Analysis of nocturnal actigraphic sleep measures in patients with COPD and their association with daytime physical activity.

BACKGROUND: Sleep disturbances are common in patients with chronic obstructive pulmonary disease (COPD) with a considerable negative impact on their quality of life. However, factors associated with measures of sleep in daily life have not been investigated before nor has the association between sleep and the ability to engage in physical activity on a day-to-day basis been studied. AIMS: To provide insight into the relationship between actigraphic sleep measures and disease severity, exertional dyspnoea, gender and parts of the week; and to investigate the association between sleep measures and next day physical activity. METHODS: Data were analysed from 932 patients with COPD (66% male, 66.4±8.3 years, FEV1% predicted=50.8±20.5). Participants had sleep and physical activity continuously monitored using a multisensor activity monitor for a median of 6 days. Linear mixed effects models were applied to investigate the factors associated with sleep impairment and the association between nocturnal sleep and patients' subsequent daytime physical activity. RESULTS: Actigraphic estimates of sleep impairment were greater in patients with worse airflow limitation and worse exertional dyspnoea. Patients with better sleep measures (ie, non-fragmented sleep, sleeping bouts ≥225 min, sleep efficiency ≥91% and time spent awake after sleep onset <57 min) spent significantly more time in light (p<0.01) and moderate-to-vigorous physical activity (p<0.01). CONCLUSIONS: There is a relationship between measures of sleep in patients with COPD and the amount of activity they undertake during the waking day. Identifying groups with specific sleep characteristics may be useful information when designing physical activity-enhancing interventions.

Prognosis and longitudinal changes of physical activity in idiopathic pulmonary fibrosis.

BACKGROUND: Physical activity (PA) is associated with disease severity in idiopathic pulmonary fibrosis (IPF), but longitudinal studies evaluating its prognostic value and changes over time are lacking. METHODS: We measured PA (steps per day, SPD) in a cohort of 46 IPF-patients (mean age, 67 years; mean FVC, 76.1%pred.) by accelerometry at baseline, recorded survival status during 3 years follow-up and repeated measurements in survivors. We compared the prognostic value of PA to established mortality predictors including lung function (FVC, DLCO) and 6-min walking-distance (6MWD). RESULTS: During follow-up (median 34 months) 20 patients (43%) died. SPD and FVC best identified non-survivors (AUROC-curve 0.79, p < 0.01). After adjustment for confounders (sex, age, therapy), a standardized increase (i.e. one SD) in SPD, FVC%pred. or DLCO%pred. was associated with a more than halved risk of death (HR < 0.50; p < 0.01). Compared to baseline, SPD, FVC, and 6MWD annually declined in survivors by 973 SPD, 130 ml and 9 m, resulting in relative declines of 48.3% (p < 0.001), 13.3% (p < 0.001) and 7.8% (p = 0.055), respectively. CONCLUSION: While PA predicts mortality of IPF patients similar to established functional measures, longitudinal decline of PA seems to be disproportionally large. Our data suggest that the clinical impact of disease progression could be underestimated by established functional measures.

Reduced physical activity in lymphangioleiomyomatosis compared with COPD and healthy controls: disease-specific impact and clinical correlates.

RATIONALE: Sporadic lymphangioleiomyomatosis (LAM) is an orphan lung disease for which daily physical activity has not been studied so far and it is unclear whether a disease-specific impact beyond airflow limitation exists. Clinical correlates indicating reduced physical activity in addition to established parameters like airflow limitation and hypoxaemia are largely undetermined. METHOD: We measured physical activity (steps per day, SPD; physical activity level, PAL; minutes of moderate activity, MMA) in 34 women with LAM, 32 FEV1-matched female patients with COPD and 15 age-matched healthy women for 1 week using an accelerometer. In addition, we assessed lung function measurements, questionnaires for generic and respiratory health status (12-Item Short Form Survey, SF-12; St. George's Respiratory Questionnaire, SGRQ), dyspnoea (modified Medical Research Council dyspnoea scale, mMRC) and fatigue (Multidimensional Fatigue Inventory, MFI-20). RESULTS: Patients with LAM (mean age 52.7 years, mean FEV1 62.7% predicted) showed reduced SPD, PAL and MMA (p<0.01) compared with healthy controls and reduced MMA (p=0.032) compared with female patients with COPD (mean age 65.2 years, mean FEV1 62.6% predicted). In multivariate regression analyses, adjusting for FEV1 and long-term oxygen therapy, either generic health status (SF-12 physical health) or fatigue (MFI-20) were the strongest independent predictors for SPD in patients with LAM (p=0.006 and p=0.004, respectively). CONCLUSIONS: Physical activity in daily life is substatially reduced in LAM, when compared with healthy controls and COPD - indicating a disease specific impact. The regular assessment of fatigue and generic health status may improve disease management in LAM by taking daily physical activity of patients with LAM more adequately into account.

Clinical Correlates of Reduced Physical Activity in Idiopathic Pulmonary Fibrosis.

BACKGROUND: Little is known about the consequences of idiopathic pulmonary fibrosis (IPF) for physical activity (PA). OBJECTIVES: We aimed to investigate levels of PA in IPF and to study associations of PA with lung function, exercise capacity, symptoms, and quality of life. METHODS: In stable patients with IPF we measured PA (steps per day, SPD; physical activity level, PAL; minutes of moderate activity, MMA) by accelerometry (SenseWear Armband) for 1 week. We also assessed lung function (forced vital capacity, FVC; diffusing capacity for carbon monoxide, DLCO); exercise capacity (6-minute walking distance, 6MWD); dyspnea (modified Medical Research Council, mMRC); fatigue (Multidimensional Fatigue Inventory, MFI-20), and generic (12-Item Short Form Survey, SF-12) and health-related quality of life (St. George's Respiratory Questionnaire) as further clinical variables. RESULTS: We investigated 48 patients with IPF in two centers (mean age, 67 years; 75% male; 23% on long-term oxygen therapy; mean FVC 75%pred.; mean DLCO 43%pred.; mean 6MWD 355 ± 140 m; mean SPD 5,017 ± 3,360). On a bivariate level, all clinical variables were significantly associated with SPD (p < 0.05). The associations of mMRC, MFI-20, SF-12 (physical health), and 6MWD with SPD were independent of impaired lung function (p < 0.05). At multivariate analyses, either 6MWD (total explained variance of the model, total R2: 42%) or MFI-20 (total R2: 39%) were the strongest independent predictors of SPD. CONCLUSION: Fatigue and exercise capacity are strong and independent predictors of PA in patients with IPF, which suggests that both measures should be assessed when the consequences of IPF for PA in daily life are studied.