Prevalence and reliability of asthma symptoms in primary school children in Cape Town

Childhood asthma is believed to be a serious problem in Cape Town, South Africa. This study aimed to measure the prevalence and reliability of asthma symptoms and reported asthma in Cape Town schoolchildren aged mainly 7 and 8 years, and to assess underdiagnosis.

A questionnaire was completed by parents of 1955 children, followed by 620 personal interviews repeating the questions.

The prevalence of recent wheeze (previous 12 months) (26.8%) was high by international comparison, but not that of reported asthma (10.8%). Among children with more than 12 recent attacks of wheeze, only 60% were reported as asthmatic and 55% as receiving regular treatment. Symptom prevalences varied with the respondent's familial relationship to the child. On some questions the interview produced higher wheeze prevalences than the self-administered questionnaire. Repeatability of questions varied: asthma over (kappa = 0.69), recent wheeze (kappa = 0.59), and recent sleep disturbance by wheeze (kappa = 0.56) were the most reliable.

Prevalence based on symptom reports may vary with the respondent and between self- and interviewer-administered questionnaires. Also, certain questions currently proposed for childhood asthma questionnaires may be unreliable. Nevertheless, it can be concluded that the prevalence of wheeze is high in this population, and that underdiagnosis and undertreatment of asthma are a problem.