The fracking debate is moving to the clinic

Drilling into shale to release natural gas, a process described in scientific literature as “unconventional natural gas development” (UNGD) but more commonly known as “fracking” was considered a political hot potato in the 2020 presidential battleground state of Pennsylvania when the issue was defined in purely economic terms, but a study in the Journal of the American College of Cardiology, raises a serious health concern.

Tara P. McAlexander, PhD, MPH, and colleagues from the Johns Hopkins Bloomberg School of Public Health in Baltimore, looked at hospitalization rates for 9,054 heart failure patients who were treated from January 1, 2008 through July 31, 2015 at outpatient and inpatient centers run by the Geisinger, a large integrated health system covering most of Pennsylvania. The average age of patients included in the analysis was 71 and 47.7% were women.

They analyzed electronic health records from 5,839 heart failure hospitalizations that occurred during the study period and cross-referenced the timing of the hospitalizations to the level of fracking activity in the area at that time. For purposes of their study, they identified four levels of fracking activity: preparation of the pad, drilling, stimulation, and production. They also sought to determine if any association could be related to the type of heart failure: reduced ejection fraction (HFrEF) versus preserved ejection fraction (HFpEF).

In their analysis, McAlexander and colleagues also calculated proximity to fracking wells, number of wells, and depth of the wells.

They analyzed the exposure metrics together and divided the results into quartiles: highest to lowest exposures.

At the highest exposure risk quartile, three of the four UNGD activity categories were associated with increased risk, but interestingly there was no increase risk during the actual drilling phase.

“Comparing 4th to 1st quartiles, adjusted odds ratios (95% confidence interval) for hospitalization were 1.70 (1.35-2.13),0.97 (0.75-1.27), 1.80 (1.35-2.40), and 1.62 (1.07-2.45) for pad preparation, drilling, stimulation, and production metrics, respectively. We did not find effect modification by HFrEF or HFpEF status,” they wrote.

As might be expected, the associations between fracking activity and hospitalizations were more common among those with severe HF at baseline.

“We believe this heart failure severity measure was valid, because persons who could be phenotyped (versus not phenotyped) were more likely to die, were more likely be hospitalized for heart failure, had other relevant diagnoses (e.g. myocardial infarction), were taking more medications, and had a higher Charlson index,” they wrote. “This suggests that vulnerable persons with severe heart failure might be more susceptible to the adverse effects of UNGD activity that could lead to hospitalization. This is an important finding for several reasons. First, it underscores the importance of our primary associations between UNGD activity and hospitalization; second, it alleviates concerns that our primary results could be an artifact of spatial or temporal confounding; and third, it suggests that biological mechanisms due to disease severity likely mediate the associations observed between increasing UNGD activity and increasing likelihood of hospitalization for heart failure.”

What does this tell us?

As Barrak Alahmad, MBCHB, MPH, and Haitham Khraishah, MD, of Harvard’s T.H. Chan School of Public Health and Harvard Medical School, wrote in an accompanying editorial, the study by McAlexander and collegues is an important addemdum to an accumulating body of evidence about potential health risks of UNGD. “Moving forward, we need to better understand the mediating effects by air and water pollutants, as well as particle radioactivity, and the existence of racial disparities in the fracking impacts. We also need a better understanding of the effects of various environmental exposures on cardiovascular health,” Alahmad and Khraishah wrote. “Fine-tuning of cause-specific cardiovascular morbidity and mortality along with translational studies are needed to further characterize the pathophysiological pathways.”

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McAlexander and colleagues noted a number of limitations, including the reliance on ICD-9 codes to identify heart failure, “which is less specific than other methods of case assessment.” Also, the EHR data didn’t include information on diet, alcohol use or physical activity, all of which are factors that could influence hospitalizations.

They concluded that they “observed significantly increased odds of hospitalization among heart failure subjects in relation to increasing UNGD activity for several phases, including pad preparation, stimulation, and production, with stronger associations among persons with more severe heart failure. These associations are plausible given environmental (e.g., air pollution, water contamination, noise, traffic) and community impacts of UNGD. Understanding how people living with heart failure are susceptible to environmental exposures is especially important given the growing prevalence of heart failure and the possibility that environmental factors play a role in clinical heart failure outcomes.”

  1. Analysis of patient records from a large Pennsylvania health system suggests an association between the rate of heart failure hospitalizations and exposure to air pollutants produced by “unconventional nature gas development” more commonly known as “fracking”.

  2. Additional research is needed to understand the pathophysiological mechanisms through which fracking may exacerbate heart failure hospitalizations.

Peggy Peck, Editor-in-Chief, BreakingMED™

This research was supported by funding from the National Institute of Environmental Health Sciences.

The authors have reported that they have no relationships relevant to the contents of this paper to disclose.

Cat ID: 102

Topic ID: 74,102,102,3,914,192,151,925