Increased occurrence of asthma and allergy: critical appraisal of studies using allergic sensitization, bronchial hyperresponsiveness and lung function measurements

Background Many studies have reported an increase in the occurrence of asth ma and respiratory allergies in recent decades, but this increase is mostly based on studies using rather subjective measurements of asthma and allerg ies, such as questionnaires and doctor's diagnosis. None of the reviews spe cifically focused on studies using more 'objective' measurements, such as s ensitization (specific IgE or skin prick testing (SPT)), bronchial hyper-re sponsiveness (BHR) or lung function (LF). Objective To review articles studying a time trend of occurrence of these ' more objective' measurements. Methods A MEDLINE-search (1966-February 2000) was performed. The following criteria were used: population-based, using IgE, SPT, BHR or LF measurement s in the same age-group at least twice, with at least 2 years between and u sing similar methods. Results The MEDLINE-search resulted in only 16 articles, performed in 13 po pulations in seven different countries. Nine articles used the same objecti ve measurements twice in the whole population. Three of these reported a no n-significant increase or decrease. The other six articles found a signific ant increase in at least one objective measurement and of these only three reported a consistent significant increase. Conclusions The increase in the occurrence of reported asthma and allergy i s supported by only a few articles confirming these results with 'more obje ctive measurements'.