Assessment of sedentary behaviour in individuals with COPD: how many days are necessary?

Objective: The objective of the present study was to define the minimum number of monitoring days required for the adequate cross-sectional assessment of sedentary behaviour in individuals with chronic obstructive pulmonary disease (COPD). Methods: In this cross-sectional study, the sedentary behaviour of individuals with COPD was assessed using two physical activity monitors during awake time for seven consecutive days. Time spent per day in activities requiring ≤1.5 metabolic equivalents (METs) and in sitting, lying and sitting+lying positions was calculated taking into account the average of 7 days (as a reference in all analyses) and of all 119 possible combinations of 2---6 days. Intraclass correlation coefficients (ICCs) and linear regression analyses were performed for all combinations. Results: 91 individuals were analysed (47 female, 66±9 years, forced expiratory volume in 1 s 50±15% predicted). For the variables time spent per day in activities ≤1.5METs and sitting, the average of any combination of at least four assessment days was sufficient to adequately reflect the average of 7 days (adjusted R2≥0.929, ICC≥0.962, p<0.0001 for all). For time spent per day lying and sitting+lying, only two assessment days were enough (adjusted R2≥0.937, ICC≥0.968, p<0.0001 for all). Results were maintained independently of patient sex, disease severity, day of the week, daylight time or daytime naps. Conclusions: The average of 4 days of objective monitoring was sufficient to adequately reflect the results of a 1-week assessment of the main outcomes related to sedentary behaviour in individuals with moderate to very severe COPD, regardless of sex, disease severity, day of the week, daylight time and occurrence of daytime naps.

Sleep-onset time variability and sleep characteristics on weekday and weekend nights in patients with COPD.

OBJECTIVE: To evaluate sleep-onset time variability, as well as sleep characteristics on weekday and weekend nights, in individuals with moderate-to-severe COPD. METHODS: Sleep was objectively assessed by an activity/sleep monitor for seven consecutive nights in individuals with COPD. For analysis, individuals were divided into two groups according to sleep-onset time variability results, characterized by intrasubject standard deviation of sleep-onset time (SOTV) ≥ 60 min or < 60 min. RESULTS: The sample comprised 55 individuals (28 males; mean age = 66 ± 8 years; and median FEV1 % of predicted = 55 [38-62]). When compared with the SOTV<60min group (n = 24), the SOTV≥60min group (n = 31) presented shorter total sleep time (5.1 ± 1.3 h vs. 6.0 ± 1.3 h; p = 0.006), lower sleep efficiency (73 ± 12% vs. 65 ± 13%; p = 0.030), longer wake time after sleep onset (155 ± 66 min vs. 115 ± 52 min; p = 0.023), longer duration of wake bouts (19 [16-28] min vs. 16 [13-22] min; p = 0.025), and higher number of steps at night (143 [104-213] vs. 80 [59-135]; p = 0.002). In general, sleep characteristics were poor regardless of the day of the week, the only significant difference being that the participants woke up about 30 min later on weekends than on weekdays (p = 0.013). CONCLUSIONS: Sleep-onset time varied over 1 h in a standard week in the majority of individuals with COPD in this sample, and a more irregular sleep onset indicated poor sleep quality both on weekdays and weekends. Sleep hygiene guidance could benefit these individuals if it is integrated with their health care.

Sleep-onset time variability and sleep characteristics on weekday and weekend nights in patients with COPD / Variabilidade do tempo de início do sono e características do sono durante a semana e o fim de semana em pacientes com DPOC

ABSTRACT Objective: To evaluate sleep-onset time variability, as well as sleep characteristics on weekday and weekend nights, in individuals with moderate-to-severe COPD. Methods: Sleep was objectively assessed by an activity/sleep monitor for seven consecutive nights in individuals with COPD. For analysis, individuals were divided into two groups according to sleep-onset time variability results, characterized by intrasubject standard deviation of sleep-onset time (SOTV) ≥ 60 min or < 60 min. Results: The sample comprised 55 individuals (28 males; mean age = 66 ± 8 years; and median FEV1 % of predicted = 55 [38-62]). When compared with the SOTV<60min group (n = 24), the SOTV≥60min group (n = 31) presented shorter total sleep time (5.1 ± 1.3 h vs. 6.0 ± 1.3 h; p = 0.006), lower sleep efficiency (73 ± 12% vs. 65 ± 13%; p = 0.030), longer wake time after sleep onset (155 ± 66 min vs. 115 ± 52 min; p = 0.023), longer duration of wake bouts (19 [16-28] min vs. 16 [13-22] min; p = 0.025), and higher number of steps at night (143 [104-213] vs. 80 [59-135]; p = 0.002). In general, sleep characteristics were poor regardless of the day of the week, the only significant difference being that the participants woke up about 30 min later on weekends than on weekdays (p = 0.013). Conclusions: Sleep-onset time varied over 1 h in a standard week in the majority of individuals with COPD in this sample, and a more irregular sleep onset indicated poor sleep quality both on weekdays and weekends. Sleep hygiene guidance could benefit these individuals if it is integrated with their health care.

RESUMO Objetivo: Avaliar a variabilidade do tempo de início do sono, bem como as características do sono durante a semana e o fim de semana, em indivíduos com DPOC moderada a grave. Métodos: O sono foi avaliado objetivamente por meio de um monitor de atividade/sono durante sete noites consecutivas em indivíduos com DPOC. Para a análise, os indivíduos foram divididos em dois grupos, de acordo com a variabilidade do tempo de início do sono, caracterizada pelo desvio-padrão do tempo de início do sono (TISV) ≥ 60 min ou < 60 min em um mesmo indivíduo. Resultados: A amostra foi composta por 55 indivíduos [28 homens; média de idade = 66 ± 8 anos; mediana do VEF1 em % do previsto = 55 (38-62)]. Em comparação com o grupo TISV<60min (n = 24), o grupo TISV≥60min (n = 31) apresentou menor tempo total de sono (5,1 ± 1,3 h vs. 6,0 ± 1,3 h; p = 0,006), menor eficiência do sono (73 ± 12% vs. 65 ± 13%; p = 0,030), maior tempo de vigília após o início do sono (155 ± 66 min vs. 115 ± 52 min; p = 0,023), blocos de vigília mais longos [19 (16-28) min vs. 16 (13-22) min; p = 0,025] e maior número de passos dados à noite [143 (104-213) vs. 80 (59-135); p = 0,002]. Em geral, as características do sono foram ruins independentemente do dia da semana; a única diferença significativa foi que os participantes acordaram cerca de 30 min mais tarde nos fins de semana do que nos dias de semana (p = 0,013). Conclusões: O tempo de início do sono variou mais de 1 h em uma semana-padrão na maioria dos indivíduos com DPOC da amostra, e um início de sono mais irregular indicou má qualidade do sono tanto nos dias de semana como nos fins de semana. A orientação a respeito da higiene do sono pode ser benéfica se for integrada à atenção à saúde desses pacientes.

The Gini Coefficient: A New Approach to Assess Physical Activity Inequality in COPD.

Increasing physical activity (PA) is a complex and challenging task in patients with chronic obstructive pulmonary disease (COPD). However, some questions are raised regarding the evaluation of PA in these patients: Have all aspects of PA evaluation in patients with COPD already been explored in the scientific literature and clinical practice? What is the clinical importance of assessing PA inequality? PA inequality is defined as the Gini coefficient (Ginicoef) of the PA distribution of a population and is already shown to have implications for public health in the general population. It is a simple tool that might allow a better understanding of PA disparities among different COPD populations, although to our knowledge there is no previous investigation of PA inequality in patients with COPD using the Ginicoef. In this perspective study we have provided examples of the Ginicoef use in different scenarios. Future studies might try to apply it in order to identify subpopulations with higher PA inequality, and perhaps are therefore more prone to benefit most from interventions specifically tailored to promote PA. In summary, we propose the quantification of PA inequality with the Ginicoef as a tool that might allow us to see PA even more comprehensively than we already do, expanding our perspective on PA in patients with COPD.

Tossing and turning: association of sleep quantity-quality with physical activity in COPD.

The association between characteristics of sleep and physical activity in daily life (PADL) has not yet been investigated in depth in subjects with COPD. This study evaluated whether time spent per day in physical activity (PA) and sedentary behaviour are associated with sleep quantity and quality in this population. Sleep and PADL were objectively assessed by an activity monitor for 7 days and analysed on a minute-by-minute basis. Subjects also underwent spirometry and 6-min walking test (6MWT). Fifty-five subjects with moderate-to-severe COPD (28 male, 67±8 years) were studied. Subjects with total time in bed (TIB) per night ≥9 h had higher wake-after-sleep onset than TIB 7-9 h and TIB ≤7 h (195 (147-218) versus 117 (75-167) and 106 (84-156) min) and more fragmented sleep than TIB ≤7 h (8.2 (6.7-14.3) versus 6.3 (5.6-6.9) sleeping bouts; p<0.05 for all). Subjects with TIB ≥9 h also spent more time per day in sedentary behaviour and less time per day in PA of light and moderate-to-vigorous intensity than those with TIB 7-9 h and ≤7 h. In multiple linear regression, TIB ≥9 h was the only significant predictor of physical inactivity (ß=-3.3 (-5.1, -1.6), p≤0.0001), accounting for 20% of its variation. Sleep fragmentation was frequent and more pronounced in physically inactive than active patients (7.5 (6.3-9.6) versus 6.4 (5.5-7.3) sleeping bouts; p=0.027). In summary, subjects with COPD with TIB ≥9 h·night-1 have more fragmented sleep, are more sedentary and less physically active than those with <9 h·night-1, independently of the awake time. Sleep quality is frequently poor and even worse in patients classified as physically inactive.