International Journal of Technology 11(1) 167-179 (2020) Received August 2018 / Revised October 2018 / Accepted September 2019 International Journal of Technology http://ijtech.eng.ui.ac.id Human Factor Analysis and Classification System (HFACS) in the Evaluation of Outpatient Medication Errors Ari Widyanti 1* , Asyifa Reyhannisa 1 1 Laboratory for Work System Design and Ergonomics, Department of Industrial Engineering, Bandung Institute of Technology (ITB), Ganesa 10, Bandung 40132, Indonesia Abstract. Medication errors happen frequently, meaning there is an urgent need for a systematic analysis tool to minimize their occurrence. The aim of this study is to implement the Human Factor Analysis and Classification System (HFACS), a tool used in human error identification, in the case of outpatient medication errors. Nine such cases that occurred in a pharmacy unit of an Indonesian hospital were evaluated by 40 participants, consisting of the Head of the Pharmacy Department, the heads of units under this department, pharmacists, and staff of the Patient Safety Unit. An HFACS questionnaire developed by the United States Department of Defense was adopted in an Indonesian context. Each participant was asked to evaluate four or five cases of medication errors based on items in the questionnaire. The results show that the causes of such errors mainly lie in the layers of unsafe acts (performance-based error), precondition of acts (mental awareness), and organizational influence (an organizational instruction or policy which creates an unsafe situation). Breaking down the HFACS into its sublayers, the most prevalent causes of medication error found in this study were information overload and fatigue, although the level of agreement among the participants when giving HFACS ratings was low. The paper concludes by discussing the implications of the results. Keywords: HFACS; Medication error; Outpatient; Percentage of agreement 1. Introduction To err is human (Kohn et al., 2000); however, when errors are related to human life their negative consequences are crucial, which is particularly relevant in the case of errors occurring in hospitals. Research emphasis has been on errors in hospitals involving doctors, nurses and other hospital or healthcare system workers in relatation to patient safety, defined as “the prevention of harm to patients” (Institute of Medicine/IOM, in Aspden et al., 2004). Patient safety terms include error prevention; learning from errors that do occur; and a safety culture that involves health care professionals, organizations and patients. There are various types of error in the healthcare system. These can be classified according to where they occurred, incident reports, the individuals involved in the error, and system causes. One common error is related to medication, which is usually referred to as medication error (AHRQ, 2007), which is defined as “any preventable event that may cause or lead to inappropriate medication use or * Corresponding author’s email: widyanti@mail.ti.itb.ac.id, Tel.: +62-22-2508124 doi: 10.14716/ijtech.v11i1.2278