Prediagnostic lung function impairment common in older asthma patients

By Shreeya Nanda, Senior medwireNews Reporter

Older adults with newly diagnosed asthma are not only more likely to have pre-existing lung function impairment than younger adults, but they also experience a more rapid decline of lung function, a Danish team reports in Respiratory Medicine.

“Our findings emphasize the need for a high level of diagnostic attention in older adults with symptoms suggestive of asthma, as a large proportion have a significantly reduced lung function when diagnosed, which increases the risk of misdiagnosis of asthma as [chronic obstructive pulmonary disease]”, say Celeste Porsbjerg (Bispebjerg Hospital, Copenhagen) and co-workers.

The study included 4983 participants of the Copenhagen City Heart Study with baseline and follow-up data, collected during the 1991 to 1994 and 2001 to 2003 periods, respectively, who did not self-report asthma at baseline.

The incidence of newly diagnosed asthma at the 10-year follow-up was comparable among the 668 young (20–34 years), 3147 middle-aged (35–64 years) and 1168 older participants (>64 years).

But among those who developed asthma during follow-up, older and middle-aged adults had greater impairment of prediagnostic lung function than younger participants, as shown by the significantly lower baseline forced expiratory volume in 1 second (FEV1), at 80.8% and 80.8% versus 90.2%.

Baseline airflow obstruction, assessed by the ratio of FEV1 to forced vital capacity, was also more pronounced in the older and middle-aged participants compared with the young age group, at 0.70, 0.74 and 0.81, respectively.

Lung function decline during the observation period was accelerated in those with newly diagnosed asthma compared with never asthmatics, but this decline was significantly greater in older participants than middle-aged or younger participants, with a difference of 30.8 mL/year, 18.2 mL/year and 11.0 mL/year, respectively, compared with never-asthmatics in the corresponding age groups.

The three age groups were similar with regard to the prevalence of baseline respiratory symptoms, such as wheeze and dyspnoea, which indicates that the study findings are “not explained by undiagnosed asthma in older adults”, observe the researchers.

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