A middle-aged woman attended a routine primary care visit. She felt well and had no significant medical history. Before leaving, a test is ordered “just in case.” This test leads to another referral and eventually to a diagnosis that no one was actively seeking. For weeks, she lived through the possibility of a serious illness that was ultimately ruled out. Clinically, no changes were observed. Psychologically, anxiety, fear, and lingering doubts persist.

Such situations are not uncommon and do not result from obvious medical errors. They occur daily in primary care clinics and hospitals across the US and Europe. Even well-intentioned protocols and screening programs have contributed, along with increasingly sensitive diagnostic tools that can detect even the slightest abnormalities. In the fine line between prevention and excess and between care and unnecessary intervention, a quieter form of harm emerges: iatrogenesis related to overdiagnosis and overtreatment of patients.

As an ethical and clinical response, a largely unknown concept has begun to gain focus in the healthcare debate: quaternary prevention (QP). It does not propose fewer medications. It promotes exercising medicine with greater prudence. The central question shifts from “What can we do?” to “What should we refrain from doing to avoid harming those we seek to protect?”

Redefining Iatrogenesis

Iatrogenesis was narrowly defined as a medical error or an unavoidable adverse effect of a properly indicated treatment. Today, the term is understood more broadly as any unintended harm caused by healthcare, even when that care conforms to accepted guidelines, protocols, or good practices.

This broader definition includes adverse drug reactions, procedural complications, excessive diagnostic and preventive interventions, cascades of unnecessary testing, and psychosocial harm arising from the labeling, uncertainty, or medicalization of everyday life.

These reframing shifts attention from individual clinician responsibility toward the systemic factors that generate harm: rigid protocols, performance-based incentives, diagnostic pressure, and a healthcare culture that tends to equate more intervention with better care. In this context, iatrogenesis ceases to be an isolated accident and becomes a structural risk to the health system.

Within this framework, QP, also termed P4, acquires its full meaning: deliberate action to protect patients from unnecessary medical interventions, particularly when the probable harm exceeds the expected benefit, even if those interventions are technically feasible or socially demanded.

Unlike traditional prevention, QP questions the indiscriminate use of screening, early diagnosis, and marginal benefit treatments. It is grounded in person-centered medicine, clinical communication, shared decision-making, and the clinician’s critical self-awareness in the face of overmedicalization. The objective is not to “do nothing.” It is important to act with greater awareness and prudence in the future.

The foundational work of Alberto Ortiz Lobo, MD, at the Centro de Salud Mental de Salamanca, Madrid, Spain, illustrates how prevention, screening, and treatment can generate harm across the entire care continuum. Although recent empirical evidence remains limited, these insights are essential for understanding the risks of intervening without a clear balance between harm and benefit, always considering alternatives, and exercising utmost caution to ensure patient safety and autonomy.

Primary Care

Much of the recent literature on iatrogenesis and QP relies less on classic quantitative trials and more on conceptual frameworks, qualitative studies, implementation projects, and policy analyses, primarily in primary care settings. This reflects the inherent difficulty in measuring the impact of interventions that have never been performed and in evaluating complex phenomena that are deeply dependent on the health system context.

A 2022 qualitative study published in Atención Primaria Práctica examined how family physicians understand and experience so-called “unnecessary medical interventions.” Through in-depth interviews, clinicians identified overdiagnosis, pressure to rigidly apply protocols, and tension between clinical guidelines and individual patient contexts as common sources of iatrogenesis.

This study describes primary care consultation as the natural setting for quaternary prevention, not because of a passive attitude but because clinicians must constantly decide when not to initiate a diagnostic or therapeutic cascade in asymptomatic populations. Primary care is especially vulnerable to preventive iatrogenesis, given the enormous population exposure to screening, vaccination, risk factor control, and periodic health examinations. These interventions often offer only modest benefits while carrying poorly visible potential harm.

A 2024 qualitative study in BMJ Open offers a complementary perspective from implementation science. Through interviews with experts and clinicians experienced in quaternary prevention, the authors identified facilitators and structural barriers to its real-world implementation. Facilitators include the quality of the patient-clinician relationship, continuity of care, training in critical thinking, and an organizational culture that tolerates clinical uncertainty. Barriers consistently cited include limited consultation time, large patient panels, quality indicators focused on activity volume, and institutional pressure to “do more.”

System Changes

Although QP is often conceptualized at the bedside, evidence indicates that its real-world impact depends substantially on organizational decisions and health policies.

One critical domain is medication-related iatrogenesis in primary care, particularly among older adults with multimorbidity and polypharmacy, a population repeatedly identified as high-risk. In this group, drug-related harm is not only clinical but also systemic, and much of it is preventable.

European implementation projects, such as STOP IATRO, which involve primary care services in Andalusia, Spain, address this challenge in the prevention of iatrogenesis. The project focuses on preventing adverse drug events and iatrogenic medication dependence through structured reviews and deprescribing strategies, which are clearly aligned with the principles of quaternary prevention. In its first phase, in 2024, the program assessed clinician and patient knowledge and practices. Subsequent training and pilot interventions in health centers and homes are planned for 2025-2026. These actions are grounded in the World Health Organization Integrated Care for Older People framework, which promotes integrated person-centered care for older adults.

From a broader perspective, the intervention framework proposed by Jian Yang and colleagues (2023) emphasized that medical innovation can both increase and help mitigate iatrogenesis. The authors recommend analyzing internal factors — clinical decision-making and local organization — alongside external drivers, such as health policy, incentives, and technology. Among these recommendations is the explicit integration of iatrogenesis into the patient safety system.

Taken together, these studies point to a consistent conclusion that protection against overuse and iatrogenesis cannot depend solely on individual clinical judgment. It requires policies that recalibrate protocols, quality metrics, and incentives. It also requires that deprescribing, declining to initiate, or de-escalating low-value interventions be recognized as legitimate and necessary components of high-quality evidence-based clinical practice.

Better Practice

Understood as a transversal response to medical overuse, QP centers on several actionable domains: critically reassessing screening programs, adjusting risk factor control targets to individual contexts, promoting deprescribing, and limiting low-yield diagnostic testing in low-risk populations. These strategies are no exception. They are integral to clinical practice and are grounded in the harm-benefit balance.

Qualitative and implementation studies consistently converge on the conditions required to enact these measures: relational continuity, adequate consultation time, and structured, shared decision-making. In addition, there is a need to train clinicians to communicate their uncertainty and manage their expectations. A substantial portion of overintervention stems not from knowledge deficits but from the difficulty in tolerating clinical uncertainty and systemic pressure to act.

Innovative strategies to reduce medicalization have emerged in Spanish primary care. The EvalRA project (2023) promotes social prescribing as an alternative to pharmacotherapy for problems such as loneliness, mild emotional distress, and subclinical anxiety. These models align closely with the principles of quaternary prevention by prioritizing community and psychosocial resources over diagnostic and pharmaceutical interventions, particularly in vulnerable populations.

However, Spain’s historically robust primary care system is now strained by workload pressure, lengthening wait times, and erosion of relational continuity, all of which are determinants of both overuse and avoidable iatrogenesis. The clinical dilemma does not disappear; rather, it has been redefined. How can we sustain prudent, person-centered medicine within systems that reward doing more than doing better?

Prudent Medicine

The woman who attended her routine visit never became ill. However, neither did she emerge unscathed. This cascade of unnecessary tests did not result in clinical sequelae. However, it leaves a residue of uncertainty, fear, and distrust.

Cases like this remind us that not everything technically possible is clinically desirable and that healthcare harm is not always measured in complications or diagnostic errors.

The QP does not offer definitive answers or immediate solutions. Rather, it is a challenge to daily practice and the health system itself. This is not an additional technique or a new protocol. It is a cultural shift that questions the logic of “just in case” intervention and refocuses on clinical judgment, the patient-clinician relationship, and shared deliberation about risks and benefits.

Integrating QP into health policies, medical education, and quality assessment does not weaken the medical field. It strengthens medicine as a reflective, person-centered practice capable of protecting patients from excess as well as deficiency.

Whether the health system is prepared to embrace this shift and measure quality and success by the interventions it does not perform remains an open question.

This story was translated from El Medico Interactivo, part of the Medscape Professional Network.