Hospitalization for Heart Failure Possibly Linked to Fracking

Patients with heart failure, both the preserved ejection fraction and reduced ejection fraction subtypes, were shown in a recent Journal of the American College of Cardiology article to be at higher risk for hospitalization in areas of unconventional natural gas development (UNGD), particularly fracking.

“Combined and cumulative impacts of UNGD can adversely affect psychosocial stress and community well-being,” the study authors noted. “To our knowledge, no previous epidemiological studies have examined associations between measures of UNGD activity and heart failure outcomes.”

Their case control study recruited data on 9054 patients with heart failure (mean [SD] age, 71.7 [12.7] years) who accounted for 5839 hospitalizations between January 1, 2008, and July 31, 2015, in emergency department electronic health records of Geisinger Health System in central Pennsylvania. Controls were matched by date.

The patients were stratified by ejection status (“not classifiable” was also available), and UNGD was classified into 4 phases, based on data obtained from the Pennsylvania Department of Environmental Protection: well pad preparation (eg, clearing of site, delivery of equipment and personnel), well drilling (ie, starting at the spud [drilling] date), well stimulation (hydraulic fracturing), and natural gas production.

Overall results show that the stimulation (ie, hydraulic fracturing, or fracking) phase of UNGD had the highest adjusted odds ratio (aOR) for hospitalization, coming in at 1.80 (95% CI, 1.35-2.40), when comparing the fourth and first quartiles (based on US Census data) of community socioeconomic deprivation. This was followed by pad preparation, with an aOR of 1.70 (95% CI, 1.35-2.13); production, with 1.62 (95% CI, 1.07-2.45); and drilling, at 0.97 (95% CI, 0.75-1.27).

Accounting for ejection status did not have an effect on the results, but the degree of heart failure severity at baseline showed several associations with most UNGD metrics, the authors noted.

Analysis of heart failure phenotype also found the following among the patients with preserved or reduced ejection fraction:

• More had died by the end of the study period
• Higher likelihood of hospitalization
• Higher proportions were taking antihypertensives, antihyperlipidemics, and anticoagulants
• More comorbidities
• Higher mean Charlson Comorbidity Index score

Most of the patients with heart failure with reduced ejection fraction or preserved ejection fraction—76.5% and 85.1%, respectively—also had hypertension. Valve disorders (24.4% and 29.8%), diabetes (45.8% and 48.5%), and chronic kidney disease (30.4% and 35.4%) were also common.

“These associations are plausible given [the] environmental (eg, air pollution, water contamination, noise, traffic) and community impacts of UNGD,” the authors concluded. “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.”

Study strengths include the large sample size and the incidence density case sampling, which aided in concerns about residual temporal confounding. Limitations include using International Classification of Diseases, Ninth Revision codes and lack of information on dietary intake and physical activity, but the authors believe the latter would not have affected their results.

Reference

McAlexander TP, Bandeen-Roche K, Buckley JP, et al. Unconventional natural gas development and hospitalization for heart failure in Pennsylvania. J Am Coll Cardiol. 2020;76(24):2862-2874. doi:10.1016/j.jacc.2020.10.023