Association between Comorbidities and Preserved Ratio Impaired Spirometry: Using the Korean National Health and Nutrition Examination Survey IV–VI

Abstract

<b><i>Background:</i></b> Preserved ratio impaired spirometry (PRISm) patients have more frequent respiratory symptoms and an increased risk of mortality. However, studies on comorbidities in these patients are lacking. <b><i>Objectives:</i></b> We investigated the association between PRISm and comorbidities using the Korea National Health and Nutrition Examination Survey (KNHANES). <b><i>Method:</i></b> This cross-sectional study included participants aged ≥50 years from the KNHANES (2007–2015). Participants who did not undergo spirometry or performed inadequately were excluded. We classified participants into 3 groups according to spirometry: PRISm (forced expiratory volume in one second [FEV1] /forced vital capacity [FVC] ≥ 0.7 and FEV1 &#x3c;80%), chronic obstructive pulmonary disease (COPD) (FEV1/ FVC &#x3c;0.7), and normal. Multivariate logistic regression analyses were used to evaluate the risk of comorbidities in the PRISm group compared to that in the normal group. <b><i>Result:</i></b> The study included 17,515 participants: 12,777 (73.0%), 1,563 (8.9%), and 3,175 (18.1%) in normal, PRISm, and COPD groups, respectively. After adjustment for known risk factors of each disease, hypertension (adjusted odds ratio [95% confidence interval]; 1.31 [1.14–1.50]), diabetes (1.51 [1.29–1.78]), hypercholesterolemia (1.20 [1.04–1.37]), obesity (1.31 [1.15–1.48]), ischemic heart disease (1.58 [1.13–2.22]), chronic renal disease (2.31 [1.09–4.88]), and thyroid disease (1.41 [1.09–1.83]) risks were significantly higher in the PRISm group than in the normal group. The average number of comorbidities was 2.45 in the PRISm group, which was higher than that in the normal (2.1) and COPD (2.03) groups (<i>p</i> &#x3c; 0.05). <b><i>Conclusion:</i></b> The number of comorbidities was significantly higher in the PRISm group than in others. Hypertension, diabetes, obesity, ischemic heart disease, chronic renal disease, and thyroid disease were associated with PRISm after adjustment for risk factors.