JMIR Publications

ABSTRACT

Background:

Due to climate change, exposure to hot temperatures is becoming more common even in countries with temperate climate. For patients with chronic diseases, there are significant health risks associated with heat. Patient empowerment is an essential element of protecting the population from adverse effects of heat. In this context, self-reports of protective behaviour are often used to gain mutual understanding of the patients’ problems. However, it is unclear to which extent self-reported behaviour is associated with health complaints.

Objective:

To describe the association between light and moderate heat and health complaints in everyday life, and to analyse if self-reported protective behaviour and related psychosocial factors were associated with these complaints.

Methods:

We conducted a pilot cohort study based on internet climate data merged with an online survey of patients with chronic diseases recruited by GP practices. Patients were included if they were 18 years or older and suffered from at least one chronic disease. Heat was modelled by temperature and humidity. Health complaints were assessed on up to seven follow-up assessments on the days with the highest temperature in each week of observation. Data were analysed in three nested models by mixed-effects multivariable linear regression analyses adjusted for random effects on climate measuring station level and study participant level. Model 1 included heat, socio-demographic data and chronic diseases, model 2 added protective behaviour and health literacy and model 3 self-efficacy and somatosensory amplification, ie, the tendency to catastrophise normal bodily sensations like insect bites.

Results:

Of 291 eligible, 61 (21.0%) patients with 294 observations participated in the study. On average, participants were 61 ± 14 years old, and 31 (50.8%) were men. Most prevalent were cardiovascular diseases (23 participants, 37.7%) and diabetes mellitus (20, 32.8%). Most frequently, participants reported tiredness/fatigue (232 observations, 78.9%) and shortness of breath (142, 48.3%). Compared to 27°C or less, a heat index between more than 27°C and 32°C ( coefficient: 1.02, 95% confidence interval: 0.08/1.96, P=.03) and of more than 32°C (1.35, 0.35/2.35, P=.008) were associated with higher symptom burden. Lower health literacy (-0.25, -0.49/-0.01, P=.04) and better self-reported protective behaviour (0.65, 0.29/1.00, P<.001) were associated with elevated burden, but lost statistical significance in model 3. Instead, lower self-efficacy (-0.39, -0.54/-0.23, P<.001) and higher somatosensory amplification (0.18, 0.07/0.28, P=.001) were associated with higher symptom burden.

Conclusions:

Compared to colder weather, light and moderate heat were associated with more severe health complaints. Symptom burden was lower if participants had higher self-efficacy and if they showed less somatosensory amplification. Self-reported protective behaviour was not associated with lower symptom burden. Instead, we found that patients tending more to catastrophise normal bodily sensations reported better protective behaviour and higher symptom burden at the same time. Clinical Trial: clinicaltrials.gov (NCT05961163)