Center for Clinical Epidemiology, Lady Davis Institute-Jewish General Hospital, and the Departments of Epidemiology and Biostatistics and of Medicine, McGill University, Montreal, QC, Canada.
Center for Clinical Epidemiology, Lady Davis Institute-Jewish General Hospital, and the Departments of Epidemiology and Biostatistics and of Medicine, McGill University, Montreal, QC, Canada.
Chest. 2018 Aug;154(2):257-265. doi: 10.1016/j.chest.2018.04.006. Epub 2018 Apr 19.
Randomized controlled trials at times investigate findings suggested by observational studies. For example, the Towards a Revolution in COPD Health (TORCH) trial, which did not show a mortality reduction with inhaled corticosteroids (ICS) in COPD, was motivated by some observational studies that suggested considerable reductions in mortality with these drugs. Reasons for these discrepancies are unclear.
The literature was searched to identify all observational studies, including cohort and case-control studies, investigating the effectiveness of ICS on major outcomes in patients with COPD; these outcomes included death and hospitalization for COPD.
A total of 21 studies were identified. Nine studies were affected by immortal time bias, five by immeasurable time bias, and seven by the "asthma factor" bias; some studies were affected by more than one bias. These studies found important reductions in the rates of major COPD outcomes with ICS use, with pooled rate ratios of 0.71 (95% CI, 0.67-0.76), 0.76 (95% CI, 0.70-0.83), and 0.79 (95% CI, 0.73-0.87), respectively, for the three sources of bias. In contrast, the five studies unaffected by these major biases did not find an association (pooled rate ratio, 1.02 [95% CI, 0.88-1.17]).
Observational studies are important to provide evidence from real-world data on medication effects. However, appropriate study design and analysis are essential to avoid biases and ensure randomized trials with greater chances of success. The observational studies suggesting potential beneficial effects of nonrespiratory drugs to treat COPD, such as statins and beta-blockers, will also need careful review before long and expensive randomized trials are conducted.
随机对照试验有时会调查观察性研究提出的发现。例如，在 COPD 健康革命（TORCH）试验中，吸入皮质类固醇（ICS）并未显示出降低 COPD 的死亡率，这是因为一些观察性研究表明，这些药物可显著降低死亡率。造成这些差异的原因尚不清楚。
检索文献，以确定所有观察性研究，包括队列研究和病例对照研究，调查 ICS 对 COPD 患者主要结局（包括死亡和 COPD 住院）的有效性；这些结局包括死亡和 COPD 住院。
共确定了 21 项研究。其中 9 项研究受到不朽时间偏倚的影响，5 项研究受到不可衡量时间偏倚的影响，7 项研究受到“哮喘因素”偏倚的影响；一些研究受到不止一种偏倚的影响。这些研究发现，ICS 使用可显著降低 COPD 主要结局的发生率，合并后的率比分别为 0.71（95%CI，0.67-0.76）、0.76（95%CI，0.70-0.83）和 0.79（95%CI，0.73-0.87）。相比之下，不受这些主要偏倚影响的 5 项研究并未发现相关性（合并后的率比为 1.02（95%CI，0.88-1.17））。
观察性研究对于从真实世界数据中提供药物效果的证据非常重要。然而，适当的研究设计和分析对于避免偏倚以及确保随机试验具有更大的成功机会至关重要。对于那些可能有益的非呼吸药物（如他汀类药物和β受体阻滞剂）治疗 COPD 的观察性研究，在进行昂贵的长期随机试验之前，也需要进行仔细审查。
Zotero 插件