The cross-sectional and longitudinal association of the BODE index with quality of life in patients with chronic obstructive pulmonary disease

Background The body mass index, airflow obstruction, dyspnea, and exercise capacity （BODE） index was shown at predicting the risk of death, exacerbation and disease severity among patients with COPD, but few studies verified relationship between BODE index and health related quality of life （HRQoL） among Chinese COPD patients. The objective of this study was to evaluate the relationship between BODE index and HRQoL in cross-sectional and longitudinal association analyses. Methods A multi-center prospective cohort study was initially conducted in 491 stable COPD patients in Beijing, China. Health status （HRQoL） was assessed by St. George＇s Respiratory Questionnaire （SGRQ）; the BODE index was calculated for each patient; dyspnea was assessed using the 5-grade Medical Research Council dyspnea scale. Other measurements included socio-demographic, body mass index （BMI）, lung function test and 6-minute-walk test （6MWT）. Patients were then followed monthly for 12 months. Results Only 450 patients completed the 1-year follow up and were enrolled in our present analyses. Mean age was （65.2 ±10.6）years,＇ men 309 （68.7%）. The BODE index was categorized into 4 subgroups： 0-2, 3-4, 5-6 and 7-10. At baseline BODE index was gradually increased with baseline total SGRQ and SGRQ subscales （P trend 〈0.001）. For individual components of BODE index, with the decrease of airflow limitation, and 6MWD, and with the increase of Medical Research Council （MRC） dyspnea grade, total SGRQ and SGRQ subscales were increased correspondingly, P trend 〈0.05, respectively. Similar association patterns were found between baseline BODE index and its individual components and mean SGRQ scores at the end of 1-year follow up. By multiple linear regression analyses, baseline BODE index was not only significantly associated with SGRQ score at baseline but also with SGRQ score at the end of 1-year follow up after adjustment for age, male, current smoking, 13s being 0.434 and 0.378, respectively. Conclusions BODE index is associated with SGRQ score cross-sectionally and longitudinally among stable COPD patients. BODE index might have potential to be used as a sensitive tool to assess the status of quality of life and to monitor disease progression among stable COPD patients.

Oxidative stress and peripheral skeletal muscle dysfunction in rats with emphysema

Background Peripheral skeletal muscle dysfunction in patients with chronic obstructive pulmonary disease （COPD） may be due to the disease per se or as a result of concomitant confounding factors. Although the mechanistic basis for this functional impairment is uncertain, oxidative stress may play a role. The purpose of this study was to investigate whether local oxidative stress is associated with the reduced peripheral skeletal muscle performance in rats with emphysema. Methods In situ mechanical properties of gastrocnemius were measured in Sprague-Dawley rats 5 months after intratracheal instillation of either elastase （EMP, n=-10） or normal saline （CON, n=10）. Lipofuscin inclusions, myocyte apoptosis and antioxidant enzyme activities were examined in the gastrocnemius muscle. Results Lipofuscin inclusions were significantly higher in the gastrocnemius muscle of EMP compared with CON （3.2_--,-0.4 vs. 1.7_＋0.4, P〈0.01 ）. The activities of antioxidant enzymes were significantly increased in muscle homogenates of EMP as compared to CON. No significant differences were found in myocyte apoptosis between EMP and CON （1.2±0.9 vs. 1.0±0.8, P 〉0.05）. EMP decreased the fatigue endurance of gastrocnemius muscle （half-time to fatigue recovery： （150.0±55.4） seconds vs. （55.2±29.3） seconds, P 〈0.01） and had no effect on maximal tetanic force （（467.4±36.6） g vs. （493.2±30.5） g, P 〉0.05）. A significantly positive correlation was found between the level of lipofuscin inclusions and the half-time to fatigue recovery of gastrocnemius muscle in EMP （r=0.664, P 〈0.05）. Conclusion Local oxidative stress may have important functional consequences for peripheral skeletal muscle in rats with EMP.