The prevalence of reversible airways obstruction has been assessed in children in three areas in Zimbabwe-northern Harare (high socioeconomic class urban children), southern Harare (low socioeconomic class urban children), and Wedza Communal Land (rural children from peasant families). Peak expiratory flow (PEF) was measured before and after six minutes' free running in 2055 Zimbabwean primary school children aged 7-9 years. Height and weight were measured and nutritional state expressed as a percentage of the 50th centile for age (Tanner-Whitehouse standards). Reversible airways obstruction was deemed to be present when peak expiratory flow was below the 2-5th centile for height before exercise and rose by more than 15% after inhalation of salbutamol and when it fell by 15% or more after exercise and rose again after salbutamol. The prevalence of reversible airways obstruction was 5-8% (95% confidence interval 4-1-7-5%) in northern Harare (n = 726); 3-1% (1P8-45%) in southern Harare (n = 642), and 0-1% (0-0-0-4%) in Wedza (n = 687). In northern Harare, the only study area in which white children were found, the prevalence of reversible airways obstruction was similar in white (5-3%, 10/188) and black (5 9%, 32/538) children. Indicators of nutritional state also showed no significant differences between white and black children in northern Harare but were lower in southern Harare and lower still in Wedza. Urban living and higher material standards of living appear to be associated with a higher prevalence of reversible airways obstruction in children in Zimbabwe.Childhood asthma is an extremely common problem in industrialised countries and there is evidence that the prevalence may have increased in the last 20 years.`15 Studies from the developing world have shown large variations in asthma prevalence in genetically similar populations living in different environments.' Both lines of evidence suggest that the major determinants of asthma prevalence in any particular population are environmental. Knowledge of different prevalence rates in differing environments should help to guide the design of further studies in an attempt to identify which factors in the environment are relevant to the development of asthma in genetically predisposed individuals.The epidemiological study of asthma is beset by problems of definition,9 and comparison of the results of the various studies is made difficult by differences between the methods of data collection. The measurement of change in peak expiratory flow (PEF) in a free running exercise challenge test, however, is a sensitive method of screening for bronchial hyperreactivity in children'0 and can easily be used to screen large numbers of children.7"' Careful adherence to method within a particular study allows confidence in the significance of differences between groups-The study of Van Niekerk and others7 in South Africa showed the prevalence of exercise induced bronchoconstriction in Xhosa children to be 20 times higher in an urban setting than in a rural setting....

Globally, asthma morbidity remains unacceptably high. If outcomes are to be improved, it is crucial that routine review consultations in primary care are performed to a high standard. Key components of a review include: * Assessment of control using specific morbidity questions to elucidate the presence of symptoms, in conjunction with the frequency of use of short-acting bronchodilators and any recent history of acute attacks * After consideration of the diagnosis, and an assessment of compliance, inhaler technique, smoking status, triggers, and rhinitis, identification of poor control should result in a step-up of treatment in accordance with evidence-based guideline recommendations * Discussion should address understanding of the condition, patient-centred management goals and attitudes to regular treatment, and should include personalised self-management education Regular review of people with asthma coupled with provision of self-management education improves outcomes. Underpinned by a theoretical framework integrating professional reviews and patient self-care we discuss the practical barriers to implementing guided selfmanagement in routine clinical practice.

A way forward for clinicians while we streamline the guideline process

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