Adverse Drug Event Trigger Tool: A Practical Methodology

The article “Adverse drug event trigger tool: a practical methodology for measuring medication related harm” by J. D. Rozich, C. R. Haraden, and R. K. Resar, published in Quality and Safety in Health Care, introduces a modified and practical methodology for identifying and quantifying Adverse Drug Events (ADEs) in hospital inpatients. This approach was developed to address the significant and persistent challenge of medication-related harm, which is recognized as the single most frequent source of healthcare mishaps, continuously putting patients at risk.

Here is a more detailed breakdown of the methodology and its significance:

The Problem with Traditional ADE Detection

• High Incidence of Harm: Despite efforts, medication errors and ADEs remain the largest source of repetitive healthcare mishaps, endangering and often harming patients.
• Ineffective Traditional Methods: Historically, assessing the actual safety of drug use has been difficult because traditional methods like chart audits and voluntary reporting are expensive, insensitive, and largely ineffective for detecting mistakes in drug administration and drug-related adverse clinical events. These methods often fail to accurately capture the true rate of ADEs.

Classen’s Original “Trigger Tool” Methodology

The new methodology builds upon a pioneering computerized approach developed by Classen:

• Computerized Surveillance: Classen developed an electronic ADE monitor that used customized software linked to an integrated hospital information system, including pharmacy databases.
• Sentinel Signals (“Triggers”): This system identified specific events or “triggers” in a patient’s medical record that could indicate a potential ADE. These triggers included the ordering of certain drugs, antidotes, specific abnormal laboratory values, and abrupt medication stop orders.
• Rapid and Comprehensive Review: This electronic screening provided a rapid, comprehensive, and near “real-time” review of a patient’s medical record, without requiring staff time for the initial screening.
• Limitations of Original Tool: Despite its effectiveness in circumventing labor-intensive chart reviews, Classen’s method was expensive and required specialized software, limiting its applicability due to fiscal and technological constraints in many hospitals.

Development of the Modified “Low Tech” Trigger Tool

Recognizing the limitations of Classen’s original tool and the widespread need for a more accessible solution, the Institute for Healthcare Improvement (IHI) and Premier (a healthcare alliance) developed a modified, “low tech” and relatively low-cost version of the trigger tool.

• Collaborative Effort: In January 2000, IHI and Premier convened a group of experts from various healthcare organizations to develop a model for redesigning the medication system, with a key requirement being a robust measurement tool for ADEs applicable throughout the healthcare system.
• Focus on Harm (ADEs) over Errors: A critical distinction made during development was the focus on Adverse Drug Events (ADEs) rather than medication errors.
  • Medication Error: Defined as any mishap or mistake in drug administration, which may not always result in negative clinical effects. It is process-focused.
  • Adverse Drug Event (ADE): Defined by the World Health Organization (WHO) as “a response to a drug which is noxious and unintended and which occurs at doses normally used in man for prophylaxis, diagnosis, or therapy of disease, or the modification of physiological function“. ADEs are outcome-focused, directly linked to patient harm, and include unintended effects even if the drug was administered appropriately. This shift in focus prevents organizations from concentrating efforts on errors that yield only marginal reductions in patient harm.
• Harm Classification: Identified ADEs were further classified using the National Coordinating Council for Medication Error Reporting and Prevention (NCC MERP) index, which categorizes harm from Category E (temporary harm requiring intervention) to Category I (harm contributing to patient death).

How the Modified Trigger Tool Works

The modified trigger tool aims for broad applicability by training medical staff to audit charts without relying on electronic clinical databases, which are often unavailable.

• Expanded Triggers: The tool utilizes an expanded list of 24 specific “triggers” (T1–T23, with T24 customized for each institution) to initiate a detailed chart review [20, 22, Appendix 1]. These triggers fall into several categories:
  • Antidotes/Reversing Agents: Such as diphenhydramine (T1) for hypersensitivity reactions, Vitamin K (T2) for over-anticoagulation with warfarin, flumazenil (T3) for benzodiazepine oversedation, and naloxone (T5) for narcotic oversedation.
  • Other Medications/Agents: Including antiemetics (T4) for nausea/emesis related to drug use, antidiarrheals (T6), and sodium polystyrene (T7) for hyperkalemia.
  • Abnormal Laboratory Values: Such as PTT >100 seconds (T8) or INR >6 (T9) indicating over-anticoagulation, WBC <3000 (T10) for neutropenia, serum glucose <50 mg/dl (T11) for hypoglycemia, rising serum creatinine (T12) for renal insufficiency, and various toxic drug levels (e.g., Digoxin T14, Lidocaine T15, Gentamicin T16, Vancomycin T18, Theophylline T19).
  • Clinical Findings/Events: Including Clostridium difficile positive stool (T13) related to antibiotic exposure, oversedation, lethargy, falls (T20), rash (T21), abrupt medication stop (T22), and transfer to higher level of care (T23).
• Two-Phase Chart Review Process:
  1. Initial Screening: Reviewers examine specific sections of closed patient charts (e.g., discharge summary, procedure notes, physician progress notes, laboratory reports, medication administration records, nursing notes) for the presence of any of the 24 triggers.
  2. Detailed Review and Judgment: If a trigger is found, a more detailed review of the chart is conducted by trained healthcare professionals (experienced nurses, pharmacists, physicians, or medical staff with a medical background) to determine if the trigger was indeed in response to an ADE. This requires professional judgment to discriminate between an ADE and other uses of medications (e.g., diphenhydramine used for an allergic reaction vs. for sedation).
• Review Standards: Reviews are conducted on closed charts with a minimum hospital stay of 2 days, chosen randomly (excluding obstetrics and behavioral health). A goal of 20 minutes per chart review was set, and medication doses were determined by financial data or administration records.

Testing and Results

The trigger tool was tested on a broad scale across 86 hospitals in four different medication safety collaboratives, reviewing 2837 patient charts and over 268,000 medication doses.

• Feasibility and Training:
  • Healthcare professionals could be quickly and competently instructed in the trigger tool methodology.
  • Training new reviewers took an average of 30–60 minutes.
  • A “buddy system” was recommended for the first 10 charts to confirm competency.
  • The two-person pilot teams consistently demonstrated the operational feasibility of the trigger tool and that training was straightforward.
• Increased ADE Detection Rate: The modified trigger tool methodology significantly increased the rate of ADE detection. In a subset of hospitals with experience in chart review, only five (1.8%) of the 274 ADEs found by the trigger tool were identified by traditional reporting methodologies such as incident reports, pharmacy interventions, or E codes. This indicates an approximately 50-fold increase in ADE detection compared to traditional methods.
• Consistency and Reproducibility: The methodology proved feasible to implement and consistently reproducible across different inpatient organizations. ADE rates per 1000 doses were consistent across various hospital groups (average of 2.68, ranging from 2.47 to 4.81).
• Scope and Extent of ADEs:
  • Out of 2837 charts reviewed, 720 ADEs were identified from 268,796 medication doses delivered.
  • The majority of ADEs (79.9%) were classified as Category E (temporary harm requiring intervention) according to NCC MERP.
  • More serious harm was also detected, including Category H (requiring life-sustaining intervention, 4.7%) and Category I (contributing to patient death, 1.8%).
  • The most frequently positive trigger was the use of an antiemetic (T4), found 916 times, leading to 64 ADEs.
  • The trigger with the highest percentage yield of ADEs was an “abrupt medication stop” (T22), found 248 times with 86 ADEs attributed to its use (35% yield).

Utility and Limitations

• Intended Use: The trigger tool is designed to serve as a standard for examining ADEs within an institution to establish a baseline rate of ADEs and track changes over time. It helps organizations monitor the effectiveness of safety initiatives and pinpoint high-risk environments.
• Not for Benchmarking: Importantly, the tool should not be used as a benchmarking tool between institutions because its accuracy had not been validated across diverse settings, and cross-institutional comparisons could be counterproductive.
• Benefits: It provides a mechanism for longitudinally monitoring the effect of system changes and whether those changes have resulted in improvement. It also offers a focused analysis of clinical events previously hidden from routine assessment and eliminates wasted effort on quantifying errors that do not lead to harm.
• Limitations: Potential limitations include the lack of a “gold standard” for assessing the true rate of ADEs, which can lead to confusion and underreporting. While the study suggests minimal interobserver variation, this remains a potential concern, as does the generalizability of the methodology across all healthcare organizations and diverse reviewer sophistication.

In conclusion, the modified trigger tool methodology provides a practical, efficient, and reproducible method for quantifying ADEs in inpatients, significantly outperforming traditional detection methods. Its “low tech” and low-cost nature makes it widely applicable, offering a valuable instrument for improving patient safety within healthcare institutions by focusing on actual harm and monitoring the effectiveness of safety interventions.

Reference: Rozich, J. D., Haraden, C. R., & Resar, R. K. (2003). Adverse drug event trigger tool: a practical methodology for measuring medication related harm. Quality and Safety in Health Care, 12(3), 194–200.