Chronic obstructive pulmonary disease (COPD) patients with high ESI are at higher risk of death due to respiratory cause, according to a recent study from Sweden published in Respiratory Medicine Journal.¹

In this study, researchers examined the clinical utility of the emphysema severity index (ESI) in predicting all-cause, respiratory and non-respiratory mortality at 10 years, after adjusting for age, sex, smoking, forced vital capacity (FVC) and forced expiratory volume in one second (FEV1). The ESI index is a quantitative score ranging from 0 to 10. ESI is derived from the mathematical modeling of the descending limb of the maximal expiratory flow volume (MEFV) curve. It has been shown to correlate with the quantitative assessment of emphysema on CT scan.²

A total of 3974 participants with acceptable spirometry were selected from the ongoing Gott Åldrande i Skåne  (GAS) study, a part of the Swedish National Study on Aging and Care (SNAC). The mean age of the participants was 70.8 years and more than half (53.4%) of them were women.

Results showed that patients aged ≥90 years, male patients and those who had lower FEV1 and higher ESI were at higher risk of respiratory death with hazard ratios of 1.36, 1,11, 0.39 and 1.57, respectively. The study also found a significant association of ESI with respiratory death, but not with non-respiratory death. Male sex and low FEV1 were associated with both non-respiratory and respiratory mortality. Increase in ESI score by one unit increased the odds of all-cause mortality by 20% and mortality due to respiratory cause by 57%. No association with all-cause or respiratory mortality was noted for FEV1/FVC. Current smokers were at a higher risk of respiratory death but this finding was not statistically significant.

This study has demonstrated the potential usefulness of ESI as a clinical marker for severity of emphysema given its association with respiratory death. It can be used to tailor treatment for the individual patient with COPD and predict prognosis. This index can be calculated from standard spirometry; hence, it is a quick, easily obtained and easy to implement parameter.

References

1. Luoto J, et al. Emphysema severity index (ESI) associated with respiratory death in a large Swedish general population. Respiratory Medicine Journal. June 07, 2022. DOI: https://doi.org/10.1016/j.rmed.2022.106899.
2. RW Dal Negro, et al. Standard spirometry to assess emphysema in patients with chronic obstructive pulmonary disease: the Emphysema Severity Index (ESI). Multidiscip Respi Med. 2021;16:805.