National Study Finds Colder Weather Is Tied to More Heart Failure Hospitalizations in Older Medicare Patients

A national analysis of Medicare data suggests that colder days are associated with higher odds of hospitalization for heart failure among older adults, while hot days show no similar increase. In the study, very cold days were linked to roughly 12% higher odds than a 75-degree day, according to research published in JAMA Network Open.

Investigators from Thomas Jefferson University, Rutgers, and other institutions reviewed more than 1.5 million heart failure hospitalizations among nearly 996,000 adults age 65 and older from 2007 through 2022. The researchers emphasized that the study shows an association, not proof that low temperatures directly cause hospital admissions.

The findings are relevant to the millions of older Americans living with heart failure, as well as the family members and caregivers who help manage medications, appointments, and everyday routines. About 7.7 million U.S. adults have heart failure, according to the Heart Failure Society of America's latest statistics report, Spectrum News reported.

What the Medicare Data Showed

The researchers used a case-crossover design, comparing the conditions on the day a patient was hospitalized with other days for the same person. This method helps account for factors that do not change from day to day, including age, sex, and baseline health status.

Temperatures were assigned based on each patient's ZIP code. The analysis used 75 degrees Fahrenheit as the reference point and examined the combined impact of colder temperatures over a 14-day period.

Nationally, the coldest 5% of local temperatures were associated with about 12% higher odds of heart failure hospitalization. Temperatures at the 25th percentile, which were cool rather than extreme, were linked to about 16% higher odds.

The relationship appeared across all regions at moderately cold temperatures, though the strength of the association varied. The strongest links were seen in the West North Central region, which includes Minnesota, Iowa, and the Dakotas, as well as in the West, Northwest, and Southwest. Temperatures above 75 degrees did not show a meaningful national association, and in the South, the hottest days were associated with slightly fewer admissions.

“This study found that among Medicare beneficiaries, colder ambient temperatures were associated with increased HF hospitalizations, whereas warmer temperatures were not,” the authors wrote.

Moderate Cold May Matter More Than Rare Extremes

One practical takeaway is that risk was not confined to severe cold snaps. In an accompanying editorial, University of Pennsylvania researchers noted that moderately cold weather may contribute more total risk than the rare extreme events that usually trigger weather warnings.

The editorial said cold weather narrows blood vessels, which can raise blood pressure and increase the heart's need for oxygen. Respiratory viruses, which circulate more often during colder months, are another concern, TCTMD reported.

Dr. Jamal Rana, a Kaiser Permanente cardiologist who was not involved in the study, summed up the message for patients by saying, “We should take the pill during the chill.” Skipping heart failure medication can lead to fluid buildup and hospitalization at any time of year.

The new results are consistent with earlier work. A Swedish study of 482,000 heart failure hospitalizations, presented at ESC Congress 2026, also found that cold spells were followed by higher hospitalization risk two to six days later.

What the Study Cannot Prove

This was an observational study based on billing records. It shows that cold days and hospitalizations occurred together more often, but it does not prove that cold temperatures directly caused the admissions.

The data did not include clinical details such as heart pumping function, symptom severity, or the cause of each patient's heart failure. Researchers also could not account for indoor heating, air conditioning use, or recent viral infections, all of which could affect risk.

Because temperatures were assigned by ZIP code, they may not reflect the exact conditions each person experienced. The study focused only on traditional Medicare beneficiaries age 65 and older, so the results may not apply to younger adults or to people in Medicare Advantage plans. The cold-weather findings also changed when the researchers used shorter time windows.

The research was funded by the National Institute on Aging and the National Institute on Minority Health and Health Disparities. The senior author reported grants and personal fees from several drug companies for work unrelated to this study.

Current heart failure treatment guidelines have not changed because of these findings. The results may help identify who needs closer monitoring during colder months, but they do not mean every older adult faces the same level of risk on a cool day.

Winter Preparation for Patients and Caregivers

People with heart failure should keep taking prescribed medications on schedule and refill them before winter storms arrive. Daily weight checks can help catch fluid buildup early. According to the American Heart Association, gaining more than 2 to 3 pounds in a day or 5 pounds in a week is a reason to call a clinician.

Wearing layers, keeping homes warm enough, and avoiding sudden exertion in the cold, such as snow shoveling, may reduce strain on the heart. Flu and COVID-19 vaccines may also lower the chance of a virus triggering a hospital stay, and Medicare covers the flu shot at no cost from providers who accept assignment.

Families on fixed incomes who are struggling with heating bills can contact their state's Low Income Home Energy Assistance Program office. Telehealth visits may also help patients who have difficulty traveling in icy conditions.

Emergency care is needed for chest pain, severe shortness of breath, fainting, confusion, or breathing that worsens when lying down. Swelling in the legs or abdomen, a persistent cough, and unusual fatigue should prompt a call to a clinician.

The researchers said continued regional monitoring will be important. For older adults and caregivers, the message is straightforward: winter deserves a heart failure plan, not just summer heat.

Key Points

What did the study find? Cold days were linked to about 12% higher odds of heart failure hospitalization among Medicare patients age 65 and older compared with 75-degree days.

Did hot weather raise the risk? No meaningful national link was found for hot days.

Does this prove cold causes heart failure hospitalizations? No. It is an observational study that shows an association.

Which regions showed the strongest link? The West North Central region, along with the West, Northwest, and Southwest.

Who is most affected? Older adults with heart failure, especially those exposed to cold or respiratory infections.

What can patients do this winter? Take medicines on schedule, check weight daily, stay warm, avoid sudden exertion in the cold, and keep vaccines current.