The use of non-invasive ventilation (NIV) in patients with chronic obstructive pulmonary disease (COPD) is now widespread, and is a key element of the management of acute and chronic hypercapnic respiratory failure. Many of these patients suffer from multiple comorbidities and the prevalence of COPD increases with age. In other medical specialties, analyses have reported that elderly patients and patients with comorbidities tend to be excluded from randomized studies. We sought to establish whether trials evaluating the efficacy of NIV in COPD included populations of patients that were seen in clinical practice, or if they are skewed towards younger and healthier patients. Since NIV was introduced, 106 randomized controlled trials (RCT) specifically investigating NIV in COPD (acute: 45%, stable disease: 55%) have been published in the literature. By analysing the demographic data from these trials (85 trials included (nonEnglish language studies excluded), totalling 5610 patients), we were able to establish the mean age, gender, ethnicity and excluded comorbidities of participants in these trials (Table 1) and compare these to epidemiological data for the wider COPD population. The mean (SD) age of participants across all available NIV COPD RCT was 67 (4) years (acute trials mean (SD): 69 (5) years, stable disease mean: 66 (3) years). This compares well with the mean age of stable COPD patients, reported in the HOmeVent registry at 66 years but not so well with those requiring NIV acutely. An analysis of the quality of care provided to patients receiving acute NIV reported that the average was 71 years for males and 72 years for females. Few studies have been conducted investigating tolerance and outcome of NIV in COPD specifically in patients over 65 years. In addition, there are no NIV COPD-specific RCT concentrating on an older target age group, and very few reported any participants over the age of 85. Fifteen percent of the COPD trials instead had an upper age limit of 75–80. This clearly demonstrates that elderly patients are a minority in NIV COPD RCT, and may suggest that elderly patients are being excluded. Gender of participants was reported in 76% of papers, and overall male percentage was 67%. The earlier trials were more heavily populated by males, with >80% male throughout the 1990s. Equality of gender representation is improving and the mean for 2010–2018 is 64% male; however, recent epidemiological data suggest that COPD is slightly more prevalent in women than men, particularly those receiving acute NIV. Therefore, despite the upward trend in the proportion of females included in RCT, females remain considerably under-represented when compared to the population being treated. Fifty-three percent of trials excluded patients with one or more comorbidities (49% in acute trials and 56% in stable trials). The most commonly excluded comorbidity was cardiovascular disease (48%), followed by other respiratory disorders (32%) and malignancy (20%). COPD patients are likely to have at least one comorbidity, reported in some cases as high as 68%; more than half of the patients in the HOmeVent registry suffered from cardiovascular disease. It is therefore difficult to generalize the results of RCT conducted in patients with only COPD to the wider population. Disappointingly, no ethnicity data were published in any NIV COPD RCT. Analysing data from trial location, 65% were conducted in Europe, with 91% of these in Western Europe. The remainder of the trials were from Asia (15%), South America (11%), North America (6%) and Oceania (1%). As the majority of studies were carried out in Europe, it is likely the results are not representative of a diverse ethnic population. Due to a lack of global COPD studies, the wider ethnic distribution of COPD patients is not known; however, the World Health Organization (WHO) data report that the condition is prevalent across all continents, and studies have

中文翻译：

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研究 COPD 患者无创通气的随机对照试验的普遍性

在慢性阻塞性肺疾病 (COPD) 患者中使用无创通气 (NIV) 现在很普遍，并且是管理急性和慢性高碳酸血症呼吸衰竭的关键因素。这些患者中有许多患有多种合并症，并且 COPD 的患病率随着年龄的增长而增加。在其他医学专业中，分析表明老年患者和有合并症的患者往往被排除在随机研究之外。我们试图确定评估 NIV 在 COPD 中的疗效的试验是否包括在临床实践中看到的患者群体，或者他们是否偏向于更年轻和更健康的患者。自从引入 NIV 以来，文献中已经发表了 106 项专门研究 COPD 中 NIV（急性：45%，稳定疾病：55%）的随机对照试验 (RCT)。通过分析这些试验（包括 85 项试验（排除非英语语言研究），共 5610 名患者）的人口统计学数据，我们能够确定这些试验参与者的平均年龄、性别、种族和排除的合并症（表 1）并比较这些数据用于更广泛的 COPD 人群的流行病学数据。所有可用 NIV COPD RCT 参与者的平均 (SD) 年龄为 67 (4) 岁（急性试验平均 (SD)：69 (5) 岁，疾病稳定平均：66 (3) 岁）。这与 HOmeVent 登记处报告的稳定 COPD 患者的平均年龄为 66 岁比较好，但与那些急需 NIV 的患者相比不太好。对接受急性 NIV 的患者提供的护理质量的分析报告称，男性的平均年龄为 71 岁，女性为 72 岁。很少有研究专门针对 65 岁以上的 COPD 患者调查 NIV 的耐受性和结果。此外，没有针对老年目标年龄组的 NIV COPD 特异性 RCT，并且很少报告任何超过 85 岁的参与者。 15% 的 COPD 试验的年龄上限为 75-80 岁。这清楚地表明，在 NIV COPD RCT 中老年患者是少数，并且可能表明老年患者被排除在外。76% 的论文报告了参与者的性别，总体男性百分比为 67%。较早的试验以男性为主，整个 1990 年代男性占 80% 以上。性别代表性的平等正在改善，2010-2018 年的平均男性为 64%；然而，最近的流行病学数据表明，COPD 在女性中的发病率略高于男性，尤其是那些接受急性 NIV 的女性。因此，尽管纳入 RCT 的女性比例呈上升趋势，但与接受治疗的人群相比，女性的代表性仍然明显不足。53% 的试验排除了患有一种或多种合并症的患者（急性试验中为 49%，稳定试验中为 56%）。最常被排除的合并症是心血管疾病（48%），其次是其他呼吸系统疾病（32%）和恶性肿瘤（20%）。COPD 患者可能至少有一种合并症，据报道在某些情况下高达 68%；HOmeVent 注册中超过一半的患者患有心血管疾病。因此，很难将在仅患有 COPD 的患者中进行的 RCT 结果推广到更广泛的人群。令人失望的是，在任何 NIV COPD RCT 中都没有发表种族数据。分析来自试验地点的数据，65% 在欧洲进行，其中 91% 在西欧进行。其余试验来自亚洲（15%）、南美洲（11%）、北美洲（6%）和大洋洲（1%）。由于大多数研究是在欧洲进行的，因此结果很可能不能代表不同种族的人群。由于缺乏全球 COPD 研究，COPD 患者更广泛的种族分布尚不清楚；然而，世界卫生组织 (WHO) 的数据报告称，这种情况在各大洲都很普遍，研究表明 任何 NIV COPD RCT 均未发表种族数据。分析来自试验地点的数据，65% 在欧洲进行，其中 91% 在西欧进行。其余试验来自亚洲（15%）、南美洲（11%）、北美洲（6%）和大洋洲（1%）。由于大多数研究是在欧洲进行的，因此结果很可能不能代表不同种族的人群。由于缺乏全球 COPD 研究，COPD 患者更广泛的种族分布尚不清楚；然而，世界卫生组织 (WHO) 的数据报告称，这种情况在各大洲都很普遍，研究表明 任何 NIV COPD RCT 均未发表种族数据。分析来自试验地点的数据，65% 在欧洲进行，其中 91% 在西欧进行。其余试验来自亚洲（15%）、南美洲（11%）、北美洲（6%）和大洋洲（1%）。由于大多数研究是在欧洲进行的，因此结果很可能不能代表不同种族的人群。由于缺乏全球 COPD 研究，COPD 患者更广泛的种族分布尚不清楚；然而，世界卫生组织 (WHO) 的数据报告称，这种情况在各大洲都很普遍，研究表明 由于大多数研究是在欧洲进行的，因此结果很可能不能代表不同种族的人群。由于缺乏全球 COPD 研究，COPD 患者更广泛的种族分布尚不清楚；然而，世界卫生组织 (WHO) 的数据报告称，这种情况在各大洲都很普遍，研究表明 由于大多数研究是在欧洲进行的，因此结果很可能不能代表不同种族的人群。由于缺乏全球 COPD 研究，COPD 患者更广泛的种族分布尚不清楚；然而，世界卫生组织 (WHO) 的数据报告称，这种情况在各大洲都很普遍，研究表明