Bernal’s Ecological Validity Model (EVM, Table 2) was used to produce a culturally adapted version of STAIR for Spanish speakers. The EVM consists of eight culturally sensitive elements that are important to strengthen the cultural relevance of interventions. These elements include language (whether it is appropriate and culturally syntonic); person (if the person is comfortable with the therapy relationship); metaphors (symbols and concepts included in the treatment manual that are common for the population); content (cultural relevance for Spanish-speaking persons); concepts (treatment concepts consonant with culture and context); goals (support of positive and adaptive cultural values); methods (cultural appropriateness of treatment methods); and context (consideration of contextual aspects, such as economic and social context). We used a multi-phase approach for the translation: translations (forward and backward), bilingual general clinicians’ review, bilingual veterans’ review, PTSD clinicians’ review, and STAIR group participants’ revision. This helped us address semantic and conceptual equivalence and the revision of the content, technical, and cultural appropriateness of the intervention for our study population. The aim was to use standard or neutral Spanish that Spanish-speaking populations could easily understand.

Table 2

Participants were recruited at the VA Caribbean Healthcare System using convenience sampling approaches. Eligible participants were mentally competent Puerto Rican Veterans, aged 21 or older, exhibiting PTSD symptoms and receiving treatment at the Primary Care level of care. Eligibility criteria required a T score of 50 or higher on the Inventory of Interpersonal Problems (IIP-32) and/or a score of 80 or more on the Difficulties in Emotion Regulation scale (DERS). Veterans with PTSD not in PC-MHI or with a cognitive impairment (Mini Mental State Examination (MMSE ≤ 23)) were ineligible.

The study was approved by both the Institutional Review Board and Research & Development Committee of the VA Caribbean Healthcare System and the Institutional Review Board of the Albizu University. The study followed the Universal Declaration of Ethical Principles for Psychologists, the International Ethical Guidelines for Biomedical Research Involving Human Subjects, and the declarations of the ISP regarding ethical behavior. All participants underwent the consent process, and the study adhered to ethical guidelines governing human subject research. Authors have no conflicts of interest to report.

After finishing the translation and cultural adaptation process of the manuals, symptomatology was measured at three critical points: baseline, session 8 (end of treatment), and one-month post-therapy. Participants were recruited, consented to, provided baseline documents, and randomized at baseline. Intervention group participants received a call to initiate group therapy, led by a VA clinical psychologist. Then, data collection occurred at the last therapy week and one month later, including a semi-structured interview ( Table 3) to continue assessing for semantic and conceptual equivalence, acceptability and feasibility of the intervention with the STAIR group participants. Treatment as Usual (TAU) group participants were scheduled for data collection a week in advance. Our proposed methods alongside the characteristics of the participants allowed us to assess the representativeness of the target population and culture towards obtaining sampling equivalence.

Table 3

Friedman’s ANOVA and descriptive statistics were applied to participants characteristics, primary outcomes (PCL-5, DERS, IIP-32) at 3 different time points (baseline, end-of-treatment and 1-month later), secondary outcomes CES-S and sociodemographic data, and treatment acceptability and feasibility (AIM, FIM) using SPSS, version 25. While content analysis was performed on the qualitative interview transcripts.

Culturally adapting an intervention using the EVM framework ensures the adapted version maintains external validity and increases engagement with the new target group (O'Connor et al., 2020). This study systematically adapted the intervention to Spanish, addressing all EVM components—language, goals, concepts, methods, content, persons, metaphors, and context—without losing the core components of the original manual. To enhance the final version, experts were involved at various stages, aligning with recommendations for language examination. The veterans who participated in the testing phase also contributed as experts, providing valuable insights into the adaptation process.

In the PCL-5, a 5–10-point change signifies reliable change, while a 10–20-point change is clinically significant. Participants in the STAIR group experienced clinically significant changes (13-23 points). This aligns with findings from another study comparing STAIR with TAU in primary care ( Jain et al., 2020) and with other Latino samples in English ( Jackson, et al., 2019; Guidiño, et al., 2015). The DERS results showed mixed outcomes, with two STAIR participants experiencing decreases in emotion dysregulation, while one increased, possibly due to attendance issues. In the IIP-32, STAIR participants did not report high interpersonal difficulties, indicating that STAIR did not worsen these issues. In contrast, one TAU participant displayed increasing levels of interpersonal difficulties. Overall, STAIR seemed effective in reducing PTSD symptoms and emotion dysregulation, while not exacerbating interpersonal problems.

The study aimed to assess the feasibility and acceptability of the STAIR intervention in a translated and adapted Spanish version. It is important to notice how the changes brought by COVID-19 pandemic to in-person services may have affected recruitment as this was the first group therapeutic intervention post-pandemic at VACHS. Three participants completed the STAIR intervention, and post-measures on acceptability and feasibility were obtained. The findings suggest that participants were able to understand the therapy concepts, improve emotion regulation, and the feasibility of conducting STAIR in a primary care setting, consistent with other studies exploring STAIR in various formats.

This study aimed to culturally adapt the STAIR therapy manual, assess symptom progression through a two-group comparison, and evaluate the feasibility and acceptability of the intervention in a primary care setting at VACHS. Despite STAIR's original design for sexual trauma, its effectiveness was observed in reducing PTSD symptoms among participants with military combat experiences. Notably, there were no dropouts in the STAIR group, highlighting the intervention's potential to align with patient goals and provide valuable strategies for trauma-related symptoms, emotion regulation, and interpersonal efficacy. This is particularly relevant with this population because when compared to non-Hispanic whites, Latinos rely more in primary care for mental health interventions ( Jones et al., 2018). Also, the study's outcomes contribute to expanding STAIR's applicability across languages, populations, and settings, addressing social justice principles, and improving access for Spanish-speaking veterans in the Caribbean. The availability of the adapted manual holds promises for enhancing psychosocial well-being and reducing health care disparities through improving access among Spanish speaking individuals undergoing STAIR therapy after traumatic experiences.

This study made significant contributions by culturally adapting the STAIR therapy manual in Spanish, assessing its acceptability and feasibility in a PC-MHI setting, and observing a reduction in PTSD symptoms among participants. However, certain limitations need consideration. Even when small sample size could cause analytical and design inconveniences, small sample research is critically important because it usually occurs when studying serious health concerns and vulnerable and underrepresented populations ( Etz & Arroyo, 2015). Furthermore, the proliferation of small sample studies has called for innovation in analyses that could provide reliable results despite sample size ( Etz & Arroyo, 2015). The present study had a small sample size that limited the generalizability of findings while the short follow-up duration prevented the sustainability of treatment gains over time. Additionally, budget constraints focused on translating and adapting the participant's manual, potentially restricting broader study scope. Despite these limitations, the study provides valuable insights into the use of a Spanish manual and its acceptability and feasibility at PCMHI. Future studies with larger sample sizes and a control group are needed to offer a more definitive, well-powered test of the current promising findings. Investigating STAIR with patients with depression lacking trauma exposure and examining the benefits of bilingual therapists as interventionists are worthwhile future directions. Furthermore, considerations for sampling methods and randomization strategies, particularly their impact on chronicity when comparing groups, should be explored in future studies.