PURPOSE

This study aimed to evaluate the prevalence, trends, and factors of preserved ratio with impaired spirometry (PRISm) by using a nationally representative sample.

PATIENTS AND METHODS

The datasets of the Korea National Health and Nutrition Examination Survey 2010-2019 were used: of total 32,949 participants aged ≥40 and no missing data on spirometry, 24,523 with normal, 4,623 with obstructive, and 3,803 with PRISm were identified. PRISm was defined as FEV1/FVC ≥70% and FEV1% of the predicted value (%pred) <80. PRISm-lower limit of normal (LLN) was defined when FEV1/FVC ≥LLN and FEV1 <LLN. The prevalence and trend of PRISm were estimated using the Joinpoint regression method. The trend was calculated for the periods 2010-2015 and 2017-2019, due to a change in spirometry device in June, 2016. A complex sample multivariable-adjusted regression model was used to identify factors associating PRISm.

RESULTS

Estimated average prevalence of PRISm was 10.4% (PRISm-LLN 11.1%). Joinpoint regression analyses found a relatively stable trend of PRISm for both fixed ratio and LLN. The multivariable-adjusted logistic regression model showed female sex, BMI ≥25 kg/m2, metabolic syndrome, hypertriglyceridemia, abdominal obesity, low HDL-choleterol, hypertension, and diabetes were associated with the increased probability of PRISm.

CONCLUSION

Whenever a PRISm pattern is identified in a clinical context, it may be necessary to measure absolute lung volumes to investigate underlying physiological abnormalities and to identify factors that is modifiable.