Adherence describes the degree to which a person’s behavior corresponds with the recommendations agreed upon with a healthcare provider. These recommendations extend beyond simply taking medication and include following dietary changes, attending appointments, or completing a course of physical therapy. Adherence is a dynamic process, not a fixed state, which can fluctuate over the course of a patient’s life and treatment plan.
Non-adherence is the failure to follow medical advice or instructions, representing a significant challenge in managing chronic conditions such as diabetes, hypertension, and heart disease. When patients do not consistently follow a prescribed regimen, the intended therapeutic effect is compromised, diminishing positive health outcomes and preventing disease control.
Defining Non-Adherence and Its Forms
Non-adherence is categorized into two types based on the point in the treatment timeline when failure occurs. Primary non-adherence describes the situation where a patient is given a prescription but never actually fills it or picks it up from the pharmacy. This means the prescribed therapy is never initiated. Studies have shown that this can occur for nearly one-third of new prescriptions in certain patient groups.
Secondary non-adherence occurs after the initial prescription has been obtained. This refers to the failure to take the medication as directed, also called persistence failure. Examples include missing doses, taking the wrong amount, or stopping the medication entirely before the course is finished. For patients on long-term therapies, secondary non-adherence is quite common, with estimates suggesting that nearly half of patients with chronic conditions struggle to maintain full adherence.
Non-adherence is also classified by the patient’s intent, distinguishing between intentional and unintentional actions. Intentional non-adherence is a conscious decision to alter the prescribed regimen, such as skipping a dose to avoid a perceived side effect or “drug holiday” to ration the supply. This is often a rationalized choice based on weighing the perceived necessity against concerns about the medication.
Conversely, unintentional non-adherence is a passive failure, primarily due to practical barriers beyond the patient’s immediate control. This includes simple forgetfulness, misunderstanding the dosing instructions, or physical limitations that make opening packaging or swallowing pills difficult. Both primary and secondary forms of non-adherence can stem from either intentional or unintentional factors.
Factors Contributing to Non-Adherence
The reasons for non-adherence are complex, often grouped into categories related to the therapy, the patient, and the socioeconomic environment. Therapy-related factors include treatment complexity, where regimens involving multiple medications or frequent daily dosing increase the likelihood of missed doses. The length of the treatment or the occurrence of unpleasant side effects can also lead a patient to discontinue the medication prematurely.
Patient-related factors involve an individual’s personal beliefs and understanding of their condition or treatment. Non-adherence may occur if a patient does not fully understand the medication’s purpose or lacks confidence in managing a complicated schedule. Furthermore, if a chronic condition like high blood pressure has no immediate symptoms, patients may not perceive a need for the drug, leading to intentional non-adherence. Psychological factors like depression, anxiety, or cognitive issues can also directly impair a patient’s ability to consistently adhere to instructions.
Socioeconomic factors often present significant external barriers that impede a patient’s ability to remain adherent. The cost of medication is a major contributor, frequently leading patients to ration their pills or to not fill the prescription at all. Financial hardships are compounded by issues such as:
- A lack of adequate health insurance.
- Unstable housing.
- Insufficient transportation to reach a pharmacy or clinic.
These external pressures create systemic hurdles that can override a patient’s desire to follow their prescribed regimen.
Consequences of Untreated Non-Adherence
The repercussions of non-adherence affect individual patient health, the healthcare system, and public health. From a clinical outcome perspective, non-adherence causes treatment failure and accelerates disease progression. When medication is not taken consistently, the resulting poor health outcomes can lead a provider to mistakenly assume the drug is ineffective, prompting a change to a more aggressive, costly, or complex treatment.
Non-adherent patients face an elevated risk of morbidity and mortality, experiencing worsening symptoms and complications. This diminished therapeutic effect is a primary reason for the persistent gap between the efficacy observed in clinical trials and the effectiveness seen in real-world practice.
The economic burden of non-adherence is substantial, primarily due to increased utilization of expensive healthcare resources. Non-adherent patients are significantly more likely to require hospital admissions and emergency room visits to manage complications that could have been prevented. In the United States, the total avoidable medical expenditure associated with non-adherence is estimated to be as high as $100 to $300 billion annually.
Non-adherence also carries a public health implication, particularly when it involves antibiotics. Stopping an antibiotic course prematurely means that the most resilient bacteria may survive exposure to the drug. These surviving pathogens can then mutate and develop resistance, contributing to the global crisis of antimicrobial resistance. Failure to complete treatment results in therapeutic failure for the individual and creates a threat to the community by breeding drug-resistant superbugs.