Date Published: February 27, 2007
Publisher: Public Library of Science
Author(s): Emmanuel O. D Addo-Yobo, Ashley Woodcock, Adorkor Allotey, Benjamin Baffoe-Bonnie, David Strachan, Adnan Custovic, Peter J Barnes
Abstract: BackgroundAsthma and allergic diseases have increased in the developed countries. It is important to determine whether the same trends are occurring in the developing countries in Africa. We aimed to determine the time trend in the prevalence of exercise-induced bronchospasm (EIB) and atopic sensitisation over a ten-year period in Ghanaian schoolchildren.Methods and FindingsTwo surveys conducted using the same methodology ten years apart (1993 and 2003) among schoolchildren aged 9–16 years attending urban rich (UR), urban poor (UP), and rural (R) schools. Exercise provocation consisted of free running for six minutes. Children were skin tested to mite, cat, and dog allergen. 1,095 children were exercised in 1993 and 1,848 in 2003; 916 were skin tested in 1993 and 1,861 in 2003. The prevalence of EIB increased from 3.1% (95% CI 2.2%–4.3%) to 5.2% (4.3%–6.3%); absolute percentage increase 2.1% (95% CI 0.6%–3.5%, p < 0.01); among UR, UP, and R children EIB had approximately doubled from 4.2%, 1.4%, and 2.2% to 8.3%, 3.0% and 3.9% respectively. The prevalence of sensitisation had also doubled from 10.6%, 4.7%, and 4.4% to 20.2%, 10.3%, and 9.9% (UR, UP, and R respectively). Mite sensitisation remained unchanged (5.6% versus 6.4%), but sensitisation to cat and dog increased considerably from 0.7% and 0.3% to 4.6% and 3.1%, respectively. In the multiple logistic regression analysis, sensitisation (odds ratio [OR] 1.77, 95% CI 1.12–2.81), age (OR 0.88, 95% CI 0.79–0.98), school (the risk being was significantly lower in UP and R schools: OR 0.40, 95% CI 0.23–0.68 and OR 0.54, 95% CI 0.34–0.86, respectively) and year of the study (OR 1.73, 95% CI 1.13–2.66) remained significant and independent associates of EIB.ConclusionsThe prevalence of both EIB and sensitisation has approximately doubled over the ten-year period amongst 9- to 16-year-old Ghanaian children irrespective of location, with both EIB and atopy being more common among the UR than the UP and R children.
Partial Text: Early reports from developing countries in Africa over three decades ago suggested that childhood asthma was uncommon and not associated with atopic sensitisation [1–6]. However, due to cultural and linguistic differences in this region it is often difficult to adopt a universally accepted asthma definition and accurately compare the findings between different areas. This problem is emphasised by the fact that there is no word for wheeze or asthma in most of the local dialects. To circumvent this, exercise-induced bronchospasm (EIB) may be used as an objective indicator of asthma , although its value may be limited by environmental factors (e.g., temperature, humidity, air pollution) .
All children aged 9–16 y attending the schools participated in the study. A total of 1,095 children (557 [50.9%] male) were exercised in 1993 (599 UR, 220 UP, and 276 R) and 1,848 (935 [50.6%] male) in 2003 (651 UR, 559 UP, and 638 R); 916 parents and children consented to skin testing in 1993 and 1,861 in 2003. In 1993, one child in the rural school was not allowed to run because of severe sickle cell anaemia. No child was excluded because of low baseline PEFR. In 2003, a total of 16 children (4 UR, 5 UP, 7 R) were excluded from exercise test response analysis because they failed to complete the 6-min free running exercise. None of them had an abnormal baseline PEFR.