A nationwide study in France has reported that during the 2019 heatwave, increased temperatures were closely linked with weight loss in heart failure patients, indicating a worsening of their condition. The findings of the study are published today in ESC Heart Failure, a journal of the European Society of Cardiology.
“This study is the first to show a strict relationship between ambient temperature and body weight in heart failure patients. The finding is timely given the heatwaves again this year. The weight loss we observed in people with heart failure may lead to low blood pressure, especially when standing up, and renal failure, and is potentially life-threatening. With rising temperatures forecast for the future, clinicians and patients should be ready to reduce the dose of diuretics when weight loss occurs,” said study author Professor François Roubille of Montpellier University Hospital, France in a statement on Thursday.
According to the researcher, in patients with heart failure, the heart does not pump blood around the body as well as it should.
“Waste products accumulate, causing shortness of breath and fluid build-up in the lungs, legs and abdomen. Weight is the cornerstone of monitoring because weight gain is related to congestion, the main reason for the hospital admission. Diuretics, also called water pills, are used to increase urine output and reduce breathlessness and swelling. ESC guidelines recommend educating patients to increase their diuretic dose or alert their healthcare team if they experience an increase in breathlessness or swelling or a sudden unexpected weight gain of more than two kg in three days. Weight loss has received less attention,” the study revealed.
The authors of the current study hypothesised that the body weight of patients with heart failure could change during a heatwave.
“When healthy people drink more fluids during hot weather, the body automatically regulates urine output. This does not apply to patients with heart failure because they take diuretics,” Professor Roubille stated on Thursday.
While conducting the study the researchers examined the relationship between body weight and air temperature between 1 June and 20 September 2019, which covered the two heatwaves at the end of June and the end of July.
1,420 patients with chronic heart failure had participated in the study. Moreover, the median age was 73 years, 28% were women, and the average weight was 78 kg. A national telemonitoring system was used to remotely obtain information on weight and symptoms.
As a part of the study, patients weighed themselves every day using a connected weighing scale that automatically sent measurements to the clinic. Patients reported daily symptoms such as oedema, fatigue, breathlessness and cough by answering questions on a personal device (e.g. smartphone, tablet), with answers sent automatically to the clinic. Daily temperatures (at noon) were obtained using data from the closest weather station to each patient’s home.
Moreover, the researchers analysed the association between patient weight, ambient temperature on the same day, and temperature two days prior to the weight measurement. The relationship between temperature and weight was very strong, with weight dropping as temperature rose. The strongest relationship was found with temperatures two days prior to the weight measurement, it stated.
“The weight loss we observed during the heatwave was clinically relevant. Patients weighing 78 kg lost 1.5 kg in a short period of time. We were surprised to see that weight dropped with hot temperatures, as we had expected the opposite. For this reason, the telemonitoring system was programmed to alert clinicians when patients gained weight,” Professor Roubille stated on Thursday.