Abstract
Background:
Studies reporting the prevalence of headaches in Croatia have methodological differences that make it difficult to consolidate their results. This study aimed to assess the prevalence of the most common primary headaches in a student population using the standardized HARDSHIP questionnaire (in Croatian).
Methods:
This cross-sectional epidemiological study collected data regarding the 1-year prevalence of headaches in a student population using the diagnostic algorithm of the HARDSHIP questionnaire. The chi-squared test was used to analyze gender differences, and Cramer’s V was used for effect size interpretation.
Results:
The questionnaire was administered to 1350 university students enrolled in health profession programs (81.3% female; 18.7% male; average age: 23 years). The 1-year prevalence of migraine was 38.9% (male: female ratio, 1:1.5), and that of tension-type headache was 35.6% (male: female ratio, 1:0.9). Overall, 91.0% of participants responded positively to the question regarding the incidence of headache in the past 12 months.
Conclusions:
We report a high prevalence of primary headaches among students of health professions in Croatia. The differences in prevalence may be attributed to various sociocultural, geographical, genetic, and methodological differences. Population-specific studies may facilitate a more accurate assessment of headache prevalence and enable more effective targeting of public health activities.
Introduction
Primary headaches manifest via different pathophysiological mechanisms and clinical presentations. They also differ in terms of incidence, prevalence, duration, frequency, pain quality, and accompanying symptoms. Assessing the prevalence of primary headaches would allow us to evaluate the magnitude of this public health problem, based on which we can raise awareness among the public, health professionals, and public health decision makers. 1
In Croatia, the prevalence of headaches has only been documented to a partial degree. During 1999–2015, a total of eight published studies reported the prevalence of headaches in Croatia. Three cross-sectional studies assessed headache prevalence among adolescents, whereas four reported headache prevalence among adults. 2 Of the four studies in adults, two were based on door-to-door sampling and face-to-face interviews among residents of the city of Bakar. 3,4 Another study reported the 1-year prevalence of migraines, probable migraines, and tension-type headache among adults in four Croatian cities (Zagreb, Split, Osijek, and Dubrovnik) using a self-report questionnaire. 5 However, the large methodological differences between studies and variable research quality make it difficult to compare the reported prevalence rates and to consolidate the results of these studies. This highlights the need for a consensus regarding the research methodology and instruments used in studies examining the prevalence of headaches in Croatia. 2
Lifting The Burden (LTB) is a non-governmental organization registered in the United Kingdom that manages the Global Headache Campaign under the auspices of the World Health Organization and supports population-based headache research in several countries. 1 To facilitate such studies, the LBT has developed a standardized methodology and research instrument called the Headache-Attributed Restriction, Disability, Social Handicap and Impaired Participation (HARDSHIP) questionnaire. 6 As such, the HARDSHIP questionnaire is a globally recognized instrument for conducting population-level research on the epidemiology of primary headaches.
In this study, we used the validated Croatian translation of the HARDSHIP questionnaire to estimate the prevalence of the most common primary headaches (migraines and tension-type headaches) in a student population at the University of Applied Health Sciences in Zagreb.
Methods
Ethical approval
This study was approved by the Ethics committee of the University of Applied Health Sciences in Zagreb (Class: 602-04/15-18/321; Reg. no.: 251-379-1-15-02).
Participants and research design
This cross-sectional epidemiological study was conducted from January to February 2020. The participants were university students enrolled in various programs related to health professions during the 2019/20 academic year at the University of Applied Health Sciences in Zagreb, Croatia.
Participants were invited to complete the HARDSHIP questionnaire anonymously and on a volunteer basis. Before being administered the questionnaire, the participants were introduced to the purpose and goal of the study and were given detailed instructions for completing the questionnaire. Those who were absent or unwilling to participate in the study were excluded. Two participants were excluded due to irregularities in their responses.
The questionnaire was administered to participants in small groups of 15–20 students in a university classroom setting. After the researcher had described the questionnaire in detail and provided an opportunity for questions or clarification, each student completed the questionnaire independently. The questionnaire was completed in approximately 15 minutes (average).
The HARDSHIP diagnostic questionnaire
The HARDSHIP questionnaire was used to collect data regarding various demographic characteristics and the 1-year prevalence of headaches. This questionnaire has a modular structure and includes a demographic survey, headache screening questions, a set of diagnostic questions based on the ICHD-3 beta criteria, and questions regarding several measurable components of headache-induced stress. It is designed to be used for data collection by trained lay interviewers during face-to-face examination. The interviewers are not expected to diagnose the headache type; instead, this diagnosis is performed algorithmically using a set of diagnostic questions. The sensitivity and specificity of this diagnostic algorithm for migraine and tension-type headache have been demonstrated several cultural contexts and has been validated in 20 countries and 19 languages. 6 To determine headache prevalence in the present study, the HARDSHIP questionnaire was translated from the original English into Croatian in accordance with the LTB translation protocol for hybrid documents. 7 The Croatian version of the HARDSHIP diagnostic questionnaire has been validated previously, showing good performance in university students.
For the screening questions, we found a 100% agreement between headache incidence versus non-incidence (no headache in the preceding year) in the validation subsample (N = 145). For the diagnostic questions, we found very high sensitivity (95%) and high specificity (89%) for migraine, with a positive predictive value (PPV) of 89%, a negative predictive value (NPV) of 95%, and very good agreement (κ = 0.85). For tension-type headache, we found somewhat lower sensitivity (78%), very high specificity (94%), a PPV of 83%, an NPV of 93%, and good agreement (κ = 0.74). 8
A diagnostic algorithm was used to convert responses to the HARDSHIP questionnaire into diagnoses. Based on this, only one type of headache—the most bothersome headache—was assessed in each participant. Using this algorithm, we first applied specific criteria for migraine, followed by criteria for tension-type headache, probable migraine, and probable tension-type headache. Participants that did not meet the above criteria were classified as having undifferentiated headache, defined as headache with a duration of less than 1 hour and of mild intensity. 9
For the purposes of assessing prevalence, definitive and probable migraine were considered migraine, and definitive and probable tension-type headache were considered tension-type headache. This approach has previously been used by Herekar et al., 10 Yu et al. (who considered it “practical and pragmatic”), 11 and Ayzenberg et al. 12
Data analysis
The results are presented using descriptive statistics (M: arithmetic mean; SD: standard deviation). Frequencies are reported as absolute values, and relative ratios are reported with the 95% confidence interval (CI). Gender differences in frequencies of prevalence and diagnosis were tested using the chi-squared (χ2) test. Cramer’s V was used for effect size interpretation. The probability of type I error was set at 5%. The data are available upon reasonable request.
Results
Epidemiological indicators
Of the 1365 students enrolled in full-time study programs at the University of Applied Health Sciences in Zagreb, 1350 participated in the present study (participation rate: 98.9%). Of these, 253 (18.7%) were male and 1097 (81.3%) were female. The mean age was 22 years (M ± SD: 21.9 ± 2.27), with an age range of 18–53 years (Table 1).
Lifelong and 1-year prevalence of headaches in a population of health profession students and Chi-square test results with effect size.
Incidence of headache according to different diagnostic criteria
Overall, 525 (38.9%) respondents tested positive for migraine, 481 (35.6%) tested positive for tension-type headache, and 223 (16.5%) met the criteria for undifferentiated headache. There were statistically significant differences between genders in terms of lifelong prevalence (χ2 = 3.19; p = 0.074, V = 0.05), 1-year prevalence (χ2 = 36.73; p < 0.001; V = 0.17), and frequency of individual diagnoses (χ2 = 46.78; p < 0.001; V = 0.19). Migraine diagnoses were significantly more common among female students (41.7%; N = 457) than among male students (26.9%; N = 68; M: F ratio, 1:1.5). Tension-type headache was diagnosed in 35% (N = 384) of female students and 38.3% (N = 97) of male students (M: F ratio, 1:0.9).
Table 1 summarizes the data on lifelong and 1-year prevalence of headaches among students and lists the results of chi-squared tests with the corresponding effect sizes (Cramer’s V).
Discussion
In the present study, we applied the HARDSHIP diagnostic algorithm to estimate the 1-year prevalence of migraine and tension-type headache among students of health professions at the University of Applied Health Sciences in Croatia. Overall, 91% of participants responded positively to the question regarding the incidence of headache in the past 12 months. Of these respondents, nearly three-quarters tested positive for migraine and tension-type headache, and the rest were classified into the category of undifferentiated headache. Migraine diagnoses were significantly more common among female students, with 41.7% and 26.9% of female and male respondents meeting the diagnostic criteria for migraine (M: F ratio, 1:1.5). In contrast, tension-type headaches were more common among male students (35% of female students; 38.3% of male students; M: F ratio, 1:0.9).
Our results indicate that the prevalence of primary headaches is higher in the student population of the University of Applied Health Sciences than in the general population, as reported in previous studies that were mostly focused on residents of a particular region and/or country. A recent global assessment by Steiner and Stovner reported prevalence rates of 48.0% for all primary headaches, 11.2% for migraines, and 23.4% for tension-type headaches. 13 Moreover, the GBD 2016 assessment reported 1-year prevalence rates of 14.4% for migraines and 26.1% for tension-type headaches. 14 Recent studies in the Republic of Croatia compared these global projections with prevalence rates in the Croatian general population and found no significant deviations. The prevalence of tension-type headaches in adults ranged from 21.2% (on average, 23.2% among women and 19.1% among men) to 34.8%. In contrast, the 1-year prevalence was 7.5% for migraine (9.5% among women and 4.6% among men) and 11.3% for probable migraine (14.9% among women and 6.1% among men). 2 However, the proportion of respondents who tested positive for the screening criteria for primary headaches was higher in this study than in previous studies.
Headache prevalence in specific populations can differ from that observed in the general population. This research was conducted with a group of students from a single university. Therefore, when comparing prevalence results across studies, it is important to consider the age and gender distribution as well as the nature of the study population (in this case, students of health profession studies in the field of biomedicine and health). In this context, the 1-year prevalence rates of migraine and tension-type headaches reported in the present study were compared with those reported in other similar studies that estimated headache prevalence among students in health profession fields.
Differences in estimated headache prevalence rates among university students in the health profession fields
To our knowledge, only one observational, individual, and uncontrolled study estimated the prevalence of headaches among students in the Republic of Croatia. This 2003 study included 314 first- and sixth-year students at the University of Zagreb School of Medicine and reported prevalence rates of 8.86% and 10.90% for migraine and 60.13% and 57.69% for tension-type headaches among first- and sixth-year students, respectively. 15 Large differences in recorded prevalence are immediately evident when these findings are compared with the results of the present study.
Previous studies in other countries have reported different prevalence rates for migraine, tension-type headache, and all primary headaches. A 2001 study examining the prevalence of headaches among medical students in Oman reported a lifelong prevalence of 98.3% and a 1-year prevalence of 96.8%, which are slightly higher than the estimates reported in the present study. The researchers observed that migraine and tension-type headaches were equally prevalent (both 12.2%), although with a marked gender difference (migraine: 15.5% among females and 6.6% among males); tension-type headaches: 11.1% among females and 13.9% among males). 16 These prevalence rates for migraine and tension-type headache are lower than those estimated in the present study, both overall and in terms of the gender distribution. A 2011 study by Barros et al. reported a 91% 1-year prevalence of headaches among medical and psychology students. Compared with our findings, Barros et al. reported a lower prevalence of migraine (22.6% overall; 18.5% among females and 18.8% among males) and higher prevalence of tension-type headaches (59.9% overall; 56.0% among females and 67.5% among males), with the prevalence of unclassified headaches being 16.3%. 17
Several studies in other countries have reported lower prevalence rates for headaches compared with those reported in this study. A 2008 study on students in Turkey reported prevalence rates of 22.64% for tension-type headache (22.98% among females and 22.33% among males) and 17.89% for migraines (23.50% among females 12.89% and among males). 18 A 2014 study conducted in Ethiopia reported that the 1-year prevalence of headaches was 67.2% among undergraduate students in medical and health studies. The prevalence rates were 13.06% for migraine (16.0% among females and 11.92% among males), 66.81% for tension-type headache, and 1.25% for unclassified headaches. 19 A 2009 study on medical students in Nigeria reported prevalence rates of 18.1% for tension-type headache (19.2% among females and 17.3% among males) and 6.4% for migraine (10.9% among females, which was 3 times the prevalence rate of 3.2% among males). 20
A 2016 study evaluated the prevalence, patterns, and psychosocial factors related to headaches using the HARDSHIP questionnaire among undergraduate health professionals in India. The 1-year prevalence of headache was 73.1% (migraine: 33.3%; tension-type headache: 19.2%). 21 A 2000 study in Brazil reported a prevalence rate of 60.7% for primary headaches; the prevalence of migraine (54.3%) was higher than those of tension-type headache (33.2%) and all other types of headaches (12.3%). 22 Three studies have investigated the prevalence of primary headaches in Saudi Arabia. A 2017 study reported a headache prevalence of 68.4% among female students (migraine: 32.5%; tension-type headache: 29.5%). 23 Another 2017 study reported that the prevalence rate of migraine was 36.5% (40.1% among female students and 25.0% among male students). 23 The latest study, conducted in 2020, recorded a very high prevalence of migraine among male students (71.6%). 24
In 2017, Lebedeva et al. reported headache prevalence rates of 95.1% among female students and 87.9% among male students; for migraine, the prevalence rates were 34.7% and 14.8% among female and male students, respectively; for tension-type headaches, the prevalence rates were 76.7% and 79.2% among female and male students, respectively. 25 As in the present study, the prevalence rates of migraine and tension-type headache were very high in this group of students.
A 2015 meta-analysis of migraine prevalence among university students combined data from 56 independent studies and analyzed the results for a total sample of 34,904 students. The results of this analysis indicated an overall migraine prevalence of 16.1% (21.7% among females and 11.3% among males). Moreover, subgroup analysis revealed that the diagnostic criteria and gender distribution significantly influenced the estimates of migraine prevalence. 26 Thus, the observed differences in estimated prevalence rates among students in health profession fields could be attributed to inconsistent sampling, gender distribution, age range, and cultural differences.
In the present study, migraine was slightly more prevalent (38.9%) than tension-type headache (35.6%). This pattern has also been reported by recent epidemiological studies in selected student populations in India (migraines: 33.3%; tension-type headaches: 19.2%), 21 Saudi Arabia (migraines: 32.5%; tension-type headaches: 29.5%), 23 and Brazil (migraines: 54.3%; tension-type headaches 33.2%). 22
Gender-related prevalence rates
Most epidemiological studies examining the prevalence of headaches report a higher incidence of all types of headaches among women than in men. Overall, the ratio of prevalence in men vs. that in women is 1:1.3 for all headaches and 1:1.2 for tension-type headaches. The largest gender differences are observed for migraines, where the prevalence is 2–3 times higher among females than among males. 13
In the present study, the prevalence of migraines was higher among female students (41.7%) than among male students (26.9%), with a M: F ratio of 1:1.5. Similar results were reported by Ibrahim et al., who estimated migraine prevalence rates of 40.1% and 25% among female and male students, respectively. This gender ratio of migraine prevalence was also similar to those reported in most epidemiological studies in a selected student population. 27 However, we found that the prevalence of tension-type headaches was higher among male students (38.3%) than among female students (35.0%). Lebedeva et al. also found a slightly higher prevalence of tension-type headaches among male students (79.2%) than among female students (76.7%). 25
In our study, the prevalence of migraine among men was higher than that reported previously, and the ratio of prevalence in men vs. women was lower than expected. A 2022 meta-analysis reported that the global prevalence of migraine was 13.8% among females and 6.9% among males (M: F ratio, 1:2). 28 In the same year, Flynn et al. published a meta-analysis of data on the global prevalence of migraine among university students and reported a prevalence of 23% among females and 12% among males (M: F ratio, 1:1.9). 29
To identify the potential factors influencing the male vs. female ratio of prevalence in our study, we evaluated the ratios of migraine prevalence reported in other studies among men and women in a similar age group (Table 2). Živadinov et al. previously reported a lower ratio of prevalence among men vs. women in Croatia; among 101 respondents in the age group of 20–29 years, the prevalence of migraine was 14.1% among females and 10.3% among males (M: F ratio, 1:1.36). 3 In a recent German study on a population-based sample, Yoon et al. reported that the prevalence of migraine was 23.9% among females and 11.1% among males (age range, 18–66 years; M: F ratio, 1: 2.2). However, in the age group 18–25 years, the prevalence rates were 18.7% and 13.4% among females and males, respectively (M: F ratio, 1:1.4). This ratio is similar to that reported in the present study. Yoon et al. presented data on people with more than one type of headache, so that the prevalence rates of migraine and tension-type headache were 20% among women and 13.6% among men in the age group of 18–25 years (M: F ratio, 1:1.47). Taken together, the total prevalence of migraine in this age group was 38.7% among women and 27% among men (M: F ratio, 1:1.43). 30 There were some methodological differences between our study and the study by Yoon et al. (e.g., focus on the type of headache that is most bothersome or interferes the most instead of a separate group of subjects with more than one headache). Nevertheless, we can reasonably assume that the common sociocultural and historical framework (i.e., selected populations in Central Europe) of these studies provides an appropriate background for comparing their results.
Comparison of migraine prevalence values for women and men between our study and other studies in a similar age range.
The differences in prevalence between males vs. females may be related to gender differences in the age of onset of migraine. Stewart et al. estimated age-specific incidences of migraine using self-reported data relevant to the identification of migraine cases, age of onset of migraine, and age at interview. The median age of onset was 25 years and 24 years among female and male patients, respectively. Migraine incidence peaked between the ages of 20 and 24 years in female patients (18.2/1000 person-years) and 15 and 19 years in male patients (6.2/1000 person-years). After the age of 20 years, migraine incidence showed a more gradual increase and decline in the male population. 35
Overall, a comparison of the results of the present study with those of previous similar studies reveals substantial variations in the reported prevalence rates of headaches. When comparing studies that apply the diagnostic criteria of the International Classification of Headache Disorders (ICHD), it is important to consider the version of the classification that was current at the time of any given study. When research is grouped based on the ICHD criteria applied in each study, there is a noticeable increase in the prevalence of primary headaches in selected populations of students over time. As such, it may be assumed that the application of modern diagnostic criteria—that are constantly being updated and changed according to new scientific knowledge—has enabled the identification of a greater number of cases positive for primary headaches. This also suggests that the number of diagnosed cases was very likely underestimated in previous studies.
A comparison of our findings with those of previous epidemiological studies worldwide reveals numerous differences in the 1-year prevalence rates of primary headaches. Indeed, such differences in prevalence rates are evident across existing epidemiological research and may be attributed to differences in various sociocultural, geographical, genetic, and methodological factors. It is impossible to avoid variations in age and gender distributions when conducting epidemiological studies with selected populations, and both variables can influence the prevalence rates in a given sample or population. Therefore, caution should be exercised when interpreting and comparing the results of studies examining headache prevalence. Particular attention should be paid to the selected population and methodology used in any given study.
The present study was conducted according to published standardized methodology, and diagnoses were made according to a standard algorithm that was translated into the Croatian language and validated previously. However, this study has some limitations. This was a single-center study on a population of students in health profession programs. This population is traditionally dominated by women, and the gender distribution in the selected population was uneven. Although we achieved an enviable participation rate (98.9%) for the selected population, these results may not be representative of the overall student population in Croatia.
Further epidemiological research is needed in Croatia, and studies using a uniform methodology in accordance with modern diagnostic criteria should be encouraged. Focusing on selected populations would enable researchers to assess headache prevalence more accurately, based on which public health activities can be targeted more effectively.
Public health relevance
Students of health profession programs show a very high prevalence of primary headaches Migraines are more prevalent among female students Tension-type headaches are more prevalent among male students This high prevalence may be due to the availability of better diagnostic tools, suggesting that previous studies may have underestimated the prevalence of headaches
Footnotes
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Ethic approval and patient consent
This study was approved by the Ethics committee of the University of Applied Health Sciences in Zagreb (Class: 602-04/15-18/321; Reg. no.: 251-379-1-15-02). Written informed consent was obtained from all participants.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
