Theory corresponds with approved recommendations from a health

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Theory of Planned Behavior:

A Framework for Medication Adherence

Latrice J. Berry

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Stephen F. Austin State University




Theory of Planned Behavior:

 A Framework for Medication Adherence

Cross wrote, (as cited in Alligood, 2014) “theory without practice is empty and practice without theory is blind” (p.716).  This quote clearly and concisely defines the relationship between theory and clinical practice.  Simply put, without practice, theory would not have substance, and without theory, practice does not have a guide.  To put this relationship into perspective, this paper will use the theory of planned behavior as a framework for solving the clinical problem of poor medication adherence.  This paper will demonstrate how the theory of planned behavior can be used to successfully understand and predict behavior and intention to adhere to medications amongst individuals diagnosed with chronic conditions.  With an understanding of intent and behavior, a proper intervention can then be tailored individually to improve the medication adherence behaviors of patients with chronic conditions (Lam & Fresco, 2015).

Problem Identification

Medication adherence plays a vital role in patient care and clinical goals (Lam & Fresco, 2015).  Poor medication adherence can result in significant mortality, morbidity, and financial costs ( Rich, Brandes, Mullan, & Hagger, 2015).  In other words, not taking medication as prescribed can be fatal, harmful, and costly. Poor medication adherence can be especially harmful for patients with chronic conditions (Dear, 2017). For example hypertension is a chronic condition in which medication non-adherence is quite common (Dear, 2017).  Adhering to hypertension medications help reduce the risks of  strokes, heart disease (Alhalaiqa, Deane, Nawafleh, Clark, & Gray, 2012) and kidney failure (Sontakke,  Budania, Bajait, Jaiswal, & Pimpalkhute , 2015) to name a few. But, not adhering to these medications increases these risks. In other words, medication adherence is directly correlated to health outcomes.

Related Concepts

Adherence, according to the World Health Organization (as cited in Lam & Fresco, 2015) is the extent to which a person’s behavior corresponds with approved recommendations from a health care provider. There is a complexity in adherence behaviors, ranging from completely ceasing the behavior, partially engaging in the behavior, or performing the behavior in ways other than instructed (Rich, Brandes, Mullan, & Hagger, 2017)  Medication adherence refers to whether an individual actually and continuously takes their medications as prescribed (Dear, 2017).  Therefore, medication adherence can be complex, ranging from completely ceasing to take prescribed medications, to taking only some, to taking them in a way that differs from instructions (Rich, Brandes, Mullan, & Hagger, 2017).

Theory Identification

The theory of planned behavior is known to be one of the most popular theories identified in predicting and explaining human behaviors. The original journal article written by Icek Ajzen was published in 1991 as an extension of the theory of reasoned action. The theory of planned behavior distinguishes between three types of beliefs, and within those beliefs lays six constructs that collectively represent an individual’s actual control over their behavior (Lamorte, 2016). The three beliefs proposed by Ajzen are behavioral beliefs, normative beliefs, and control beliefs. The six constructs within the three beliefs are: attitude, behavioral intention, subjective norms, social norms, perceived power, and perceived behavioral control (Lamorte, 2016). These three beliefs according to Ajzen, are what determine intentions and behavior. The theory also proposes that behavioral intention is the most significant predictor of human behavior.

In regard to behavioral beliefs, these beliefs are assumed to influence the construct of attitudes and behavior intention toward behaviors (Ajzen, 1991). In other words, what an individual believes about a behavior has an impact on the attitude toward that behavior, and that impact can influence behavior intentions. For instance, if an individual has a negative belief about a behavior, then their attitude toward that behavior will also be negative, and vice versa.  Having a negative behavior and attitude in regards to a behavior will significantly impact the behavior intentions.

In regard to normative beliefs, these beliefs constitute the underlying determinants of the construct of social and subjective norms (Ajzen, 1991). In other words, normative beliefs are concerned with the likelihood that important referent individuals will approve or disapprove the behavior (Ajzen, 1991). For instance if an important referent individual disapproves a behavior, the subject may also disapprove of the behavior, and vice versa. 

Control beliefs provide the basis for the construct of perceived behavioral control and perceived power (Ajzen, 1991). In other words, control beliefs are the basis of how hard or easy (the perception of behavior) is in relation to the requisite resources and opportunities (Ajzen, 1991). Control beliefs also take into account past experience with the behavior as well as second-hand information in reference to the behavior (Ajzen, 1991). For instance, if an individual perceives to be powerless in reference to a behavior, or believes that the behavior is hard to accomplish due to past experiences, or an acquaintance had difficulty in performing the behavior,  the likelihood of performing that  behavior is minimal, and vice versa.

The key component of the theory of planned behavior is intent (Lamorte, 2016). “Intentions are assumed to capture the motivational factors that influence a behavior (Ajzen, 1991).  Ajzen (1991) suggests that the stronger the intention to engage in a behavior, the more the likelihood of its performance. In other words, the stronger the motivational factors that influence a behavior, the stronger the intentions. Ajzen (1991) also suggests that as a general rule, the more favorable the attitude and subjective norm toward a behavior, and the greater the perceived behavioral control, the stronger an individual’s intention to perform the behavior.

Theory Analysis

The theory of planned behavior is a well-known model for use in predicting a wide range of complex human behaviors.  Poor medication adherence is a complex human behavior that when guided by the theory of planned behavior, can be understood, explained and predicted.   The author makes use of this theory in relation to poor medication adherence.


Beginning with behavioral beliefs, if an individual believes that adhering to a prescribed medication is a negative act, the patient’s attitude towards the act is therefore negative. Medication adherence would not likely occur based up on the negative belief and relative attitude toward this behavior.  For example, if a patient does not believe that their health depends on medicines, worry about having to take medicine or are concerned about the side effects of medicine, they are less likely to adhere to treatment than patients with more positive treatment attitudes (Alhalaiqa, Deane, Nawafleh, Clark, & Gray, 2012).  From the analysis of behavioral beliefs, it be concluded that behavioral beliefs can independently predict medication adherence.

In regard to normative beliefs, if the peers or culture norms of an individual approve or disapprove medication adherence the individual may also approve or disapprove the medication adherence behavior.  Normative beliefs can predict and explain medication adherence. However, normative beliefs are not an independent factor like that of behavior beliefs in the prediction of and explaining this behavior.

In regard to control beliefs, if an individual’s perception of medication adherence is complex or easy, this perceived behavioral control will influence or decrease the likelihood of that behavior becoming performed. As an example of control beliefs, if an individual believes that it is hard to adhere to medication due to factors such work scheduling; they may feel that they do not have control over the behavior because they do not have control over their work schedule. Therefore, the behavior will less likely occur due to a lack of perceived behavioral control.

Strengths and Weaknesses

Despite the popularity of the theory of planned behavior, this theory is not without its strengths and weaknesses, especially in relation to poor medication adherence. A major strength of this theory in relation to poor medication adherence is the theories undoubtedly ability to predict and understand poor medication adherence. Furthermore, this theory has been successfully used to predict and understand other long-term behaviors such as diet, exercise, and even medication adherence in patients with HIV (Rich, Brandes, Mullan, & Hagger, 2017).

  A major weakness of this theory in relation to poor medication adherence is that the theory fails to take into account the emotional state of the individual at the time of the desired behavior. For example, many people living with chronic medical conditions also have major depression (UT Southwestern Medical Center, 2017). Depressive symptoms can negatively affect adherence behaviors (Goldstein, Gathright, Garcia, 2017), thus leading to poor medication adherence.

Potential Impact

The theory of planned behavior can have a profound impact on poor medication adherence.  This theory can be used for understanding and predicting the likelihood of poor medication adherence amongst individuals diagnosed with chronic conditions.  Once this behavior is understood and predicted, interventions can be developed and implemented that promote compliance, thus improving health outcomes.  For example, if a nurse or primary health care provider can predict and understand the intentions and beliefs of patients diagnosed with chronic conditions in regard to medication and medication adherence, these healthcare providers can intervene in an attempt to change these intentions and beliefs in order improve or prevent poor medication adherence. Dear (2017) writes, “Improving poor medication adherence may be one of the most effective and efficient ways to improve health outcomes” ( para 3). 


A leading challenge in healthcare t is the growing prevalence and deaths due to chronic diseases (Dalvi & Mekoth, 2017).  This worrisome phenomenon can be attributed to several factors, the gravest being poor medication adherence (Dalvi & Mekoth, 2017).  Intention, perception of behavioral control, attitude toward the behavior, and subjective norm each reveals a different aspect of poor medication adherence, and each can serve as a point of attack in attempts to improve it (Ajzen, 2017).  Poor medication adherence has multifactorial causes that need to be understood before interventions can be designed to improve medication adherence (Lam & Fresco, 2015).  Nurses and providers alike should recognize the problem of non-adherence and be aware of factors that have been shown to affect adherence in order to prevent, or even eliminate the problem (Dear, 2017).  Adherence to treatment will increase positive health outcomes, improve the patient’s quality of live, and reduce the burden on the healthcare systems (Dalvi & Mekoth, 2017).  Improving adherence amongst patients diagnosed with chronic conditions can be difficult, but not impossible (Hyman & Pavlik, 2015), if guided by the theory of planned behavior.
















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