The association of unconventional natural gas development with diagnosis and treatment of internalizing disorders among adolescents in Pennsylvania using electronic health records

Abstract

Background: Unconventional natural gas development (UNGD) introduces physical and psychosocial hazards into communities, which could contribute to psychosocial stress in adolescents and an increased risk of internalizing disorders, common and impactful health outcomes.

Objectives: To evaluate associations between a 180-day composite UNGD activity metric and new onset of internalizing disorders, overall and separately for anxiety and depressive disorders, and effect modification by sex.

Methods: We used a nested case-control design from 2008 to 2016 in 38 Pennsylvania counties using electronic health records from adolescent Geisinger subjects. Cases were defined by at least two diagnoses or medication orders indicating new onset of an internalizing disorder, and controls frequency-matched 4:1 on age, sex, and year. To evaluate associations, we used generalized estimating equations, with logit link, robust standard errors, and an exchangeable correlation structure within community.

Results: We identified 7,974 adolescents (65.9% female, mean age 15.0 years) with new onset internalizing disorders. There were no associations when we used data from the entire study period. When restricted to years with higher UNGD activity (2010-2016), comparing the highest to lowest quartile, UNGD activity was associated (odds ratio [95% confidence level]) with new onset internalizing disorders (1.15 [1.06, 1.25]). Associations were slightly stronger for depressive disorders. Associations were only present in females (p = 0.009).

Discussion: This is the first epidemiologic study of UNGD in relation to adolescent mental health, an important health outcome in a potentially susceptible group to the environmental and community impacts of UNGD. UNGD activity was associated with new onset internalizing disorders in females in this large sample in an area of active UNGD.

Keywords: Anxiety; Depression; Environmental epidemiology; Fracking; Psychosocial stress.

Figure 1.

Spatial distribution of (A) subjects and (B) UNGD wells by year in Pennsylvania.

Figure 2.

Distribution of (A) UNGD activity (6-month composite z-score metrics) by year, (B) UNGD activity metrics, zoomed into values −2 to 2, and (C) unconventional natural gas wells in Pennsylvania by year and phase within and outside of Geisinger region.

Figure 3.

Effect modification by sex of the associations of UNGD with new onset internalizing disorders in Pennsylvania adolescents in 2010-16 (Models 8A-B) Abbreviations: UNGD = unconventional natural gas development; Q = quartile (Q1 = reference group). Dots indicate the point estimate of the odds ratio for the relevant quartile, comparing odds to the first quartile reference group, with bars indicating the width of the confidence interval. Model 8A (female only) included 4422 cases and 17,687 controls; Model 8B (male only) included 2237 cases and 8948 controls; and Model 8C (to evaluate effect modification by sex with cross-product term between UNGD and sex) included all 6659 cases and 26,635 controls. All models conducted with logistic regression models using generalized estimating equations with robust standard errors, adjusted for sex, age, age², and age³, Non-White race, Hispanic ethnicity, Medical Assistance (≥ 50% of the time), ever smoker prior to internalizing disorder or control date, obese (body mass index > 95th percentile), ever vs. never asthma or allergic disease prior to internalizing disorder or control date, and ever vs. never attention deficit and hyperactivity disorder prior to internalizing disorder or control date. Quartile range of values in Q1, Q2, Q3, and Q4 UNGD activity metric were −2.37 to −0.52, −0.52 to 0.06, 0.06 to 0.71, and 0.71 to 177.35, respectively. The global test for effect modification (Model 8C) was X² (3, N = 33,294) = 11.5, p = 0.009.