a b s t r a c t

Aim: Migraine is common in society and is one of the primary causes of chronic headache with episodes. In this study, we aimed to determine the role of meteorologic parameters and moon phase on triggering migraine at- tacks and effects on the number of patients presenting to the emergency department with migraine headaches. Materials and Methods: Patients admitted to the emergency department due to a migraine headache during a 1- year period were studied retrospectively.

Correlation between moon phases, pressure, temperature, humidity, wind speed values of meteorologic observa- tion, and recording station located in the same city and daily number of patients was analyzed.

Results: A total of 3491 patients, of whom 72% (n = 2518) were women, were enrolled. The average daily number of patients was 9.6 +- 4 (3-24). A statistically significant correlation was found between the number of daily pa- tients and daily maximum temperature (P = .005), mean temperature (P = .013), minimum temperature (P =

.041), and daily temperature change (P = .003). In addition, a negative correlation was found between the daily number of patients presenting to the emergency department and daily relative humidity (in percentage; P =

.031). No significant relationship was found between moon phases and the number of patients.

Conclusion: We have determined that the number of patients admitted to the emergency department with mi- graine headache has increased with high temperature and low humidity and that there is no relationship be- tween the number of patients and moon phases.

(C) 2014

Introduction

Migraine, most common disease in the community, is one of the pri- mary causes of chronic headache with periods of remission and exacer- bations. It is seen in about 12% of population, and it is more common in women [1,2]. Migraine causes individuals to limit their daily activities because it has attacks that last for hours and even days, and these at- tacks cause occasional Severe headaches [3,4]. Although causes that trig- ger migraine attacks and their mechanisms of action are not fully identified, many internal (personal) or external (environmental) factors such as hormonal changes, menstrual periods, emotional stress, hunger, fatigue, odors, noise, and sleep pattern changes trigger a migraine attack or cause an increase in headaches [5]. Identification and avoidance of the factors that trigger or aggravate migraine attacks constitutes the first and most important step in the prevention of migraine attacks. Be- cause avoidance of trigger factors can significantly decrease severity or frequency of attacks, studies for identifying factors that trigger migraine attacks continue [6,7]. The results of the studies that examine whether

* Corresponding author. Department of Emergency Medicine, Firat University Faculty of Medicine, 23200 Elazig, Turkey. Tel.: +90 424 2370000/1443.

E-mail addresses: [email protected] (M. Yilmaz), [email protected]

(M. Gurger), [email protected] (M. Atescelik), [email protected] (M. Yildiz), [email protected] (S. Gurbuz).

there is a relationship between migraine attacks and meteorologic pa- rameters, an external cause, are different, so this suggests that the mys- tery of this issue is still unsolved and further studies are needed. Although positive correlations between migraine and bright snow cover, atmospheric pressure, wind, and temperature have been report- ed, some meteorologic parameters have been shown to have negative correlation or even no relationship. Hence, those results reveal the dif- ference between the results of studies [7-13].

In the literature, the number of studies examining the correlation between the meteorologic parameters and the number of emergency department patients presenting with migraine attack is very low [14,15]. In our study, we also aimed to investigate whether meteorolog- ic parameters affect the daily number of patients admitted to the emer- gency department with migraine headaches. In addition, we also investigated whether the daily number of patients with migraine at- tacks is affected according to moon phases. Our study differs from sev- eral previous studies because there are no subjective records such as headache diaries, personal comments are avoided by not making indi- vidual interviews, and a more objective evaluation was done. In addi- tion, we aimed to determine the effect of our regional weather variables on the number of patients admitted to the emergency depart- ment with a migraine attack and share the results because most studies examining the effects of meteorologic parameters on migraine head- ache have different results.

http://dx.doi.org/10.1016/j.ajem.2014.12.056

0735-6757/(C) 2014

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Patients

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

hours*

Female Male

Fig. 1. The number of patients presenting to the emergency department by hours (*1 = 0100-0159; 2 = 0200-0259; 3 = 0300-0359 … etc).

Materials and methods

Study patients

A total of 3491 patients older than 18 years who admitted to emer- gency department of a regional hospital located in Turkey between Jan- uary 1 and December 31, 2013, with a headache that is consistent with migraine and whose diagnosis were encoded as G-43 from International Classification for Diseases, 10th Revision Coding system were retrospec- tively evaluated. Patients who had other diseases causing headache (hy- pertension, subarachnoid bleeding, sinusitis, trauma, etc) were excluded from the study. Patients with recurrent Hospital visits due to migraine attacks in 1 year were also included in the study.

Meteorologic data

Daily average-maximum-minimum (max-min) temperature (in de- grees Celsius), atmospheric pressure (in millibars), humidity (in percent- age), and wind speed (in meters per second) values were obtained from meteorologic observation and recording station located in the same city. Also daily max-min difference of atmospheric pressure and temperature was calculated. In addition, for each month, moon phases were enrolled in the study as new moon, first quarter, full moon, last quarter, and other days. For each moon phase (new moon, first quarter, full moon, last quarter), 1 day before and 1 day after were also included. Thus 3- day data were assessed for each moon phase. Number of patients in the days including each moon phase for a year was identified, and correlation between moon phases and number of patients admitted to the emergen- cy department with a migraine headache was examined.

Statistical analysis

Statistical Package for the Social Sciences (SPSS 21, Chicago, IL) statisti- cal software was used for data analysis. Numerical variables were expressed as mean +- SD and categorical variables as percentage. Independent-sample t test or 1-way analysis of variance was used for nu- merical data analysis and ?² test for categorical variables analysis. Pearson correlation test was used to determine the relationship between the nu- merical parameters. P b .05 was considered statistically significant.

Results

A total of 3491 patients who admitted to the emergency department with migraine headaches for a period of 12 months were included in our study. Patients with migraine headaches constituted 1.97% of all patients

(3491/176909) who admitted to the emergency department within 1 year. Seventy-two percent (n = 2518) of patients were female, and the av- erage age of all patients was 36 +- 11 years. There was no difference be- tween men and women according to the mean age (P N .05).

The average daily number of patients was 9.6 +- 4 (3-24). Regarding the time of day, migraine attacks were highest between 2000 and 2100 hours, and a total of 367 patients (270 female and 97 male) with migraine headaches were admitted to emergency department. Also, it was found that more mi- graine patients were admitted to the emergency department in the evening compared with other times of the day. Fifty-five percent (n = 1921) of all mi- graine patients were admitted to emergency department in the evening be- tween 1700 and 2359.More than half (73.5%; n = 1412) of these patients were female. Arrival times of the patients by sex are shown in Fig. 1.

Most of the female patients had migraine attacks on Sunday (16.6%) and Saturday (15.3%). Most of the male patients were admitted to emer- gency department on Tuesday (15.4%) and Sunday (15.2%) (Fig. 2).

Most of the patients were admitted to emergency department with a migraine headache in October (10.5%) and November (10.6%). The number of patients presenting to the emergency department by month was presented in Fig. 3.

Statistically significant correlations were found between the daily number of patients and daily maximum temperature (P = .005), mean temperature (P = .013), minimum temperature (P = .041), and daily tem- perature change (P = .003). A negative correlation was found between the number of patients presenting to the emergency department and daily av- erage relative humidity (P = .031). The relationship between daily num- ber of patients and average temperature (minimum, average, and maximum) and the relationship between daily number of patients and av- erage relative humidity are shown in Figs. 4 and 5.

No statistically significant correlation was found between the daily number of patients presenting to the emergency department and daily maximum-minimum, mean pressure, and daily pressure changes (P N .05). Although a positive correlation was seen between the number of pa- tients with migraine and daily average wind speed (in meters per second), this was not statistically significant (P N .05). The correlation between the

daily number of patients and weather variables is shown in Table.

No significant correlation was found between the number of patients with migraine headaches and moon phases (P N .05). We also compared the moon phases and the number of patients for 4 seasons, but it did not provide a meaningful result.

Discussion

Causes that trigger migraine attacks are not elucidated and internal or external factors play a role. The effects of changes in meteorologic

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Monday Tuesday Wednesday Thursday Friday Saturday Sunday

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Fig. 2. The number of patients admitted to the emergency department with migraine headache by days.

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Patient

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Fig. 3. The number of patients admitted to the emergency department with migraine headache by months.

Fig. 4. The relationship between daily number of patients and average temperatures (maximum, average, and minimum temperature).

Fig. 5. The relationship between the daily number of patients and average relative humidity.

parameters, one of the external factors, on migraine attacks were investi- gated several times and different results were obtained. Migraines are known to be triggered by multi factorial reasons and studies to identify these trigger reasons continue. Pathophysiological mechanisms of chang- es in the weather in causing headaches are not exactly known [16]. We found in our research that the number of patients who were admitted to the emergency department because of migraine headaches is more in the days when the temperature increases and humidity decreases.

There have been published studies in the literature showing that high relative humidity increases frequency of migraine attacks [12,17]. In 2 studies on patients admitted to the emergency department with migraine headaches, no relationship has been reported between hu- midity and the number of patients with migraine attacks [14,15]. Mean- while Gomersall and Stuart [9] found similar results to our study showing a negative correlation with humidity in his study with data ob- tained from headache diaries of 56 patients. Hence, increase in the num- ber of patients with migraine attacks is seen with low humidity.

Increase in the frequency of migraine attacks with increase in tem- perature is supported by many studies [14,18,19]. Nevertheless, there are publications showing that the temperature increase or decrease has no relationship with migraine headaches [12,15]. In recent years, Hoffmann et al [17] showed increased frequency of migraine headaches in a study conducted at Low Temperature. The results of the 2 studies are different in which patients with migraine headaches admitted to the emergency department were selected and there were many patients [13,14]. Villeneuve et al [15] reported no association between the num- ber of patients presenting to the emergency department with migraine attacks and temperature in their study on 4039 patients. In a study by Mukamal et al [14] on 7054 patients, they concluded similarly to our

Table

Comparison of meteorologic data with the daily number of patients

r (Pearson correlation) P

study that the number of patients with migraine headaches increases with temperature rise. In the same study, it was also shown that every 5?C increase increases headache risk by 7.5%, and this is parallel with our result of increase in the number of patients admitted to the emer- gency department with increased daily temperature changes.

Although there are studies [18,19] showing that migraine attacks in- crease with high atmospheric pressure, our results are similar to the results of studies showing no relationship between migraine headache and atmo- spheric pressure [14,15,17,20]. In addition, there are studies showing that migraine attacks increase with low atmospheric pressure [9,12].

Results published by several authors on possible effects of meteorologic parameters such as relative humidity, air temperature, and atmospheric pressure are different. This situation suggests that meteorologic parame- ters alone do not have a direct effect on the number of patients presenting to the emergency department with a migraine headache, but suggesting that other trigger factors play role together with weather parameters.

Stress disorders, changes in sleeping character, or insomnia is known to trigger headaches often [5,21,22]. Stress is a process resulting from interaction with social or natural environment. As there is a com- mon belief that stress is increased during full moon, we have included possible relationship between the number of patients who referred to the emergency department with migraine headaches and moon phases. Although acute behavioral disorders, tendency to violence in Psychiatric patients [21,23], and sleep disorders [24] have been reported to be more during full moon in several publications, we did not find a significant re- lationship between moon phases and the number of patients admitted to the emergency department with migraine headaches.

Conclusion

Different results were obtained from studies examining the relation- ship between meteorologic parameters and migraine headaches. There- fore, as a result of our study in which we investigated the effect of

Mean relative humidity -0.113 .031

No. of patients/d	Maximum temperature	0.146	.005	regional meteorologic parameters on the number of patients admitting
	Minimum temperature	0.107	.041	to emergency department with migraine headache, we have detected
	Mean temperature Max-min temperature	0.130 0.153	.013 .003	that the number of patients admitting to the emergency department with migraine headaches increase with high temperature and low hu-

Maximum pressure 0.01 .848

midity. In addition, we have concluded that there is no relationship be-

Minimum pressure	0.029	.585	tween moon phases and the number of patients admitting to the
Mean pressure	0.021	.685	emergency department with migraine headaches. Further studies are

needed for a more detailed description of factors that trigger migraine attacks and affect the number of migraine attack patients.

	Max-min pressure	-0.066	.212
	Mean windy rate	0.008	.880

Study limitations

Other trigger factors that cause migraine attacks in patients cannot be questioned and the exact time of headache start cannot be deter- mined as our study is retrospectively conducted.

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