Early and late adult asthma: similar but different


By Nicola Garrett

16 Jun 2016

Early and late onset adult asthma has similar clinical manifestations but major phenotypic differences, the world’s longest running population study of respiratory diseases confirms.

The Tasmanian Longitudinal Health Study spanning over four decades found that early-onset adult asthma was associated with greater pre-bronchodilator and post bronchodilator airflow obstruction compared to people with later-onset asthma (mean difference pre-bronchodilator (BD) FEV/FVC −2.8% predicted (−5.3 to −0.3); post-BD FEFVC −2.6% predicted (−5.0 to −0.1).

Nocturnal asthma symptoms and hospitalisation in the preceding year were also more pronounced in those with early onset disease.

Asthma severity and score did not differ between the groups, reported the researchers led by Dr Shyamali Dharmage from the Murdoch Childrens Institute in Melbourne.

Atopy and family history were more common in early-onset asthma while female gender, current smoking and low socioeconomic status were more common in late-onset asthma.

The results reaffirm that age-at-onset is an important distinguishing factor of adult asthma phenotypes, the researchers concluded in their paper which was published in Thorax.

“While clinically, adults with early-onset and late-onset asthma have similar overall disease severity and symptom frequency, key differences in their sociodemographic characteristics suggest the two phenotypes may have differing aetiological factors and detailed pathophysiologies,” they wrote.

Of the entire TAHS cohort 7.7% (95% CI 6.6% to 9.0%) were categorised as having early-onset asthma and 7.8% (95% CI 6.4% to 9.4%) as late-onset asthma at age 44.

Asthma was defined as  asthma-related symptoms and/or healthcare usage in the last 12 months, and was categorised as early-onset (asthma or ‘wheezy breathing’ in the 1968 and/or 1974 surveys) or late-onset (no asthma or wheezy breathing in both the 1968 and 1974 surveys). Age 13 was used to delineate the two age-of-onset subgroups.

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