As hypothesized, COVID-19-related discrimination was associated with subsequent PTSD symptom severity in hospital staff. The findings were consistent throughout the models with different adjustments. While our findings align with the previous cross-sectional study suggesting the association between COVID-19-related discrimination and PTSD symptom severity [14], this study is the first to show the longitudinal association that allows causal interpretation.
For PTSD symptom severity, we evaluated intrusive images, nightmares, and physical reactions when reminded of the trauma, corresponding to B1, B2, and B5 of the DSM-5 criteria, respectively [15]. Note that we did not evaluate other symptoms, namely reliving of the trauma (B3) and being emotionally upset when reminded of the trauma (B4) [26]. While COVID-19-related discrimination was associated with subsequent PTSD symptom severity, such association may appear counterintuitive given that the discrimination per se may not fulfill the criterion A for PTSD defined by DSM-5, i.e., exposure to actual or threatened death, serious injury, or sexual violence [15]. In this context, our study examined the indirect pathway from COVID-19-related discrimination to PTSD symptom severity and showed that 28.1–38.8% of the association was indeed mediated by psychological distress. Thus, such discrimination may initially lead to increased psychological distress, which, in turn, may result in greater PTSD symptom severity. Our study adds evidence on the mechanism of the association between COVID-19-related discrimination and subsequent PTSD symptom severity. Furthermore, our findings may help guide future studies investigating the mechanism for other kinds of discrimination associated with PTSD, e.g., racial discrimination [27].
Based on the presented association between COVID-19-related discrimination and PTSD symptom severity in hospital staff, mediated by psychological distress, clinical and public health interventions could be strategically designed. From a mechanistic standpoint, intervening in this psychological distress may potentially be meaningful, although the proportion mediated in our study does not necessarily suggest that the portion can be actually eliminated by interventions. These interventions may include stress management strategies within the workplace context [28, 29]. In addition, performing regular mental health assessments may help identify those at risk of PTSD symptoms. On a broader scale, public health initiatives may offer anti-discrimination campaigns that help reduce the overall level of discrimination [30, 31].
Several limitations should be acknowledged here. First, our sample size was 660, which was not sufficient to obtain other estimates such as risk difference and risk ratio. While the association found in this study may be plausible, the interpretation of β is not as straightforward as that of risk difference and risk ratio for dichotomous outcomes. Three-item PDS has a validated cutoff [18], and analyzing the dichotomous presence of PTSD in a larger sample may provide more easily interpretable information. Second, we used self-report measures, which might have resulted in measurement bias. This applies to the exposure (COVID-19-related discrimination) and mediator (psychological distress) as well as the outcome (PTSD symptom severity). Third, we carefully controlled for potential confounders, including the preexisting outcome and mediator, using the disjunctive cause criterion [20]. Nevertheless, unmeasured confounders such as other psychosocial factors might still have introduced some bias. Finally, the hospital staff consisted of an Asian-dominant population, more than 99% of whom were vaccinated. Also, COVID-19-related discrimination might happen in a highly heterogeneous manner, dependent on regions or countries. Taken together, caution should be exercised when generalizing our findings to different populations and settings.