Anomalously warm weather and acute care visits in patients with multiple sclerosis: A retrospective study of privately insured individuals in the US

Abstract

Background As the global climate changes in response to anthropogenic greenhouse gas emissions, weather and temperature are expected to become increasingly variable. Although heat sensitivity is a recognized clinical feature of multiple sclerosis (MS), a chronic demyelinating disorder of the central nervous system, few studies have examined the implications of climate change for patients with this disease. Methods and findings We conducted a retrospective cohort study of individuals with MS ages 18–64 years in a nationwide United States patient-level commercial and Medicare Advantage claims database from 2003 to 2017. We defined anomalously warm weather as any month in which local average temperatures exceeded the long-term average by ≥1.5°C. We estimated the association between anomalously warm weather and MS-related inpatient, outpatient, and emergency department visits using generalized log-linear models. From 75,395,334 individuals, we identified 106,225 with MS. The majority were women (76.6%) aged 36–55 years (59.0%). Anomalously warm weather was associated with increased risk for emergency department visits (risk ratio [RR] = 1.043, 95% CI: 1.025–1.063) and inpatient visits (RR = 1.032, 95% CI: 1.010–1.054). There was limited evidence of an association between anomalously warm weather and MS-related outpatient visits (RR = 1.010, 95% CI: 1.005–1.015). Estimates were similar for men and women, strongest among older individuals, and exhibited substantial variation by season, region, and climate zone. Limitations of the present study include the absence of key individual-level measures of socioeconomic position (i.e., race/ethnicity, occupational status, and housing quality) that may determine where individuals live—and therefore the extent of their exposure to anomalously warm weather—as well as their propensity to seek treatment for neurologic symptoms. Conclusions Our findings suggest that as global temperatures rise, individuals with MS may represent a particularly susceptible subpopulation, a finding with implications for both healthcare providers and systems.

Heat and cold sensitivity in multiple sclerosis: A patient-centred perspective on triggers, symptoms, and thermal resilience practices

“…spring to summer), and during humid heatwaves (47). The general climate may also play a role, as pwMS who live in more tropical climates with high temperature and humidity levels throughout the year might be affected more than pwMS living in more temperate climatic zones (48). Finally, when combined with high environmental temperatures, high humidity may have implications for perceived fatigue and therefore the general wellbeing of patients (49).…”

Climate Change and Physiatry

“…For example, people with multiple sclerosis demonstrate elevated resting body temperatures, and uncharacteristically warm weather is associated with multiple sclerosis exacerbations. 8,19 Environmental heat worsens fatigue and preexisting mobility limitations, further restricting access to cooled communal spaces. 6,7 Individuals with higher-level spinal cord injury (SCI) demonstrate disturbed thermoregulatory responses due to altered vasodilatory, sudomotor, and shivering responses, and people with all levels of SCI are more vulnerable to changes in environmental temperature due to diminished mobility, sensory dysfunction, and reliance on external devices.…”

“…People with thermoregulation deficits due to neurological disease or age, those with mobility deficits that cannot easily escape heat, or those with cognitive or communication deficits that make it difficult to express symptoms of overheating are particularly vulnerable to heat injuries. For example, people with multiple sclerosis demonstrate elevated resting body temperatures, and uncharacteristically warm weather is associated with multiple sclerosis exacerbations 8,19 . Environmental heat worsens fatigue and preexisting mobility limitations, further restricting access to cooled communal spaces 6,7 …”

“…5 The ways in which climate change negatively impacts the health of people with disabilities are varied and include an increased risk of heatrelated injury due to rising ambient temperatures, cardiopulmonary disease from wildfire smoke and air pollution, and harm from natural disasters due to decreased mobility and dependence on technology and caregiver support. 3,[6][7][8][9][10][11][12] The indirect effects of climate change include the emergence and changing landscape of infectious disease, which are associated with increased symptom severity in people with disability due to underlying medical conditions and barriers to accessing care. 13,14 In addition to the direct costs to human health, the economic costs of the health effects of climate change are estimated at more than $800 billion annually in the United States (US) and will only increase with time.…”

“…Not only are people with disabilities more vulnerable to the health effects of climate change, they are also less resilient 4 . Indeed, in July of 2019, the United Nations Human Rights Council adopted a resolution on climate change and the rights of people with disabilities “recognizing that persons with disabilities are among the most adversely affected in an emergency, sustaining disproportionately higher rates of morbidity and mortality, and at the same time being among those least able to have access to emergency support.” 5 The ways in which climate change negatively impacts the health of people with disabilities are varied and include an increased risk of heat-related injury due to rising ambient temperatures, cardiopulmonary disease from wildfire smoke and air pollution, and harm from natural disasters due to decreased mobility and dependence on technology and caregiver support 3,6–12 . The indirect effects of climate change include the emergence and changing landscape of infectious disease, which are associated with increased symptom severity in people with disability due to underlying medical conditions and barriers to accessing care 13,14 …”