Prognostic Value of the Six-Second Spirometry in Patients with Chronic Obstructive Pulmonary Disease: A Cohort Study

Abstract

BackgroundThe six-second spirometry has been proposed as an alternative to diagnose airflow limitation, although its prognostic value in patients with chronic obstructive pulmonary disease (COPD) remains unknown. The purpose of this study was to determine the prognostic value of the postbronchodilator forced expiratory volume in 1 second (FEV1)/forced expiratory volume in 6 seconds (FEV6) ratio and FEV6 in COPD patients.Methods and FindingsThe study population consisted of 2,614 consecutive stable patients with COPD. The patients were monitored for an average period of 4.3 years regarding mortality, hospitalizations by COPD exacerbations, diagnosis of lung cancer, and annual lung function decline. The overall rate of death was 10.7 (95%CI: 8.7–12.7) per 1000 person-years. In addition to male gender, age and comorbidity, FEV6 (hazard ratio [HR]: 0.981, 95%CI: 0.968–0.003) and FEV1/FEV6 quartiles (lowest quartile (<74% pred.): HR 3.558, 95%CI: 1.752–7.224; and second quartile (74–84% pred.): HR 2.599, 95%CI: 1.215–5.561; versus best quartile (>0.89% pred.)) were independently associated with mortality, whereas FEV1 was not retained in the model. 809 patients (30.9%) had at least one hospital admission due to COPD exacerbation. In addition to sex, age, smoking and comorbidity, FEV1 and FEV1/FEV6 quartiles were independent risk factors of hospitalization. FEV6 was the only spirometric parameter independently related with lung function annual decline, while the FEV6 and FEV1/FEV6 quartiles were independent risk factors for lung cancer.ConclusionsIn a general COPD outpatient population, airflow obstruction assessed by the FEV1/FEV6 is an independent risk factor for both death and hospitalization.

Screening for Chronic Obstructive Pulmonary Disease: Validity and Reliability of a Portable Device in Non-Specialized Healthcare Settings

“…The use of the FEV1/FEV6 ratio as a substitute for the FEV1/FVC ratio has already been accepted[ 8 , 9 ].According to the PLATINO longitudinal study data, FEV1/FEV6 is a better indicator of airflow obstruction, likely due to comparing volumes at fixed times of the expiratory manoeuvre and avoiding inconsistencies due to changes in the quality of the spirometries, especially in forced expiratory time across different technicians, centres, or along time[ 15 ]. Postbronchodilator FEV6 and FEV1/FEV6 as percentage of predicted are also independent prognostic factors in stable outpatients with COPD[ 16 ]. In any case,there is no consensus on the FEV1/FEV6 cut-off point considered to define obstruction[ 8 , 9 , 12 ].…”

Classification of Airflow Limitation Based on z-Score Underestimates Mortality in Patients with Chronic Obstructive Pulmonary Disease

“…Between April 2004 and December 2008, a total of 2,614 outpatients with COPD were recruited in the context of the Fuenlabrada cohort study. Details are available elsewhere (14). Briefly, the study included all subjects aged 40 or older with airflow limitation and a clinical diagnosis of COPD treated by general practitioners or pulmonologists in the ninth district of the Madrid Metropolitan Area, Spain.…”

Factors associated with the rate of COPD exacerbations that require hospitalization

“…This could explain the significant difference in FVC values in favor of the control group, which was a significantly older group (as shown in Table 1). However, valid expiration during spirometry testing is considered to be one lasting at least 6 s (35), suggesting that our hypothesis could be confirmed or invalidated by assessing values of FEV6 measurements, which is a more stable indicator of expiration accuracy (36) independently related to annual lung function decline (37) and eliminates the potential age factor in interpretation of FVC values. Further studies are needed to investigate this issue.…”