Headache among children and adolescents in Zambia: revised prevalence estimates, and estimates of attributed burden, from a national schools-based study

BACKGROUND: In our earlier report of headache prevalence among children (6-11 years) and adolescents (12-17) in Zambia, we defined undifferentiated headache (UdH) conventionally as mild headache lasting < 1 h. However, we recognised diagnostic uncertainties, which also occurred in our similar studies elsewhere in sub-Saharan Africa (Ethiopia and Benin). Here we use a modified definition of UdH, making new estimates of prevalence accordingly, and estimates based on these of headache-attributed burden. The study was part of the global schools-based programme conducted by the Global Campaign against Headache. METHODS: In a cross-sectional survey using the standardised protocol of the global programme, the child and adolescent versions of the HARDSHIP questionnaire, translated into the local languages, were completed by pupils in mediated sessions within their classes in nine schools representative of Zambia's urban/rural divide. Headache diagnostic questions were based on ICHD-3 except for UdH, which we redefined as mild or moderate headache lasting < 1 h. Enquiry included multiple aspects of attributed burden. RESULTS: Of 2,759 potential participants, 2,089 (615 children [29.4%], 1,474 adolescents [70.6%]) completed questionnaires (participating proportion 75.7%). The unfeasibly high observed prevalence of migraine reported earlier (51.6%, including probable migraine) was reduced by redefining UdH to 42.9%, still highly questionable. Nonetheless, burden measures clearly distinguished migraine from tension-type headache (TTH) and UdH. Migraine headache was the most intense, most frequent and longest lasting, but proportion of time in ictal state (pTIS) was only 1.3%. However, pTIS was much greater among those with probable medication-overuse headache (7.9%) or other headache on ≥ 15 days/month (9.0%). Headache accounted for an estimated loss of 3.5% of school time in those affected, migraine having twice the impact of TTH or UdH, while H15 + accounted for > 15% of lost school time. Almost one in six parents (15.9%) lost time from their own work. Migraine had greater impact than TTH and UdH on both emotional impact and quality-of-life scores. CONCLUSIONS: Headache, prevalent among children and adolescents in Zambia, is associated with burdens that include lost school time, with, potentially, lifelong negative impact. These findings are of importance to national educational and health policies. Our modified definition of UdH was a step towards diagnostic veracity, but did not resolve the diagnostic difficulties among young people. Future studies might consider further modifications, but full review of the ICHD criteria for migraine in these age groups is needed.