A home-based telehealth randomized controlled trial of skills training in affective and interpersonal regulation versus present-centered therapy for women veterans who have experienced military sexual trauma.

OBJECTIVE: This randomized trial tested the effectiveness of Skills Training in Affective and Interpersonal Regulation (STAIR) compared to present-centered therapy (PCT) delivered virtually to women veterans who had experienced military sexual trauma (MST) and screened positive for posttraumatic stress disorder (PTSD). METHOD: One hundred sixty-one eligible women veterans were randomized into the study. The primary outcome was clinician-assessed PTSD severity (Clinician-Administered PTSD Scale-5), while secondary outcomes included social support and several other symptom measures at posttreatment through 2- and 4-month follow-up. RESULTS: PTSD severity decreased in both conditions by posttreatment but significantly more (p = .028, d = 0.39) in STAIR (d = 1.12 [0.87, 1.37]) than PCT (d = .78 [0.54, 1.02]). STAIR was also superior in improving social support and emotion regulation and reducing depression and negative cognitions. Improvement in psychosocial functioning was moderate and did not differ between conditions. All changes were maintained through 2- and 4-month follow-ups. Dropout rates were low and did not differ (19.0% and 12.2%, respectively). CONCLUSION: STAIR provided superior outcomes compared to PCT regarding PTSD, social support, and multiple types of mental health problems among women veterans with MST. The application of STAIR to other populations with social support and related concerns warrants investigation. The substantial effect sizes for PTSD symptoms in both treatments suggest that they are practical alternatives for individuals who do not wish to participate in trauma-focused therapy and may increase engagement in mental health services. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

STAIR Narrative Therapy for complex posttraumatic stress disorder: Treating sexual and gender minority trauma.

BACKGROUND: Complex PTSD is a recent addition to the ICD-11 diagnostic system. AIMS: This case study describes the delivery of Skills Training in Affective and Interpersonal Regulation and Narrative Therapy (SNT), a flexible, multi-component therapy that addresses the symptoms of complex posttraumatic stress disorder. SNT balances interventions that address current-day stressors with those that reappraise the meaning of traumatic past events. This paper outlines 16 sessions of SNT with a 55-year-old gay man. DISCUSSION: The case analysis describes the ways in which SNT is relevant and effective in addressing the client's mulitple concerns. The skills work helped the client effectively  manage ongoing minority stress, discrimination, and micro-aggressions related to his identity as a gay man. Review and re-appraisal of his traumatic memories, which focused on the sudden death of his partner from AIDS along with discussion of events from his childhood that shaped his reactions to this loss, allowed the client to create a more integrated sense of self as well as a more compassionate view of himself. Implications regarding the relevance of SNT for sexual and gender minority individuals are discussed.

Healthcare utilization is a collider: an introduction to collider bias in EHR data reuse.

OBJECTIVES: Collider bias is a common threat to internal validity in clinical research but is rarely mentioned in informatics education or literature. Conditioning on a collider, which is a variable that is the shared causal descendant of an exposure and outcome, may result in spurious associations between the exposure and outcome. Our objective is to introduce readers to collider bias and its corollaries in the retrospective analysis of electronic health record (EHR) data. TARGET AUDIENCE: Collider bias is likely to arise in the reuse of EHR data, due to data-generating mechanisms and the nature of healthcare access and utilization in the United States. Therefore, this tutorial is aimed at informaticians and other EHR data consumers without a background in epidemiological methods or causal inference. SCOPE: We focus specifically on problems that may arise from conditioning on forms of healthcare utilization, a common collider that is an implicit selection criterion when one reuses EHR data. Directed acyclic graphs (DAGs) are introduced as a tool for identifying potential sources of bias during study design and planning. References for additional resources on causal inference and DAG construction are provided.

Comparing the Ratio of Therapist Support to Internet Sessions in a Blended Therapy Delivered to Trauma-Exposed Veterans: Quasi-experimental Comparison Study.

BACKGROUND: Blended models of therapy, which incorporate elements of both internet and face-to-face methods, have been shown to be effective, but therapists and patients have expressed concerns that fewer face-to-face therapy sessions than self-guided internet sessions may be associated with lower therapeutic alliance, lower program completion rates, and poorer outcomes. OBJECTIVE: A multisite quasi-experimental comparison study with a noninferiority design implemented in routine clinical care was used to assess webSTAIR, a 10-module blended therapy derived from STAIR (skills training in affective and interpersonal regulation) for trauma-exposed individuals delivered with 10 weekly therapist sessions (termed Coach10) compared to 5 biweekly sessions (Coach5). It was hypothesized that Coach5 would be as good as Coach10 in a range of outcomes. METHODS: A total of 202 veterans were enrolled in the study with 101 assigned to Coach5 and 101 to Coach10. Posttraumatic stress disorder (PTSD) symptoms, depression, emotion regulation, interpersonal problems, and social functioning measures were collected pre-, mid-, and posttreatment, and at a 3-month follow-up. Noninferiority analyses were conducted on symptom outcome measures. Comparisons were made of continuous and categorical measures regarding participant and therapist activities. RESULTS: Participants reported moderate to severe levels of baseline PTSD, depression, or both. Significant reductions were obtained in all symptom measures posttreatment and at the 3-month follow up. Coach5 was not inferior to Coach10 in any outcome. Therapeutic alliance was at an equivalently high level across the 2 treatment conditions; completion rates and web usage were similar. Total session time was substantially less for the Coach5 therapists than the Coach10 therapists. Both programs were associated with a low, but equal number of therapist activities related to scheduling and crisis or motivational sessions. CONCLUSIONS: A blended model delivered with 5 sessions of therapist support was noninferior to 10 sessions in individuals with moderate to severe symptoms. Future studies identifying patient characteristics as moderators of outcomes with high versus low doses of therapist support will help create flexible, technology-based intervention programming.

Increasing access to care for trauma-exposed rural veterans: A mixed methods outcome evaluation of a web-based skills training program with telehealth-delivered coaching.

PURPOSE: While rural veterans with trauma exposure report high rates of posttraumatic stress disorder (PTSD), depression, and functional impairment, utilization of health services is low. This pilot study used mixed qualitative and quantitative methods to evaluate the potential benefits of a transdiagnostic web-based skills training program paired with telehealth-delivered coaching to address a range of symptoms and functional difficulties. The study directed substantial outreach efforts to women veterans who had experienced military sexual trauma given their growing representation in the Veterans Healthcare Administration (VHA) and identified need for services. METHODS: Participants were 32 trauma-exposed veterans enrolled in rural-serving VHA facilities who screened positive for either PTSD or depression. Symptoms of PTSD, depression, emotion regulation, and interpersonal problems were assessed at baseline, midpoint, posttreatment, and 3-month follow-up. Veterans completed exit interviews to identify benefits and limitations of the program. RESULTS: Intent-to-treat analyses revealed significant symptom reduction for all outcomes, with large to moderate effect sizes at 3-month follow-up. Outcomes did not differ by gender or military sexual trauma status. Veterans' rating of the therapeutic alliance was high and interview responses indicated that the presence of the coach was critical to success in the program. CONCLUSION: This remotely delivered transdiagnostic intervention provided significant benefits across a range of symptoms and functional outcomes and was viewed positively by veterans. The results indicate that further research (ie, a randomized controlled trial) is warranted. Attention to the role of the coach as a means by which to increase engagement and retention in technology-delivered interventions is warranted.

A Resource Building Virtual Care Programme: improving symptoms and social functioning among female and male rural veterans.

Background: Veterans have higher rates of PTSD and depression compared to the general population and experience substantial functional impairment. Impairment in social functioning has been a significant concern among Veterans, particularly rural Veterans, who have limited access to mental health care and are at risk for social isolation. Objective: A mixed-method study was implemented to evaluate the feasibility and effectiveness of webSTAIR, a web-based skills training programme, paired with home-based telehealth sessions. It was hypothesized that the programme would lead not only to reductions in PTSD and depression but also to improvements in social functioning. Method: Participants were 80 trauma-exposed Veterans enrolled in rural-serving VHA facilities with clinically elevated symptoms of either PTSD or depression. The study directed substantial outreach efforts to rural women Veterans and those who have experienced military sexual trauma (MST). Results: Significant improvements were obtained with PTSD and depression symptoms as well as in social functioning, emotion regulation, and interpersonal problems at post-treatment and 3-month follow-up. Ratings of therapeutic alliance were high as were reports of overall satisfaction in the programme. There were no differences by gender or MST status in symptom outcomes or satisfaction. Conclusions: The results support the feasibility and effectiveness of this integrated telehealth web-based skills training programme for both male and female Veterans as well as for those with and without MST. The focus on resource building and improved functioning make this programme of particular interest. Further testing is warranted.

Antecedentes: Los veteranos tienen tasas más altas de TEPT y depresión en comparación con la población general y experimentan un deterioro funcional sustancial. El deterioro del funcionamiento social ha sido una preocupación importante entre los Veteranos, particularmente los Veteranos rurales, que tienen acceso limitado a la atención de salud mental y están en riesgo de aislamiento social, lo que contribuye significativamente a problemas de salud.Objetivo: Se implementó un estudio de método mixto para evaluar la viabilidad y efectividad de webSTAIR, un programmea de capacitación en habilidades basado en la web, combinado con sesiones de telesalud en el hogar. Se planteó la hipótesis de que el programmea conduciría no solo a reducciones en el trastorno de estrés postraumático y la depresión, sino también a mejoras en el funcionamiento social.Método: Los participantes fueron 80 Veteranos expuestos a traumas inscritos en el sistema VHA de servicio rural, con síntomas clínicamente elevados de TEPT o depresión. El estudio dirigió importantes esfuerzos de divulgación a las mujeres rurales Veteranas y aquellas que han experimentado un trauma sexual militar (TSM).Resultados: Se obtuvieron mejoras significativas con el TEPT y los síntomas de depresión, así como en el funcionamiento social, la regulación de las emociones y los problemas interpersonales en el postratamiento y en el seguimiento a los 3 meses. Las puntuaciones de la alianza terapéutica fueron altas, al igual que los informes de satisfacción general en el programmea. No hubo diferencias por sexo o estado de TSM en los resultados de los síntomas o la satisfacción.Conclusiones: Los resultados respaldan la viabilidad y efectividad de este programmea integrado de capacitación en habilidades de telesalud basado en la web para veteranos masculinos y femeninos, así como para aquellos con y sin MST. El enfoque en el desarrollo de recursos y la mejora del funcionamiento hace que este programmea sea de especial interés. Se requieren nuevos estudios.

Mujeres Fuertes y Corazones Saludables, a Culturally Tailored Physical Activity and Nutrition Program for Rural Latinas: Findings from a Pilot Study.

In the United States, Latino adults, compared with non-Hispanic white adults, are less likely to meet physical activity and dietary recommendations, and have higher rates of obesity. There is an urgent need for culturally adapted health promotion programs that meet the needs of the growing Latino population in the United States. We systematically adapted StrongWomen-Healthy Hearts, an evidence-based physical activity and nutrition program, for rural Latinas. This paper reports results from a pilot study of the adapted program. We used mixed methods to assess the feasibility and efficacy of the adapted program, Mujeres Fuertes y Corazones Saludables, in a nonprofit community organization serving rural Latinos. The intervention consisted of sixty-minute classes held twice weekly for 12 weeks and included 30 minutes of physical activity and 30 minutes of nutrition education. To assess efficacy, we used a one-group, pre⁻post design with overweight/obese, sedentary, middle-aged or older, Spanish-speaking rural Latinas (n = 15). Outcome measures included weight, height, body mass index (BMI), waist circumference, cardiorespiratory fitness, physical activity, dietary behavior, and self-efficacy for diet and physical activity. Process outcomes included attendance, end of class surveys, mid-program evaluation survey, and a post-program focus group. We calculated means and standard deviations, paproired t-tests, and Cohen's D effect size. Qualitative data were analyzed using qualitative description. Significant changes pre- to post-program included weight (-1.5 kg; p = 0.009), BMI (-0.6; p = 0.005), waist circumference (-3.0 cm; p = 0.008), 6-minute walk test (69.7 m; p < 0.001), frequency of sugar-added drink consumption (-0.7 servings; p = 0.008), fruit and vegetable intake (1.3 servings; p = 0.035), and physical activity self-efficacy (0.9 points; p = 0.022). Participants found the program motivating and enjoyable, and on average participants attended 62% of classes and fidelity was maintained. This pilot study suggests that this culturally adapted physical activity and nutrition program for rural Latinas shows promise in improving physical activity, diet, and obesity.

STAIR Group Treatment for Veterans with PTSD: Efficacy and Impact of Gender on Outcome.

Introduction: Group Skills Training in Affective and Interpersonal Regulation (STAIR) is an evidence-based, manualized treatment for individuals with post-traumatic stress symptoms, that focuses on improving functioning through mood management (e.g., emotion regulation) and relationship skills development. To date, no study has evaluated the potential benefit of group STAIR among Veterans. Feasibility of delivering STAIR in a mixed-gender group format and the potential impact of gender on outcome were examined. Materials and Methods: Participants (n = 39) were Veterans enrolled in a post-traumatic stress disorder (PTSD) Clinic at a large VA Medical Center. Veterans participated in one of four mixed-gender STAIR groups and completed self-report questionnaires of PTSD symptoms and general psychological distress at pre-treatment and post-treatment. Institutional review board approval was obtained for this study. Results: There was significant pre-treatment to post-treatment improvements in PTSD symptoms as measured by the Post-traumatic Stress Checklist (PCL) (Cohen's d = 0.91), as well as in general psychological distress as measured by the Brief Symptom Inventory (BSI) (Cohen's d = 0.90). Change in PTSD symptoms from pre-treatment to post-treatment did not differ across gender. However, the interaction between gender and time on change in (BSI) was significant, where change in general psychological distress significantly decreased from pre-treatment to post-treatment for male Veterans but not for female Veterans. Conclusion: The results from this study demonstrate the feasibility and initial effectiveness of STAIR delivered in a mixed-gender group format for Veterans with PTSD. It should be noted, however, that male Veterans benefited more from this approach than female Veterans. The findings suggest the value of investigating Veterans' attitudes and beliefs about the benefits and drawbacks of mixed-gender group therapy for trauma-related difficulties.

Self-Compassion and Responses to Trauma: The Role of Emotion Regulation.

Emerging literature suggests that self-compassion may be an important concept for understanding recovery from the impact of trauma and posttraumatic stress disorder (PTSD). The present study explored the interconnection among self-compassion, resilience, emotion dysregulation, and PTSD symptom severity in a sample of treatment-seeking women with PTSD. We predicted that self-compassion would be negatively related to PTSD symptom severity and to emotion dysregulation, and positively related to resilience. The results supported our main hypotheses. In addition, emotion dysregulation mediated the relationship between PTSD symptom severity and self-compassion and affected the relationship between self-compassion and resilience. These findings corroborate previous research that points to the important role of self-compassion in mental health and in the aftermath of stressful life events. The present study expands this research by demonstrating that PTSD symptom severity is negatively related to self-compassion in a clinical population of women with experiences of severe and repeated interpersonal trauma.

Mujeres Fuertes y Corazones Saludables: adaptation of the StrongWomen -healthy hearts program for rural Latinas using an intervention mapping approach.

OBJECTIVE: To describe our use of intervention mapping as a systematic method to adapt an evidence-based physical activity and nutrition program to reflect the needs of rural Latinas. METHODS: An intervention mapping process involving six steps guided the adaptation of an evidence based physical activity and nutrition program, using a community-based participatory research approach. We partnered with a community advisory board of rural Latinas throughout the adaptation process. RESULTS: A needs assessment and logic models were used to ascertain which program was the best fit for adaptation. Once identified, we collaborated with one of the developers of the original program (StrongWomen - Healthy Hearts) during the adaptation process. First, essential theoretical methods and program elements were identified, and additional elements were added or adapted. Next, we reviewed and made changes to reflect the community and cultural context of the practical applications, intervention strategies, program curriculum, materials, and participant information. Finally, we planned for the implementation and evaluation of the adapted program, Mujeres Fuertes y Corazones Saludables, within the context of the rural community. A pilot study will be conducted with overweight, sedentary, middle-aged, Spanish-speaking Latinas. Outcome measures will assess change in weight, physical fitness, physical activity, and nutrition behavior. CONCLUSIONS: The intervention mapping process was feasible and provided a systematic approach to balance fit and fidelity in the adaptation of an evidence-based program. Collaboration with community members ensured that the components of the curriculum that were adapted were culturally appropriate and relevant within the local community context.

Case Reports: STAIR for Strengthening Social Support and Relationships Among Veterans With Military Sexual Trauma and PTSD.

Military sexual trauma (MST) is associated with high rates of post-traumatic stress disorder (PTSD) and multiple comorbid symptoms. In addition, women Veterans with MST report negative perceptions of social support, poor relationships, and difficulties in social and role functioning. Treatments for PTSD do not provide interventions to improve social or relationship functioning and do not consistently produce positive benefits regarding these outcomes. This article presents a series of case studies in which an intervention focused on building social support and relationship skills is delivered to Veterans with PTSD and MST. The intervention, Skills Training in Affective and Interpersonal Regulation (STAIR) promotes social engagement and skills that support greater role functioning. It can be used as a stand-alone treatment, as an adjunctive intervention to PTSD therapies or as part of a combination therapy in which skills precede trauma-focused work (STAIR Narrative Therapy). Further investigation is suggested to determine the added benefits of incorporating skills building to PTSD or other diagnosis-specific interventions.

Group trauma-informed treatment for adolescent psychiatric inpatients: a preliminary uncontrolled trial.

Despite high rates of trauma exposure (46%-96%) and significant posttraumatic stress disorder (PTSD; 21%-29%) symptoms in adolescent psychiatric inpatients, there is a dearth of research on effective interventions delivered in inpatient settings. The current report describes the development of Brief STAIR-A, a repeatable 3-module version of skills training in affective and interpersonal regulation (STAIR) developed for adolescents in inpatient care. An uncontrolled design was used to conduct a preliminary examination of the group intervention's effectiveness. Adolescent psychiatric inpatients (N = 38; ages 12 years-17 years) admitted to a public hospital participated in Brief STAIR-A and attended a median of 6 sessions (range 3-36). They completed measures of PTSD and depressive symptom severity, coping skill use, and coping efficacy upon admission and again prior to discharge. Participants reported significant reductions in symptom severity (d = 0.65-0.67), no change in the absolute level of coping skills used (d = 0.16), but greater coping efficacy when discharged from care (d = 0.75). Results from this pilot study suggest that this brief group treatment shows promise for treating adolescents' trauma-related difficulties in inpatient psychiatry settings, but additional research examining its effectiveness is essential.

A multi-site single-blind clinical study to compare the effects of STAIR Narrative Therapy to treatment as usual among women with PTSD in public sector mental health settings: study protocol for a randomized controlled trial.

BACKGROUND: This article provides a description of the rationale, design, and methods of a multisite clinical trial which evaluates the potential benefits of an evidence-based psychosocial treatment, STAIR Narrative Therapy, among women with posttraumatic stress disorder (PTSD) related to interpersonal violence who are seeking services in public sector community mental health clinics. This is the first large multisite trial of an evidence-based treatment for PTSD provided in the context of community settings that are dedicated to the treatment of poverty-level patient populations. METHODS: The study is enrolling 352 participants in a minimum of 4 community clinics. Participants are randomized into either STAIR Narrative Therapy or Treatment As Usual (TAU). Primary outcomes are PTSD, emotion management and interpersonal problems. The study will allow a flexible application of the protocol determined by patient need and preferences. Secondary analyses will assess the relationship of outcomes to different patterns of treatment implementation for different levels of baseline symptom severity. DISCUSSION: The article discusses the rationale and study issues related to the use of a flexible delivery of a protocol treatment and of the selection of treatment as it is actually practiced in the community as the comparator. TRIAL REGISTRATION: Clinicaltrials.gov identifier: NCT01488539.

Treatment for PTSD related to childhood abuse: a randomized controlled trial.

OBJECTIVE: Posttraumatic stress disorder (PTSD) related to childhood abuse is associated with features of affect regulation and interpersonal disturbances that substantially contribute to impairment. Existing treatments do not address these problems or the difficulties they may pose in the exploration of trauma memories, an efficacious and frequently recommended approach to resolving PTSD. The authors evaluated the benefits and risks of a treatment combining an initial preparatory phase of skills training in affect and interpersonal regulation (STAIR) followed by exposure by comparing it against two control conditions: Supportive Counseling followed by Exposure (Support/Exposure) and skills training followed by Supportive Counseling (STAIR/Support). METHOD: Participants were women with PTSD related to childhood abuse (N=104) who were randomly assigned to the STAIR/Exposure condition, Support/Exposure condition (exposure comparator), or STAIR/Support condition (skills comparator) and assessed at posttreatment, 3 months, and 6 months. RESULTS: The STAIR/Exposure group was more likely to achieve sustained and full PTSD remission relative to the exposure comparator, while the skills comparator condition fell in the middle (27% versus 13% versus 0%). STAIR/Exposure produced greater improvements in emotion regulation than the exposure comparator and greater improvements in interpersonal problems than both conditions. The STAIR/Exposure dropout rate was lower than the rate for the exposure comparator and similar to the rate for the skills comparator. There were significantly lower session-to-session PTSD symptoms during the exposure phase in the STAIR/Exposure condition than in the Support/Exposure condition. STAIR/Exposure was associated with fewer cases of PTSD worsening relative to both of the other two conditions. CONCLUSIONS: For a PTSD population with chronic and early-life trauma, a phase-based skills-to-exposure treatment was associated with greater benefits and fewer adverse effects than treatments that excluded either skills training or exposure.

Assessment of exercise-induced alterations in neutrophil function in horses.

OBJECTIVE: To evaluate the effects of a standardized exercise test to exhaustion in horses on leukocyte function ex vivo. ANIMALS: 6 Thoroughbred geldings. PROCEDURES: Blood samples were obtained from each horse before exercise; at exhaustion (termed failure); and at 2, 6, 24, 48, and 72 hours after exercise to evaluate hematologic changes, rate of leukocyte apoptosis, and leukocyte production of reactive oxygen species (ROS) ex vivo. To assess leukocyte function, leukocyte ROS production in response to stimulation with lipopolysaccharide, peptidoglycan, zymosan, and phorbol myristate acetate was evaluated. Apoptosis was evaluated via assessment of caspase activity in leukocyte lysates. RESULTS: In response to lipopolysaccharide, production of ROS by leukocytes was significantly increased at 2 hours and remained increased (albeit not significantly) at 6 hours after exercise, compared with the preexercise value. In the absence of any stimulus, leukocyte ROS production was significantly increased at 6 and 24 hours after exercise. In contrast, ROS production in response to phorbol myristate acetate was significantly decreased at 6, 24, and 72 hours after exercise. Leukocyte ROS production induced by zymosan or peptidoglycan was not altered by exercise. Leukocytosis was evident for 24 hours after exercise, and neutrophilia was detected during the first 6 hours. A significant increase in the rate of leukocyte apoptosis was detected at failure and 72 hours after exercise. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that strenuous exercise undertaken by horses causes alterations in innate immune system functions, some of which persist for as long as 72 hours after exercise.

Exercise-induced alterations in pro-inflammatory cytokines and prostaglandin F2alpha in horses.

Using an established standardized exercise test on a high-speed treadmill, thirteen Thoroughbred racehorses were exercised to fatigue (failure); blood samples were obtained before exercise, at failure, and at 2, 6, 24, 48, and 72 h after exercise. The exercise test induced a systemic inflammatory response characterized by a mild transient endotoxemia, leukocytosis, increased leukocyte expression of mRNA for tumor necrosis factor-alpha (TNF-alpha), IL-1 beta, and IL-6, and increased circulating concentrations of TNF-alpha and prostaglandin F2 alpha (PGF 2 alpha), with the most pronounced changes being evident at failure and 2h after exercise. Expression of mRNA for IL-6, TNF-alpha, and IL-1 beta was increased by 120-fold, three-fold, and four-fold, respectively, when compared to pre-exercise values. Plasma concentrations of 6-keto-PGF1alpha and PGE2 did not change in response to the exercise test. Collectively, these findings indicate that brief, strenuous exercise induces endotoxemia and a systemic pro-inflammatory response in horses that persists for at least 2h.

Effects of caffeine on exercise performance of physically fit Thoroughbreds.

OBJECTIVE: To determine the effects of a dose of caffeine (2.5 mg/kg, IV) administered to physically fit Thoroughbreds during incremental exercise testing to fatigue on a treadmill. ANIMALS: 10 conditioned Thoroughbreds. PROCEDURE: Horses were randomly assigned to receive caffeine or a control solution. Each horse received both treatments in a crossover design with a 3-week interval between treatments. Each horse was administered caffeine (2.5 mg/kg) or an equivalent amount of a control solution IV. One hour after injection, each horse performed an incremental exercise test to exhaustion. Hematologic values, heart rate, oxygen consumption, carbon dioxide production, plasma lactate concentration, urine and serum concentrations of caffeine and metabolites, and time until exhaustion were monitored. Statistical analysis was performed by use of a mixed-effects linear model. RESULTS: Significant differences in measured values when horses were treated with caffeine or the control solution were not detected. CONCLUSIONS AND CLINICAL RELEVANCE: A dose of caffeine (2.5 mg/kg, IV) appears to have no effect on any performance variable of physically fit Thoroughbreds during incremental exercise testing to fatigue.