Manmade earthquakes and healthcare visits for anxiety disorders in Oklahoma, 2010–2019

Background: Since 2010, seismicity in Oklahoma has increased from wastewater injection. It remains unknown if these earthquakes have resulted in increased treatment seeking for mental healthcare services. Methods: Using data from a nationwide United States patient-level commercial and Medicare Advantage claims database from 2010 to 2019, we identified healthcare encounters for anxiety disorders using diagnostic codes and subclassified them as adjustment reaction; anxiety-related disorders; physical symptoms of anxiety; and stress disorders. With U.S. Geological Survey Advanced National Seismic System data, we generated county-level 6-month rolling counts of felt earthquakes (≥M 4) and linked them to patient residential county at the time of the healthcare visit. In this repeated measures, individual-level analysis we used generalized estimating equations to estimate the odds of monthly anxiety-related healthcare visits as a function of the frequency of ≥M 4 earthquakes in the previous 6 months. Results: We identified 4,594 individuals in Oklahoma observed from 2010 to 2019. For every additional five ≥M 4 earthquakes in the preceding 6 months, the odds of healthcare visits for stress disorders increased (odds ratio [OR] = 1.27; 95% confidence interval [CI] = 1.03, 1.57). We found no evidence of an association with adjustment reaction (OR = 1.05; 95% CI = 0.89, 1.23), anxiety-related disorders (OR = 0.96; 95% CI = 0.90, 1.03), or physical symptoms of anxiety (OR = 1.03; 95% CI = 0.98, 1.09). Conclusions: We report an association between increased frequency of felt earthquakes and treatment seeking for stress disorders. This finding should motivate ongoing study of the potential consequences of the oil and gas industry for mental health outcomes including anxiety disorders.