Living near hydraulic fracturing is associated with increased risk of hospitalization in people with heart failure (HF), a new study from Pennsylvania suggests.
The link was strongest among those with more severe heart failure but patients with either HF phenotype showed this association of increased risk with exposure to fracking activities, according to the investigators, led by Tara P. McAlexander, PhD, MPH, Drexel University Dornsife School of Public Health in Philadelphia.
“Our understanding has expanded well beyond the famous Harvard Six Cities study to know that it’s not just a short-term uptick in air pollution that’s going to send someone to the hospital a couple days later,” said McAlexander interview, referring to the study conducted from the mid-1970s through 1991. “We know that people who live in these environments and are exposed for long periods of time may have long-term detrimental effects.”
Although questions remain about specific mechanisms and how best to assess exposure, the evidence is mounting in a way that is consistent with the biologic hypotheses of how fracking would adversely affect health, McAlexander said. “We have many studies now on adverse pregnancy and birth outcomes, and that’s just the tip of the iceberg.”
Pennsylvania is a hot spot for fracking, also known as unconventional natural gas development (UNGD), with more than 12,000 wells drilled in the Marcellus shale since 2004. The shale extends from upstate New York in the north to northeastern Kentucky and Tennessee in the south and covers about 72,000 square miles. Last year, Pennsylvania pledged $3 million to study clusters of rare pediatric cancers and asthma near fracking operations. A recent grand jury report concluded government officials failed to protect residents from the health effects of fracking.
Fracking involves a cascade of activities that can trigger neural circuitry, sympathetic activation, and inflammation — all well-known pathways that potentiate heart failure, said Sanjay Rajagopalan, MD, who has researched the health effects of air pollution for two decades and was not involved with the study.
“If you think about it, it’s like environmental perturbation on steroids in some ways where they are pulling the trigger from a variety of different ways: noise, air pollution, social displacement, psychosocial impacts, economic disparities. So it’s not at all surprising that they saw an association,” said Rajagopalan, chief of cardiovascular medicine, University Hospitals Harrington Heart & Vascular Institute, and director of the Case Western Cardiovascular Research Institute in Cleveland, Ohio.
As reported in the Journal of the American College of Cardiology, McAlexander and colleagues at Johns Hopkins University used electronic health data from the Geisinger Health System to identify 9054 patients with heart failure seen between 2008 and 2015. Of these, 5839 patients had an incident HF hospitalization and 3215 served as controls. Geisinger operates 13 hospitals and two research centers in 45 of Pennsylvania’s 67 counties, serving more than 3 million of the state’s residents.
Patients’ residential addresses were used to identify latitude and longitude coordinates that were matched with 9669 UNGD wells in Pennsylvania and the location of major and minor roadways. The researchers also calculated a measure of community socioeconomic deprivation.
The adjusted odds of hospitalization were higher for patients in the highest quartile of exposure for three of the four UNGD phases: pad preparation (odds ratio [OR] 1.70; 95% CI, 1.35 – 2.13), stimulation or the actual fracking (OR, 1.80; 95% CI, 1.35 – 2.40), and production (OR, 1.62; 95% CI, 1.07 – 2.45).
McAlexander said she initially thought the lack of association with drilling (OR, 0.97; 95% CI, 0.75 – 1.27) was a mistake but noted that the drilling metric reflects a shorter time period than, for example, 30 days needed to clear the well pad and bring in the necessary equipment.
Stronger associations between pad preparation, fracking, and production are also consistent with the known increases in air pollution, traffic, and noise associated with these phases.
Individuals with more severe HF had greater odds of hospitalization but the effect sizes were generally comparable between HF with preserved vs reduced ejection fraction. For those with the highest exposure to fracking, the odds ratios for hospitalization reached 2.25 (95% CI, 1.56 – 3.25) and 2.09 (95% CI, 1.44 – 3.03), respectively.
Notably, patients who could be phenotyped vs those who could not were more likely to die, to be hospitalized for HF, and to have a higher Charlson Comorbidity Index and other relevant diagnoses like myocardial infarction.
“Clinicians need to be increasingly aware that the environments their patients are in are a huge factor in their disease progression and outlook,” McAlexander said. “We know that UNGD, specifically now, is something that could be impacting a heart failure patient’s survival.”
She also suggested that the findings may also spur more advocacy work and “across-silo” collaboration between clinicians and environmental researchers.
Rajagopalan said there is increasing recognition that physicians need to be aware of environmental health links as extreme events like the California and Oregon wildfires and coastal flooding become increasingly common. “Unfortunately, unconventional is becoming the new convention.”
The problem for many physicians, however, is just having enough bandwidth to get through the day and get enough learning to keep above water, he said. Artificial intelligence could be used to seed electronic medical records with other personalized information from a bevy of sources including smartphones and the internet of things (IoT), but fundamental changes are also needed in the educational process to emphasize the environment.
“It’s going to take a huge societal shift in the way we view commodities, what we consider healthy, etc, but it can happen very quickly because all it takes is a crisis like COVID-19 to bring people to their knees and make them understand how this is going to take over our lives over the next decade,” Rajagopalan said.
The scientific community has been calling for “good” epidemiologic studies on the health effects of fracking since the early 2010s, Barrak Alahmad, MBChB, MPH, Harvard T.H. Chan School of Public Health, and Haitham Khraishah, MD, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, point out in an accompanying editorial.
The current study applied “extensive and rigorous methods” involving both the design and statistical approach, including use of a negative control analysis to assess for sources of spurious causal inference, several sensitivity analyses, and controlled for a wide range of covariates.
“Their results were consistent and robust across all these measures,” the editorialists write. “Most importantly, the effect size is probably too large to be explained away by an unmeasured confounder.”
Alahmad and Khraishah call for advancements in exposure assessment, citing a recent study reporting that ambient particle radioactivity near unconventional oil and gas sites could induce adverse health effects. Other unmet needs include a better understanding of racial disparities in the impacts of fracking and a fine-tuning of cause-specific cardiovascular morbidity and mortality.
The study was supported by training grants from the National Institute of Environmental Health Sciences to McAlexander and principal investigator Brian Schwartz, MD. The authors, Rajagopalan, Alahmad, and Khraishah have disclosed no relevant financial relationships.
J Am Coll Cardiol. Published December 7, 2020. Full text, Editorial
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