采用分层分析策略评估在 COPD 随机环境干预中减少室内空气污染对健康的益处：来自 CLEAN AIR 研究的结果。
Principal stratification analysis to determine health benefit of indoor air pollution reduction in a randomized environmental intervention in COPD: Results from the CLEAN AIR study.
机构信息
Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Department of Environmental Health and Engineering, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
出版信息
Sci Total Environ. 2023 Apr 10;868:161573. doi: 10.1016/j.scitotenv.2023.161573. Epub 2023 Jan 18.
BACKGROUND
Indoor air quality represents a modifiable exposure to Chronic Obstructive Pulmonary Disease (COPD) health. In a randomized controlled trial (CLEAN AIR study), air cleaner assignment had causal effect in improving COPD outcomes. It is unclear, however, what is the treatment effect among those for whom intervention reduced air pollution and whether it was reduction in fine particulate matter (PM) or nitrogen dioxide (NO) that contributed to such improvement. Because pollution is a posttreatment variable, treatment effect cannot be assessed while controlling for pollution using intention-to-treat (ITT) analysis.
OBJECTIVE
Using principal stratification method, we assess indoor pollutants as the intermediate variable, and determine the causal effect of reducing indoor air pollution on COPD health.
METHOD
In randomized controlled trial, former smokers with COPD received either active or placebo HEPA air cleaners and were followed for 6 months. Saint George's Respiratory Questionnaire (SGRQ) was the primary outcome and secondary measures included SGRQ subscales, COPD assessment test (CAT), dyspnea (mMRC), and breathlessness, cough, and sputum scale (BCSS). Indoor PM and NO were measured. Principal stratification analysis was performed to assess the treatment effect while controlling for pollution reduction.
RESULTS
Among those showing at least 40 % PM reduction through air cleaners, the intervention showed improvement in respiratory symptoms for the active (vs. placebo), and the size of treatment effect shown for this subgroup was larger than that for the overall sample. In this subgroup, those with active air cleaners (vs. placebo) showed 7.7 points better SGRQ (95%CI: -14.3, -1.1), better CAT (β = -5.5; 95%CI: -9.8, -1.2), mMRC (β = -0.6; 95%CI: -1.1, -0.1), and BCSS (β = -1.8; 95%CI: -3.0, -0.5). Among those showing at least 40 % NO reduction through air cleaners, there was no intervention difference in outcomes.
CONCLUSION
Air cleaners caused clinically significant improvement in respiratory health for individuals with COPD through reduction in indoor PM.
TRIAL REGISTRATION
ClinicalTrials.gov: NCT02236858.
背景
室内空气质量是影响慢性阻塞性肺疾病（COPD）健康的可改变因素。在一项随机对照试验（CLEAN AIR 研究）中，空气净化器的分配对改善 COPD 结局有因果效应。然而，尚不清楚干预措施降低空气污染的情况下，哪些患者会出现治疗效果，以及改善的原因是细颗粒物（PM）还是二氧化氮（NO）的减少。由于污染是治疗后的变量，因此不能通过意向治疗（ITT）分析来控制污染，从而评估治疗效果。
目的
我们使用主分层方法将室内污染物作为中间变量，并确定降低室内空气污染对 COPD 健康的因果效应。
方法
在一项随机对照试验中，患有 COPD 的前吸烟者接受了活性或安慰剂高效空气净化器，并随访了 6 个月。圣乔治呼吸问卷（SGRQ）是主要结局，次要措施包括 SGRQ 子量表、COPD 评估测试（CAT）、呼吸困难（mMRC）和呼吸急促、咳嗽和咳痰量表（BCSS）。测量室内 PM 和 NO。进行主分层分析以评估在控制污染减少的情况下的治疗效果。
结果
在至少有 40%的 PM 通过空气净化器减少的人群中，干预对活性（与安慰剂相比）的呼吸症状有改善作用，并且该亚组的治疗效果大于总体样本。在这个亚组中，使用活性空气净化器（与安慰剂相比）的患者 SGRQ 评分改善了 7.7 分（95%CI：-14.3，-1.1），CAT 评分改善了 5.5 分（95%CI：-9.8，-1.2），mMRC 评分改善了 0.6 分（95%CI：-1.1，-0.1），BCSS 评分改善了 1.8 分（95%CI：-3.0，-0.5）。在至少有 40%的 NO 通过空气净化器减少的人群中，结局没有出现干预差异。
结论
空气净化器通过减少室内 PM，为 COPD 患者的呼吸健康带来了显著的临床改善。
试验注册
ClinicalTrials.gov：NCT02236858。
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