Associations between lifetime potentially traumatic events and chronic physical conditions in the South African Stress and Health Survey: a cross-sectional study

Exposure to potentially traumatic events (PTE) has been associated with a range of physical health problems (eg [1‐4]) with effect sizes similar to PTE-consequent mental health outcomes [5, 6]. This presents a significant public health concern given the rates of PTE occurrence and posttraumatic stress disorder (PTSD) prevalence in South Africa [7], and the high and rising burden of non-communicable diseases in Africa [8]. Thus, examining the link between PTEs, their mental health sequelae, and chronic physical conditions is important.

PTEs have been associated with a wide range of biomarkers (eg, immune system inflammation, cortisol response) representing mechanisms believed to underlie health problems [9]. Several disease states including cardiovascular disease [3, 10‐12], chronic pain [13‐16] and headaches [17], arthritis and other autoimmune diseases [4, 18‐20], pulmonary problems [3, 21, 22], Type II diabetes [23‐26], digestive problems [26], and even disease mortality [27, 28] have been related to PTEs. Studies examining violence exposure-witnessing or experiencing-including intimate partner violence, physical and/or sexual abuse [10, 29‐31], as well as motor vehicle accidents [32], and combat exposure [12, 14, 27], among other trauma types, suggest that exposure to PTEs and/or developing PTSD are risk factors for physical health conditions.

Despite this burgeoning literature, some key issues remain under examined. First, there is debate as to whether PTE exposure itself is a sufficient risk factor for poor health, or whether PTE sequelae, particularly PTSD, are necessary factors [33‐35] for chronic physical health problems. Relatedly, while several studies have shown a dose-response between exposure to number of PTEs and increased risk of physical health problems (eg [1, 17, 19, 36]), some reports suggest that cumulative PTE exposure may be confounded with PTSD [37‐39]. Unraveling these issues has important implications for public health policy, since prevalence rates of PTE exposure are significantly higher than PTSD [40]. Accordingly, this also has implications for how intervention efforts are targeted-will treating PTSD also address the risk for poor physical health sequelae, or is a more comprehensive preventive approach to trauma exposure warranted? Thus far, when compared to studies focused on specific types of trauma, findings from population-based studies that examine lifetime cumulative PTE exposure, including samples from the United States [19] and cross-national data [1, 41], suggest that exposure to PTEs and PTSD are independently associated with physical health outcomes. Based on these findings, this study sought to investigate the association between both the type and cumulative number of lifetime PTEs, and chronic physical conditions. Relatedly, this study also aims to provide evidence to guide interventions designed to address PTE sequelae and chronic physical conditions, particularly in South Africa. Second, it is notable that most studies examining the impact of PTEs on physical health have been carried out in the U.S. and other relatively high-income countries. There is some evidence to suggest that these associations may vary by country [1]. Additionally, previous work on PTEs and PTSD in South Africa has shown that these distributions differ significantly from those seen in more developed countries [7]. Therefore, this study also seeks to highlight areas of future inquiry to understand the impact of PTEs in South Africa.

This study found consistent evidence of associations between PTE exposures and increased risk for a wide range of chronic physical health conditions. These associations were independent of PTSD, other mental disorders, and sociodemographic factors. With respect to cumulative lifetime PTEs, findings suggest a linear dose-response association between number of PTEs experienced and prevalence of all physical conditions. This trend was most prominent with chronic pain, which was also the most prevalent physical condition. The dose-response relationship observed between multiple PTE exposures and increasing risk of a chronic physical conditions is well established in population-based [1, 19, 36, 37, 41] and other studies (eg [17, 21]).

This study is the first to examine the association between PTE exposure and chronic physical conditions in an African general population sample. Among other population-based studies controlling for mental disorders including PTSD, a 14-country cross-national study, and a U.S-based national sample, both reported increasing risk for a range of chronic physical health conditions with greater exposures to lifetime PTEs [1, 36]. However, in another study from the U.S, with a predominately African American sample, from Detroit, Michigan, Keyes and colleagues [19] reported a dose-dependent positive relationship only in relation to assaultive violence or other threats to physical integrity and risk of an arthritic condition. The study did not find similar associations for other types of PTEs or other health conditions.

Our study also found an increased risk of comorbidity in physical conditions with increasing numbers of PTEs. Specifically, those who reported only one lifetime PTE had a significantly higher risk for respiratory conditions only. Among individuals with two or more PTEs, the odds of having cardiovascular, respiratory, chronic pain, other problems, or any physical health condition, were significantly higher than those without PTE exposure. Finally, exposure to four or more PTEs was associated with increased risk of all the physical conditions examined. Our findings are consistent with studies suggesting “broad-spectrum effects” of PTEs and risk for a range of chronic physical problems [1, 41].

Compared to those individuals reporting no PTE exposure, respondents with any PTE exposure had increased odds of all assessed physical conditions. However, specific PTE types-sexual violence, physical violence, unexpected death of a loved one, and network PTEs-were associated with greater odds for most of the physical conditions assessed. While Keyes and colleagues (2013) found specific effects for assaultive violence or other threats to physical integrity only, our findings are more consistent with other studies reporting physical health problems following exposure to a range of PTEs [1].

This study also found that the odds of any type of physical condition were significantly higher for individuals experiencing any type of PTE except accidents or war events. It is possible that accidents may not show the same association with health outcomes because they maybe more likely to be acute single-incident stressors requiring short term biological adaptations, relative to other PTEs that are often repeated chronic stressors, which are associated with more biological wear and tear [52, 53]. With respect to war events, two other population-based studies [1, 36] have reported a similar lack of association with physical health problems. As previously noted in the literature, this finding may reflect the “healthy warrior” effect ie a sampling bias because individuals selected for deployment are medically screened and represent a healthier subset of a larger sample [1, 36, 54, 55], or they may be more likely to receive ongoing preventive medical attention [1, 55]. Another possibility is that the type of war-related PTE may moderate health outcomes; war veterans without direct combat exposure may not be at increased risk for certain health problems relative to those with combat exposure [56]. In our study, war exposure included a broad range of experiences (ie direct combat exposure, relief work or civilian presence in a war zone, refugee and purposely injured, and torturing or killing someone else). Thus, it is possible that certain types of war-related experiences may show different associations with physical conditions. Finally, it is plausible that PTE exposure during developmentally critical or sensitive periods in childhood may influence later health outcomes differently [57], and future studies should examine how timing of PTE exposure at various developmental stages influences chronic health problems.

Extant literature provides several possibilities for explanatory mechanisms for the associations between PTE exposures and chronic physical health outcomes. One possibility is that experience-dependent changes, in the context of chronic stressors such as PTEs may lead to abnormalities in multiple interlinked biological systems (eg, cortisol response, neurocognitive structure and function, immune functioning), which may underlie physical health outcomes [9]. Additionally, common posttraumatic reactions or behavioral coping mechanisms such as sleep problems [58], smoking [21, 59], or physical inactivity [28] may also underlie the observed associations. Finally, certain psychological coping styles (eg, emotional suppression) following PTEs may also influence physical health outcomes [9].

This study has important limitations. First, we relied on retrospective self-reports of PTE exposures, a method that is likely to underreport most events. Our use of a detailed PTE checklist may have mitigated the likelihood of under-reporting, but reporting bias cannot be completely eliminated [7]. Future studies should consider multi-method assessments for PTE exposures (eg, clinician interviews). Second, physical health conditions were also based on self-report. While self-reports have often shown concordance with physician or medical record diagnoses [60, 61], the possibility of misclassification cannot be ruled out. Finally, the cross-sectional observational nature of our study precludes causal attributions. However, our findings are in line with related longitudinal studies [62] which provide strong evidence associations between PTE and physical health outcomes. Future studies should build on this and related clinical guidelines [63, 64], and seek to evaluate the feasibility and utility of trauma-informed screenings/intervention in primary care.

This study adds to an increasing body of research suggesting that PTE exposure is not only a risk factor for mental disorders, but also for physical health conditions. Our findings also show that associations between PTEs and physical health conditions are not fully mediated by psychiatric disorders including common PTE sequelae (eg, PTSD). We found a dose-response association between cumulative exposure to PTEs and the odds of reporting chronic physical health conditions and believe that clinical evaluations of trauma survivors should consider assessments of mental and physical health.