Use of 6-minute walk test for assessing severity of interstitial lung disease: an observational study.

BACKGROUND: The 6-minute walk test (6MWT) is a potential tool for assessing the severity of interstitial lung disease (ILD). OBJECTIVES: To explore the relationship between 6MWT results and traditional measures including pulmonary function and chest computed tomography(CT) and to determine factors that might influence the 6-minute walk distance (6MWD). METHODS: Seventy-three patients with ILD were enrolled at Peking University First Hospital. All patients underwent 6MWT, pulmonary CT, and pulmonary function tests and their correlations were analyzed. Multivariate regression analysis was used to identify factors that might impact 6MWD.  Results: Thirty (41.4%) of the patients were female and the mean age was 66.1 ± 9.6 years. 6MWD was correlated with forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), total lung capacity (TLC), diffusing capacity for carbon monoxide (DLCO) and DLCO%pred. The decrease in oxygen saturation (SpO2) after the test was correlated with FEV1%pred, FVC%pred, TLC, TLC%pred, DLCO, DLCO%pred and the percentage of normal lung calculated by quantitative CT. The increase in Borg dyspnea scale was correlated with FEV1, DLCO and the percentage of normal lung. The backward multivariate model (F = 15.257, P < 0.001, adjusted R2 = 0.498) indicated that 6MWD was predicted by age, height, body weight, increase in heart rate, and DLCO. CONCLUSIONS: The 6MWT results were closely correlated with pulmonary function and quantitative CT in patients with ILD. However, in addition to disease severity, 6MWD was also influenced by individual characteristics and the degree of patient effort, which should thus be considered by clinicians when interpreting 6WMT results.

Serum surfactant protein D, lung function decline, and incident chronic obstructive pulmonary disease: a longitudinal study in Beijing.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) has become a major public-health problem in China. Surfactant protein D (SP-D) is a very promising biomarker and therapeutic target for COPD. To assess whether baseline serum SP-D is associated with lung function decline and incident COPD. METHODS: This longitudinal study was initiated in 2009 in a community in Beijing. Data were collected on spirometry, and the baseline level of serum SP-D was measured in 772 non-COPD subjects aged 40-70 years old. In 2012, spirometry was repeated in 364 individuals, 37 of whom subjects had incident COPD. RESULTS: From 2009 to 2012, subjects with incident COPD had a more rapid decline in FEV1 (MD 98.27 vs. MD 43.41 mL) compared with those without COPD. There was no association between baseline serum SP-D and the COPD incidence. Smoking (OR =2.72; P=0.002) and age (OR =1.06; P=0.000) were risk factors for COPD. The rate of FEV1 decline varies widely in the general population, and the univariate analysis showed that baseline serum SP-D levels (R=-0.169; P=0.003), income level, home-road distance, and statin use were inversely correlated with the decline in FEV1. After multivariable analyses, only smoking was consistently associated with the decline in FEV1. CONCLUSIONS: There was no correlation between baseline serum SP-D levels and incident COPD in a general population. Smoking and age were major risk factors for COPD. The effect of serum SP-D levels on the decline in FEV1 needs further investigation.

Influenza A virus exposure may cause increased symptom severity and deaths in coronavirus disease 2019.

BACKGROUND: The coronavirus disease 2019 (COVID-19) outbreak occurred during the flu season around the world. This study aimed to analyze the impact of influenza A virus (IAV) exposure on COVID-19. METHODS: Seventy COVID-19 patients admitted to the hospital during January and February 2020 in Wuhan, China were included in this retrospective study. Serum tests including respiratory pathogen immunoglobulin M (IgM) and inflammation biomarkers were performed upon admission. Patients were divided into common, severe, and critical types according to disease severity. Symptoms, inflammation indices, disease severity, and fatality rate were compared between anti-IAV IgM-positive and anti-IAV IgM-negative groups. The effects of the empirical use of oseltamivir were also analyzed in both groups. For comparison between groups, t tests and the Mann-Whitney U test were used according to data distribution. The Chi-squared test was used to compare disease severity and fatality between groups. RESULTS: Thirty-two (45.71%) of the 70 patients had positive anti-IAV IgM. Compared with the IAV-negative group, the positive group showed significantly higher proportions of female patients (59.38% vs. 34.21%, χ = 4.43, P = 0.035) and patients with fatigue (59.38% vs. 34.21%, χ = 4.43, P = 0.035). The levels of soluble interleukin 2 receptor (median 791.00 vs. 1075.50 IU/mL, Z = -2.70, P = 0.007) and tumor necrosis factor α (median 10.75 vs. 11.50 pg/mL, Z = -2.18, P = 0.029) were significantly lower in the IAV-positive group. Furthermore, this group tended to have a higher proportion of critical patients (31.25% vs. 15.79%, P = 0.066) and a higher fatality rate (21.88% vs. 7.89%, P = 0.169). Notably, in the IAV-positive group, patients who received oseltamivir had a significantly lower fatality rate (0 vs. 36.84%, P = 0.025) compared with those not receiving oseltamivir. CONCLUSIONS: The study suggests that during the flu season, close attention should be paid to the probability of IAV exposure in COVID-19 patients. Prospective studies with larger sample sizes are needed to clarify whether IAV increases the fatality rate of COVID-19 and to elucidate any benefits of empirical usage of oseltamivir.

Living near a Major Road in Beijing: Association with Lower Lung Function, Airway Acidification, and Chronic Cough.

BACKGROUND: The effects of near-road pollution on lung function in China have not been well studied. We aimed to investigate the effects of long-term exposure to traffic-related air pollution on lung function, airway inflammation, and respiratory symptoms. METHODS: We enrolled 1003 residents aged 57.96 ± 8.99 years living in the Shichahai Community in Beijing. Distances between home addresses and the nearest major roads were measured to calculate home-road distance. We used the distance categories 1, 2, and 3, representing <100 m, 100-200 m, and >200 m, respectively, as the dose indicator for traffic-related air pollution exposure. Lung function, exhaled breath condensate (EBC) pH, and interleukin 6 levels were measured. As a follow-up, 398 participants had a second lung function assessment about 3 years later, and lung function decline was also examined as an outcome. We used regression analysis to assess the impacts of home-road distance on lung function and respiratory symptoms. As the EBC biomarker data were not normally distributed, we performed correlation analysis between home-road distance categories and EBC biomarkers. RESULTS: Participants living a shorter distance from major roads had lower percentage of predicted value of forced expiratory volume in 1 s (FEV1% -1.54, 95% confidence interval [CI]: -0.20 to -2.89). The odds ratio for chronic cough was 2.54 (95% CI: 1.57-4.10) for category 1 and 1.97 (95% CI: 1.16-3.37) for category 2, compared with category 3. EBC pH was positively correlated with road distance (rank correlation coefficient of Spearman [rs] = 0.176, P < 0.001). CONCLUSIONS: Long-term exposure to traffic-related air pollution in people who live near major roads in Beijing is associated with lower lung function, airway acidification, and a higher prevalence of chronic cough. EBC pH is a potential useful biomarker for evaluating air pollution exposure.