Rapid urbanisation is thought to be damaging adolescent health, say researchers, whose recent study found that millions of teenagers in Africa are suffering from asthma, the majority of them having had no diagnosis and thus no treatment.
The study, published in The Lancet Child and Adolescent Health, involved 27 000 pupils from urban areas in South Africa, Malawi, Zimbabwe, Uganda, Ghana and Nigeria. It found more than 3 000 reported asthma symptoms, but only about 600 had a formal diagnosis.
Many of the children reported missing school or having their sleep disrupted by wheezing, reports The Guardian.
“If our data are generalisable, there are millions of adolescents with undiagnosed asthma symptoms in sub-Saharan Africa,” said Dr Gioia Mosler of Queen Mary University of London, the study’s research manager.
The team that led the study, whose research on the impact of pollution on lung health was instrumental in introducing the ultra low-emission zone (Ulez) in London, said there was an urgent need for medicines and diagnostic tests in the region.
Rates of asthma have increased in sub-Saharan Africa over the past few decades, a trend attributed to rapid urbanisation which exposes children to more risk factors such as air pollution. The climate crisis was also likely to have an impact, experts said.
The study by the Achieving Control of Asthma in Children and Adolescents in Africa (Acacia) team – a collaboration of researchers based at several universities across Africa and the UK – recruited pupils aged between 12 and 14. Screening revealed that while 12% reported asthma symptoms, only 20% of that group had received a formal diagnosis of asthma.
Lung function tests suggested nearly half of undiagnosed participants with severe symptoms were “very likely” to have asthma.
Even among those who had received a formal diagnosis, about a third were not using any medicine to control their condition, found the study.
Dr Rebecca Nantanda of Makerere University in Kampala, who led the research in Uganda, said: “Undiagnosed and poorly controlled asthma greatly impacts on the physical and psychosocial well-being of the affected children and their caregivers. The high burden of severe undiagnosed asthma revealed by the Acacia study requires urgent attention, including access to medicines and diagnostics.”
Professor Jonathan Grigg of Queen Mary University of London said asthma was worsened by exposure to small particles of pollutants, with the impact of the climate crisis yet to become clear. “In some areas in sub-Saharan Africa, climate change is likely to result in increased exposure of these vulnerable children to dust and natural fires.
“On the other hand, climate change mitigation will, hopefully, reduce exposure to fossil fuel-derived particles in this region.
“The pharmaceutical industry has been hesitant to support asthma research and initiatives. For example, companies may feel that they cannot support research in countries where they do not intend to market their asthma product,” he said.
“Innovations such as handheld wheeze detectors and asthma clinics delivered at schools also have the potential to substantially reduce the burden of asthma.”
Study details
Asthma symptoms, severity, and control with and without a clinical diagnosis of asthma in early adolescence in sub-Saharan Africa: a multi-country, school-based, cross-sectional study
Victoria Oyenuga, Gioia Mosler, Farida Fortune et al.
Published in The Lancet on 21 October 2024
Summary
Background
Rapid urbanisation and population growth in sub-Saharan Africa has increased the incidence of asthma in children and adolescents. One major barrier to achieving good asthma control in these adolescents is obtaining a clinical diagnosis. To date, there are scant data on prevalence and severity of asthma in undiagnosed yet symptomatic adolescents. We therefore aimed to assess symptom prevalence and severity, the effect of symptoms on daily life, and objective evidence of asthma in young adolescents from sub-Saharan Africa with and without a clinical diagnosis of asthma by spirometry and fractional exhaled nitric oxide (FeNO).
Methods
We designed a two-phase, multi-country, school-based, cross-sectional study to assess symptom prevalence and severity in sub-Saharan African adolescents. In phase 1 we surveyed young adolescents aged 12–14 years who were attending selected primary and secondary schools in Blantyre in Malawi, Durban in South Africa, Harare in Zimbabwe, Kampala in Uganda, Kumasi in Ghana, and Lagos in Nigeria. The adolescents were screened for asthma symptoms using the International Study of Asthma and Allergies in Children (ISAAC) questionnaire. Then, after opt-in consent, symptomatic adolescents were invited to complete a detailed survey on asthma severity, treatment, and exposure to environmental risk factors for phase 2. Adolescents performed the European Respiratory Society’s diagnostic tests for childhood asthma. A positive asthma test was classified as a forced expiratory volume in 1 sec (FEV1) predicted under 80%, a FEV1 under the lower limits of normal, or FEV1 divided by forced vital capacity (FEV1/FVC) under the lower limits of normal; positive bronchodilator responsiveness or reversibility was defined as either an increase in absolute FEV1 of 12% or more, or an increase of 200 mL or more, or both, after 400 μg of salbutamol (shortacting β2 agonist) administered via a metered-dose inhaler and spacer, or FeNO of 25 parts per billion or higher, or any combination of these.
Findings
Between Nov 1, 2018, and Nov 1, 2021, we recruited 149 schools from six regions in six sub-Saharan countries to participate in the study. We administered phase 1 asthma questionnaires from Jan 20, 2019 to Nov 11, 2021, and from 27 407 adolescents who were screened, we obtained data for 27 272 (99·5%). Overall, 14 918 (54·7%) adolescents were female and 12 354 (45·3%) adolescents were male, and the mean age was 13 years (IQR 12–13); nearly all recruited adolescents were of black African ethnicity (26 821 [98·3%] of 27 272). In phase 1, a total of 3236 (11·9% [95% CI 11·5–12·3]) reported wheeze in the past 12 months, and 644 (19·9%) of 3236 had a formal clinical diagnosis of asthma. The prevalence of adolescents with asthma symptoms ranged from 23·8% in Durban, South Africa to 4·2% Blantyre, Malawi. Using ISAAC criteria, severe asthma symptoms were reported by 2146 (66·3%) of 3236 adolescents, the majority of whom (1672 [77·9%] of 2146) had no diagnosis of asthma by a clinician. Between July 16, 2019, and Nov 26, 2021, we administered the phase 2 questionnaire to the 1654 adolescents who had asthma symptoms in phase 1 and consented to proceed to the second phase. In the phase 2 cohort, 959 (58·0%) were female and 695 (42·0%) were male, and the mean age was 13 years (IQR 12–14). One or more diagnostic tests for asthma were obtained in 1546 (93·5%) of 1654 participants. One or more positive asthma tests were found in 374 (48·8%) of 767 undiagnosed adolescents with severe symptoms, and 176 (42·4%) of 415 of undiagnosed adolescents with mild-to-moderate symptoms. Of the 392 adolescents in phase 2 with clinician-diagnosed asthma, 294 (75·0%) reported severe asthma symptoms, with 94 (32·0%) of those with severe symptoms not using any asthma medication. In general, findings in both phases 1 and 2 were consistent across sub-Saharan African countries.
Interpretation
A large proportion of adolescents in sub-Saharan Africa with symptoms of severe asthma do not have a formal diagnosis of asthma and are therefore not receiving appropriate asthma therapy. To improve the poor state of asthma control in sub-Saharan Africa, potential solutions such as educational programmes, better diagnosis, and treatment and screening in schools should be considered.
The Guardian article – Millions of teenagers in Africa have undiagnosed asthma – study (Open access)
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