CHANGING PATTERNS IN ASTHMA MORBIDITY AND MORTALITY

Asthma morbidity and mortality have increased in many countries over t he last 10 years or more. in some countries, epidemics of deaths have occurred, while others have shown gradual increases. The New Zealand N ational Asthma Mortality Study associated mortality with severe asthma , underassessment of severity, undertreatment with corticosteroids, ov erreliance on bronchodilators, discontinuity of medical care and delay in seeking help. Case-control studies of asthma mortality in New Zeal and linked prescription of fenoterol with a higher risk of death from asthma than prescription of salbutamol; this higher risk was not negat ed by adjustment for mark ers of severity. A study in Saskatchewan, Ca nada confirmed the increased risk associated with fenoterol use, but a lso found a significantly elevated risk associated with salbutamol, es pecially at higher doses. A randomized, placebo-controlled, crossover study of regular versus as-needed beta-agonists undertaken in New Zeal and showed increased morbidity from asthma during regular treatment, w ith increased symptoms, decreased pulmonary function, increased airway s responsiveness and overall poorer control of asthma despite constant inhaled corticosteroid treatment. Similar findings were evident in so me earlier studies of regular salbutamol. Taken together, several rece nt studies suggest a deleterious effect of frequent use of inhaled bet a-agonists, particularly higher potency preparations. Increased respon siveness to allergen is one possible mechanism for this effect, but wh atever the mechanism, frequent use of beta-agonists appears to ha ve c aused a shift in the chronic severity of asthma, leading to increased morbidity and mortality. The reduction in morbidity and mortality in N ew Zealand following withdrawal of the most potent beta-agonist strong ly suggests a causal relationship. Strategies to reduce mortality incl ude recognition of the high-risk patient with severe asthma, reduction in reliance on beta-agonists, increased use of antiinflammatory thera py and education in optimum asthma control.