Ibadan Centre

Personnel

• Dr Adegoke Falade
• Professor Babatunde O Onadeko

Why was this centre selected for ISAAC?

Ibadan, the capital of Oyo State is located in southwestern Nigeria, 130 km inland from Lagos and is a prominent transit point between the coastal region and the areas to the northern Nigeria. The total area is 1,189.2 sq mi (3,080 km2). It is the third most populated city in Nigeria, behind Lagos and Kano. Indeed, its population rose to 2,550,593 according to 2006 Nigeria census results. Ibadan is divided into 11 local government areas (LGAs): 6 are urban and 5 periurban /rural. The possible adverse health effects of dense population and resultant outdoor air pollution due to the urbanisation informed the choice of this centre for the Phase One study.

The ISAAC phase 1 study involved two age groups: children 6 – 7 years old and adolescents 13 – 14 years old. The aims were to describe the prevalence and severity of asthma, allergic rhinitis and eczema in children in Ibadan using the ISAAC protocol and to obtain baseline measures for assessing future trends in the prevalence and severity of these diseases. We did not participate in phase 2 study. In phase 3, the aim of the study was to evaluate the changes in prevalence of symptoms of asthma and allergies by comparing the data from Phase One and Phase Three of the ISAAC surveys.

Our experience of ISAAC

Phase 1: The study populations were the children 6-7 year olds in primary schools, and the 13-14 year olds in secondary schools in Ibadan. Data was collected from 1,704 children (797 boys and 907 girls; M:F ratio 1:1.14); and 3,058 randomly selected children aged 13 -14 years(1,659 females and 1,399 males; M:F ratio 1:1.2).The study demonstrated a high prevalence of atopic conditions among children 6-7 years old (ref. 1) and the 13-14 years old (ref. 2).

Phase 3: This study was a comparison of cross-sectional data from ISAAC written questionnaire surveys carried out from January 1 to May 31, 1995 (phase I) and May 2001 to July 2002 (phase III). Detailed times of collection of data for the phase III being 11 May to 19 June, 2001 and 13 February to 18 June, 2002. These time frames were essentially within the months of January to June; as a result they did not constitute any significant difference in the months of collection of the data. The study populations were the children 6-7 year olds in primary schools, and the 13-14 year olds in secondary schools in Ibadan(ref. 3).

The random sampling methods were identical for the two surveys. Thirty one primary schools, 15 secondary schools (phase I), and 25 primary schools, 23 secondary schools (phase III) were selected in Ibadan. The ages of the children were ascertained from the class registers. Questionnaires were distributed to the children, who took them home for their parents or guardians to complete, then returned them to their teachers (6-7 year olds) or self completed(13-14 year olds) in the class rooms. The prevalence of current wheeze increased non-significantly in the 6-7 year age group (4.8% to 5.5%) and significantly in 13-14 year age group (10.7% to 13.0%) (p=0.249 and p=0.005, respectively). The 12-month prevalence of allergic rhinoconjuctivitis decreased insignificantly in the 6-7 year age group (p=0.833) but decreased significantly in the 13-14 year age group (p=0.001). Diagnosis of eczema decreased in both age groups. Whereas, eczema and rhinoconjunctivitis have decreased appreciably in the 13-14 year age group, only rhinoconjunctivitis increased in the 6-7 year age group (ref. 3). The current findings suggest that the “epidemic" of asthma is beginning in Nigeria.

References.

1. Falade AG, Olawuyi F, Osinusi K, Onadeko BO. (2004). Prevalence and severity of symptoms of asthma, allergic rhino-conjunctivitis and atopic eczema in 6 –7 year old Nigerian primary school children: the international study of asthma and allergies in childhood (ISAAC). Medical Principles and Practice 2004; 13: 20-25.
2. Falade AG, Olawuyi F, Osinusi K, Onadeko BO. Prevalence and severity of symptoms of asthma, allergic rhino-conjunctivitis and atopic eczema in secondary school children in Ibadan, Nigeria. East African Medical Journal 1998; 75: 695-698.
3. Falade AG, Ige OM, Yusuf BO, Onadeko MO, Onadeko BO. Trends in the prevalence and severity of symptoms of asthma, allergic rhinoconjunctivitis, and atopic eczema. Journal of the National Medical Association 2009; 101:414- 418.

Acknowledgements

We are grateful to Chief Bode Akindele, Dr . Raymond Zard, management of Glaxo Wellcome, Nigeria for financial support. Our thanks also go to all the children, parents and school staff who helped in the surveys, as well as all our fieldworkers for their hard work throughout the studies.