Role of physical activity in daily life in Chronic Obstructive Pulmonary Disease (COPD)
Mantoani, Leandro Cruz
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Background: Chronic obstructive pulmonary disease (COPD) is an important common chronic lung condition that is a leading cause of morbidity and mortality worldwide, resulting in a substantial and increasing economic and social burden to health care systems. Physical activity (PA) is the strongest predictor of mortality in this population, playing an important role determining the quality of life in COPD, with better outcomes being reported by those who have higher levels of PA. Therefore, improving PA levels has been considered a key component in the management of patients with COPD. Likewise, it is important to understand the mechanisms that lead to inactivity, as it is to develop accurate methods of measuring PA in this population. Aims of the thesis: 1) To identify and to summarize the interventions able to increase PA levels in patients with COPD; 2) To understand the longitudinal interaction between muscle mass and function and PA levels in COPD; 3) To study the acceptability and the suitability of a new activity monitor (TracMor D – Philips, the Netherlands) for home coaching in daily routine of patients with COPD; and 4) To investigate whether a PA enhancing programme with set targets and feedback would constitute a successful intervention to increase PA levels in patients with COPD attending pulmonary rehabilitation (PR). Methods: To achieve the first aim of the thesis I performed a systematic review summarizing interventional studies that assessed PA as an outcome in patients with COPD. For the second aim, I analysed some multicentric longitudinal data (one year follow-up) on PA and muscle mass/function in COPD. The third aim was achieved with a pilot study I conducted in Edinburgh, where patients with COPD wore three TracMor D in different body places simultaneously with the criterion method (Actigraph GT3x activity monitor) for a week. To accomplish the fourth and main aim of my PhD, I conducted a randomised controlled trial (RCT) where patients with COPD undergoing PR were randomised to either receive PR only or PR plus a PA coaching programme using the TracMor D activity monitor for 12 weeks. Main Results: Study 1: Sixty studies were considered for data extraction in the systematic review. Seven types of intervention with the potential to increase PA levels in patients with COPD were identified. PR programmes with more than 12 weeks of duration and PA coaching programmes with feedback of an activity monitor are promising interventions to increase activity levels in patients with COPD. Overall, the quality of evidence across interventional studies was graded as very low. Study 2: The longitudinal study showed that there were weak correlations between PA levels and muscle strength at baseline (0.19 ≤ r ≤ 0.33 p<0.001 for all). No correlations were found between changes in PA and muscle strength (-509 [-1295-362] vs -0.4 [-3.5-2.6] - 12 months minus baseline - respectively) and future muscle mass (p>0.05). Baseline PA levels are related to future muscle strength (0.30 ≤ r ≤ 0.41, p<.0001) but not with muscle mass. Study 3: This study showed that TracMor D had strong correlations with Actigraph GT3x in terms of Kcal consumption in all three positions (necklace, pocket and hip) (0.84≥r<0.86, p<0.001 for all). TracMor D was considered comfortable and easy to use at home, receiving a mean usability score of 98 out of 100 maximum points. Study 4: My RCT showed that the proposed PA intervention was effective in changing steps/day (1251 ± 2408 vs control -410 ± 1118, p=0.01), time spent in light activities (21 ± 60 vs -37 ± 55, p=0.004), exercise capacity (99 ± 139 vs 3 ± 83 meters; 85 ± 114 vs 2 ± 62 seconds, p<0.03 for both) and muscle strength (15 ± 20 vs -5 ± 18, p=0.01) among others when compared to the control group. Conclusions: Strategies focussing specifically on increasing PA and longer PR programmes may have greater impacts on PA levels in COPD. Well-designed clinical trials with objective assessment of PA in patients with COPD are needed. PA levels are not related to one-year changes in muscle mass and muscle strength in patients with COPD. However, higher PA levels at baseline are related to having higher muscle strength at one-year. TracMor D strongly correlated with the criterion method and was highly accepted by patients with COPD in their daily routine, being considered comfortable and easy to use at home. The combination of PR with a physical activity enhancing programme using a PA monitor to set targets and give feedback on activity levels significantly improves PA, exercise capacity, muscle strength, quality of life, and anxiety and depression levels in patients with COPD.