The goal of this pilot study is to evaluate the feasibility and preliminary effectiveness of a brief auricular acupuncture program delivered by mental health nurses as a complementary therapy for adults hospitalized with borderline personality disorder (BPD). The main questions it aims to answer are:

• Is participation in the five-session auricular acupuncture program feasible (in terms of attendance) for hospitalized adults with borderline personality disorder?

• Does the auricular acupuncture intervention show potential benefits on emotional regulation, anxiety, sleep quality, and overall clinical status?

  15 hospitalized adults with BPD will receive 5 individual ear acupuncture sessions, over a 9-day period, based on the National Acupuncture Detoxification Association (N.A.D.A.) protocol in addition to treatment as usual. Participants will complete brief questionnaires at several time points. The findings will inform the feasibility of the study procedures and guide the development of a future larger-scale clinical trial.

The study "ACUPSY" is a single-center, quasi-experimental, single-arm pilot trial conducted in a French-speaking university hospital in Switzerland, designed to evaluate the feasibility and preliminary effectiveness of a brief auricular acupuncture intervention delivered by trained mental health nurses as a complement to treatment as usual (TAU) for adults hospitalized with borderline personality disorder (BPD).

Background and rationale Borderline personality disorder is associated with severe emotional and impulse dysregulation, high psychiatric comorbidity, and elevated risk of suicide. Despite relatively high reported levels of satisfaction (66-88%) and perceived helpfulness (64-90%) of mental health services, substantial variability exists across service types, diagnostic groups, and care settings. Among individuals with BPD, previous studies have identified significant unmet needs in symptom management, treatment satisfaction, and quality of life, with patients frequently reporting difficulty coping with persistent and severe symptoms.

Improving mental health care for individuals with BPD may benefit from the integration of empirically supported complementary therapies. This approach aligns with the growing interest among both patients and healthcare professionals in complementary and alternative medicine (CAM) for mental health care.

Acupuncture has demonstrated potential benefits in mental health settings, particularly for anxiety, depression, sleep disturbances, substance use, and emotional distress. The National Acupuncture Detoxification Association (N.A.D.A.) protocol is a standardized and accessible form of auricular acupuncture targeting three to five specific ear points and is widely used in behavioral health settings. However, the feasibility and potential benefits of brief auricular acupuncture interventions during psychiatric hospitalization for individuals with BPD remain unexplored.

This pilot study aims to generate preliminary evidence on feasibility and potential clinical effects to inform the design of a future larger-scale trial.

Study design The study uses a single-arm, pretest-posttest design. Fifteen adults diagnosed with BPD and hospitalized in psychiatric units at the Prangins site of the Lausanne University Hospital (CHUV) will be recruited using convenience sampling.

All participants receive the auricular acupuncture intervention in addition to TAU. There is no control group.

Intervention The intervention consists of a standardized auricular acupuncture program based on the N.A.D.A. protocol.

Participants receive five individual ear acupuncture sessions over a nine-day period, with 24 hours between consecutive sessions. Sessions are scheduled between 4:00 p.m. and 8:00 p.m. and are conducted in the participant's hospital room.

Each session is delivered by a mental health nurse certified as a N.A.D.A. practitioner. Sterile, single-use needles are inserted at five standardized auricular points bilaterally, according to the protocol. Each acupuncture session last 45 minutes.

Treatment as usual All participants continue to receive standard inpatient psychiatric care throughout the study period. TAU includes supportive psychotherapeutic approaches as well as symptom-focused pharmacological treatment, and multidisciplinary care provided by psychiatrists, nurses, physical therapists, occupational therapists, and social workers.

Participation in the study does not modify or restrict access to standard treatments.

Study procedures and data collection Following informed consent and baseline assessment (Day 0), participants complete a series of study visits and assessments across multiple predefined time points (Day 0 to Day 8 + Day 11).

The study includes six visits during the hospital stay:

• Five intervention visits corresponding to acupuncture sessions (Day 0, 2, 4, 6, 8, with a 24-interval between each sessions)
• One follow-up visit two days after completion of the intervention (Day 11, two days after the end of the program) Participants also complete brief self-administered questionnaires during the intervals between acupuncture sessions. Questionnaires may be completed independently on paper or with assistance from the study nurse if needed.

Baseline assessments include sociodemographic and health-related information. Repeated measures assess emotional regulation, anxiety, self-harm behaviours, relaxation, sleep quality, treatment satisfaction, clinical severity, and psychotropic medication use.

Attendance at each acupuncture session is recorded and serves as the primary outcome (feasibility). Additional feasibility indicators include recruitment rate, retention rate, questionnaire completion, and acceptability of procedures.

Safety monitoring The intervention is classified as minimal risk (category A). Sessions are conducted exclusively by certified nurses trained in the N.A.D.A. protocol.

Before and after each session, the nurse assesses for bruising, bleeding, localized pain, infection, vasovagal reactions, or other discomfort. Appropriate measures, including cold packs, antiseptic application, session adjustment, or discontinuation, may be applied if needed.

Participants have access to a call button during sessions and may pause or stop the intervention at any time without consequences.

All adverse events are documented. If a participant's mental health deteriorates (e.g., increased distress, agitation, or anxiety), the principal investigator may suspend participation and, with consent, inform the treating psychiatrist.

Recruitment and consent Potential participants are identified and pre-screened by the clinical team. Eligibility is then confirmed by a trained study nurse independent from the psychiatric units.

Participants receive oral and written study information and provide written informed consent before enrolment. Participation is voluntary, and participants may withdraw at any time without impact on their medical care.

Compensation Participants receive a CHF 20 Swiss francs gift card in a grocery store at the end of each study visit, for a maximum total compensation of CHF 120 Swiss francs. No costs are incurred by participants or their health insurers.

Data management and confidentiality Study data are collected using standardized case report forms and stored in a secure REDCap database. Participants are assigned unique identification codes. Personal identifying information is stored separately from study data.Data handling complies with Swiss data protection regulations and Good Clinical Practice guidelines.

Statistical considerations As a pilot study, the sample size is based on feasibility considerations rather than formal power calculation. The study aims to include 13 hospitalized patients with borderline personality disorder. Allowing an anticipated dropout rate of approximately 15%, a total of 15 participants will be recruited.

Statistical analyses will be primarily descriptive and exploratory. Feasibility outcomes will be summarized using attendance rates, retention rates, and questionnaire completion rates. Continuous variables will be described using means and standard deviations or medians and interquartile ranges, as appropriate, while categorical variables will be summarized using frequencies and percentages.

Changes in clinical outcomes over time will be explored using within-subject comparisons across measurement time points. Depending on data distribution, appropriate parametric or non-parametric methods will be applied (e.g., paired t-tests or Wilcoxon signed-rank tests). When relevant, exploratory longitudinal analyses may be conducted to examine trends across repeated measurements.

Missing data patterns and dropout rates will be examined and reported. No formal hypothesis testing or adjustment for multiple comparisons is planned, as the study is not powered for confirmatory analyses.

Results will be used to refine study procedures, assess outcome measure sensitivity, and inform sample size estimation and design considerations for a future randomized controlled trial.

Dissemination Study findings may be presented at scientific conferences and published in peer-reviewed journals. Only aggregated data will be reported. Individual participants will not be identifiable in publications.

Inclusion criteria

• Aged 18 years or older
• Currently hospitalized in a psychiatric unit at the Prangins site of Lausanne University Hospital (CHUV)
• Diagnosed with borderline personality disorder, as documented in the medical record
• Able to speak and understand French
• Able to communicate verbally
• Clinically stable enough to participate, as determined by the healthcare team
• Able to understand the study information and provide written informed consent

Exclusion criteria

• Presence of severe clinical instability, such as: marked agitation, high risk of suicide, risk of harm to others
• Inability to provide informed consent (for example, due to impaired judgment or legal protective measures)
• Currently hospitalized in a seclusion or isolation room
• Expected discharge from hospital before completion of the five acupuncture sessions
• Current treatment with anticoagulant (blood-thinning) medications
• Current treatment with immunosuppressive medications
• Currently receiving acupuncture treatment for any reason
• Received acupuncture within the past three months for anxiety, emotional regulation, relaxation, or sleep problems
• Participation in intensive behavioral therapy programs outside usual care that target similar outcomes
• Presence of skin lesions, irritation, or infection on the ears
• Severe fear of needles
• Inability to remain still during acupuncture sessions

Aggregated study results will be made publicly available through scientific publications and presentations. Data handling complies with Swiss data protection regulations.