The effect of earthquake hazards induced by natural gas mining on Medically Unexplained Physical Symptoms and psychosocial problems: a longitudinal analysis.

Study/Objective: To determine whether the chronic threat of exposure to mining-induced earthquakes in the northern part of the Netherlands, is accompanied by a higher prevalence of medically Unexplained Physical Symptoms (MUPS) and psychosocial problems. Background: The Groningen natural gas field is among the largest in the world and uniquely located in a populated area. Decades of mining activities burdened the region with increased earthquake hazards, several times higher than 3.0 on the Richter scale (one 3.6, in 2012). Inhabitants were confronted with ground shaking, damaged houses, loss of livelihood, social unrest, and public anger towards the mining company and authorities. In 2013 future earthquakes with a magnitude over 5.0 were considered likely, contributing to lack of positive prospects and chronic stress: factors that are not beneficial from a public health perspective. Methods: Data covering a five-year period (2011-2015), was extracted from electronic patient records of general practitioners. Two dependent variables were constructed: MUPS (physical symptoms clustered per organ system) and psychological and social problems (mood and anxiety disorders, suicide and problems in personal relations or work). Statistical analysis was conducted in steps to test differences in prevalence in health issues in the earthquake region and a comparison group; and to determine the predictive value of gender, age, socioeconomic status, and earthquake magnitude and depth, considering the cross-classified data structure with patients nested in general practices and postal codes. Results: The results indicate whether the prevalence of MUPS and psychosocial problems was significantly higher in the earthquake region regardless of gender and age, after controlling for socio-economic status and earthquake magnitude and depth. Conclusion: The health impact of chronic stress linked to earthquake-threat could be determined apart from other relevant explanatory factors