Low FVC/TLC in Preserved Ratio Impaired Spirometry (PRISm) is associated with features of and progression to obstructive lung disease

Abstract

One quarter of individuals with Preserved Ratio Impaired Spirometry (PRISm) will develop airflow obstruction, but there are no established methods to identify these individuals. We examined the utility of FVC/TLC in identifying features of obstructive lung disease. The ratio of post-bronchodilator FVC and tLc ct from chest ct (fVc/tLc ct) among current and former smokers with pRiSm (feV 1 /fVc ≥ 0.7 and FEV1 < 80%) in COPDGene was used to stratify subjects into quartiles: very high, high, low, and very low. We examined the associations between FVC/TLC ct quartiles and (1) baseline characteristics, (2) respiratory exacerbations, (3) progression to COPD at 5 years, and (4) all-cause mortality. Among participants with pRiSm at baseline (n = 1,131), the very low FVC/TLC ct quartile was associated with increased gas trapping and emphysema, and higher rates of progression to COPD at 5 years (36% versus 17%; p < 0.001) relative to the very high quartile. The very low FVC/TLC ct quartile was associated with increased total (iRR = 1.65; 95% CI [1.07-2.54]) and severe (IRR = 2.24; 95% CI [1.29-3.89]) respiratory exacerbations. Mortality was lower in the very high FVC/TLC ct quartile relative to the other quartiles combined. Reduced FVC/TLC ct ratio in PRISm is associated with increased symptoms, radiographic emphysema and gas trapping, exacerbations, and progression to COPD.

Quality Standard Position Statements for Health System Policy Changes in Diagnosis and Management of COPD: A Global Perspective

“…Healthcare practitioners also should recognize that while 17–24% of patients with preserved lung function may not fulfill the spirometry criterion for a diagnosis of COPD [ 39 ], they may nonetheless experience respiratory symptoms, exacerbation-like events, and activity limitations with some evidence of airway disease [ 40 ]. Notably, a subset of patients with preserved ratio impaired spirometry (PRISm) eventually progress to meet the spirometric criterion for COPD and are at increased risk of respiratory symptoms, respiratory exacerbations, and mortality [ 41 – 43 ]. Currently, however, GOLD recommendations do not address the therapeutic management of patients with PRISm, who represent a heterogenous population, that is possibly underdiagnosed and underappreciated.…”

Ratio of FEV1/Slow Vital Capacity of < 0.7 Is Associated With Clinical, Functional, and Radiologic Features of Obstructive Lung Disease in Smokers With Preserved Lung Function

“…4,40,41 Air trapping based on radiographic lung volumes predicts accelerated spirometry decline and progression to COPD in smokers without obstruction. 4,33,40,41 Based on the above, we conclude that FEV 1 to SVC ratio can be a simple, routinely available spirometric index that can identify individuals who may benefit from early intervention such as smoking cessation. Confirmation of obstructive lung disease by an objective measurement like FEV 1 to SVC ratio may motivate smokers to quit smoking, 42,43 which is the only proven intervention that can modify disease progression.…”

“…In individuals with mild obstructive lung disease, this phenomenon may result in pseudonormalization of the FEV 1 to FVC ratio, whereas in those with substantial obstructive lung disease, it may result in preserved ratio impaired spirometry results. [32][33][34] Using the FEV 1 to SVC ratio instead of the FEV 1 to FVC ratio results in an increase in the reported prevalence of COPD 35,36 and may lead to overdiagnosis, in particular among elderly individuals. 7 Nevertheless, in the absence of a true gold standard for COPD diagnosis, the usefulness of a diagnostic test is related highly to its association with the clinical, functional, and radiographic features of a disease.…”

Physical performance in relation to preserved ratio impaired spirometry: a cross-sectional study of community-dwelling older Japanese adults

“…Previous studies have reported prevalence rates for PRISm as between 12 and 24% [1][2][3][4] . In this study, the prevalence rate was 12.0%, which was similar to that reported in some other countries.…”