The goal of this clinical study is to evaluate whether a digital decision support tool integrated into the electronic medical record improves antibiotic prescribing in hospitalized patients with a reported allergy to penicillin.

Around 5 out of 100 hospitalized patients at our center have a penicillin allergy label in their medical record. However, this allergy is confirmed in less than 10 out of 100 cases. Despite this, more than 90 out of 100 of these patients receive alternative antibiotics that may be less effective or less aligned with clinical guidelines.

This study includes adults older than 16 years treated at Hospital Sant Joan de Déu de Manresa (Althaia) for infections that require systemic antibiotic treatment. Participants are those with a recorded penicillin allergy in their medical record or who report an allergy during their current hospital admission.

The main questions this study aims to answer are:

Does the use of a digital decision support tool increase the use of beta-lactam antibiotics (such as penicillins and cephalosporins) in patients with a reported penicillin allergy? Does the tool reduce the use of alternative antibiotic treatments that are less aligned with hospital guidelines?

Participants will receive standard clinical care. In addition, healthcare professionals will use a digital tool integrated into the electronic medical record. This tool supports clinical decision-making by assessing individual allergy risk and aligning antibiotic selection with hospital treatment guidelines.

The study will last approximately 15 months and will be conducted at a single hospital center.

Study design and setting

This is a prospective, open-label, single-center study conducted at Hospital Sant Joan de Déu de Manresa (Althaia University Healthcare Network). The study evaluates the implementation of a digital clinical decision support tool integrated into the electronic medical record (EMR) to optimize antibiotic prescribing in hospitalized patients with a reported penicillin allergy.

The study includes two phases:

Pre-implementation phase

A retrospective cohort is used to describe antibiotic prescribing patterns in patients meeting eligibility criteria before implementation of the digital tool. Patients are identified through a digital EMR filter implemented in March 2024 that detects hospitalized patients or emergency department visits longer than 16 hours with a recorded penicillin allergy label.

Post-implementation phase

A prospective cohort includes consecutive eligible patients after implementation of the digital decision support tool. Patients are included after providing informed consent.

Intervention and implementation strategy

The intervention consists of a digital decision support tool integrated into the EMR. The tool is structured as a decision tree adapted from the hospital's 2025 adult empirical antibiotic treatment guideline.

The tool systematically evaluates the individual risk of penicillin allergy and provides recommendations to support antibiotic selection according to hospital guidelines.

Implementation includes:

• Training sessions for emergency department physicians, who are the main prescribers of empirical antibiotics in this population.
• Hospital-wide dissemination campaign through EMR communication channels to promote awareness and use of the tool.

Study population and data collection

The study includes patients older than 16 years treated at the hospital for infections requiring systemic antibiotic therapy who:

• Have a documented penicillin allergy in the EMR, or
• Report a penicillin allergy during the current admission.

Data collected include:

• Demographic variables (age, sex).
• Clinical setting (emergency, medical, surgical, obstetric/gynecological, day hospital, dialysis units).
• Infection focus (respiratory, urinary, abdominal, skin/soft tissue, bloodstream infection, osteoarticular, central nervous system).
• Characteristics of reported penicillin allergy, including timing and type of reaction (immediate, delayed, immunological or non-immunological reactions).
• Allergy risk stratification using the PEN-FAST score.
• History of allergy to non-beta-lactam antibiotics.

Antibiotic treatment variables.

Antibiotic prescribing is recorded for empirical and modified treatments, including:

• Beta-lactams (penicillins, cephalosporins, carbapenems, monobactams).
• Alternative antibiotics (fluoroquinolones, glycopeptides, lipopeptides, oxazolidinones, aminoglycosides, lincosamides, sulfonamides, macrolides).

Data include:

• Start and end dates of empirical and modified antibiotic therapy.
• Treatment modifications and reasons (guideline adherence, targeted therapy, adverse reactions).
• Final antibiotic regimen after modification.

Outcomes and follow-up

Patients are followed until hospital discharge or day +30 after inclusion.

Outcomes include:

• Antibiotic prescribing patterns, including beta-lactam use.
• Guideline-concordant empirical therapy.
• Adverse drug reactions to beta-lactams.
• Changes in allergy label status after clinical evaluation.
• Hospital length of stay.
• In-hospital mortality and 30-day status (discharge, hospitalization, death).

Data management and statistical analysis

Data are collected in a secure REDCap database hosted by the institution.

Statistical analysis is performed using SPSS version 26. Categorical variables are expressed as frequencies and percentages. Continuous variables are expressed as mean ± standard deviation or median with interquartile range, depending on distribution. Normality is assessed using the Kolmogorov-Smirnov test.

Group comparisons are performed using chi-square or Fisher's exact test for categorical variables, and t-test or rank-sum test for continuous variables. Confidence intervals at 95% are reported for primary and secondary outcomes.

Study timeline

The study includes:

• Pre-implementation retrospective cohort
• Development and implementation of the digital tool
• Training and dissemination phase
• Prospective post-implementation recruitment
• Final data analysis and dissemination of results

Total study duration is 15 months.

Ethics and data protection

The study has been approved by the institutional ethics committee. It is conducted in accordance with the Declaration of Helsinki (2024 revision), Good Clinical Practice guidelines, and applicable Spanish and European data protection regulations (EU Regulation 2016/679 and Organic Law 3/2018).

All patient data are pseudonymized and stored securely. Retrospective data use is performed under applicable legal provisions for research use of pseudonymized health data without informed consent when authorized by the ethics committee.

Quality assurance and implementation procedures

The study includes EMR-based data validation and structured data extraction. The digital tool implementation is supported by clinician training and institutional communication strategies to ensure correct use and adherence.

Expected impact

The study aims to improve antibiotic prescribing in patients with reported penicillin allergy by increasing appropriate use of beta-lactam antibiotics, improving adherence to institutional guidelines, enhancing allergy documentation, and potentially reducing hospital length of stay.

Inclusion Criteria:

• Age ≥ 16 years
• Hospitalized patients
• Diagnosis of infection requiring systemic antibiotic therapy
• Documented penicillin and/or cephalosporin allergy in the electronic medical record or self-reported allergy during current admission
• For the retrospective cohort: patients previously admitted to hospital or emergency department (≥16 hours) with a recorded penicillin allergy label
• Ability to understand study information and provision of written informed consent (prospective cohort only)

Exclusion Criteria:

• Patients with a reported penicillin allergy who do not require systemic antibiotic treatment
• Patients admitted to intensive care or intermediate care units
• Patients receiving outpatient hospital care or dialysis units
• Patients in end-of-life care or receiving palliative care
• Patients receiving antibiotics for surgical prophylaxis only

The study population consists of hospitalized adult patients (aged 16 years or older) treated for infections requiring systemic antibiotic therapy, who have a documented or self-reported penicillin allergy. Participants are identified in a tertiary care hospital setting and include both patients treated before and after the implementation of a digital clinical decision support tool integrated into the electronic medical record.