Treatment Adherence
Introduction
Adherence involves the extent to which a patient’s behavior corresponds with the agreed upon treatment recommendations from their health care provider. Rates of nonadherence among patients with cancer vary. For example, approximately 46% of patients with gynecologic cancer taking oral anticancer agents demonstrated nonadherence (Watson et al., 2020), and in another study, approximately 22% of patients did not complete adjuvant chemotherapy for colon cancer (Dobie et al., 2006). Nonadherence to adjuvant endocrine therapy was reported by 36% of women with breast cancer (Corter et al., 2018). Nonadherence is associated with adverse health consequences and can limit efficacy of treatment. Nonadherence is associated with greater risk of mortality; for example, Hershman et al. (2011) found nonadherence to adjuvant hormonal therapy was a predictor of mortality from breast cancer. Dobie et al. (2006) reported an increased risk of mortality when patients with colon cancer did not complete adjuvant chemotherapy.
Major Principles, Categories, Concepts
In the oncology setting, there are various types of regimens in which nonadherence is applicable. These are as follows:
- Attendance at screening appointments (e.g., mammography, colon cancer screening, etc.)
- Attendance at treatment appointments such as chemotherapy or radiation
- Recommended lifestyle changes such as dietary changes, quitting smoking, or exercise
- Oral chemotherapy medication
- Radiation therapy
- Adjuvant hormonal treatment (e.g., Tamoxifen for breast cancer)
Nonadherence can be exhibited in various ways. Some patients never fill a new prescription, some patients stop before the recommended end point of the treatment, and some patients do not follow usage instructions or take doses incorrectly or at the wrong time intervals.
Nonadherence is categorized as intentional and unintentional. Intentional nonadherence is an active decision by patients not to follow through with recommended regimens, whereas unintentional nonadherence involves such reasons as forgetfulness or misunderstanding.
Screening/Risk Factors/Evaluation
Researchers have studied many barriers to or risk factors for nonadherence. A particular challenge of adherence is the fact that every patient faces different barriers to adherence; thus, interventions must often be personalized to the individual. Researchers have grouped nonadherence intro broad categories of factors including patient-related, regimen-related, disease-related, provider-patient interaction, and system-related (see Table 1).
Table 1. Predictors and Risk Factors for Nonadherence
| Broad Category of Predictors | Examples in Category |
| Patient-related | Depression, understanding, health literacy, forgetfulness, beliefs, self-efficacy, social support, resources (time, financial, etc.) |
| Treatment or regimen-related | Side effects, complexity of regimen, frequency of doses |
| Disease-related | Severity of disease |
| Provider-patient interaction/communication-related | Shared decision-making; relationship-centered care; partnership, collaboration, open, and thorough communication |
| System-related | Cost, access to treatment |
Click here to view table as PDF
There is no “gold standard” for measuring adherence (Lehmann et al., 2014); however, there are many available methods to assess adherence, and those are listed in Table 2 below. Self-report measures may be most commonly used in clinical practice. Stirratt et al. (2015) listed some of the most commonly used self-report measures in the appendix of their review. Self-report measures of adherence that could be used in the clinical setting include the Medical Outcomes Study Adherence Scale (https://www.rand.org/health-care/surveys_tools/mos/patient-adherence.html), the Brief Medication Questionnaire (Svarstad et al., 1999), and the Adherence Estimator (a screening tool; McHorney, 2009). Another option for clinical practice is a single-item visual analogue scale, which involves assessment of what percentage of medication a patient has taken in the past month on a 1-100 scale (Kalichman et al., 2009).
Table 2. Adherence Measurement Tools
| Measurement Tool | Description | Strengths | Weaknesses |
| Patient Self-Report | There are several validated questionnaires designed to measure adherence and interviews or diaries are also self-report measurement options |
· Easy to administer · Inexpensive to administer · Require little time to complete
|
· Potential for memory recall issues · Potential for social desirability biases |
| Electronic Monitors (e.g., MEMS caps) | The pill bottle has a cap that records date/time of opening |
· Can measure adherence behavior over time (provides longitudinal data) and at particular times (e.g., right before medical visit) · Can measure changes in medication taking behaviors |
· Expensive · Could lead to patients feeling loss of control of medication taking or interfere with their daily life
|
| Pharmacy Refills Databases | Total days of medication given to a patient is divided by the number of days they should take the medication to calculate the Medication Possession Ratio (MPR) | · Can be used to analyze large amounts of data |
· Cannot measure daily variations in medication taking or ingestion of medication · Cannot be measured if medications come from pharmacies with independent databases |
| Pill Counts | Percent adherence calculated by multiplying the units of medication dispensed by the dosage and divided by the number of tablets that were supposed to be consumed | · Can be used as an overall measure of adherence |
· Risk of dumping pills out · Does not show daily variations in adherence or assess ingestion of medication |
| Blood or Urine Monitoring | Level of medication in plasma, serum, blood, or urine | · Shows that medication was taken |
· Cannot be used for all medications · Costly · Invasive |
Click here to view table as PDF
Possible Approaches/Best Practices
A critical factor in promoting adherence is open communication, trust, and collaboration between patient and health care provider. The Information-Motivation-Strategy Model (DiMatteo et al., 2011) provides a practical and flexible approach to promoting treatment adherence by addressing informational needs of patients through effective communication, patient motivation to follow through with treatment recommendations, and strategies to overcome barriers to adherence. Table 3 provides approaches to promoting adherence in practice.
Table 3. Approaches in the Clinical Setting to Promote Patient Adherence
| Tools in the clinical setting to promote adherence | Example or Technique |
| Involve patients in treatment decision process, discuss options, understand patient values, and hear patient concerns. Use decision aids. |
“How does this regimen sound to you?” “What is most important to you in making decisions about treatment?” |
|
Ask about nonadherence in a nonjudgmental way
|
“Many of our patients have difficulty taking this medication every day as prescribed (or forget to take it every day). How often do you think this happens to you?” |
| Explain the regimen clearly and ensure patients understand (e.g., use teach-back method) | “I want to be sure I have explained this new treatment clearly. Can you tell me how you will take this medication?” |
| Give written information/checklist/clear instructions/keep health literacy levels in mind | “Here is a checklist that you can use to report symptoms or side effects you are having, and we can discuss ways to address those.” |
| Encourage patients to ask questions | “We covered a lot of information about this new treatment. What questions can I answer?” |
| Provide follow-up after a new regimen starts | “You started this treatment _____ ago. I wanted to check in to see how it is going.” |
| Explain the risks and benefits of treatment | “As with any treatment, there are some potential risks, but we believe the long-term benefits outweigh the risks. Let’s discuss those now.” |
| Recommend or encourage reminder methods to help with forgetfulness | “Many patients forget to take their medications sometimes. Would you like to discuss reminder tools or mobile apps that could help you?” |
| Assess/be aware of patient mental health | Consider using a depression symptom screening tool to screen for depression. |
| Consider patient resources, including social support |
“How has your family responded to your diagnosis?” “Have you considered joining a support group of other patients with the same illness?” |
| Use motivational interviewing principles | Understand your patient’s current state of mind in regard to their treatment. Determine their barriers to change and understand their motivations. |
| Use health technologies to improve adherence | Consider tools such as e-prescribing, patient portals, automated reminders from pharmacy, appointment reminders, medication reminders (mobile apps, smart pillboxes, others) |
Click here to view table as PDF
Cultural Considerations
There are many cultural considerations to take into account when discussing patient adherence to treatment. Cultural views may drive beliefs about medications and cancer treatment, which could lead to nonadherence. Cultural competency is important in provider-patient communication, including discussion about treatment options. Language barriers may influence understanding of the treatment regimen, which could influence adherence. A professional translator can assist the patient and medical team with understanding information about treatment when there are language barriers.
Bottom Line/Conclusions
- Nonadherence to treatment is a significant challenge in the oncology setting and can limit the efficacy of treatment.
- Nonadherence should be assessed for all patients after starting a new regimen. Many self-report tools are available.
- Every patient faces unique barriers to adherence; therefore, interventions to promote adherence should be tailored to the individual.
- To promote adherence, healthcare providers should involve patients in the treatment decision making process and clearly explain the regimen; provide follow up after a new regimen starts; and use tools such as written information, handouts, or reminder methods to help with forgetfulness.
References
Corter, A.L., Broom, R., Porter, D., Harvey, V., & Findlay, M. (2018). Predicting nonadherence to adjuvant endocrine therapy in women with early stage breast cancer. Psycho-oncology, 27, 2096-2103. https://doi.org/10.1002/pon.4771
DiMatteo, M. R., Haskard-Zolnierek, K. B., & Martin, L. R. (2011). Improving patient adherence: A three-factor model to guide practice. Health Psychology Review, 1-18. https://www.researchgate.net/publication/233251626
Dobie, S.A., Baldwin, L.M., Dominitz, J.A., Matthews, B., Billilngsley, K., & Barlow, W. (2006). Completion of therapy by Medicare patients with stage III colon cancer. Journal of the National Cancer Institute, 98(9), 610-619. https://doi.org/10.1093/jnci/djj159
Hershman, D.L., Neugut, A.I., Moseley, A., Arnold, K.B., Gralow, J.R., Henry, N.L., Hillyer, G.C., Ramsey, S.D., & Unger, J.M. (2021). Patient-reported outcomes and long-term nonadherence to aromatase inhibitors. Journal of the National Cancer Institute, 113(8), 989-996. https://doi.org/10.1093/jnci/djab022
Kalichman, S. C., Amaral, C. M., Swetzes, C., Jones, M., Macy, R., Kalichman, M. O., & Cherry, C. (2009). A simple single-item rating scale to measure medication adherence: further evidence for convergent validity. Journal of the International Association of Physicians in AIDS Care, 8(6), 367–374. https://doi.org/10.1177/1545109709352884
Lehmann, A., Aslani, P., Ahmed, R., Celio, J., Gauchet, A., Bedouch, P., Bugnon, O., Allenet, B., & Schneider, M.P. (2014). Assessing medication adherence: Options to consider. International Journal of Clinical Pharmacy, 36, 55-69. https://doi.org/10.1007/s11096-013-9865-x
McHorney C. A. (2009). The Adherence Estimator: a brief, proximal screener for patient propensity to adhere to prescription medications for chronic disease. Current medical research and opinion, 25(1), 215–238. https://doi.org/10.1185/03007990802619425
Stirratt, M. J., Dunbar-Jacob, J., Crane, H. M., Simoni, J. M., Czajkowski, S., Hilliard, M. E., Aikens, J. E., Hunter, C. M., Velligan, D. I., Huntley, K., Ogedegbe, G., Rand, C. S., Schron, E., & Nilsen, W. J. (2015). Self-report measures of medication adherence behavior: recommendations on optimal use. Translational Behavioral Medicine, 5(4), 470–482. https://doi.org/10.1007/s13142-015-0315-2
Svarstad, B. L., Chewning, B. A., Sleath, B. L., & Claesson, C. (1999). The Brief Medication Questionnaire: a tool for screening patient adherence and barriers to adherence. Patient education and counseling, 37(2), 113–124. https://doi.org/10.1016/s0738-3991(98)00107-4
Watson, C.H., Fish, L.J., Falkovic, M., Monuszko, K., Lorenzo, A., Havrilesky, L.J., Secord, A.A., & Davidson, B.A. (2020). Adherence to oral anticancer therapeutics in the gynecologic oncology population. Obstetrics & Gynecology, 136(6), 1145-1153. https://doi.org/10.1097/AOG.0000000000004170