hospitalization risk went up in weeks 8-12, pointing to potential long-term impacts from dampness and mold exposure.
Trends in hospitalization rates differed in populations with higher vs lower proportions of Black residents:
- Communities with lower proportions of Black residents experienced exacerbated flood effects for nervous system diseases (up by 7.6%) during the flood event.
- Communities with higher proportions of Black residents experienced exacerbated flood effects for skin diseases (up by 6.1%) and mental health-related impacts (up by 3.0%) during the flood event.
The findings indicate a need for targeted flood-specific preparedness and adaptation strategies for elderly and racially minoritized communities.
