Emphysema severity index a novel clinical marker for respiratory death, study finds

The emphysema severity index may be a useful tool in clinical settings and treatment studies to better individualize treatments and prognosis, according to new results published in Respiratory Medicine Journal.

“Since emphysema severity index is not dependent on reference values or any additional equipment beyond that needed for conducted spirometry, it could be easily implemented in a clinical setting alongside other currently used spirometric parameters such as FEV1,” Johannes Luoto, MD, from the department of clinical sciences in the division of geriatric medicine at Skåne University Hospital at Lund University in Malmö, Sweden, and colleagues wrote. “We wanted to investigate whether emphysema severity index increased all-cause mortality and respiratory death specifically.”

The researchers aimed to establish clinical relevance of the emphysema severity index (ESI) by conducting Cox regression analyses adjusted for age, smoking, sex, FEV1 and FVC to determine whether the index is associated with all-cause mortality, respiratory mortality and non-respiratory mortality at 10 years. The study included 3,974 participants (mean age, 70.8 years; 53.4% women) with acceptable spirometry from the Gott Åldrande I Skåne study, a Swedish general population of individuals aged 65 to 102 years.

Factors that increased likelihood for respiratory death included age 90 years or older (HR = 1.36; 95% CI, 1.17-1.54), higher ESI (HR = 1.57; 95% CI, 1.27-1.94; P < .0001), lower FEV₁ (HR = 0.39; 95% CI, 0.22-0.69; P = .0013) and male sex (HR = 1.11; 95% CI, 1.08-1.15), according to the researchers.

The ESI was significantly linked with respiratory death, but not non-respiratory death, according to the researchers. Older age, male sex and low FEV₁ were associated with non-respiratory and respiratory death.

Current smoking increased the likelihood of respiratory death but this finding was not significant (P = .066). A 1 U increase in ESI increased the likelihood of all-cause death by 20% (P = .0002) and respiratory death by 57% (P < .0001).

“Since it can be derived from a standard spirometry, we consider it a marker with a potential to be used in the clinical setting as well as in treatment studies with the aim to better individualize treatments as well as prognosis,” the researchers wrote. “As a next step, our findings should be replicated, and the predictive value of phenotyping based on ESI scores evaluated.”