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PREVALENCE AND ETIOLOGY OF ASTHMA AND ITS ASSOCIATION WITH GASTRO -ESOPHAGEAL REFLEX DISEASE. A SYSTEMATIC REVIEW STUDY

Dr. Aima Imtiaz, Dr. Abdul Rehman, Dr. Zahid Gulzar,

Abstract: Background and aim: to find out the prevalence, etiology and its association with Gastro-oesophageal reflux disease (GORD).because it has been linked to a number of extra esophageal symptoms and disorders, primarily in the respiratory tract. This systematic review aimed to provide an estimate of the strength and direction of the association between GORD and asthma, prevalence and risk factors Methods: Studies that assessed the prevalence or incidence of GORD in individuals with asthma, or of asthma in individuals with GORD, or prevalence of asthma and risk factors of asthma were identified in Medline and EMBASE via a systematic search strategy. Results: There are five striking patterns: first, asthma prevalence is increasing worldwide; second, asthma is generally more common in Western countries and less common in developing countries; third, asthma is more prevalent in English-speaking countries; fourth, asthma prevalence is increasing in developing countries as they become more Westernized or communities become urbanized; and fifth, the prevalence of other allergic disorders may also be increasing worldwide. Twenty-eight studies met the selection criteria. The sample size weighted average prevalence of GORD symptoms in asthma patients was 59.2%, whereas in controls it was 38.1%. The average prevalence of asthma in individuals with GORD was 4.6%, whereas in controls it was 3.9%. Pooling the odds ratios gave an overall ratio of 2.3 (95% CI 1.8–2.8) for those studies measuring the prevalence of asthma in GORD. One longitudinal study showed a significant association between a diagnosis of asthma and a subsequent diagnosis of GORD (relative risk 1.5; 95% CI 1.2–1.8), Conclusions: This systematic review indicates that, asthma prevalence is increasing worldwide. There is a significant association between GORD and asthma, but a paucity of data on the direction of causality. Genetic predisposition is clearly evident, gene by-environment interaction probably explains much of the international variation in prevalence rates for allergy and asthma. Environmental factors such as infections and exposure to endotoxins may be protective or may act as risk factors, depending in part on the timing of exposure in infancy and childhood. But diet and nutrition, stress, use of antibiotics and mode of delivery may also affect the early development of allergy and asthma. Later in childhood, putative risk factors include exposure to allergens, family size and structure, and sex and gender. Key words: asthma prevalence, etiology of asthma, chronic cough, asthma and its association with GORD.

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