Arterial Stiffness Increases Over Time in Relation to Lung Diffusion Capacity: A Longitudinal Observation Study in COPD

Background

Cardiovascular events are, after cancer, the most common cause of death in COPD patients. Arterial stiffness is an independent predictor of all-cause mortality and cardiovascular events. Several cross-sectional studies have confirmed increased arterial stiffness in patients with COPD. Various mechanisms in the development of arterial stiffness in COPD such as reduced lung function or systemic inflammation have been proposed. However, clinical predictors of arterial stiffness that had been reported in cross-sectional studies have not yet been confirmed in a longitudinal setting. We have assessed the course of augmentation index (AIx) - a measure of systemic arterial stiffness - and possible predictors in a cohort of COPD patients over a period of up to 7 years.

Methods

COPD patients underwent annual AIx measurement by applanation tonometry for a maximum duration of 7 years. Additionally, we performed annual assessments of lung function, blood gases, systemic inflammation, serum lipids and blood pressure. Associations between the course of AIx and potential predictors were investigated through a mixed effect model.

Results

Seventy-six patients (mean (SD) age 62.4 (7.1), male 67%) were included. The AIx showed a significant annual increase of 0.91% (95% CI 0.21/1.60) adjusted for baseline. The change in diffusion capacity (DLco), low-density lipoprotein (LDL), and high-sensitivity c-reactive protein (hsCRP) was independently associated with the increasing evolution of AIx (Coef. - 0.10, p<0.001, Coef. 1.37, p=0.003, and Coef. 0.07, p=0.033, respectively).

Conclusion

This study demonstrated a meaningful increase in arterial stiffness in COPD over time. A greater annual increase in arterial stiffness was associated with the severity of emphysema (measured by DLco), systemic inflammation, and dyslipidaemia.

Clinical Trial Registration

www.ClinicalTrials.gov, NCT01527773.

"Can do, don't do" are not the lazy ones: a longitudinal study on physical functioning in patients with COPD

Background and objective

Reduced physical capacity (PC) and physical activity (PA) are common in COPD patients and associated with poor outcome. However, they represent different aspects of physical functioning and interventions do not affect them in the same manner. To address this, a new PC-PA quadrant concept was recently generated to identify clinical characteristics of sub-groups of physical functioning. The objective of this study was to I) proof the new concept and to verify their differentiating clinical characteristics, II) evaluate the consistency of the concept over time, III) assess whether patients changed their quadrant affiliation over time, IV) and to test if changes in quadrant affiliations are associated with changes in clinical characteristics.

Methods

In a longitudinal, prospective, non-interventional cohort with mild to very severe COPD patients, PC and PA as well as respiratory variables, COPD-specific health status, comorbidities, survival, and exacerbations were yearly assessed.

Results

Data from 283 patients were analysed at baseline. Mean (min/max) follow-up time was 2.4 (0.5/6.8) years. The PC-PA quadrants could be characterized as follows: I) “can’t do, don’t do”: most severe and symptomatic, several comorbidities II) “can do, don’t do”: severe but less symptomatic, several comorbidities III) “can’t do, do do”: few patients, severe and symptomatic, less comorbidities IV) “can do, do do”: mildest and less symptomatic, less comorbidities, lowest exacerbation frequency. Of the 172 patients with at least one follow-up, 58% patients never changed their quadrant affiliation, while 17% declined either PC, PA or both, 11% improved their PC, PA or both, and 14% showed improvement and decline in PC, PA or both during study period. None of the clinical characteristics or their annual changes showed consistent significant and relevant differences between all individual sub-groups.

Conclusion

Our findings suggest that there are no clinical characteristics allowing to distinguish between the PC-PA quadrants and the concept seems not able to illustrate disease process. However, the already low PA but preserved PC in the “can do, don’t do” quadrant raises the question if regularly assessment of PA in clinical practice would be more sensitive to detect progressive deterioration of COPD compared to the commonly used PC.

Clinical trial registration

www.ClinicalTrials.gov, NCT01527773.

Endocrine responses during CPAP withdrawal in obstructive sleep apnoea: data from two randomised controlled trials

The aim of this investigation was to elucidate the effect of CPAP withdrawal on neurometabolic and cardiometabolic markers in patients with obstructive sleep apnoea. We evaluated 70 patients (mean age 61±10 years, 82% men) treated with CPAP in two 2-week, parallel, randomised controlled trials. CPAP withdrawal resulted in elevated 3,4-dihydroxyphenylglycol, norepinephrine and cortisol after 2 weeks of CPAP withdrawal; however, no statistically significant changes of the renin-angiotensin-aldosterone system (RAAS) determinants were documented. In summary, CPAP withdrawal may be more prominently linked to short-term increases in sympathetic activation than hypothalamic-pituitary-adrenal axis or RAAS activation. ClinicalTrials.gov Identifier: NCT02493673 and NCT02050425.

Obstructive sleep apnea and quality of life in Fabry disease: a prospective parallel cohort study

STUDY OBJECTIVES

Patients with Fabry disease (FD) report impaired quality of life and excessive daytime sleepiness. Obstructive sleep apnea (OSA) is frequently reported among patients with FD; however, its prevalence and its influence on quality of life and daytime sleepiness in this population are unclear.

METHODS

Patients with FD in a cohort from the University Hospital Zurich (n = 52) were one-to-two matched to healthy adult controls (n = 104) according to age, sex, and body mass index. Participants underwent structured interviews (including Short Form-36) and level-3 respiratory polygraphy. An apnea-hypopnea index of ≥ 5/h was defined as OSA and the severity of FD was quantified with the Mainz Severity Score Index (MSSI). Conditional logistic regression was used to compare the outcomes.

RESULTS

In patients with FD the mean MSSI was 13.3 ± 10.5 points and OSA prevalence was 19.2% vs. 9.0% in the matched control group (p = 0.09). The apnea-hypopnea index was significantly higher in patients with FD than in the control group (0.5/h [0.2-3.0] vs. 0.2/h [0.1-1.8], p = 0.026). OSA severity was associated with impaired quality of life in four dimensions for the whole study population. Furthermore, patients with FD did report significantly higher daytime sleepiness (Epworth Sleepiness Scale 7.6 points vs. 6.3 points; p = 0.01) than healthy controls.

CONCLUSION

Patients with mild FD do not have a higher OSA prevalence than matched control subjects. Differences in OSA severity did not reach clinical significance. Further studies are warranted to determine the impact of OSA in patients with moderate-to-severe FD.

Effects of short-term continuous positive airway pressure withdrawal on cerebral vascular reactivity measured by blood oxygen level-dependent magnetic resonance imaging in obstructive sleep apnoea: a randomised controlled trial

Impaired cerebral vascular reactivity (CVR) increases long-term stroke risk. Obstructive sleep apnoea (OSA) is associated with peripheral vascular dysfunction and vascular events. The aim of this trial was to evaluate the effect of continuous positive airway pressure (CPAP) withdrawal on CVR.

41 OSA patients (88% male, mean age 57±10 years) were randomised to either subtherapeutic or continuation of therapeutic CPAP. At baseline and after 2 weeks, patients underwent a sleep study and magnetic resonance imaging (MRI). CVR was estimated by quantifying the blood oxygen level-dependent (BOLD) MRI response to breathing stimuli.

OSA did recur in the subtherapeutic CPAP group (mean treatment effect apnoea–hypopnoea index +38.0 events·h−1, 95% CI 24.2–52.0; p<0.001) but remained controlled in the therapeutic group. Although there was a significant increase in blood pressure upon CPAP withdrawal (mean treatment effect +9.37 mmHg, 95% CI 1.36–17.39; p=0.023), there was no significant effect of CPAP withdrawal on CVR assessedviaBOLD MRI under either hyperoxic or hypercapnic conditions.

Short-term CPAP withdrawal did not result in statistically significant changes in CVR as assessed by functional MRI, despite the recurrence of OSA. We thus conclude that, unlike peripheral endothelial function, CVR is not affected by short-term CPAP withdrawal.

No impact of exacerbation frequency and severity on the physical activity decline in COPD: a long-term observation

Introduction

COPD exacerbations are associated with a concomitant profound reduction in daily physical activity (PA). Thereby, exacerbation frequency and severity may have an amplifying effect. Whether the reduced level of PA returns to the level prior to exacerbation or has a sustained negative impact on activity behavior over time is unclear.

Methods

The number of steps per day over 1 week, as a measure of daily PA, was assessed annually in a cohort of patients with COPD. Exacerbation frequency and severity were documented. Uni- and multivariate mixed effect models were used to investigate associations between change in number of steps per day (dependent variable) and exacerbations. Stratification by possible confounders was performed.

Results

One hundred and eighty one COPD patients (median [quartile] age 64 [59/69] years, 65% male, median [quartiles] FEV₁ % pred. 46 [33/65]) suffered a total of 273 exacerbations during the observation period (median [quartiles] follow-up time of 2.1 [1.6/3.1] years). Neither the frequency nor the severity of exacerbations was significantly related to the overall decline in PA over time. Stratification by different possible confounders such as age, sex and disease severity did not yield a subgroup in which exacerbations enhance the decrease in PA over time.

Conclusion

The drop in PA during the phase of an acute exacerbation seems not to be a lasting phenomenon leading to a fundamental change in activity behavior.

Trial registration

www.ClinicalTrials.gov, NCT01527773

Obstructive Sleep Apnoea in Children and Adolescents with Ehlers-Danlos Syndrome

BACKGROUND

In Ehlers-Danlos syndrome (EDS), a group of monogenic disorders affecting connective tissues, obstructive sleep apnoea (OSA) is highly prevalent in adults. The prevalence of OSA in children with EDS is unknown.

OBJECTIVES

This prospective cross-sectional study aimed at determining the prevalence of OSA in paediatric EDS patients.

METHODS

Children with EDS (n = 24) were recruited from the Children's Hospital Zurich and matched to healthy controls. Participants completed home respiratory polygraphy and questionnaires (Sleep-Related Breathing Disorder Scale [SRBD], Epworth Sleepiness Scale [ESS], and Child Health Questionnaire [CHQ]). The American Academy of Sleep Medicine criteria were applied for OSA diagnosis (obstructive apnoea-hypopnoea index [oAHI] ≥1/h). Conditional logistic regression was used to compare the prevalence of OSA and to adjust for possible confounding.

RESULTS

OSA was found in 42% of paediatric EDS patients and in 13% of matched controls (OR = 4.5, 95% CI = 0.97-20.83, p = 0.054). The median oAHI was higher in EDS patients than in controls (0.77/h, IQR = 0.19-1.76, vs. 0.24/h, IQR = 0.0-0.60, p < 0.001 adjusted for age, sex, and BMI z-score). EDS patients had lower scores in most CHQ scales and higher SRBD and ESS scores than controls (0.26, IQR = 0.1-0.35, vs. 0.07, IQR = 0-0.19, p = 0.004); 7 ± 4 vs. 5 ± 4, p = 0.033, respectively).

CONCLUSION

OSA is a previously underestimated EDS-related complication increasing disease burden.

Guiding Ketogenic Diet with Breath Acetone Sensors

Ketogenic diet (KD; high fat, low carb) is a standard treatment for obesity, neurological diseases (e.g., refractory epilepsy) and a promising method for athletes to improve their endurance performance. Therein, the level of ketosis must be regulated tightly to ensure an effective therapy. Here, we introduce a compact and inexpensive breath sensor to monitor ketosis online and non-invasively. The sensor consists of Si-doped WO₃ nanoparticles that detect breath acetone selectively with non-linear response characteristics in the relevant range of 1 to 66 ppm, as identified by mass spectrometry. When tested on eleven subjects (five women and six men) undergoing a 36-h KD based on the Johns Hopkins protocol, this sensor clearly recognizes the onset and progression of ketosis. This is in good agreement to capillary blood β-hydroxybutyrate (BOHB) measurements. Despite similar dieting conditions, strong inter-subject differences in ketosis dynamics were observed and correctly identified by the sensor. These even included breath acetone patterns that could be linked to low tolerance to that diet. As a result, this portable breath sensor represents an easily applicable and reliable technology to monitor KD, possibly during medical treatment of epilepsy and weight loss.

Minimum important difference of the Epworth Sleepiness Scale in obstructive sleep apnoea: estimation from three randomised controlled trials

BACKGROUND

The Epworth Sleepiness Scale (ESS) is a widely used tool for assessing sleepiness in patients with obstructive sleep apnoea (OSA). We aimed to estimate the minimal important difference (MID) in patients with OSA.

METHODS

We used individual data from three randomised controlled trials (RCTs) in patients with OSA where the preintervention to postintervention change in ESS was used as a primary outcome. We used anchor-based linear regression and responder analysis approaches to estimate the MID. For anchors, we used the change in domains of the Functional Outcomes of Sleep Questionnaire and 36-Item Short Form Health Survey. We also used the distribution-based approaches Cohen's effect size, SE of measurement and empirical rule effect size to support the anchor-based estimates. The final MID was determined by triangulating all estimates to a single MID.

FINDINGS

A total of 639 patients with OSA were included in our analyses across the three RCTs with a median (IQR) baseline ESS score of 10 (6-13). The median (IQR) ESS change score overall was -2 (-5 to 1). The anchor-based estimates of the MID were between -1.74 and -4.21 points and estimates from the responder analysis were between -1 and -3 points. Distribution-based estimates were smaller, ranging from -1.46 to -2.36.

INTERPRETATION

We propose an MID for the ESS of 2 points in patients with OSA with a disease severity from mild to severe. This estimate provides the means to plan trials and interpret the clinical relevance of changes in ESS.

TRIAL REGISTRATION NUMBER

Provent, NCT01332175; autoCPAP trial, NCT00280800; MOSAIC,ISRCTN (3416388).

Lung volume reduction surgery does not increase daily physical activity in patients with severe chronic obstructive pulmonary disease

Background

Lung volume reduction surgery (LVRS) is a treatment option for selected patients with severe chronic obstructive pulmonary disease (COPD) and emphysema. The positive effects of LVRS on exercise capacity are well known. In contrast, the effect of LVRS on daily physical activity (PA) is less clear.

Methods

In a prospective case-control study we evaluated selected patients with severe COPD and emphysema who underwent LVRS and COPD patients following usual care. Controls were matched for age, severity of airflow obstruction (FEV₁) and hyperinflation [residual volume to total lung capacity (RV/TLC)]. Treatment effect of LVRS on activity parameters was analysed using univariable regression model adjusting for treatment group.

Results

A total of 19 patients underwent LVRS and 16 COPD patients without a surgical intervention during the study period were included. The median (quartile) FEV₁%_pred was 28% (range, 21-33%), RV/TLC was 69% (range, 64-73%) in cases while controls had a median (quartile) FEV₁%_pred of 33% (range, 28.5-49.5%) and a RV/TLC of 58% (range, 49-61%). Age and body mass index (BMI) were comparable between both groups. Number of steps per day following LVRS was comparable to before the intervention (mean change: -115, 95% CI: -994.6 to 764.3, P=0.779) and was not significantly different to the change in control subjects (mean treatment effect: 931.4, 95% CI: -252.4 to 2,115.1, P=0.117).

Conclusions

The results from this study reveal that patients undergoing LVRS did not increase their daily level of PA despite improvement of exercise capacity and symptoms.

Noninvasive Body Fat Burn Monitoring from Exhaled Acetone with Si-doped WO3-sensing Nanoparticles

Obesity is a global health threat on the rise, and its prevalence continues to grow. Yet suitable biomedical sensors to monitor body fat burn rates in situ, to guide physical activity or dietary interventions toward efficient weight loss, are missing. Here, we introduce a compact and inexpensive breath acetone sensor based on Si-doped WO₃ nanoparticles that can accurately follow body fat burn rates in real time. We tested this sensor on 20 volunteers during exercise and rest and measured their individual breath acetone concentrations in good agreement with benchtop proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS). During exercise, this sensor reveals clearly the onset and progression of increasing breath acetone levels that indicate intensified body fat metabolism, as validated by parallel venous blood β-hydroxybutyrate (BOHB) measurements. Most importantly, we found that the body fat metabolism was especially pronounced for most volunteers during fasting for 3 h after exercise, with strong variation between subjects, and this was displayed correctly by the sensor in real-time. As a result, this simple breath acetone sensor enables easily applicable and hand-held body fat burn monitoring for personalized and immediate feedback on workout effectiveness that can guide dieting as well.

Annual progression of endothelial dysfunction in patients with COPD

BACKGROUND

The risk to die from cardiovascular disease is particularly high in patients with COPD. This longitudinal study aims to evaluate changes of endothelial function over time and identify underlying mechanisms in COPD patients.

METHODS

In stable COPD patients we performed annual assessments of endothelial function by flow-mediated dilatation (FMD), lung function, systemic inflammation and cholesterol, sympathetic activation, oxygenation, physical activity and exercise capacity. Associations between annual changes of potential predictors and FMD were investigated in mixed analysis.

RESULTS

76 patients (41% GOLD stage 1/2, 30% 3, 29% 4) were included. Endothelial function significantly decreased annually by -0.14% (95%CI -0.25/-0.04), equal to a relative decrease of -5.6%. Yearly change in 6-min walking distance was significantly associated with FMD in univariable analysis (Coef. -0.00, p = 0.045). Progressive airway obstruction and increase in level of total cholesterol were borderline significant with a greater decrease in FMD (Coeff. -0.02, p = 0.097 and Coeff. -0.16, p = 0.080, respectively). In multivariable analysis a greater annual decline in FEV1 tends to be independently associated with a decrease in FMD (p = 0.085).

CONCLUSION

The findings of this study demonstrated that COPD patients experience a significant decrease in endothelial function over time. A greater annual decline in lung function tends to be associated with greater decrease in FMD. However, no other independent predictors for endothelial dysfunction could be identified.

CLINICAL TRIAL REGISTRATION

www.ClinicalTrials.gov, NCT01527773.

Accelerometer- versus questionnaire-based assessment of physical activity and their changes over time in patients with COPD

Background and objective

Physical activity (PA) is an important outcome parameter in patients with COPD regarding hospitalizations and mortality. Both objective assessment by accelerometers and self-evaluation by questionnaires were used in studies investigating PA in COPD. Whether self-reported questionnaires can adequately reflect PA and its changes over time compared to objective assessments has not been thoroughly investigated in COPD. In this COPD cohort study, we evaluated whether PA measured by accelerometer and its annual changes can also be assessed by self-reported questionnaires.

Methods

In 178 COPD patients with at least two assessments of PA, the agreement between objectively measured and self-reported activity was analyzed by Bland–Altman plots. Daily PA was assessed by a triaxial activity monitor over 1 week and by the self-reported German PA questionnaire 50+.

Results

Comparison between the two methods of measurement revealed no convincing agreement with a mean difference and limits of agreement (±1.96 standard deviation [SD]) of time spent in at least moderate PA (>3 metabolic equivalent of task [MET]) of −77.6 (−340.3/185.2) min/day, indicating a self-reported overestimation of PA by the questionnaire. The mean difference and limits of agreement (±1.96SD) in the annual change of PA was 1.2 min/day (−208.2/282.6 min/day), showing also a poor agreement on an individual level.

Conclusion

Evaluation of objectively measured and self-reported PA and their annual changes revealed no agreement in patients with COPD. Therefore, the evaluated questionnaire seems not helpful for measurement of PA and its changes over time.

Prevalence and Risk Factors of Sleep Disordered Breathing in Fabry disease: A Prospective Cohort Study

Excessive daytime sleepiness (EDS) is a frequently reported and not well-understood symptom in patients with Fabry disease (FD). Sleep-disordered breathing (SDB) is a possible factor. As deposition of glycosphingolipids in the upper airway muscles is likely, we hypothesized that obstructive sleep apnoea (OSA) is highly prevalent in FD and positively associated with its severity.All patients with FD who are followed in the Fabry cohort of the University Hospital Zurich (n = 62) were asked to participate in this prospective cohort study. Eligible patients were prospectively investigated by assessing their daytime sleepiness using the Epworth Sleepiness Scale (ESS), the severity of FD using the Mainz Severity Score Index (MSSI), and by an ambulatory overnight respiratory polygraphy between November 1, 2013, and January 31, 2015. SDB was defined as an apnea/hypopnea index (AHI) of > 5/h.Fifty-two patients (mean ± SD age 42.8 ± 14.7 years, 33% men, mean ± SD BMI 23.4 ± 3.6 kg/m) with a median (IQR) MSSI of 12 (5-19) were included. Median (IQR) ESS was 6 (2-10) and 7 patients (14%) had an ESS > 10. Thirteen patients (25%) had SDB (78% obstructive sleep apnea, 22% central sleep apnea). In the multivariable analysis, the age was the only statistically significant predictor of SDB (OR 1.11, 95% CI 1.04-1.18, P = 0.001). ESS was associated with depression (P < 0.001) but not AHI nor age.This study shows that SDB, especially obstructive sleep apnea is highly prevalent in patients with Fabry disease. However, EDS in FD seems to be related with depression rather than SDB.ClinicalTrials.gov (identifier: NCT01947634).

Lung Volume Reduction Surgery and Improvement of Endothelial Function and Blood Pressure in Patients with Chronic Obstructive Pulmonary Disease. A Randomized Controlled Trial

RATIONALE

Cardiovascular disease is a major cause of morbidity and mortality in patients with chronic obstructive pulmonary disease (COPD). Preliminary studies have shown that both airflow obstruction and systemic inflammation may contribute to endothelial dysfunction in COPD. Lung volume reduction surgery (LVRS) is a treatment option in selected patients with COPD with emphysema that improves breathing mechanics and lung function.

OBJECTIVES

To determine the effect of LVRS on endothelial function and systemic inflammation.

METHODS

We conducted a randomized controlled trial in 30 patients scheduled for LVRS. In the intervention group, immediate LVRS was performed after baseline evaluation followed by reassessment 3 months later. In the control group, reassessment followed 3 months after baseline evaluation, and thereafter LVRS was performed.

MEASUREMENTS AND MAIN RESULTS

The primary outcome measures were the treatment effect on endothelial function and systemic inflammation. In the LVRS group 14 patients completed the trial and 13 in the control group. LVRS led to a relative reduction in mean (SD) residual volume/total lung capacity of -12% (12%) and an increase in FEV1 of 29% (27%). Flow-mediated dilatation of the brachial artery increased in the intervention group as compared with the control group (+2.9%; 95% confidence interval, +2.1 to +3.6%; P < 0.001), whereas there was no significant change in systemic inflammation. A significant treatment effect on mean blood pressure was observed (-9.0 mm Hg; 95% confidence interval, -17.5 to -0.5; P = 0.039).

CONCLUSIONS

Endothelial function and blood pressure are improved 3 months after LVRS in patients with severe COPD and emphysema. LVRS may therefore have beneficial effects on cardiovascular outcomes. Clinical trial registered with www.clinicaltrials.gov (NCT 01020344).

Physical inactivity and arterial stiffness in COPD

BACKGROUND

Arterial stiffness is an important predictor of cardiovascular risk besides classic cardiovascular risk factors. Previous studies showed that arterial stiffness is increased in patients with COPD compared to healthy controls and exercise training may reduce arterial stiffness. Since physical inactivity is frequently observed in patients with COPD and exercise training may improve arterial stiffness, we hypothesized that low daily physical activity may be associated with increased arterial stiffness.

METHODS

In 123 patients with COPD (72% men; mean [standard deviation] age: 62 [7.5] years; median [quartile] forced expiratory volume in 1 second 35 [27/65] %predicted), arterial stiffness was assessed by augmentation index (AI). Daily physical activity level (PAL) was measured by an activity monitor (SenseWear Pro™) >1 week. The association between AI and PAL was investigated by univariate and multivariate regression analysis, taking into account disease-specific characteristics and comorbidities.

RESULTS

Patients suffered from moderate (35%), severe (32%), and very severe (33%) COPD, and 22% were active smokers. Median (quartile) PAL was 1.4 (1.3/1.5) and mean (standard deviation) AI 26% (9.2%). PAL showed a negative association with AI (B=-9.32, P=0.017) independent of age, sex, blood pressure, and airflow limitation.

CONCLUSION

In COPD patients, a higher PAL seems to favorably influence arterial stiffness and therefore may reduce cardiovascular risk.

CLINICAL TRIAL REGISTRATION

http://www.ClinicalTrials.gov, NCT01527773.

Coronary artery calcification, epicardial fat burden, and cardiovascular events in chronic obstructive pulmonary disease

RATIONALE

Patients with chronic obstructive pulmonary disease (COPD) suffer from significantly more cardiovascular comorbidity and mortality than would be anticipated from conventional risk factors. The aim of this study was to determine whether COPD patients have a higher coronary artery calcium score (CACS) and epicardial fat burden, compared to control subjects, and their association with cardiovascular events.

METHODS

From a registry of 1906 patients 81 patients with clinically diagnosed COPD were one-to-one matched to 81 non-COPD control subjects with a smoking history, according to their age, sex, and the number of classic cardiovascular risk factors (arterial hypertension, diabetes mellitus, dyslipidemia, family history of premature coronary artery disease). CACS, epicardial fat, and subsequent major adverse cardiovascular events (MACE) during follow-up were compared between groups.

RESULTS

Patients with COPD (Global Initiative for Chronic Obstructive Lung Disease-classification I: 5%, II: 23%, III: 16% and IV: 56%) showed no difference in CACS (median difference 68 Agatston Units [95% confidence interval -176.5 to 192.5], p=0.899) or epicardial fat volume (mean difference -0.5 cm3 [95% confidence interval -20.9 to 21.9], p=0.961) compared with controls. After a median follow-up of 42.6 months a higher incidence of MACE was observed in COPD patients (RR=2.80, p=0.016) compared with controls. Cox proportional hazard regression identified cardiac ischemias and CACS as independent predictors for MACE.

CONCLUSION

COPD patients experienced a higher MACE incidence compared to controls despite no baseline differences in coronary calcification and epicardial fat burden. Other mechanisms such as undersupply of medication seem to account for an excess cardiovascular comorbidity in COPD patients.

Impact of comorbidities on physical activity in COPD

BACKGROUND AND OBJECTIVE

Both comorbidities and physical inactivity have been shown to impair quality of life and contribute to hospital admissions and mortality in chronic obstructive pulmonary disease (COPD) patients. We hypothesized that the comorbid status predicts the level of daily physical activity (PA) in COPD.

METHODS

In 228 patients with COPD (76% men; median (quartiles) age: 64 (59/69) years; percentage of predicted forced expiratory volume in 1 s (FEV1 % pred): 44 (31/63)), comorbidities were assessed by medical history, clinical interviews, examination and blood analysis. PA level (PAL) was measured by an activity monitor (SenseWear Pro, Bodymedia Inc., Pittsburgh, PA, USA). The association between PAL and comorbidities was investigated by univariate and multivariate regression analysis.

RESULTS

Seventy-nine percent of the COPD patients had at least one additional chronic comorbidity, 56% had two or more comorbidities and 35% had three or more comorbidities. In univariate analysis body mass index, the number of pack years and having at least one additional comorbidity was negatively associated with PAL while there was a positive nonlinear association between FEV1 and PAL. The presence of at least one additional comorbidity was independently associated with PAL irrespective of airflow limitation.

CONCLUSIONS

In this cohort, almost 80% of COPD patients had at least one additional chronic comorbidity. The level of daily PA seems to be significantly impaired by the presence of comorbidities irrespective of the type of comorbidity and independent of the degree of airflow limitation.

CLINICAL TRIAL REGISTRATION

NCT01527773 at http://www.clinicalTrials.gov.

Association between peripheral muscle strength, exercise performance, and physical activity in daily life in patients with Chronic Obstructive Pulmonary Disease

Background: Resistance training of peripheral muscles has been recommended in order to increase muscle strength in patients with Chronic Obstructive Pulmonary Disease (COPD). However, whether peripheral muscle strength is associated with exercise performance (EP) and physical activity in daily life (PADL) in these patients needs to be investigated. The aim of this study is to evaluate whether strength of the quadriceps muscle (QS) is associated with EP and daily PADL in patients with COPD. Methods: We studied patients with COPD (GOLD A-D) and measured maximal isometric strength of the left QS. PADL was measured for 7 days with a SenseWear-Pro® accelerometer. EP was quantified by the 6-minute walk distance (6MWD), the number of stands in the Sit-to-Stand Test (STST), and the handgrip-strength. Univariate and multivariate analyses were used to examine possible associations between QS, PADL and EP. Results: In 27 patients with COPD with a mean (SD) FEV1 of 37.6 (17.6)% predicted, QS was associated with 6MWD, STST, and handgrip-strength but not with PADL. Multiple linear regression analyses showed that QS was independently associated with the 6MWD (β = 0.42, 95% CI 0.09 to 0.84, p = 0.019), STST (β = 0.50, 95% CI 0.11 to 0.86, p = 0.014) and with handgrip-strength (β = 0.45, 95% CI 0.05 to 0.84, p = 0.038). Conclusions: Peripheral muscle strength may be associated with exercise performance but not with physical activity in daily life. This may be due to the fact that EP tests evaluate patients’ true abilities while PADL accelerometers may not.

Association between peripheral muscle strength, exercise performance, and physical activity in daily life in patients with Chronic Obstructive Pulmonary Disease

BACKGROUND

Resistance training of peripheral muscles has been recommended in order to increase muscle strength in patients with Chronic Obstructive Pulmonary Disease (COPD). However, whether peripheral muscle strength is associated with exercise performance (EP) and physical activity in daily life (PADL) in these patients needs to be investigated. The aim of this study is to evaluate whether strength of the quadriceps muscle (QS) is associated with EP and daily PADL in patients with COPD.

METHODS

We studied patients with COPD (GOLD A-D) and measured maximal isometric strength of the left QS. PADL was measured for 7 days with a SenseWear-Pro® accelerometer. EP was quantified by the 6-minute walk distance (6MWD), the number of stands in the Sit-to-Stand Test (STST), and the handgrip-strength. Univariate and multivariate analyses were used to examine possible associations between QS, PADL and EP.

RESULTS

In 27 patients with COPD with a mean (SD) FEV1 of 37.6 (17.6)% predicted, QS was associated with 6MWD, STST, and handgrip-strength but not with PADL. Multiple linear regression analyses showed that QS was independently associated with the 6MWD (β = 0.42, 95% CI 0.09 to 0.84, p = 0.019), STST (β = 0.50, 95% CI 0.11 to 0.86, p = 0.014) and with handgrip-strength (β = 0.45, 95% CI 0.05 to 0.84, p = 0.038).

CONCLUSIONS

Peripheral muscle strength may be associated with exercise performance but not with physical activity in daily life. This may be due to the fact that EP tests evaluate patients' true abilities while PADL accelerometers may not.

High prevalence of altered cardiac repolarization in patients with COPD

BACKGROUND

Altered cardiac repolarization and increased dispersion of repolarization have been identified as risk factors for sudden cardiac death (SCD). The prevalence of and the mechanisms contributing to altered cardiac repolarization are currently unknown in COPD.

METHODS

In 91 COPD patients, 32 controls matched for age, cardiovascular risk and medication, and 41 healthy subjects, measures of cardiac repolarization and dispersion of repolarization (QTc interval, QT dispersion) were derived from 12-lead electrocardiography (ECG). Prevalence rates of heart rate corrected QT (QTc) >450ms and QT dispersion >60ms were determined to assess the number of subjects at risk for SCD. Univariate and multivariate analyses were used to identify possible factors contributing to altered cardiac repolarization.

RESULTS

QTc was found to be prolonged in 31.9% and QT dispersion in 24.2% of the COPD patients compared to 12.5% in matched controls and 0% in healthy subjects. The QTc interval was longer in COPD patients compared to matched and healthy controls respectively (437.9 ± 29.5 vs. 420.1 ± 25.3 ms, p = 0.001 and vs. 413.4 ± 18.2 ms, p < 0.001). QT dispersion was significantly increased in COPD patients compared to healthy subjects (45.4 (34.8 , 59.5) vs. 39.7 (29.3 , 54.8) ms, p = 0.049). Only oxygen saturation was independently associated with QTc duration in multivariate analysis (β = -0.29, p = 0.015).

CONCLUSION

One third of a typical COPD population has altered cardiac repolarization and increased dispersion of repolarization, which may be related to hypoxia. Altered cardiac repolarization may expose these patients to an increased risk for malignant ventricular arrhythmias and SCD.