Physical activity declines in COPD while exercise capacity remains stable: A longitudinal study over 5 years

Beyond pulmonary rehabilitation: can the PICk UP programme fill the gap? A randomised trial in COPD

INTRODUCTION AND OBJECTIVES

Pulmonary rehabilitation (PR) is a fundamental intervention to manage COPD, however, maintaining its benefits is challenging. Engaging in physical activity might help to prolong PR benefits. This study assessed the efficacy and effectiveness of a personalised community-based physical activity programme to sustain physical activity and other health-related PR benefits, in people with COPD.

MATERIALS AND METHODS

This was a multicentre, assessor blinded, randomised controlled trial. Following 12-weeks of PR, people with COPD were assigned to a six-months personalised community-based physical activity programme (experimental group), or to standard care (control group). Physical activity was assessed via: time spent in moderate to vigorous physical activities per day (primary outcome measure), steps/day and the brief physical activity assessment tool. Secondary outcomes included sedentary behaviour, functional status, peripheral muscle strength, balance, symptoms, emotional state, health-related quality of life, exacerbations and healthcare utilization. Assessments were performed immediately post-PR and after three- and six-months. Efficacy and effectiveness were evaluated using intention-to-treat and per-protocol analysis with linear mixed models.

RESULTS

Sixty-one participants (experimental group: n = 32; control group: n = 29), with balanced baseline characteristics between groups (69.6 ± 8.5 years old, 84 % male, FEV1 57.1 ± 16.7 %predicted) were included. Changes in all physical activity outcomes and in one-minute sit-to-stand were significantly different (P < 0.05) between groups at the six-month follow-up. In the remaining outcomes there were no differences between groups.

CONCLUSIONS

The community-based physical activity programme resulted in better physical activity levels and sit-to-stand performance, six-months after completing PR, in COPD. No additional benefits were observed for other secondary outcomes.

Olfactory decline develops in parallel with frailty in older US adults with obstructive lung diseases

BACKGROUND

Frailty is prevalent among older adults with asthma or chronic obstructive pulmonary disease (obstructive lung diseases [OLDs]). Frailty and OLD's co-occurrence is associated with increased hospitalization/mortality. Chemosensory dysfunction is closely connected to both OLD and frailty. We evaluated the utility of olfactory decline as a biomarker of frailty in the setting of OLD.

METHODS

We performed a prospective, longitudinal, nationally representative study of community-dwelling older US adults in the National Social Life, Health and Aging Project, an omnibus in-home survey. Respondents reported a physician's diagnosis of OLD. Decline in odor identification and sensitivity over 5 years and frailty (adapted fried frailty phenotype criteria) were measured using standard tools. Multivariate logistic regressions evaluated the association between OLD status, olfactory decline, and frailty.

RESULTS

We compared individuals with OLD (n = 98; mean age 71.2 years, 59.2% women) and those without OLD (n = 1036; mean age 69.5 years, 58.9% women). Olfactory identification decline was associated with developing frailty over the 5-year follow-up period in individuals with OLD (odds ratio [OR] = 9.1, 95% confidence interval [CI] = 2.1-38.6, p = 0.003). Olfactory decline predicted incidence of frailty in individuals with OLD (identification: OR = 4.8, 95% CI = 1.3-17.5, P = 0.018; sensitivity: OR = 6.1, 95%CI = 1.2-31.0, p = 0.030) but not in those without OLD adjusting for demographics, heavy alcohol use, current smoking, and comorbidity. Results were robust to different thresholds for olfactory decline and frailty development.

CONCLUSIONS

Older adults with OLD who experience olfactory decline face higher odds of developing frailty. Use of olfactory decline as a biomarker to identify frailty could allow earlier intervention and decrease adverse outcomes for high-risk older adults with OLD.

Longitudinal changes in habitual physical activity in adult people with cystic fibrosis in the presence or absence of treatment with elexacaftor/tezacaftor/ivacaftor

Background

Habitual physical activity (PA) and exercise training are accepted as important aspects of care for people with cystic fibrosis (pwCF) to improve health-related measures of physical fitness, which in turn have a positive impact on quality of life and prognosis. In the last decade, effective CFTR modulator therapies have become a promising treatment for pwCF by targeting the underlying cause of CF. This highly effective therapy improves clinical outcomes and quality of life in people with specific CFTR mutations. Little is known about the longitudinal pattern of PA or the impact of the highly effective modulator therapy with Elexacaftor/Tezacaftor/Ivacaftor (ETI) on PA in adult pwCF. This study assessed the course of device-based PA measurement in adult pwCF and evaluated the effects of ETI on habitual physical activity in those who were eligible for ETI.

Methods

Data from adult pwCF (aged ≥18 years) were analysed at baseline and follow-up, using identical assessments at both time points. Outcome parameters were PA in steps/day and the intensity of PA. The group that received ETI was treated for an average of 33 weeks and not for the entire duration of the period. The data were collected between 2021 and 2022, following the removal of absolute pandemic restrictions/lockdowns.

Results

Follow-up duration was 5.6 years in pwCF with ETI (ETI group, n = 21) and 6.5 years in pwCF without ETI (non-ETI group, n = 6). From baseline to follow-up, pwCF treated with ETI had a significant increase in steps/day (+25%, p = 0.019) and a non-significant increase in moderate-to-vigorous intensity time (+5.6%, p = 0.352). Conversely, individuals in the non-ETI group showed a non-significant decrease in both steps/day -3.2%, p = 0.893) and moderate-to-vigorous intensity time (-25%, p = 0.207). The ETI group showed a significant decrease in percent predicted forced expiratory volume in 1 s (ppFEV1) and FEV1 z-score before the start of ETI treatment, both of which improved significantly after therapy initiation. Body weight and body mass index also improved significantly with ETI use.

Conclusions

These data suggest that ETI treatment has a positive effect on habitual physical activity behavior in the adult pwCF studied.

Physical activity in idiopathic pulmonary fibrosis: Longitudinal change and minimal clinically important difference

BACKGROUND AND OBJECTIVE

Reference values of physical activity to interpret longitudinal changes are not available in patients with idiopathic pulmonary fibrosis (IPF). This study aimed to define the minimal clinical important difference (MCID) of longitudinal changes in physical activity in patients with IPF.

METHODS

Using accelerometry, physical activity (steps per day) was measured and compared at baseline and 6-months follow-up in patients with IPF. We calculated MCID of daily step count using multiple anchor-based and distribution-based methods. Forced vital capacity and 6-minute walk distance were applied as anchors in anchor-based methods. Effect size and standard error of measurement were used to calculate MCID in distribution-based methods.

RESULTS

One-hundred and five patients were enrolled in the study (mean age: 68.5 ± 7.5 years). Step count significantly decreased from baseline to 6-months follow-up (-461 ± 2402, p = .031). MCID calculated by anchor-based and distribution-based methods ranged from 570-1358 steps.

CONCLUSION

Daily step count significantly declined over 6-months in patients with IPF. MCID calculated by multiple anchor-based and distribution-based methods was 570 to 1358 steps/day. These findings contribute to interpretation of the longitudinal changes of physical activity that will assist its use as a clinical and research outcome in patients with IPF.

Physical activity and chronic obstructive pulmonary disease: a scoping review

Background

Reduced physical activity (PA) was the strongest predictor of all-cause mortality in patients with chronic obstructive pulmonary disease (COPD). This scoping review aimed to map the evidence on the current landscape of physical activity, barriers and facilitators, and assessment tools across COPD patients.

Methods

Arksey and O’Malley’s scoping review methodology framework guided the conduct of this review. An electronic search was conducted on five English databases (PubMed, Cochrane Library, PsycINFO, CINAHL and Web of Science) and three Chinese databases (CNKI, CQVIP and WAN-FANG) in January 2022. Two authors independently screened the literature, extracted the studies characteristics.

Results

The initial search yielded 4389 results, of which 1954 were duplicates. Of the remaining 135 articles, 42 studies met the inclusion criteria. Among the reviewed articles, there were 14 (33.3%) cross-sectional study, 9 (21.4%) cohort study, 4 (9.5%) longitudinal study, 3 qualitative study, 12 (28.7%) randomized control trials. The main barriers identified were older age, women, lung function, comorbidities, COPD symptoms (fear of breathlessness and injury, severe fatigue, anxiety and depression), GOLD stage, frequency of exacerbation, oxygen use, lack of motivation and environment-related (e.g., season and weather). Twelve studies have evaluated the effects of physical exercise (e.g., walking training, pulmonary rehabilitation (PR), pedometer, self-efficacy enhancing intervention and behavioral modification intervention) on PA and showed significant positive effects on the prognosis of patients. However, in real life it is difficult to maintain PA in people with COPD.

Conclusions

Changing PA behavior in patients with COPD requires multidisciplinary collaboration. Future studies need to identify the best instruments to measure physical activity in clinical practice. Future studies should focus on the effects of different types, time and intensity of PA in people with COPD and conduct randomized, adequately-powered, controlled trials to evaluate the long-term effectiveness of behavioral change interventions in PA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02099-4.

Experience of physical activity in patients with COPD: A systematic review and qualitative meta-synthesis

OBJECTIVE

To systematically evaluate and integrate the qualitative research on physical activity (PA) experience of patients with chronic obstructive pulmonary disease (COPD).

METHODS

Web of Science, Cochrane Library, Embase, CINAHL and other databases were searched, and the qualitative research on PA experience of patients with COPD was collected. The systematic review was conducted in line with Joanna Briggs Institute (JBI) methodology for systematic reviews of qualitative evidence.

RESULTS

12 studies were included and 3 themes were summarized, included: COPD patients experience more barriers while participating in physical activities than facilitators; COPD patients experience more positive effects post-physical activities than negative effects; Guaranteeing safety, goal setting, and establishing a professional support group improve compliance in COPD patients.

CONCLUSION

Health care professionals should help patients overcome the obstacles of PA, pay attention to the PA experience of patients, adopt diversified PA methods, improve PA participation and compliance, and make patients develop good PA habits.

"Can Do, Do Do" Quadrants and 6-Year All-Cause Mortality in Patients With COPD

BACKGROUND

Physical capacity (PC; "can do") and physical activity (PA; "do do") are prognostic indicators in COPD and can be used to subdivide patients with COPD into four exclusive subgroups (the so-called "can do, do do" quadrants). This concept may be useful to understand better the impact of PC and PA on all-cause mortality in patients with COPD.

RESEARCH QUESTION

What is the 6-year all-cause mortality risk of the "can do, do do" quadrants of patients with COPD?

STUDY DESIGN AND METHODS

This retrospective study used data from patients with COPD who underwent a comprehensive assessment at their first-ever outpatient consultation. PC was assessed using the 6-min walk distance and physical activity was assessed using an accelerometer (steps per day). All-cause mortality data were obtained from the Municipal Personal Records Database. Receiver operating characteristic curves were used to determine threshold values for PC and PA to predict 6-year all-cause mortality. Using the derived threshold values, male and female patients were divided into the four "can do, do do" quadrants.

RESULTS

Data from 829 patients were used for analyses. Best discriminatory values for 6-year mortality were 404 m and 4,125 steps/day for men and 394 m and 4,005 steps/day for women. During a median follow-up of 55 months (interquartile range, 37-71 months), 129 patients (15.6%) died. After controlling for established prognostic factors, patients in the "can do, don't do" quadrant and "can do, do do" quadrant showed significantly lower mortality risk compared with patients in the "can't do, don't do" quadrant: hazard ratios of 0.36 (95% CI, 0.14-0.93) and 0.24 (95% CI, 0.09-0.61) for men and 0.37 (95% CI, 0.38-0.99) and 0.29 (95% CI, 0.10-0.87) for women, respectively. No significant differences were found between the "can't do, do do" and "can't do, don't do" quadrants.

INTERPRETATION

Patients with COPD with a preserved PC seem to have a significantly lower 6-year mortality risk compared with patients with a decreased PC, regardless of physical activity level.

The Association of Health-Related Factors with Leisure-Time Physical Activity among Adults with COPD: A Cross-Sectional Analysis

This study aimed to examine the association of health attitudes, health appraisals and affective experience to leisure-time physical activity in adults with chronic obstructive pulmonary disease (COPD). Cross-sectional analyses were conducted with a sample of 274 adults with COPD drawn from the second wave of the Midlife in the United States (MIDUS 2) Study. Chi-square analyses and independent t-tests were used to test the differences between physically active and inactive COPD patients (active group versus inactive group) for all study variables. Multiple logistic regression was used to examine the association of each study variable with leisure-time physical activity. The results showed that there were significant differences between the active and inactive groups in terms of age, education, functional limitations, health attitudes, health appraisals and affective experience. After controlling for socio-demographic variables and functional limitations, beliefs about the importance of physical fitness and strength for a good life and comparative health appraisals were significantly related to physical activity. However, neither negative nor positive affect was associated with physical activity status. Modifiable factors, such as health attitudes toward physical fitness and strength, as well as health appraisals, should be considered for developing effective physical activity promotion interventions among COPD patients.

Exacerbations and Changes in Physical Activity and Sedentary Behaviour in Patients with Bronchiectasis after 1 Year

Background: Low physical activity and high sedentary behaviour in patients with bronchiectasis are associated with hospitalisation over one year. However, the factors associated with longitudinal changes in physical activity and sedentary behaviour have not been explored. We aimed to identify clinical and sociodemographic characteristics related to a change in physical activity and sedentary behaviour in patients with bronchiectasis after one year. Methods: This was a prospective observational study during which physical activity measurements were recorded using a SenseWear Armband for one week at baseline and at one year. At each assessment point, patients were classified as active or inactive (measured as steps per day) and as sedentary or not sedentary (measured as sedentary time). Results: 53 patients with bronchiectasis were analysed, and after one year, 18 (34%) had worse activity and sedentary levels. Specifically, 10 patients became inactive and sedentary. Multivariable analysis showed that the number of exacerbations during the follow-up period was the only outcome independently associated with change to higher inactivity and sedentary behaviour (odds ratio (OR), 2.19; 95% CI, 1.12 to 4.28). Conclusions: The number of exacerbations in patients with bronchiectasis was associated with changes in physical activity and sedentary behaviour. Exacerbation prevention may appear as a key factor in relation to physical activity and sedentary behaviour in patients with bronchiectasis.

Effectiveness of Non-Presential Individualized Exercise Training PrOgram(NIETO) in Lower Limb Physical Performance in Advanced COPD

Muscle training, a component of pulmonary rehabilitation (PR), improves the physical performance of patients with chronic obstructive pulmonary disease (COPD). Despite the existing evidence, the traditional center-based PR model is applied to a small percentage of patients and presents numerous problems of accessibility, adherence, and costs. This study presents a home model of simple muscle training, non-presential, monitored by telephone and individualized, according to the severity of the COPD. In addition, to evaluate the results, simple tests associated with the physical performance of the lower limbs, previously validated in COPD, have been used, such as the four-meter walk, speed test (4MGS) and the five-repetition test sitting and standing (5STS). The objective was to evaluate whether the Individualized Non-Presential Exercise Training PrOgram (NIETO) induces improvements in the 4MGS, 5STS and quadriceps muscle strength (QMS) tests in outpatients with advanced COPD (FEV1 ≤ 50%). After one year, the QMS was significantly higher in the intervention group (IG) than in the control group (CG) (2.44 ± 4.07 vs. 0.05 ± 4.26 kg; p = 0.009). The 4MGS and 5STS tests were significantly shorter in IG than in CG (−0.39 ± 0.86 vs. 0.37 ± 0.96 s; p = 0.001) and (−1.55 ± 2.83 vs. 0.60 ± 2.06 s; p = 0.001), respectively. A home model of simple muscle training monitored by telephone such as NIETO, can improve 4MGS, 5STS, and quadriceps strength tests in outpatients with advanced COPD.

Influence of Lung Hyperinflation on Respiratory Muscles Pressures During a Submaximal Test in Patients With COPD: A Clinical Perspective

Background and Objective:

Reduction of exercise tolerance is associated with expiratory flow-limitation (EFL) and lung hyperinflation; those are only partially reversible to bronchodilator. Lung hyperinflation lowers the diaphragm muscle provoking a mechanical disadvantage that, eventually, reduces maximal inspiratory (MIP) and expiratory (MEP) pressures. We aimed to assess the influence of the dynamic lung hyperinflation on respiratory pressures changes at rest and after a submaximal exercise test in COPD patients with and without a bronchodilator.

Methods::

We prospectively analyzed 16 COPD patients (FEV1 36.4±10% pred.; age 61.0±8 years, height 165±12 cm and BMI 25.9±6 kg/m2). MIP and MEP were measured before and after performing the six minutes walking test (6MWT) with and without bronchodilator (400 mcg of albuterol).

Results::

Nine of 16 patients increased IC more than 150 ml after bronchodilator use. Right after the 6MWT was accomplished without bronchodilator, IC decreased by 7.05% as compared to the 6MWT baseline value (p<0.01). Nine patients decreased IC more than 150ml. After bronchodilator use, patients performed the 6MWT without any IC significant reduction (p>0.05). Twelve patients increased the MIP (ranging from 70±11cmH2O to 77±10cmH2O, p = 0.0043) using 400mcg of albuterol. Thirteen patients reduced MIP after the 6MWT without bronchodilator use (p <0.007). There was no significant reduction (p> 0.05) in MIP when patients performed the 6MWT after bronchodilator use. We also found a significant correlation between MIP and inspiratory capacity (IC) and MEP and the IC before and after the 6MWT (r=0.61, p=0.0054; r=0.60, p=0.0031, respectively).

Conclusions::

Dynamic pulmonary hyperinflation directly interferes with the ability of respiratory muscles to generate inspiratory and expiratory pressures. The previous use of bronchodilators in patients with COPD reduced dynamic hyperinflation when accomplishing a sub-maximal exercise.

Patterns of Physical Activity Progression in Patients With COPD

INTRODUCTION

Although mean physical activity in COPD patients declines by 400-500steps/day annually, it is unknown whether the natural progression is the same for all patients. We aimed to identify distinct physical activity progression patterns using a hypothesis-free approach and to assess their determinants.

METHODS

We pooled data from two cohorts (usual care arm of Urban Training [NCT01897298] and PROactive initial validation [NCT01388218] studies) measuring physical activity at baseline and 12 months (Dynaport MoveMonitor). We identified clusters (patterns) of physical activity progression (based on levels and changes of steps/day) using k-means, and compared baseline sociodemographic, interpersonal, environmental, clinical and psychological characteristics across patterns.

RESULTS

In 291 COPD patients (mean±SD 68±8 years, 81% male, FEV₁ 59±19%_pred) we identified three distinct physical activity progression patterns: Inactive (n=173 [59%], baseline: 4621±1757 steps/day, 12-month change (Δ): -487±1201 steps/day), ActiveImprovers (n=49 [17%], baseline: 7727±3275 steps/day, Δ:+3378±2203 steps/day) and ActiveDecliners (n=69 [24%], baseline: 11 267±3009 steps/day, Δ: -2217±2085 steps/day). After adjustment in a mixed multinomial logistic regression model using Active Decliners as reference pattern, a lower 6-min walking distance (RRR [95% CI] 0.94 [0.90-0.98] per 10m, P=.001) and a higher mMRC dyspnea score (1.71 [1.12-2.60] per 1 point, P=.012) were independently related with being Inactive. No baseline variable was independently associated with being an Active Improver.

CONCLUSIONS

The natural progression in physical activity over time in COPD patients is heterogeneous. While Inactive patients relate to worse scores for clinical COPD characteristics, Active Improvers and Decliners cannot be predicted at baseline.

Patterns and predictors of low physical activity in patients with stable COPD: a longitudinal study

Background:

Despite the frequency and negative impact of low physical activity among patients with chronic obstructive pulmonary disease (COPD), little is known about how it persists and remits over time or the factors predicting new states of low physical activity. The aim of the study was to determine the probability of a transition between states of low and nonlow physical activity in a cohort of patients with stable COPD followed for 2 years. We also investigated different potentially modifiable factors to determine whether they can predict new states of low physical activity.

Methods:

We prospectively included 137 patients with stable COPD (mean age 66.9 ± 8.3 years). Physical activity was measured at baseline and at 1 and 2 years of follow up. Low physical activity was defined according to energy expenditure by cut-off points from the Fried frailty model. The likelihood of annual transition towards new states and recovery was calculated. We evaluated demographic, frailty, nonrespiratory, and respiratory variables as potential predictors, using generalized estimating equations.

Results:

At baseline, 37 patients (27%) presented with low physical activity. During the study period, a total of 179 annual transitions were identified with nonlow physical activity at the beginning of the year; 17.5% transitioned to low physical activity. In contrast, 34.3% of the 67 transitions that started with low physical activity recovered. Predictors of transition to new states of low physical activity were dyspnea ⩾2 (odds ratio = 3.21; 95% confidence interval: 1.20–8.61) and poor performance on the five sit-to-stand test (odds ratio = 4.75; 95% confidence interval: 1.30–17.47).

Conclusions:

The change between levels of low and nonlow physical activity is dynamic, especially for recovery. Annual transitions toward new states of low physical activity are likely among patients with dyspnea or poor performance on the five sit-to-stand test.

The reviews of this paper are available via the supplemental material section.

"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.

Long-term effects of web-based pedometer-mediated intervention on COPD exacerbations

BACKGROUND

Technology-based physical activity (PA) interventions have been shown to improve daily step counts and health-related quality of life, but their effect on long-term clinical outcomes like acute exacerbations (AEs) is unknown in persons with COPD.

METHODS

U.S. Veterans with stable COPD were randomized (1:1) to either pedometer alone (control) or pedometer plus a website with feedback, goal-setting, disease education, and a community forum (intervention) for 3 months. AEs were assessed every 3 months over a follow-up period of approximately 15 months. Pedometer-assessed daily step counts, health-related quality-of-life (HRQL), and self-efficacy were assessed at baseline, end-of-intervention at 3 months, and during follow-up approximately 6 and 12 months after enrollment. Zero-inflated Poisson models assessed the effect of the intervention on risk for AEs, compared to controls. Generalized linear mixed-effects models for repeated measures examined between-group and within-group changes in daily step count, HRQL, and self-efficacy.

RESULTS

There were no significant differences in age, FEV₁% predicted, baseline daily step count, AEs the year prior to enrollment, or duration of follow-up between the intervention (n = 57) and control (n = 52) groups. The intervention group had a significantly reduced risk of AEs (rate ratio = 0.51, [95%CI 0.31-0.85]), compared to the control group. There were no significant between-group differences in change in average daily step count, HRQL, or self-efficacy at 6 and 12 months after enrollment.

CONCLUSIONS

A 3-month internet-mediated, pedometer-based PA intervention was associated with reduced risk for AEs of COPD over 12-15 months of follow-up. ClinicalTrials.gov identifier: NCT01772082.

Progression of physical inactivity in COPD patients: the effect of time and climate conditions - a multicenter prospective cohort study

Purpose

Longitudinal data on the effect of time and environmental conditions on physical activity (PA) among COPD patients are currently scarce, but this is an important factor in the design of trials to test interventions that might impact on it. Thus, we aimed to assess the effect of time and climate conditions (temperature, day length and rainfall) on progression of PA in a cohort of COPD patients.

Patients and methods

This is a prospective, multicenter, cohort study undertaken as part of the EU/IMI PROactive project, in which we assessed 236 COPD patients simultaneously wearing two activity monitors (Dynaport MiniMod and Actigraph GT3X). A multivariable generalized linear model analysis was conducted to describe the effect of the explanatory variables on PA measures, over three time points (baseline, 6 and 12 months).

Results

At 12 months (n=157; FEV₁% predicted=57.7±21.9) there was a significant reduction in all PA measures (Actigraph step count (4284±3533 vs 3533±293)), Actigraph moderate- to vigorous-intensity PA ratio (8.8 (18.8) vs 6.1 (15.7)), Actigraph vector magnitude units (374,902.4 (265,269) vs 336,240 (214,432)), MiniMod walking time (59.1 (34.9) vs 56.9 (38.7) mins) and MiniMod PA intensity (0.183 (0) vs 0.181 (0)). Time had a significant, negative effect on most PA measures in multivariable analysis, after correcting for climate factors, study center, age, FEV₁% predicted, 6MWD and other disease severity measures. Rainfall was the only climate factor with a negative effect on most PA parameters.

Conclusion

COPD patients demonstrate a significant decrease in PA over 1 year follow-up, which is further affected by hours of rainfall, but not by other climate considerations.