FEV1 poor mortality predictor in elderly

Oct 18 2013

Research shows that forced expiratory volume in 1 second (FEV1) % predicted is ineffective for predicting mortality in elderly asthma patients.

But the results also suggest that an alternative way of expressing FEV1 may be a better indicator for mortality risk in such patients.

The authors, led by Anna Zito (Campus Biomedico University, Rome, Italy), analyzed data on 200 patients with asthma aged at least 65 years taking part in the 15-year follow-up of the Salute Respiratoria nell’ Anziano study.

The patients had a mean FEV1 of 1.5 L, a mean FEV1 % predicted of 65.6, a mean FEV1 divided by height cubed of 0.4 L/m³ and a mean FEV1 expressed as a multiple of the gender-specific first percentile (FEV1Q) of 3.4.

The team found that at 5-year follow-up, no expression of FEV1 effectively predicted mortality. By contrast, at 10 years, FEV1Q was the only spirometric parameter independently associated with mortality; each standard deviation increase resulted in a 65% lower risk for death. Similarly, this was confirmed at 15 years, when it was associated with a 62% lower risk for death.

Other factors independently associated with mortality during follow-up included age, obesity, smoking, and the presence of comorbidities.

Zito and colleagues say that while FEV1 has been shown to predict mortality in adults, the equations used to produce predicted values may not be optimal in elderly patients. Additionally, the efficacy of FEV1 for this purpose in adults was attributed mainly to ensuing chronic obstructive pulmonary disease (COPD), a diagnosis which was unlikely in their population of elderly patients.

Writing in the Annals of Allergy, Asthma & Immunology, the team says their findings indicate FEV1Q – in which FEV1 is divided by the gender-specific first percentile of the FEV1 distribution of a large population (0.5 L for men; 0.4 L for women) – may outperform FEV1 % predicted as it does not require reference equations, which can be a source of bias.

Zito et al say that, overall, in contrast to COPD, FEV1 appears to have a minor prognostic role in asthma. Nevertheless, “the association of FEV1Q with long-term mortality suggests that respiratory function also is related to survival in elderly patients with asthma and multiple morbidities and thus encourages further research on the best way of quantifying lung dysfunction in this population,” they conclude.

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