@article {8097, title = {Discriminative Accuracy of FEV1:FVC Thresholds for COPD-Related Hospitalization and Mortality.}, journal = {JAMA}, volume = {321}, year = {2019}, month = {2019 06 25}, pages = {2438-2447}, abstract = {

Importance: According to numerous current guidelines, the diagnosis of chronic obstructive pulmonary disease (COPD) requires a ratio of the forced expiratory volume in the first second to the forced vital capacity (FEV1:FVC) of less than 0.70, yet this fixed threshold is based on expert opinion and remains controversial.

Objective: To determine the discriminative accuracy of various FEV1:FVC fixed thresholds for predicting COPD-related hospitalization and mortality.

Design, Setting, and Participants: The National Heart, Lung, and Blood Institute (NHLBI) Pooled Cohorts Study harmonized and pooled data from 4 US general population-based cohorts (Atherosclerosis Risk in Communities Study; Cardiovascular Health Study; Health, Aging, and Body Composition Study; and Multi-Ethnic Study of Atherosclerosis). Participants aged 45 to 102 years were enrolled from 1987 to 2000 and received follow-up longitudinally through 2016.

Exposures: Presence of airflow obstruction, which was defined by a baseline FEV1:FVC less than a range of fixed thresholds (0.75 to 0.65) or less than the lower limit of normal as defined by Global Lung Initiative reference equations (LLN).

Main Outcomes and Measures: The primary outcome was a composite of COPD hospitalization and COPD-related mortality, defined by adjudication or administrative criteria. The optimal fixed FEV1:FVC threshold was defined by the best discrimination for these COPD-related events as indexed using the Harrell C statistic from unadjusted Cox proportional hazards models. Differences in C statistics were compared with respect to less than 0.70 and less than LLN thresholds using a nonparametric approach.

Results: Among 24 207 adults in the pooled cohort (mean [SD] age at enrollment, 63 [10.5] years; 12 990 [54\%] women; 16 794 [69\%] non-Hispanic white; 15 181 [63\%] ever smokers), complete follow-up was available for 11 077 (77\%) at 15 years. During a median follow-up of 15 years, 3925 participants experienced COPD-related events over 340 757 person-years of follow-up (incidence density rate, 11.5 per 1000 person-years), including 3563 COPD-related hospitalizations and 447 COPD-related deaths. With respect to discrimination of COPD-related events, the optimal fixed threshold (0.71; C statistic for optimal fixed threshold, 0.696) was not significantly different from the 0.70 threshold (difference, 0.001 [95\% CI, -0.002 to 0.004]) but was more accurate than the LLN threshold (difference, 0.034 [95\% CI, 0.028 to 0.041]). The 0.70 threshold provided optimal discrimination in the subgroup analysis of ever smokers and in adjusted models.

Conclusions and Relevance: Defining airflow obstruction as FEV1:FVC less than 0.70 provided discrimination of COPD-related hospitalization and mortality that was not significantly different or was more accurate than other fixed thresholds and the LLN. These results support the use of FEV1:FVC less than 0.70 to identify individuals at risk of clinically significant COPD.

}, keywords = {Aged, Aged, 80 and over, Cohort Studies, Female, Forced Expiratory Volume, Hospitalization, Humans, Male, Middle Aged, Prognosis, Proportional Hazards Models, Pulmonary Disease, Chronic Obstructive, Risk Assessment, Vital Capacity}, issn = {1538-3598}, doi = {10.1001/jama.2019.7233}, author = {Bhatt, Surya P and Balte, Pallavi P and Schwartz, Joseph E and Cassano, Patricia A and Couper, David and Jacobs, David R and Kalhan, Ravi and O{\textquoteright}Connor, George T and Yende, Sachin and Sanders, Jason L and Umans, Jason G and Dransfield, Mark T and Chaves, Paulo H and White, Wendy B and Oelsner, Elizabeth C} } @article {8623, title = {A Dyadic Growth Modeling Approach for Examining Associations Between Weight Gain and Lung Function Decline.}, journal = {Am J Epidemiol}, volume = {189}, year = {2020}, month = {2020 10 01}, pages = {1173-1184}, abstract = {

The relationship between body weight and lung function is complex. Using a dyadic multilevel linear modeling approach, treating body mass index (BMI; weight (kg)/height (m)2) and lung function as paired, within-person outcomes, we tested the hypothesis that persons with more rapid increase in BMI exhibit more rapid decline in lung function, as measured by forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and their ratio (FEV1:FVC). Models included random intercepts and slopes and adjusted for sociodemographic and smoking-related factors. A sample of 9,115 adults with paired measurements of BMI and lung function taken at >=3 visits were selected from a pooled set of 5 US population-based cohort studies (1983-2018; mean age at baseline = 46 years; median follow-up, 19 years). At age 46 years, average annual rates of change in BMI, FEV1, FVC, and FEV1:FVC ratio were 0.22 kg/m2/year, -25.50 mL/year, -21.99 mL/year, and~-0.24\%/year, respectively. Persons with steeper BMI increases had faster declines in FEV1 (r~=~-0.16) and FVC (r~=~-0.26) and slower declines in FEV1:FVC ratio (r~=~0.11) (all P~values <~0.0001). Results were similar in subgroup analyses. Residual correlations were negative (P~<~0.0001), suggesting additional interdependence between BMI and lung function. Results show that greater rates of weight gain are associated with greater rates of lung function loss.

}, keywords = {Adult, Aged, Body Mass Index, Cohort Studies, Humans, Linear Models, Lung, Middle Aged, Respiratory Function Tests, Weight Gain}, issn = {1476-6256}, doi = {10.1093/aje/kwaa059}, author = {Cornelius, Talea and Schwartz, Joseph E and Balte, Pallavi and Bhatt, Surya P and Cassano, Patricia A and Currow, David and Jacobs, David R and Johnson, Miriam and Kalhan, Ravi and Kronmal, Richard and Loehr, Laura and O{\textquoteright}Connor, George T and Smith, Benjamin and White, Wendy B and Yende, Sachin and Oelsner, Elizabeth C} }