Relationship between air mass type and emergency department visits for migraine headache across the Triangle region of North Carolina

DOI: https://doi.org/10.1007/s00484-017-1432-z

Abstract-Summary Synoptic air mass types and emergency department (ED) visits for migraine head- aches were examined over a 7-year period within a major metropolitan area of North Carolina to identify potential relationships between large-scale meteorologi- cal conditions and the incidence of migraine headaches.

Bootstrapping analysis revealed that tropical air masses (moist and dry) resulted in the greatest number of migraine ED visits over the study period, whereas polar air masses led to fewer.

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Moist polar air masses in particular were found to correspond with the fewest

number of migraine ED visits.

On transitional air mass days, the number of migraine ED visits fell between

those of tropical air mass days and polar air mass days.

No relationship was found between migraine ED visits and the magnitude of

barometric pressure changes associated with transitional air masses.

Extended: Future research on lag relationships may wish to examine cumulative frequencies of certain air masses preceding a migraine, as cumulative exposure to adverse weather conditions is often a determining factor in the occurrence of nega- tive health outcomes (e.g., extended periods of poor air quality and high tempera- tures leading to respiratory illness and heat stroke).

Introduction Such studies have compared various meteorological variables, such as barometric pressure, temperature, humidity, cloud cover and opacity, precipitation type, and the occurrence of lightning, to the incidence and frequency of migraine headaches.

The goal of this study is to determine if SSC weather types (or air mass types)

are a trigger for daily increases in migraine headache frequencies.

The relationship between SSC air mass type and the occurrence of migraine headaches was examined across three counties in central North Carolina (i.e., the Triangle region encompassing Orange, Durham, and Wake counties).

The specific objectives of this research were to (1) determine if there is a rela- tionship between air mass type and the frequency of ED visits with a primary diag- nosis of migraine headache and (2) determine if the frequency of these ED visits is related to the direction (sign) and magnitude of pressure change associated with the transitional SSC category.

Data and Methods Each value in the vector represented the number of migraine ED visits across the study area during a day with a particular air mass type.

The mean of a vector represented the average number of daily migraine ED visits

for an air mass type.

Bootstrapping was first used to determine if statistically significant differences existed between the mean numbers of daily migraine ED visits for each air mass type. Ninety-five percent bootstrap confidence intervals of mean daily migraine ED

visits for each of the air mass types were created.

Bootstrapping was used to determine if a statistically significant difference existed between the average number of daily migraine ED visits during TR air mass days with a positive (i.e., increasing) 4 a.m. to 10 p.m. pressure change and TR air mass days with a negative (i.e., decreasing) 4 a.m. to 10 p.m. pressure change.

Results The most notable differences in migraine ED visits were found between polar air masses and tropical air masses.

Both dry polar (DP) and moist polar (MP) air masses exhibited statistically fewer

ED visits for migraine compared to tropical air masses (DT and MT).

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Days with Moderate air masses (DM and MM) exhibited a statistically greater

frequency of ED visits for migraine than days with polar air masses.

The number of ED visits for migraine is greater 1 to 5 days after a tropical air mass than after a polar air mass, while the fewest number of visits occurred 1 to 5 days following a moist polar air mass.

To examining a potential relationship between the sign or direction of pressure change and the frequency of ED visits for migraine, Pearson correlation coefficients were calculated to determine if a relationship existed between the magnitude of the pressure change on TR days and the frequency of ED visits for migraine.

Discussion Statistically significant differences in ED migraine visits between air mass types were identified.

It was expected that the TR air mass type, which is defined in part by changes in barometric pressure, would exhibit the strongest relationship with migraine frequency.

Future research should examine additional subtypes of the transitional air mass category, as in Hondula and Davis [397], to determine if other characteristics of frontal passages (e.g., changes in humidity, wind direction) exhibit a stronger asso- ciation with migraine frequency.

Future research on lag relationships may wish to examine cumulative frequen- cies of certain air masses preceding a migraine, as cumulative exposure to adverse weather conditions is often a determining factor in the occurrence of negative health outcomes (e.g., extended periods of poor air quality and high temperatures leading to respiratory illness and heat stroke).

Conclusions Most studies have examined individual weather variables to determine how weather may impact migraine frequency.

This study employed an air mass approach to examine the influence of multiple weather variables and large- scale weather features on the incidence of migraine headaches across a three-county area in central North Carolina from 2007 to 2013. We found statistically significant differences in ED migraine visits between air

mass types.

The number of ED visits for migraine was greater 1 to 5 days after a tropical air

mass than after a polar air mass.

Those who suffer from migraines, especially in the study area, may consider air mass type when determining the likelihood of migraine headaches, while public health officials may use this information to advise sufferers on when to take preven- tative measures.

Acknowledgement A machine generated summary based on the work of Elcik, Christopher; Fuhrmann, Christopher M.; Mercer, Andrew E.; Davis, Robert E. 2017 in International Journal of Biometeorology.

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Acute migraine management in the emergency department: experience from a large Spanish tertiary hospital