What this is
- This study assessed headache disorders among children and adolescents in Nepal.
- It is part of a global initiative to better understand headache prevalence in young populations.
- The research aimed to estimate the prevalence of various headache types and their demographic associations.
Essence
- Headache disorders are highly prevalent among children and adolescents in Nepal, with 85.4% reporting any headache in the past year. is the most common type, particularly associated with altitude.
Key takeaways
- 85.4% of participants reported any headache in the past year, indicating a high prevalence among children and adolescents in Nepal.
- prevalence was estimated at 39.8%, making it the most common headache type in this population.
- Headache yesterday (HY) was reported by 24.3% of those with any headache, suggesting underreporting of headache frequency.
Caveats
- The study's cross-sectional design limits causal inferences about headache prevalence and its associations.
- Diagnostic challenges exist due to reliance on self-reported symptoms, which may lead to misclassification.
Definitions
- Migraine: A type of headache characterized by intense, throbbing pain, often accompanied by nausea and sensitivity to light.
- Tension-type headache (TTH): A common headache type characterized by a dull, aching pain and a sensation of tightness or pressure around the head.
- Undifferentiated headache (UdH): A short-lasting headache that does not fit the criteria for migraine or TTH, initially defined as mild headache lasting < 1 hour.
Simplified
Introduction
According to estimates from the Global Burden of Disease, Injuries and Risk Factors (GBD) study, headache disorders are among the top causes of heath loss in children and adolescents [1, 2]. These estimates are based on rather sparse data: globally, the prevalence and attributed burden of headache disorders in those aged < 18 years are very incompletely described. Specifically to address this knowledge gap, the Global Campaign against Headache commenced a programme of schools-based studies in countries around the world, completing studies in Benin [3], Ethiopia [4], Lithuania [5], Mongolia [6], Turkey [7] and Zambia [8] before the programme was interrupted by the covid-19 pandemic. This study in Nepal, conducted after schools reopened, is the first in the programme from South East Asia Region (SEAR). While no previous studies of any sort have addressed childhood and adolescent headaches in Nepal, a previous population-based survey of adults in this country revealed a very high burden of headache, and a strong association between migraine and altitude [9, 10].
Nepal’s population is young: almost 40% are under the age of 18 years [11]. Net enrolment rate in primary school (6–11 years) in 2022 was 99.0%, with > 90% transitioning to upper primary (12–14 years; net enrolment 91.7%), and > 75% to secondary school (15–18 years; net enrolment 76.0%) [12, 13]. Schools-based studies are therefore an effective and economical way of surveying these age groups, with the potential to reach all children and most adolescents.
The programme is focused on the most common headache types – and those of greatest public-health importance: migraine, tension-type headache (TTH) and headaches occurring on ≥ 15 days/month (H15+), including medication-overuse headache (MOH), along with undifferentiated headache (UdH), the short-lasting headaches believed to represent manifestations of migraine or TTH in the developing brain [7, 14]. Previous studies in other countries have found UdH to be prevalent in both children and adolescents [3–8].
The purposes of this study were to enhance understanding of the global headache burden in children and adolescents and to inform public-health and educational policies in Nepal. Here we report the prevalence of various headache types and their associations, while a subsequent paper will focus on attributed burden and consequences of these disorders.
Methods
We followed the programme’s standardised protocol [14] in a cross-sectional survey conducted in schools across Nepal. Pupils filled out a structured questionnaire in class, under the supervision of school staff.
Ethics and approvals
The protocol was approved by the Institutional Review Committee of Tribhuvan University Institute of Medicine: 169(6–11)F2 078/079. Necessary authorizations from academic and administrative authorities, and permissions from principals and class teachers, of each school were obtained.
In accordance with the ethics approval, all participants (pupils and teachers) were informed verbally of the nature and purpose of the study, and gave oral consent before enrolment. Continuing consents were evidenced by active completion of the questionnaires. In view of the non-interventional nature of the study, neither the Institutional Review Committee nor the academic and administrative authorities requested parental consent.
Data were recorded anonymously, and managed in accordance with local data protection regulations.
Sampling and recruitment
This study was carried out from March to November 2022.
In accordance with published guidelines [14, 15], we adopted a cluster-sampling methodology and aimed for 2,100 participants (about 175 from each year of age).
We included nine schools representing a mix of urban and rural populations across the socioeconomic range and from altitudes 70 to 2,860 m above sea level. They were situated in nine districts of Nepal, each in the administrative centres of six of Nepal’s seven provinces (Biratnagar and Lukla in province 1, Janakpur in province 2, Kathmandu and Dhulikhel in province 3, Pokhara and Besisahar in province 4, Butwal in province 5 and Dunai in province 6 [Fig. 1]). Province 7 in the far western region was not reachable, and administrative approvals from schools in the province were not forthcoming.
We rescheduled data collection in Lukla three times because of bad weather (the airport of Lukla is regarded as one of the most dangerous airports in the world, with flights allowed only in good visibility). In Besisahar, we rescheduled twice because of news of landslides affecting unpaved roads.
In each school included, pupils aged 6–11 years (children) or 12–17 years (adolescents) and present on the day of survey were eligible for inclusion and invited to participate. Those who declined or could not participate were counted as non-participants. Those absent from school on the survey day were not available for inclusion and therefore not counted as non-participants.
Distribution of selected schools in nine districts of Nepal
Data collection
We used the child and adolescent versions of the Headache-Attributed Restriction, Disability, Social Handicap and Impaired Participation (HARDSHIP) questionnaire, each containing 45 questions [14]. These were translated into Nepali following the Global Campaign’s translation guidelines for lay documents [16], with a pilot study in 155 children and 119 adolescents to assess usability and comprehensibility in these age groups. The questionnaires began with demographic enquiry, followed by headache screening questions. For those who reported headache in the preceding year, diagnostic questions were posed based on ICHD-3 criteria [17], followed by enquiries into attributable burden (not reported here). The timeframes of these enquiries were the preceding 1 year and 4 weeks (28 days), but additional questions about headache on the preceding day (headache yesterday [HY]) were included to identify and circumvent recall error [15].
The questionnaires were distributed to the pupils in class, who completed them under supervision by the researchers and class teacher. Guidance and clarification were provided when needed.
Separate questionnaires, completed by the teachers, enquired into each school’s location (urban or rural) and altitude, and the estimated proportions of pupils coming from low-income homes and travelling for > 1 h each day.
Headache diagnoses
Diagnoses were made by applying the HARDSHIP algorithm [7, 18] to the responses to the diagnostic question set. After identifying pupils reporting headache on ≥ 14 days in the previous 28 days (assumed to equate to ≥ 15 days in the previous 30 days [H15+]), we diagnosed those also reporting medication use on ≥ 14 days as probable MOH (pMOH); the others were not further diagnosed but categorised as “other H15+”. Among the remainder, we first identified UdH, initially as headache of mild intensity and usual duration of < 1 h (the conventional definition [7]), but subsequently as mild-to-moderate headache lasting < 1 h (see Results and Discussion). The diagnoses of pMOH, other H15 + and UdH therefore took precedence over diagnoses of definite migraine, definite TTH, probable migraine or probable TTH [7, 18], these derived by application of modified ICHD-3 criteria [17]. Definite and probable migraine were combined, as were definite and probable TTH, in subsequent analyses.
Data management
Questionnaires were securely stored at the Department of Neurology, Tribhuvan University Teaching Hospital. Data were entered into SPSS software platform 25.0. To ensure accuracy, double data entry was performed, and discrepancies reconciled by cross-referencing to the original data.
Analysis
The principal analysis was performed at University of Mersin, using the analytical methods adopted by all previous Global Campaign studies [3–8]. Additional statistical modelling to review, and revise, the diagnostic criteria for UdH was performed at NorHead.
We categorised schools by location (urban, semirural or rural) and, as a socio-economic indicator, by teachers’ estimates of proportions of pupils coming from low-income homes (< 25%, 25–49%, ≥ 50% [for simplicity we refer to these categories as “high-income”, “middle-income” and “low-income”]). We also characterised schools by proportions of pupils living at distances of > 1 h’s travel time.
In order to establish representativeness, we compared the sample with the population aged 6–17 in Nepal for demographic variables, using data from the World Bank [19].
For descriptive statistics, we used means and standard deviations (SDs) for continuous variables, and proportions (%) with 95% confidence intervals (CIs) for categorical variables.
We used conservative imputation for missing responses to the diagnostic questions: headache intensity was assumed to be moderate (this being neutral between migraine and TTH); nature of headache was assumed to be pressing when applying the algorithm for migraine (tending towards TTH), throbbing when applying the algorithm for TTH (tending towards unclassified); nausea and vomiting were assumed to be absent (since they were very likely to be reported if present).
We calculated observed prevalence of each headache type in the sample, and made population estimates by adjusting for gender and age, again using data from the World Bank [19]. To examine relationships between headache types and gender, age, altitude of dwelling and urban or rural habitation, we performed both bivariate analyses, reporting odds ratios (ORs), and binary logistic regression, reporting adjusted ORs (aORs).
We calculated the 1-day prevalence of any headache as the proportion of the entire sample reporting HY. We also calculated the proportions reporting HY of those with headache (any, and of each type) in the preceding year, along with the proportions predicted to have HY from the responses to two questions: “On how many days in the last week did you have headache?” and “On how many days in the past four weeks did you have headache?” The analyses by headache type assumed that HY was of the type described in earlier questioning.
The significance level for all analyses was set at p < 0.05.
Results
The pilot study (in 155 children and 119 adolescents) assessing usability and comprehensibility of the questionnaires found no need for modifications.
A total of 2,360 pupils (children 1,045; adolescents 1,315) were present on the survey days, available for inclusion. Of these, eight (five children, three adolescents) were non-participants, either providing incomplete responses or being unable to follow repeated instructions. The total sample was N = 2,352 (children 1,040 [44.2%]; adolescents 1,312 [55.8%]), with an overall participating proportion of 99.7%.
The sample had a preponderance of males (1,269; 54.0%) in comparison with the population aged 6–17 years (50.9% [19]; X2(1, 2352) = 4.4, p = 0.04). Mean age was 11.8 years (SD = 2.7), very similar to but nonetheless significantly higher than the mean age of this population (11.5 years [19]; t-test (df = 2351) = 5.4; p < 0.001).
Table 1 shows information about the schools provided by the teachers. Urban schools were attended by rather more than half of pupils (55.4%), with fewer than 25% at these schools travelling for > 1 h to reach them. Schools located at or above 1,000 m above sea level were attended by a similar proportion (55.5%; 24.5% >2,000 m). Two thirds (68.5%) of pupils attended high-income schools (as defined: see Methods); none were judged to come from low-income homes (Table 1).
| Variable of interest | Schools (= 9)Nn | Pupils (= 2,352)(%)Nn |
|---|---|---|
| School location | ||
| urban semirural rural | 5 2 2 | 1,302 (55.4) 474 (20.2) 576 (24.4) |
| School altitude (metres above sea level) | ||
| < 1,000 1,000–2,000 > 2,000 | 4 3 2 | 1,048 (44.6) 728 (31.0) 576 (24.5) |
| Income category according to estimated proportion of pupils from low-income homes | ||
| < 25% (“high-income” school) 25–50% (“middle-income” school) ≥ 50% (“low-income” school) | 6 3 | 1610 (68.5) 742 (31.5) |
| Estimated proportion of pupils travelling > 1 h | ||
| < 25% 25–50% ≥ 50% | 5 4 | 1,302 (55.4) 1,050 (44.6) |
Headache prevalence
Headache ever was reported by 2,138 participants, a lifetime prevalence of any headache of 90.9%. Of these, 2,008 (85.4% [95% CI: 83.9–86.8%]) reported headache in the preceding year, rather fewer males (83.5% [81.4–85.5%]) than females (87.5% [85.4–89.4%]) (Table 2).
Responses to the headache diagnostic questions were complete except for headache intensity (missing in one), throbbing/pressing (missing in two), nausea (missing in one), and vomiting (missing in one). For these, we used imputation (see). Methods
The conventional diagnostic criteria for UdH (mild headache lasting < 1 h [5]) were fulfilled by only 4.8% (3.9–5.7%) (Table 2); overall, only 7.8% reported headache of mild intensity (Table 3). With these criteria applied, 58.4% (56.4–60.4%) fulfilled those for migraine (definite 14.8% [13.4–16.3]; probable 43.6% [41.6–45.6]) (Table 2), a proportion driven by reported intensity (92.2% moderate or severe), worsening on exercise (61.1%) and nausea (59.0%), with phonophobia a near-universal experience (94.6%) during headache episodes of any type (Table 3).
Our modified criteria for UdH (mild-to-moderate headache lasting < 1 h [see Methods]) were fulfilled by 32.1% (30.2–34.0%), again rather fewer males (30.3% [27.8–32.8%]) than females (34.3% [31.5–37.1%]) (Table 4). With these modified criteria applied, migraine remained the most prevalent headache type (observed prevalence 39.8% [37.8–41.8%]; definite remaining at 14.8% [13.4–16.3]; probable reduced substantially to 25.1% [23.4–27.0]), with no gender difference (males 39.6% [36.9–42.3%]; females 40.1% [37.2–43.0]). Still contributing to these high estimates were the large proportions reporting nausea (59%) and/or vomiting (43.0%), and also, since phonophobia was almost universal (94.6%), those reporting photophobia (51.5%) (Table 3). Observed prevalence of TTH was also reduced, from 16.5% (15.0–18.0) (Table 2) to 10.5% (9.3–11.7%; definite 6.4% [5.4–7.5], probable 4.1% [3.3-5.0]). Observed prevalence of pMOH remained at 0.3% (0.1–0.5%), and of other H15 + at 2.0% (1.4–2.6) (Table 4). Adjustments for age and gender slightly reduced prevalence estimates for all headache (83.9%), migraine (39.5%), TTH (10.0%) and UdH (31.7%) (Table 4). With the modified criteria for UdH, only 0.6% of headaches remained unclassified.
| Headache type | Overall | Male | Female |
|---|---|---|---|
| % [95% confidence interval] | |||
| Any headache | 85.4 [83.9–86.8] | 83.5 [81.4–85.5] | 87.5 [85.4–89.4] |
| Migraine | 58.4 [56.4–60.4] | 57.9 [55.1–60.7] | 58.9 [55.9–61.9] |
| definite | 14.8 [13.4–16.3] | 14.7 [12.9–16.8] | 14.9 [12.8–17.2] |
| probable | 43.6 [41.6–45.6] | 43.2 [40.4–46.0] | 44.0 [41.1–47.1] |
| TTH | 16.5 [15.0–18.0] | 16.2 [14.2–18.3] | 16.8 [14.6–19.2] |
| definite | 6.4 [5.4–7.5] | 6.9 [5.6–8.4] | 5.8 [4.5–7.4] |
| probable | 10.1 [8.9–11.4] | 9.3 [7.8–11.1] | 11.0 [9.2–13.0] |
| pMOH | 0.3 [0.1–0.6] | 0.3 [0.1–0.8] | 0.3 [0.1–0.8] |
| Other H15+ | 2.0 [1.5–2.7] | 1.6 [1.0-2.4] | 2.5 [1.6–3.6] |
| UdH | 4.8 [3.9–5.7] | 4.9 [3.8–6.2] | 4.6 [3.4-6.0] |
| Unclassified | 3.5 [2.8–4.3] | 2.7 [1.9–3.7] | 4.4 [3.3–5.8] |
| Characteristic | (%)n |
|---|---|
| Location | |
| unilateral | 369 (18.4) |
| bilateral | 1,639 (81.6) |
| Pain characteristic | |
| pulsating | 828 (41.2) |
| pressing | 1,178 (58.7) |
| Intensity | |
| mild | 156 (7.8) |
| moderate | 1,285 (64.0) |
| severe | 566 (28.2) |
| Worse on exercise | 1,227 (61.1) |
| Avoid exercise | 945 (47.1) |
| Nausea | 1,185 (59.0) |
| Vomiting | 864 (43.0) |
| Photophobia | 1,034 (51.5) |
| Phonophobia | 1,900 (94.6) |
| Variable | Any headache | Migraine | TTH | pMOH | Other H15+ | UdH |
|---|---|---|---|---|---|---|
| % [95% confidence interval] | ||||||
| Observed | ||||||
| Overall (= 2,352)N | 85.4 [84.0-86.8] | 39.8 [37.8–41.8] | 10.5 [9.3–11.7] | 0.3 [0.1–0.5] | 2.0 [1.4–2.6] | 32.1 [30.2–34.0] |
| Gender | ||||||
| male (= 1,269)nfemale (= 1,083)n | 83.5 [81.5–85.5] 87.5 [85.5–89.5] | 39.6 [36.9–42.3] 40.1 [37.2–43.0] | 11.3 [9.6–13.0] 9.6 [7.9–11.3] | 0.3 [0.0-0.6] 0.3 [0.1–0.6] | 1.6 [0.9–2.3] 2.5 [1.6–3.4] | 30.3 [27.8–32.8] 34.3 [31.5–37.1] |
| Age | ||||||
| 6–11 (= 1,040)n12–17 (= 1,312)n | 77.3 [74.8–79.9] 91.8 [90.3–93.3] | 37.8 [34.9–40.8] 41.5 [38.8–44.2] | 7.4 [5.8-9.0] 13.0 [11.2–14.8] | 0.5 [0.1–0.9] 0.2 [0.0-0.4] | 1.3 [0.6-2.0] 2.6 [1.7–3.5] | 29.7 [26.9–32.5] 34.1 [31.5–36.7] |
| School altitude (metres above sea level) | ||||||
| < 1,000 (= 1,048)n1,001–2,000 (= 728)n> 2,000 (= 576)n | 84.3 [82.0-86.5] 84.3 [81.7–87.0] 88.7 [86.1–91.3] | 31.2 [28.4–34.0] 45.7 [42.1–49.4] 48.6 [44.5–52.7] | 11.0 [9.1–12.9] 10.6 [8.3–12.8] 9.4 [7.0-11.8] | 0.1 [0-0.3] 0.5 [0.1–1.1] 0.3 [0-0.8] | 1.1 [0.5–1.8] 4.3 [2.8–5.7] 0.7 [0.0-1.4] | 40.3 [37.3–43.2] 22.8 [19.8–25.9] 29.0 [25.3–32.7] |
| School location | ||||||
| urban (= 1,302)nsemirural (= 474)nrural (= 576)n | 83.2 [81.2–85.2] 87.3 [84.3–90.3] 88.7 [86.1–91.2] | 32.3 [29.8–34.8] 50.0 [45.5–54.5] 48.4 [44.3–52.5] | 11.4 [9.7–13.1] 9.3 [6.7–11.9] 9.5 [7.1–11.9] | 0.2 [0.0-0.4] 0.4 [0.0–1.0] 0.3 [0.0-0.8] | 1.4 [0.8-2.0] 5.3 [3.3–3.7] 0.7 [0.0-1.4] | 37.3 [34.7–39.9] 21.7 [18.0-25.4 29.0 [25.3–32.7] |
| Age- and gender-adjusted estimates | ||||||
| Overall | 83.9 [82.4–85.4] | 39.5 [37.5–41.5] | 10.0 [8.8–11.2] | 0.3 [0.1–0.5] | 1.9 [1.4–2.5] | 31.7 [29.8–33.6] |
Demographic associations
These, with the modified criteria for UdH applied, are shown in Tables 5 and 6.
There were no associations between gender and migraine, TTH, pMOH or UdH, while other H15 + was more common among females than males according to logistic regression analysis (Table 6). TTH and other H15 + were significantly more common among adolescents in logistic regression analysis, migraine and UdH not quite significantly so (Table 6).
Migraine became increasingly prevalent at higher altitudes in bivariate analysis, while UdH was most prevalent at low altitude (Table 5). However, correction for other demographic variables weakened these associations above 2,000 m, with migraine and UdH showing inverse relationships with altitude (Table 6). Only migraine showed a clear association with habitation (more common in semirural or rural areas); other H15 + was more common in semirural or rural areas, and UdH less common, in bivariate analysis only (Tables 5 and 6).
| Variable | Migraine | TTH | pMOH | Other H15+ | UdH | |
|---|---|---|---|---|---|---|
| Odds ratio [95% confidence interval];p | ||||||
| Gender | ||||||
| male (= 1,269)nfemale (= 1,083)n | reference1.0 [0.9–1.2]= 0.86p | reference0.8 [0.6–1.1]= 0.21p | reference0.9 [0.2-4.0]= 0.87p | reference1.6 [0.9–2.9]= 0.12p | reference1.2 [1.0-1.4]= 0.05p | |
| Age (years) | ||||||
| 6–11 (= 1,040)n12–17 (= 1,312)n | reference1.2 [1.0-1.4]= 0.08p | reference1.9 [1.4–2.5]p< 0.001 | reference0.3 [0.04–1.5]= 0.17p | reference2.1 [1.1–4.2]p= 0.02 | reference1.2 [1.0-1.5]p= 0.02 | |
| School altitude (metres above sea level) | ||||||
| < 1,000 (= 1,048)n1,001–2,000 (= 728)n> 2,000 (= 576)n | reference1.9 [1.5–2.3]p< 0.0012.1 [1.7–2.6]p< 0.001 | reference1.0 [0.7–1.3]= 0.79p0.8 [0.6–1.2]= 0.31p | reference5.8 [0.9–11.3]= 0.12p3.7 [0.3–78.6]= 0.29p | reference3.8 [2.0-7.8]p< 0.0010.6 [0.2–1.7]= 0.38p | reference0.4 [0.4–0.5]p< 0.0010.6 [0.5–0.8]p< 0.001 | |
| School location | ||||||
| urban (= 1,302)nsemirural/rural (= 1,050)n | reference2.0 [1.7–2.4]p< 0.001 | reference0.8 [0.6–1.1]= 0.14p | reference1.7 [0.4–8.4]= 0.51p | reference2.0 [1.1–3.7]p= 0.02 | reference0.6 [0.5–0.7]p< 0.001 | |
| Variable | Migraine | TTH | pMOH | Other H15+ | UdH |
|---|---|---|---|---|---|
| Adjusted odds ratio [95% confidence interval];p | |||||
| Gender | |||||
| male female | reference1.0 [0.8–1.2]= 0.97p | reference0.9 [0.7–1.1]= 0.25p | reference0.9 [0.2–4.1]= 0.91p | reference1.8 [1.0-3.4]p= 0.04 | reference1.2 [1.0-1.4]= 0.07p |
| Age (years) | |||||
| 6–11 12–17 | reference1.2 [1.0-1.4]= 0.07p | reference1.9 [1.5–2.6]p< 0.001 | reference0.3 [0.0-1.5]= 0.18p | reference2.8 [1.5–5.7]p= 0.002 | reference1.2 [1.0-1.4]= 0.06p |
| Altitude (metres above sea level) | |||||
| < 1,000 1,001–2,000 > 2,000 | reference1.4 [1.0-1.8]p= 0.041.2 [0.8–1.8]= 0.29p | reference1.2 [0.8–1.8]= 0.43p1.0 [0.6–1.9]= 0.94p | reference8.0 [0.8–172.0]= 0.09p8.6 [0.4–302.0]= 0.18p | reference2.3 [0.8-6.0]= 0.10p0.2 [0.0-0.8]p= 0.04 | reference0.5 [0.4–0.7]p< 0.0010.7 [0.5–1.1]= 0.12p |
| Habitation | |||||
| urban semirural/rural | reference1.7 [1.2–2.3]p= 0.001 | reference0.8 [0.5–1.3]= 0.30p | reference0.5 [0.1–4.1]= 0.48p | reference2.5 [1.1–6.8]= 0.05p | reference0.8 [0.6–1.2]= 0.28p |
Headache yesterday
HY was reported by 488 participants (Table 7), who were 24.3% of those with headache in the preceding year and 20.7% of the total sample (this representing the observed 1-day prevalence). More females reported HY (29.6% of those with headache in the preceding year) than males (19.5%; X2(1, 2008) = 27.8; p < 0.001). No significant difference was seen between children (22.5%) and adolescents (25.5%; X2(1, 2008) = 2.3; p = 0.13). The age- and gender-adjusted 1-day prevalence was 19.9% (18.3–21.6).
As expected, large proportions (> 70%) of those with H15+ (pMOH or other) reported HY (Table 7). Of the episodic headache types, migraine led with 28.9%, followed by TTH (20.7%) and UdH (16.0%).
For all headache types except pMOH, reported HY was higher than predicted from recalled headache frequency, whether the latter was based on the preceding 1 week or 4 weeks (Table 7). For all headache types except pMOH and other H15+, HY predicted from 1-week frequency was greater (up to 2-fold) than from 4-week frequency (Table 7).
| Recalled mean headache frequency | Headache yesterday (proportion of those with headache [any, or of the specific type] in the preceding year) | ||||
|---|---|---|---|---|---|
| Days in preceding 1 week (F7) | Days in preceding 4 weeks (F28) | Reported(%)n | Predicted (%) | ||
| from 1-week recall (F7*100/7) | from 4-week recall (F28*100/28) | ||||
| Any headache (=2,008)n | 1.2 | 2.9 | 488 (24.3) | 17.6 | 10.3 |
| males (=1,060)n | 1.1 | 2.7 | 207 (19.5) | 15.8 | 9.5 |
| females (=948)n | 1.4 | 3.1 | 281 (29.6) | 19.7 | 11.2 |
| children (=804)n | 1.3 | 2.9 | 181 (22.5) | 18.9 | 10.5 |
| adolescents (=1,204)n | 1.2 | 2.8 | 307 (25.5) | 16.8 | 10.1 |
| Migraine (=940)n | 1.4 | 3 | 272 (28.9) | 20.1 | 10.6 |
| TTH (=246)n | 1 | 2.3 | 51 (20.7) | 15 | 8.1 |
| pMOH (=7)n | 4.1 | 21.7 | 5 (71.4) | 59.2 | 77.6 |
| Other H15+ (=47)n | 4.4 | 17.9 | 37 (78.7) | 62.9 | 64 |
| UdH (=755)n | 0.9 | 1.9 | 121 (16.0) | 12.2 | 6.7 |
Discussion
This schools-based study in Nepal was the Global Campaign’s first in SEAR. We found that the vast majority of children and adolescents experienced headache in the preceding year: an estimated 83.9% corrected for age and gender, very similar to our earlier finding of 84.9% among adults in Nepal [8]). Migraine was the most common headache type. An estimated 2.2% had headache on ≥ 15 days/month, but only 0.3% in association with acute medication overuse (pMOH). Estimated 1-day prevalence was 19.9%.
The study highlighted the diagnostic difficulties commonly encountered in epidemiological studies among young people [3, 4, 8]. In large cross-sectional studies, headache diagnoses can be based only on subjective reporting of symptoms elicited by questionnaire. How questions are asked, and understood through the barriers of young age and linguistic and cultural diversities, are therefore pivotal. In previous papers [3–8] we have referred to children’s potential susceptibility to suggestion (built into leading questions), their tendency to favour affirmative responses, and their likely beliefs, reinforced in a school setting, that there are “right” and “wrong” answers. The diagnostic question set used in HARDSHIP, applying ICHD-3 criteria with regard to headache features and associated symptoms (criteria B-D), has not been formally validated: in these age groups, this is very difficult to do, requiring double interrogation with no benefit to the participant. It has, however, been used previously in nine languages and six countries [3–8], always translated in accordance with the Global Campaign’s translation protocol [16], with subsequent assessment of comprehensibility in a sample of the population of interest. In addition, in these previous studies, self-completion of questionnaires has been mediated, as it was here, by the class teacher or investigator to assist comprehension when needed. These measures have not entirely obviated diagnostic uncertainties. In particular, in countries in sub-Saharan Africa, very high proportions reporting symptoms usually associated with migraine have led to unfeasibly high estimates of migraine prevalence (definite + probable) [3, 4, 8]. Furthermore, specifically in Nepal, our previous study among adults encountered almost universal reporting of photophobia by those with headache, so that this symptom had no value in differential diagnosis [9]. In the present study, almost 95% of those with headache reported phonophobia (94.6%), and an unlikely proportion reported vomiting (43.0%). Also troublesome was that the conventional diagnostic criteria for UdH (mild headache lasting < 1 h) did not behave as in most previous studies [4–8], capturing only 4.8% of participants because very few reported mild headache (7.8%).
Our solution here was to modify the criteria for UdH, to include moderate headache but retaining the essential criterion of short duration (< 1 h). In justification, distinction between mild and moderate headache (the actual terms used were “not bad” [in Nepali: garho hudaina] and “quite bad” [madhyam garho]) is obviously highly subjective at any age, and diagnostic distinction ought not to turn upon this. The result of this modification was prevalence estimates for UdH of 31.7% (up from 4.8%) and for migraine of 39.8% (still high, but down from a very improbable 58.4%).
The observed 1-year prevalence of any headache (85.4%) falls near the higher end of the range (61.3–88.5%) found in other schools-based studies in this series conducted by the Global Campaign [3–8]. Higher prevalence among females than males, and among adolescents than children, are universal in these studies [3–8]. Both in Benin [3] and Zambia [8], estimates of migraine prevalence were implausibly high (53.2% and 53.4% respectively), with diagnosis driven by high proportions reporting nausea and/or vomiting [8] or photophobia and phonophobia [3]. In both countries, substantial proportions of those classified as probable migraine reported usual headache durations of < 1 h [3, 8]. In these studies, modification of the criteria for UdH to include moderate headache would markedly reduce the estimates of migraine prevalence, bringing them into the plausible range. We suggest this supports this modification.
With the modified criteria applied, observed prevalence of headache overall was higher among adolescents than among children (77.3% vs. 91.8% [Table 4]), as were estimates for migraine, TTH, UdH and other H15+, although increases in migraine and UdH did not quite reach significance after adjustment (Table 6). As a proportion of all headache, UdH declined very slightly among adolescents. However, these differences were small: headache is highly prevalent even among children in Nepal, at levels comparable to those among adults [9].
On this last point, the present study is nicely complementary to our previous study in adults [9, 10], informing health (and educational) policy in Nepal that headache affects the great majority of those aged 6–17 years as well as the great majority of adults aged 18–65. There are differences, of course: principally in the occurrence in children and adolescents of UdH (believed to be headache in the developing brain yet to manifest as migraine or TTH [6]), but there is also a strikingly lower prevalence of H15 + among children and adolescents (2.2% vs. 7.4% among adults). MOH is known to take time to develop [20]. Other H15 + was likely to have included chronic migraine and chronic TTH, which evolve from their episodic precursors, again over time [21, 22]. This highlights the theoretical opportunity for preventative intervention in childhood and adolescence to avert much lost health in adulthood – an attractive postulate, but unfortunately it remains unsupported by empirical evidence.
An important concordance between the present results and those of our adult study in Nepal is the positive association between migraine and altitude, appearing in both studies to weaken above 2,000 m [23]. In a recent similar adult study in Peru, we found a more robust association [24]. This, therefore, is the third time we have been able to demonstrate this relationship, and, to our knowledge, the first time it has been demonstrated in children and adolescents. The cause remains unclear [23]. Our finding here that UdH was negatively associated with altitude, in a manner that was the inverse of that of migraine, is thought-provoking: what would manifest as UdH at low altitude perhaps acquires the attributes of migraine at high altitude.
Finally, we note that the 20.7% of the sample reporting HY (24.3% of those reporting any headache in the preceding year) were a clearly higher proportion than predicted from reported headache frequency, which was based on recall, with 1-week recall (17.6%) giving a closer match than 4-week recall (10.3%). This pattern was repeated across genders and ages for all the episodic headaches (Table 7). On this evidence, children and adolescents underreport headache frequency – as we have seen in previous schools-based studies [3–8]. In fact, this tendency has been a robust finding across geography, culture and age, since it has been reported in adult studies also [24–27] – though to a lesser degree, perhaps because adults have a better sense of time.
Because, in Global Campaign methodology, UdH takes diagnostic precedence over migraine and TTH [7], prevalence estimates from studies using this methodology cannot sensibly be compared with those that have not taken account of UdH. Many published studies of children and adolescents have found large proportions of unclassified headache that might have been UdH but were not identified as such (for discussion of this, see [7]).
The strengths of this study were in the use of standardised methodology, albeit with modifications to the questionnaire [14, 15], coupled with an adequate sample size derived from almost nationwide sampling. As noted in Methods, we could not sample in Province 7. Most characteristics of Province 7 (cultural, geographic and economic) are a mixture of those of Provinces 5 and 6, all remote and relatively underdeveloped. These three provinces have similar literacy levels, life expectancies, ethnic diversity, traditional lifestyle and religious practices [28, 29]. The principal limitations were those inherent in cross-sectional surveys, and in the uncertain reliability of information gathered from children. The additional uncertainties in recall over the past 4 weeks were countered by separate enquiry into HY. Already discussed in length are the diagnostic issues, and our modification of the standard HARDSHIP algorithm with regard to UdH. There may be an underlying limitation in the ICHD criteria themselves in that they do not apply well to children, particularly with regard to duration [30]. We believe this underpins the importance of including UdH as a separate diagnosis, rather than stretching the criteria for migraine as has been suggested [30], although it is not yet clearly established how UdH should be defined.
Conclusion
These findings complement those of our previous study in adults, showing that headache is highly prevalent also among children and adolescents in Nepal, and confirming the positive association between migraine prevalence and altitude of dwelling. The finding of less pMOH and other H15 + among children and adolescents than among adults suggests an opportunity to avert lost health in adulthood through preventative intervention in childhood and adolescence.
A separate paper will describe headache-attributed burden, including functional impairment and lost time from school and other activities, which will be more informative to health and educational policies.
Acknowledgements
The study was supported by Lifting The Burden (LTB), a United Kingdom-based non-governmental organization conducting the Global Campaign against Headache in official relations with the World Health Organization.We acknowledge with gratitude the contributions of doctors from regional hospitals of Nepal (Dr Pukar Ghimire, Dr Sumit Shahi, Dr Aashish Shrestha, Dr Akhanda Upadhaya, Dr Anees KC, Dr Hari Panthi, Dr Padam Joshi, Dr Jayant Kumar Yadav, Dr Sushil Yadav, Dr Susmin Karki, Dr Asmita Parajuli, Dr Sobin Pant, Dr Sanjeev Kharel, Dr Roshan Aryal, Dr Prakash Shrestha, Dr Kaushal Sigdel and Dr Suraz Shrestha), who assisted in data collection and coordinated administration in the local schools. We also thank the teachers and pupils of the participating schools.
Abbreviations
Authors’ contributions
RO, DU and TJS conceived the study and developed the protocol. RO was principal investigator. RO, RK, BPG, RR, NG, BD, AT, AA, RRT and GN were responsible for communications with the schools and data collection, with guidance from DU as coordinator of the global programme. RO and RK performed the data entry. TS and BNBY performed the principal statistical analysis, with data interpretation by AKH, AB-U and TJS. AB-U and AKH performed additional analyses in order to review the diagnostic criteria. AKH, AB-U and TJS drafted the manuscript. All authors contributed to manuscript review, and approved the final version.
Funding
Open access funding provided by NTNU Norwegian University of Science and Technology (incl St. Olavs Hospital - Trondheim University Hospital). Otherwise none.
Data availability
The original data are held at Tribhuvan University Teaching Hospital, Kathmandu, Nepal, and the analytical set at University of Mersin, Mersin, Turkey, and at Norwegian University of Science and Technology, Trondheim, Norway. When analyses are completed, anonymised data will be available on request for academic purposes, in line with the policy of the Global Campaign against Headache.
Declarations
Ethics approval and consent to participate
The protocol was approved by the Institutional Review Committee of Tribhuvan University Institute of Medicine: 169(6–11)F2 078/079. Necessary authorizations from academic and administrative authorities, and permissions from principals and class teachers, of each school were obtained.
In accordance with the ethics approval, all participants (pupils and teachers) were informed verbally of the nature and purpose of the study, and gave oral consent before enrolment. Continuing consents were evidenced by active completion of the questionnaires. In view of the non-interventional nature of the study, neither the Institutional Review Committee nor the academic and administrative authorities requested parental consent.
Consent for publication
N/A.
Competing interests
AKH and TJS are Directors and Trustees of Lifting The Burden. AKH is a member of the Editorial Board of The Journal of Headache and Pain. TJS is associate editor of The Journal of Headache and Pain. Otherwise, no author declares a conflict of interest.
Footnotes
References
Associated Data
Data Availability Statement
The original data are held at Tribhuvan University Teaching Hospital, Kathmandu, Nepal, and the analytical set at University of Mersin, Mersin, Turkey, and at Norwegian University of Science and Technology, Trondheim, Norway. When analyses are completed, anonymised data will be available on request for academic purposes, in line with the policy of the Global Campaign against Headache.