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.

中文翻译：

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“可以做，不可以做”并不是懒惰的：关于COPD患者身体功能的纵向研究。

背景与目的慢性阻塞性肺病患者的身体容量（PC）和体力活动（PA）降低很常见，并与不良预后相关。但是，它们代表了身体机能的不同方面，干预措施不会以相同的方式影响他们。为了解决这个问题，最近产生了一个新的PC-PA象限概念，以识别身体功能亚组的临床特征。这项研究的目的是：I）验证新概念并验证其区别性临床特征，II）随时间推移评估概念的一致性，III）评估患者是否随时间改变象限隶属关系，IV）并测试是否象限隶属关系的变化与临床特征的变化有关。方法纵向，前瞻性 每年评估轻度至重度COPD患者，PC和PA以及呼吸系统变量，COPD特定的健康状况，合并症，生存率和恶化情况的非干预队列。结果在基线时分析了283例患者的数据。平均（最小/最大）随访时间为2.4（0.5 / 6.8）年。PC-PA象限的特征如下：I）“不能做，不做”：最严重和有症状，几种合并症II）“可以做，不做”：严重，但没有症状，一些合并症III）“不能做，可以做”：少数患者，严重且有症状，合并症较少IV）“可以做，可以做”：最轻，症状较少，合并症更少，加重频率最低。在172名患者中，至少进行了一次随访，58％的患者从未改变其象限隶属关系，而17％的患者在PC，PA或两者同时下降，11％的PC，PA或两者均有改善，而14％的患者PC，PA或两者均有改善和下降。没有任何临床特征或其年度变化显示出所有个体亚组之间的一致显着和相关差异。结论我们的发现表明，没有临床特征可以区分PC-PA象限，该概念似乎无法说明疾病过程。但是，已经很低的PA但保留在“可以做，不可以做”象限中的PC提出了一个问题，即与常规PC相比，在临床实践中定期评估PA对检测COPD进行性恶化是否更敏感。临床试验注册www。