Adverse Event

01Definitions and Core Concepts

The exam frequently tests whether you understand the distinction between an adverse event (AE) and an adverse drug reaction (ADR), because the two terms are not interchangeable even though they are often confused.

An adverse event is any unfavorable medical occurrence in a patient who has been administered a pharmaceutical product, and it does not require a proven causal relationship with the treatment. The definition is deliberately broad. A patient who develops pneumonia while taking metformin has experienced an adverse event, even if metformin played no role whatsoever. The ICH E2A guideline established this definition, and it is the standard used internationally, including in Indonesia where the equivalent Indonesian term is KTD (Kejadian Tidak Diinginkan).

An adverse drug reaction, by contrast, is a response to a medicinal product that is noxious and unintended and that occurs at doses normally used in humans for prophylaxis, diagnosis, or therapy. The critical difference is that an ADR implies at least a reasonable possibility of a causal relationship between the drug and the event. In Indonesian regulatory terminology, ADR is referred to as ESO (Efek Samping Obat).

A serious adverse event (SAE) is not defined by severity but by outcome. An adverse event is classified as serious when it results in death, is life-threatening, requires or prolongs hospitalization, causes persistent or significant disability or incapacity, results in a congenital anomaly or birth defect, or is a medically important event that may jeopardize the patient and require intervention to prevent one of the above outcomes. Notice that "serious" and "severe" are different concepts: a severe headache is not an SAE, while a mild stroke that requires hospitalization is.

A Suspected Unexpected Serious Adverse Reaction (SUSAR) is a reaction that meets all three criteria simultaneously: it is a suspected adverse reaction, it is serious, and it is unexpected (meaning its nature, severity, or outcome is not consistent with the product's reference safety information). SUSARs trigger expedited regulatory reporting.

02Classification of Adverse Drug Reactions

The extended Rawlins-Thompson classification is the most commonly tested framework. It divides ADRs into six types based on mechanism, predictability, and time course.

Type A reactions are the bread and butter of exam questions. They are predictable from the drug's pharmacology, dose-dependent, and account for roughly 80% of all ADRs encountered in clinical practice. They are generally manageable by dose reduction alone. Type B reactions, on the other hand, are pharmacologically unpredictable, tend to be host-dependent (immunological or genetic basis), and carry higher mortality. They account for the majority of drug withdrawals from the market.

Severity grading is a separate axis from seriousness. Each individual adverse event is also graded by the clinician on a three-tier scale:

An event can be severe without being serious (e.g., a severe migraine), and an event can be serious without being severe (e.g., a mild allergic reaction that causes bronchospasm needing emergency care). The exam loves to test this distinction.

03Causality Assessment Tools

The exam tests two causality assessment systems in particular. Knowing how each one works and when to apply each is important.

Naranjo Adverse Drug Reaction Probability Scale

The Naranjo algorithm is a structured, questionnaire-based tool consisting of 10 questions, each answered as "Yes," "No," or "Do Not Know." Each answer is assigned a point value, and the total score places the ADR into one of four probability categories.

The 10 Naranjo questions evaluate: (1) prior conclusive reports, (2) temporal sequence after drug administration, (3) improvement upon drug withdrawal (dechallenge), (4) reappearance on re-administration (rechallenge), (5) exclusion of alternative causes, (6) response to placebo, (7) drug detected at toxic concentrations, (8) dose-response relationship, (9) similar reaction to the same or similar drug on previous exposure, and (10) confirmation by objective evidence.

The key limitation of the Naranjo scale is that it does not account for drug-drug interactions and that many of the 10 questions frequently score as "Do Not Know" in real clinical practice, which limits discriminating power.

WHO-UMC Causality Assessment System

The WHO-Uppsala Monitoring Centre system is the globally recommended expert-judgment method. Unlike Naranjo, it does not use a numerical score. Instead, it assigns one of six categories based on clinical reasoning.

The WHO-UMC system is the method recommended by BPOM in Indonesia. The Naranjo scale is more commonly used in clinical research and bedside teaching because of its structured scoring format.

04Indonesian Regulatory Framework and Reporting

Legal Basis

On 23 February 2026, BPOM issued Regulation Number 4 of 2026 on the Implementation of Pharmacovigilance, which revokes and replaces the prior Regulation Number 15 of 2022. This regulation defines pharmacovigilance as end-to-end activities covering detection, assessment, understanding, communication, control, and prevention of adverse effects or other issues related to the use of products, including drugs, natural products, supplements, cosmetics, and quasi-drugs.

The regulation implements Article 410 paragraph (1) of Government Regulation Number 28 of 2024, which in turn is the implementing regulation of Law Number 17 of 2023 on Health.

Who Reports

ADR reporting in Indonesia is voluntary for healthcare professionals, who use the "Yellow Form" (Formulir Kuning), and for consumers through an online reporting system. However, reporting is mandatory for Marketing Authorization Holders (MAH) and manufacturers, who submit reports using the CIOMS form. Under BPOM Regulation 4/2026, every MAH in Indonesia must appoint a local pharmacovigilance responsible person (Penanggung Jawab Farmakovigilans), and must also designate an official deputy to ensure continuity.

Reporting Timelines Under BPOM Regulation 4/2026

The exam commonly tests which reporting deadline applies to which category of event. This table summarizes the current timelines.

Violations of these reporting provisions may result in administrative sanctions up to the temporary suspension of medicinal product registration activities, with a compliance adjustment deadline set for 26 February 2027.

KIPI (Kejadian Ikutan Pasca Imunisasi) / Adverse Event Following Immunization

For vaccine-related adverse events, Indonesia uses a parallel system called KIPI. KIPI is defined as any undesirable medical event occurring after immunization that does not necessarily have a causal relationship with the vaccine. WHO classifies AEFI into five categories:

In Indonesia, district or city health offices are required to report KIPI within 24 hours of case discovery. Provincial health offices or the Regional KIPI Committee (Komda PP KIPI) must report within 24 to 72 hours, and the Sub-directorate of Immunization or the National KIPI Committee (Komnas PP KIPI) must report within 24 hours to 7 days of case discovery.

Key Indonesian Pharmacovigilance Terminology

05Differential Terminology and Distractors

06Traps and High-Yield Pearls

The single most common trap in adverse event questions is confusing "serious" with "severe." A vignette might describe a patient with an intensely painful injection-site reaction (severe) and ask whether it qualifies as a serious adverse event. Unless that reaction leads to hospitalization, disability, or one of the other qualifying outcomes, the answer is no. The exam tests your understanding that seriousness is defined by consequence, not intensity.

The second common trap involves causality logic. Students often see a temporal association between a drug and an adverse event and immediately conclude the drug caused the event. The concept being tested is that temporal association alone does not establish causation. A "possible" Naranjo score means the event could be explained by the patient's underlying disease. A "probable" score requires that you can exclude alternative causes. A "definite" score demands positive rechallenge data, which is rarely available in clinical practice. The vignette will usually provide clues about dechallenge (the event improved when the drug was stopped) and rechallenge (the event recurred when the drug was restarted) to guide you.

The third trap involves Type A versus Type B reactions. A question might describe a patient taking an anticoagulant who develops bleeding. Students who recall that Type B reactions are "more dangerous" might incorrectly classify this as Type B. The correct answer is Type A, because bleeding is a predictable, dose-dependent extension of the drug's pharmacological mechanism. Type B reactions, by definition, cannot be predicted from the drug's known pharmacology.

Finally, for the Indonesian regulatory context, know that the 24-hour reporting deadline applies only to deaths following vaccination (AEFI/KIPI with fatal outcome). All other serious adverse events follow a 15-calendar-day timeline. Non-serious events have a longer window of 90 calendar days. A question that gives you a serious but non-fatal vaccine adverse event and asks for the reporting deadline is testing whether you incorrectly apply the 24-hour rule to all serious events, when in fact 15 days is the correct answer for non-fatal serious cases.

The core competency being tested across all adverse event questions is your ability to correctly classify, assess causality, and apply the appropriate reporting obligation to a clinical scenario. The examiner wants to see that you understand the regulatory and clinical framework, not just the clinical presentation.