Rasmussen Sara G, Ogburn Elizabeth L, McCormack Meredith, Casey Joan A, Bandeen-Roche Karen, Mercer Dione G, Schwartz Brian S
Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
JAMA Intern Med. 2016 Sep 1;176(9):1334-43. doi: 10.1001/jamainternmed.2016.2436.
Asthma is common and can be exacerbated by air pollution and stress. Unconventional natural gas development (UNGD) has community and environmental impacts. In Pennsylvania, UNGD began in 2005, and by 2012, 6253 wells had been drilled. There are no prior studies of UNGD and objective respiratory outcomes.
To evaluate associations between UNGD and asthma exacerbations.
A nested case-control study comparing patients with asthma with and without exacerbations from 2005 through 2012 treated at the Geisinger Clinic, which provides primary care services to over 400 000 patients in Pennsylvania. Patients with asthma aged 5 to 90 years (n = 35 508) were identified in electronic health records; those with exacerbations were frequency matched on age, sex, and year of event to those without.
On the day before each patient's index date (cases, date of event or medication order; controls, contact date), we estimated activity metrics for 4 UNGD phases (pad preparation, drilling, stimulation [hydraulic fracturing, or "fracking"], and production) using distance from the patient's home to the well, well characteristics, and the dates and durations of phases.
We identified and defined asthma exacerbations as mild (new oral corticosteroid medication order), moderate (emergency department encounter), or severe (hospitalization).
We identified 20 749 mild, 1870 moderate, and 4782 severe asthma exacerbations, and frequency matched these to 18 693, 9350, and 14 104 control index dates, respectively. In 3-level adjusted models, there was an association between the highest group of the activity metric for each UNGD phase compared with the lowest group for 11 of 12 UNGD-outcome pairs: odds ratios (ORs) ranged from 1.5 (95% CI, 1.2-1.7) for the association of the pad metric with severe exacerbations to 4.4 (95% CI, 3.8-5.2) for the association of the production metric with mild exacerbations. Six of the 12 UNGD-outcome associations had increasing ORs across quartiles. Our findings were robust to increasing levels of covariate control and in sensitivity analyses that included evaluation of some possible sources of unmeasured confounding.
Residential UNGD activity metrics were statistically associated with increased risk of mild, moderate, and severe asthma exacerbations. Whether these associations are causal awaits further investigation, including more detailed exposure assessment.
哮喘很常见，空气污染和压力会使其加重。非常规天然气开发（UNGD）会对社区和环境产生影响。在宾夕法尼亚州，UNGD始于2005年，到2012年时已钻了6253口井。此前尚无关于UNGD与客观呼吸结果的研究。
评估UNGD与哮喘加重之间的关联。
一项巢式病例对照研究，比较2005年至2012年在盖辛格诊所接受治疗的有和没有哮喘加重的患者，该诊所为宾夕法尼亚州40多万患者提供初级保健服务。在电子健康记录中识别出年龄在5至90岁的哮喘患者（n = 35508）；将有加重情况的患者按年龄、性别和事件年份与无加重情况的患者进行频率匹配。
在每位患者的索引日期（病例为事件或用药订单日期；对照为接触日期）的前一天，我们使用患者家到油井的距离、油井特征以及各阶段的日期和持续时间，估算了4个UNGD阶段（平台准备、钻井、增产措施[水力压裂，即“压裂”]和生产）的活动指标。
我们将哮喘加重识别并定义为轻度（新开口服皮质类固醇药物订单）、中度（急诊就诊）或重度（住院）。
我们识别出20749例轻度、1870例中度和4782例重度哮喘加重病例，并分别将这些病例与18693个、9350个和14104个对照索引日期进行频率匹配。在三级调整模型中，12个UNGD - 结局对中的11个中，与每个UNGD阶段活动指标最低组相比，最高组之间存在关联：优势比（OR）范围从平台指标与重度加重关联的1.5（95%CI，1.2 - 1.7）到生产指标与轻度加重关联的4.4（95%CI，3.8 - 5.2）。12个UNGD - 结局关联中的6个在四分位数间OR值呈上升趋势。我们的研究结果在增加协变量控制水平以及包括评估一些未测量混杂因素的可能来源在内的敏感性分析中具有稳健性。
居住区域的UNGD活动指标与轻度、中度和重度哮喘加重风险增加在统计学上相关。这些关联是否具有因果关系有待进一步调查，包括更详细的暴露评估。
