gh-2020_2 DEF.qxp_Hrev_master 15/01/21 12:45 Pagina 236 Geospatial Health 2020; volume 15:886 Changes in geographic clustering of post-traumatic stress disorder and post-traumatic growth seven years after an earthquake in Cauquenes, Chile Marcelo Leiva-Bianchi,1 Carlos Mena,2 Yony Ormazábal,2 Carlos Serrano,1 Pedro Rojas1 1Faculty of Psychology, Laboratory of Methodology for Behaviour and Neurosciences, University of Talca; 2Faculty of Forestry Sciences, Geomatics Center, University of Talca, Talca, Chile possibilities, appreciation of life, PTSD symptoms, PTSD reac- Abstract tions and PTSD in total). The spatial identifications found could Recent findings indicate that both disruptive Post-Traumatic facilitate the comparison of mental health conditions in popula- Stress Disorder (PTSD) and healthy Post-Traumatic Growth tions and the impact of recovery programmes in communities (PTG) responses have some spatial distribution depending on exposed to disasters. where they are measured and the different degrees of exposure that people may have to a critical event (e.g., earthquake). Less is known about how these responses change as a function of space and time after these events. The objective of this study was to Introduction only enter deeper into this relationship analysing how PTSD and PTG During the course of life, people can be exposed to critical responses vary in their spatial distribution 6 and 7 years after an events, such as natural disasters, illness, unemployment, even the earthquake (such as the one that occurred on 27 February, 2010 in death of a loved one. Such events test adaptive capacity and can Cauquenes City, Chile). Spatial analyses based on Geographic alter people’s mental health both for the short and the long term Information Systems (GIS) were performed to detect global and (IASC, 2007). Notuse all people face these events equally, nor is their local geographic clustering. Investigating 171 (2016) and 106 resilience the same. For example, an earthquake can elicit disrup- (2017) randomly selected adults from Cauquenes, we demonstrat- tive responses, e.g., Post-Traumatic Stress Disorder (PTSD), anx- ed that 7 years after the event only 4 variables were spatially clus- iety, depression, substance abuse and suicidal ideation, although tered, i.e. personal mental strength, interpersonal relations, new healthy responses, such as Post-Traumatic Growth (PTG), social possibilities and appreciation of life), all of them PTG dimensions; support and resilience are also likely to emerge (Bonanno et al., This result contrasted with the situation the previous year (2016), 2005). These authors (2010) and Cairo et al. (2010) indicate that when 7 variables were clustered (total PTG, spiritual change, new disasters produce at most 30% of disruptive responses. Variables of exposure-protection to the event, such as social support, being farther from the epicentre or having fewer material losses (Leiva- Bianchi et al., 2017), are related to greater psychological well- Correspondence: Yony Ormazábal, Faculty of Forestry Sciences, being and the emergence of healthier responses, such as engage- Geomatics Center, University of Talca, Talca, Chile. ment in interpersonal contacts, beliefs about mutual helpfulness E-mail: [email protected] Tel.: +56.71.2201654. and benevolence (Kaniasty, 2012). In this sense, healthy responses of the PTG type are directly Key words: Post-traumatic stress disorder; post-traumatic growth; related to PTSDs. This dependency is presented as an illusion of earthquake; Geographic Information Non-commercialSystems; Moran’s I; Getis-Ord impact control in the face of a difficult event (Hobfoll et al., Gi*; Chile. 2007). Likewise, from the perspective of psychosocial impact, healthy responses are considered to correspond to the absence of Funding: This work was supported by the FONDECYT-Chile 1190578 disruptive responses and the appearance of adaptive responses and CONICYT Doctorado en Ciencias Humanas 21181845. (Leiva-Bianchi et al., 2017). This adaptation can be successful if the strategy is appropriate for the stressful event to which the indi- Conflict of interests: The authors declare no potential conflict of interests. vidual is exposed (Bonanno et al., 2004; Cheng, 2001). Furthermore, both the absence or presence of these responses and Received for publication: 7 April 2020. Accepted for publication: 6 September 2020. the exposure-protection before the event can be organized into continuums of healthy-disruptive and exposure-protection ©Copyright: the Author(s), 2020 responses, respectively. Four types of impact combine them: Licensee PAGEPress, Italy resilience (to respond in a healthy manner when exposed to a par- Geospatial Health 2020; 15:886 ticular event), trauma (to respond disruptively when exposed), doi:10.4081/gh.2020.886 safety, i.e. to be a bystander (to respond in healthy manner when protected) and paradoxical (to respond disruptively when protect- This article is distributed under the terms of the Creative Commons ed from the event) as proposed by Leiva-Bianchi et al. (2019). Attribution Noncommercial License (CC BY-NC 4.0) which permits any noncommercial use, distribution, and reproduction in any medium, pro- Impacts can have different trajectories over time (Bonanno, vided the original author(s) and source are credited. 2004), which makes the prevalence of disruptive or healthy respons- es vary according to when they are measured (Bonanno et al., 2010; [page 236] [Geospatial Health 2020; 15:886] gh-2020_2 DEF.qxp_Hrev_master 15/01/21 12:45 Pagina 237 Article Milliken et al., 2007). Recently, it has been discovered that both dis- Maule Region, Chile (Figure 1). The city is made up of the follow- ruptive and healthy responses have a special distribution that ing sectors and villages: the city centre (downtown) which concen- depends on where they occur and the different degrees of exposure trates the commercial activities in combination with the oldest res- that people may have before a shocking event (Leiva-Bianchi et al., idential sectors; in the Northwest, the “Los Poetas” and “Bombero 2019). Likewise, people may be exposed to more than one event of Venegas” suburbs, which are working-class residential sectors a similar nature at different times, in these exposure time periods, with medium urban development; in the Northeast, the both healthy and disruptive responses can coexist in the same person “Fernández” suburb is a residential sector with high poverty rates (Morland et al., 2008; Morgan et al., 2011; Leiva-Bianchi et al., and poor urban development; and in the South, the “Estación” sub- 2017). Natural disasters occur frequently in Chile (e.g., earthquakes urb that is a residential sector characterized by the higher income and tsunamis in 2010, forest fires in 2017 and droughts in 2012- and greater urban development. 2019) and when their size and severity are considerable with large The registered effects of the 27F earthquake in the county number of people affected, disaster areas are decreed by the govern- according to the post-earthquake survey of the Ministry of ment (Diario Oficial de la República de Chile, 2010; 2017; 2019). Planning (Ministerio de Planificación, MIDEPLAN, 2010) indi- The objective of this study is to enter more deeply into the interac- cate that 25.1% of the population experienced no damage, 41.3% tion between space and time that the disruptive or healthy responses minor damage, 16.2% major damage and 17.4% saw a total loss of have after a critical event such as a natural disaster. For this, the fre- their dwellings. By 2016, data collected for this study indicate that quency and spatial distribution of PTSD and PTG responses are 24.6% of the population experienced no damage, 32.2% minor compared, six and seven years after the earthquake of 27 February, damage, 19.9% major damage and 23.4% lost all of their 2010 (27F) in the urban nucleus of Cauquenes in Chile. dwellings. For its part, in 2017, it was registered that 7.5% experi- enced no damage, 17% minor damage, 30.2% major damage and 45.3% saw a total loss of their dwellings. Participants only Materials and methods From a total of 13,695 dwellings distributed over 466 blocks in the urban area of the Cauquenes borough (INE, 2019a), a sub-sam- Study site and impact ple or two-stage sample was built (the first stage was the urban The study was conducted in the urban centre of Cauquenes, blocks and usewithin these the dwellings). The participation of a suit- Non-commercial Figure 1. Localisation of the study area. [Geospatial Health 2020; 15:886] [page 237] gh-2020_2 DEF.qxp_Hrev_master 15/01/21 12:45 Pagina 238 Article able informant was required for each dwelling, e.g., a person over under study that present a global clustering. The index values can 18 and head of the household. The data were collected longitudi- range between −1 to +1, where a value near +1 indicates that the nally (same house and same person) during the months of July and variable tends to cluster, meaning that values registered for partic- September of 2016 and 2017. The estimates were subject to a max- ipants at one location are similar between neighbours; and a value imum error of 7.5%, a confidence level of 95%, a power of 80% near -1 indicates that higher and lower measurement values are and a maximum variance of 50%. In 2016, 171 people (65.5% heterogeneously distributed in the analysed area. The threshold women) participated and in 2017, a total of 106 people (70.8% distance used in the analyses for the searching ratio was 700 m, a women) (Table 1). The age group with the highest frequency was distance that represent a mean size of a suburb-sector of the city. the >65 years age-group (33.3%) in 2016 and the same (36.8%) in The Gi* local statistic (Ord and Getis, 1995) was used to anal- 2017. Although 38% of the original sample was lost in the survey yse the spatial correlation among post-traumatic indices of neigh- application in 2017, this percentage is within what is acceptable as bouring participants in order to detect statistically significant spa- indicated by the National Institute of Statistics (Instituto Nacional tial clusters of high value (hotspots) or the opposite (coldspots).