The burden of headache disorders in Nepal: estimates from a population-based survey

The Nepal Health Research Council, the Institutional Review Committee of Kathmandu University School of Medical Sciences, Dhulikhel Hospital, and the Regional Committee for Health and Research Ethics in Central Norway all approved the study protocol.

All participants were informed about the nature and purpose of the study and this was documented in accordance with requirements of the three committees.

The study design, sampling and data collection procedures have been reported in detail previously [16]. In summary, this was a cross-sectional survey using structured interviews administered by trained health workers making unannounced door-to-door visits during May, 2013. To obtain a nationally representative sample, we used multistage stratified cluster sampling in all three physiographic divisions of the country and, within each division, all five development regions (Far-Western, Midwestern, Western, Central and Eastern). We randomly selected one eligible adult (aged 18–65 years, Nepalese-speaking and living in Nepal) from each household.

We used the Headache-Attributed Restriction, Disability, Social Handicap and Impaired Participation (HARDSHIP) questionnaire developed by Lifting The Burden (LTB) for population-based studies [17]. The original English-language version was translated into Nepalese according to LTB’s translation protocol for hybrid documents [18] and modified according to Nepalese culture [19]. The questionnaire consisted of four parts relevant to this report. For all participants there were (i) personal and demographic enquiry and (ii) a neutral headache screening question (“Have you had a headache during the last 12 months?”). Those who answered “no” to the latter were classified as headache-free. Those who answered “yes” were asked whether their headaches were of one or more types and, if more than one, to focus only on the most bothersome type. Only those who answered positively to the screening question were also asked (iii) diagnostic questions in line with the International Classification of Headache Disorders (ICHD-3 beta) [20], and (iv) questions ascertaining various aspects of headache burden.

We measured symptom burden in terms of frequency (days/month), intensity (with response options “not bad”, “quite bad” and “very bad”, which we interpreted as mild, moderate and severe) and duration (hours).

We enquired into willingness to pay (WTP) as an overall measure of burden [17] using a bidding game method [21]. We asked how much participants would be willing to pay per month for an effective treatment such that their headaches would no longer bother them. Bidding began at NPR 100/month (at the time of the survey, NPR 100 ≈ USD 1): was the respondent willing to pay this amount? If “yes”, the interviewer incremented the bidding stepwise (NPR 200, 400, 1000 and 2000) until the answer was “no”, or it was clear that the participant would pay > NPR 2000. If the opening bid of NPR 100 was declined, the interviewer instead reduced stepwise (NPR 40 and 20) until the participant said “yes”, or it became clear that nothing would be paid. Finally, in every case, an exact amount was agreed upon as the individual’s WTP-value.

We assessed QoL using the World Health Organization Quality of Life-8 (WHOQOL-8) questionnaire [22]. Its eight items addressed subjective wellbeing and satisfaction in four domains (two in each): psychological, physical, social and environmental [17]. Each item was graded on a scale of 1–5, with a higher score indicating better QoL.

We estimated lost time due to headache during the preceding 3 months using the Headache-Attributed Lost Time (HALT) questionnaire [23]. Its first two questions asked for the numbers of days in that period (i) completely missed from paid work and (ii) with <50 % productivity because of headache while at work; the next two asked for numbers of days of household work (iii) completely missed and (iv) with <50 % productivity; the last enquired into (v) the number of days on which family, social or leisure activities were missed because of headache.

The diagnostic method has been described previously [14]. Diagnoses were not made during the interviews but later according to an algorithm. Participants reporting headache on ≥15 days/month were first separated as a distinct group because they cannot be fully diagnosed by questionnaire. Those who in addition were overusing acute medication were considered to have pMOH [24]; the remainder were categorised as “other headache on ≥15 days/month”. To all others, reporting headache on ≤14 days/month, the algorithm applied modified ICHD-3 beta criteria [20] in the following order: definite migraine, definite TTH, probable migraine and probable TTH. Definite and probable migraine were subsequently considered together, and likewise definite and probable TTH, for attribution of burden. The few remaining cases were unclassifiable.

Categorical variables are presented as numbers and percentages. Continuous variables are presented as means with standard deviations (SDs) and/or medians with interquartile ranges (IQRs).

We transformed the categorical variable for headache intensity (mild, moderate, and severe) into a numerical scale 0–3 (0 being no pain), and treated these results as continuous data.

We summed responses to the first four items (i-iv) of HALT to estimate total productivity loss. These scores were treated as continuous variables. We separately summed the first and second items (i, ii) to estimate lost paid worktime, and the third and fourth (iii, iv) to estimate lost household worktime.

We estimated individual and population-level disability attributable to migraine, TTH and pMOH using the disability weights (DWs) from GBD2013 [3] for the ictal states of each. We calculated the mean absolute time spent in the ictal state (T_abs) as the product of mean attack frequency (AF) and mean attack duration (D). For migraine, because headache frequency (HF) had been recorded as days/month, we assumed participants with attacks lasting >24 h had counted days affected rather than number of attacks per month. Therefore, to calculate mean AF we made separate computations for those with attack durations of ≥24 h and <24 h, using the formula AF = HF/D in the former group. We then took the weighted mean of the two groups. We did not need to perform the same manipulation for TTH, because the mean duration of headache was <24 h (Table 1). For pMOH, we made separate calculations for those describing durations of <24 h and those asserting pain “never goes away”, for whom we assumed AF = 30 and D = 24; there were no respondents in between. Again we took the weighted mean. From T_abs (in hours/year) we calculated the proportion of total available time that was spent in the ictal state (T_pro) by dividing by (24*365). We multiplied this proportion by the DW for the disorder in question to calculate individual disability (DIS_per), and then by the prevalence of the disorder to arrive at population-level disability (DIS_pop).

We used Student’s t-test for significance of differences between means of two groups and one-way analysis of variance (ANOVA) for more than two groups. Since most of the continuous variables were skewed in distribution, we also used the non-parametric Mann–Whitney U-test or Kruskal-Wallis test to examine differences between groups. We considered p < 0.05 as statistically significant. All data were analysed with SPSS 21.0 software (SPSS Inc., Chicago, IL, USA).

Symptom burden is presented in Table 1 by headache type and gender. From a public-health perspective it was substantial: the mean overall reported headache frequency was 3.8 days/month – 1 day in every eight – and mean overall reported intensity was 2.1. Half of all participants with headache (901; 50.2 %) reported moderate headache and another nearly one third (520; 29.0 %) reported severe headache. By headache type, pMOH was of course the most frequent headache; it was followed by migraine, then TTH. The same rank order was seen for both headache intensity and duration. On every measure, females were worse affected than males with regard to all headache and TTH, but not significantly so with regard to migraine or (taking both means and medians into account) pMOH.

Participants without headache had significantly higher (ie, better) WHOQOL-8 scores than those with headache (median 29.0 [IQR: 27.0–31.0] vs 28.0 [25.0–30]; p < 0.001). WHOQOL-8 scores differed significantly between headache types (p < 0.001), being lowest among people with pMOH closely followed by those with migraine (Table 2). However, WHOQOL scores were negatively associated with frequency and intensity of headache (both p < 0.001); accordingly, among participants with headache, QoL was best in those with TTH (Table 2).

Participants with headache were willing to pay on average NPR 1134 ± 2760 (median 250 [IQR: 100–1000]) per month for effective headache care. WTP differed significantly (p = 0.013) between headache types, being highest among those with pMOH. WTP was positively associated with both frequency and intensity of headache (p < 0.001), and therefore least in TTH (Table 2).

Among the 728 participants with migraine, 289 reported attacks of ≥24 h’ duration, with a mean of 57.1 h (D1) and a headache frequency of 2.38 days/month (HF1) (Table 3). Using the formula AF = HF/D (see Methods), we calculated AF for this group as AF1 = 2.38/(57.1/24), which we took to be 1. Among the 46 with pMOH, 17 reported headache that “never goes away”. We took their attack frequency (AF1) as 30, and duration (D1) as 24. All other calculations of disability are explained in the Methods section and set out in Table 3.

Mean DIS_per for migraine was 2.4 %; DIS_pop was 0.81 %. The corresponding values for TTH were substantially lower (0.15 and 0.06 %). For pMOH, however, DIS_per was very much higher, at 9.7 %, while DIS_pop was only 0.20 % because of the low prevalence.

Headache-attributed lost time in the preceding 3 months is presented by headache type in Table 4. All summed scores (total lost productive time, lost paid worktime and lost household worktime) had much higher means for pMOH than for migraine, which itself had means more than double those of TTH. However, it should be noted that, for all five individual items and all headache types, including pMOH, most medians were zero; this meant not only that distributions were very highly skewed, but also that at least half of respondents in most groups lost no time at all.

More household worktime (2.7 ± 5.9 days) was lost than paid worktime (1.7 ± 5.1 days), this difference being largely but not entirely attributable to migraine (Table 4). Regardless of headache type, males lost more paid worktime than females and the reverse was the case with household worktime.

From policy and economic perspectives, attention might focus on total lost productive time (4.4 days in 3 months) from all headache, since this was the mean loss for 85.4 % of the population. Assuming there were 13*5 working days in 3 months, this was a loss of 6.8 % for those affected, or 5.8 % for the population generally. However, 5.4 days lost in 3 months represented an 8.3 % individual loss for those with migraine. As they were 34.1 % of the population [14], this was a 2.8 % loss for the population generally.

Headache disorders are not only common in Nepal but also highly burdensome: symptom burden is heavy, there is much consequential disability and substantial lost productivity. The economic cost is certain to be high. The remedy lies in better health care for headache; structured headache-care services are urgently needed in the country. However, Nepal is among the least developed countries in the world, with uneven distribution of its limited resources [11]. Government allocation to the health sector is also scarce; gaps in specialized health care exist at all levels [35]. Furthermore, Nepal’s rural hilly/mountainous geography poses great challenges to community health services. Creating new headache-care services would certainly demand investment of additional financial and human resources in the health sector; on the other hand, refraining from doing so will leave undiminished the burden of these highly prevalent but cost-effectively treatable brain disorders [36]. Structured headache services based in primary care [37] would be an efficient, effective, affordable and equitable model for Nepal, likely to be cost-saving [4]. Such services, appropriately adapted, could be implemented within the existing health-service structure of Nepal. This potential solution requires further research in order to inform political decision-makers. Doing nothing is almost certainly a more costly option.