Factors Associated With Medication Nonadherence in Patients With COPD

Johnson George, MPharm, PhD; David C. M. Kong, BPharm, MPharm, PhD; Rambha Thoman, Dip Physio; Kay Stewart, BPharm (Hons), PhD


CHEST. 2005;128(5):3198-3204. 

In This Article


Patient beliefs, experiences, and behaviors with regards to both disease and treatment were found to be more powerful predictors of medication adherence than sociodemographic and clinical factors in patients with COPD. The variance in adherence explained by these factors was on par with or greater than those reported by other models of adherence.[39,40,41,42,43,44,45] Significant differences in health beliefs, experiences, and behaviors were observed between COPD patients with high medication adherence and suboptimal adherence. The understanding of these factors could assist in enhancing health outcomes in patients with COPD.

The extent of suboptimal adherence identified in the present study (63%) is greater than the suspected medication nonadherence in the long term for different disease conditions (50%).[6] This is a concern considering the extent of educational interventions to which the study population is likely to have been subjected. COPD being a symptomatic disease, patients are likely to alter the recommended management based on how they feel. Patient education focusing on the pathology of the disease and the need for long-term treatment might help in improving patient adherence. The prevalence of confusion about medications in the nonadherent group suggests the need for additional education and the use of adherence aids such as medication lists and dosette boxes, especially in the elderly and those with a complex medication regimen. Our findings suggest that this need exists even for patients who have undergone pulmonary rehabilitation and those who participate in respiratory support groups. This study highlights the need for doctors to spend more time with their patients, especially those whose nonadherence is of concern.

Adherent patients had greater understanding about their illness and the options for managing the illness. They also had greater confidence that current management would keep their illness under control. However, management of illness was a mystery for patients with suboptimal adherence, and they had greater faith in the safety of natural remedies. Dowell and Hudson[46] concluded that accepting the recommended treatment, especially long-term treatment perceived as powerful, requires an acceptance of the illness. Other studies[47,48,49] have shown that confidence in drug therapy could be low among COPD patients. The health belief model[50,51] suggests that a patient's perception of the effectiveness of a recommended behavior (action) predicts the likelihood of taking that behavior. Studies of various patient groups have shown patients' perceived benefits from the treatment to be associated with medication use.[21,52,53,54,55]

Satisfaction with and faith in the treating physician were found to be low among the less adherent group compared to the highly adherent group. These factors are known from other studies to be critical for optimal adherence in both COPD and other patient populations.[36,56,57] The importance of effective patient-clinician interaction for optimal adherence to therapeutic regimens is well recognized.[57,58,59] Empathic understanding is considered to be one of the most important practitioner relationship skills leading ultimately to patient health benefit.[59] Patient satisfaction was the only factor that had significant correlation with different measures of medication adherence in a study[45] on patients with chronic diseases including pulmonary disease.

Patients who reported suboptimal adherence found their medications to be more physically challenging and unpleasant compared to their counterparts. Complexity of medication regimens and the number of regular medications in the regimen were not significant predictors of nonadherence in the present study. Unlike reported in previous studies[60,61] of chronic respiratory patients, there were no differences between the adherent and less adherent groups in their concerns about side effects from the medications. Although cost of treatment is generally regarded as a barrier to adherence,[7] the differences between the two groups for the item on financial restrictions was not significant, and the responses of both the groups were negative. In Australia, prescription medications are subsidized by the government through the Pharmaceutical Benefits Scheme. This, along with special privileges for pensioners, might have made health care affordable for most study participants.

There were no significant differences between the adherent and less adherent groups in their perception of control over illness management. However, less adherent patients believed that their doctors had limited management options to offer them. According to Dowell and Hudson,[46] patients who accept their medication regimen fully as prescribed by their doctors are likely to assume a passive role in managing their illness and relinquish control to their doctor. In a study[21] of patients receiving supplemental oxygen therapy, patients had the perception that adhering to a doctor's prescription generally promoted their health; however, for proper management of their disease, many believed that they had to remain vigilant themselves and retain independence in their decisions. Nevertheless, the failure of the locus of control theory in explaining any significant proportion of variance in adherence in previous studies[18,45] confirms that control over management is not a significant independent predictor of treatment nonadherence in patients with chronic respiratory ailments.

Differences in both intentional and unintentional health behaviors were observed between the two groups. Adherent patients were less likely to be confused about their medications, which might have been the result of their greater medication knowledge. Less adherent patients were more likely to vary their recommended management to suit their lifestyle or based on how they felt. The difference between the two groups for the item on routines almost reached statistical significance. "Routinization," ie, the ability to fit a medication regimen to one's daily routine, has been recognized as a major determinant of improved adherence.[62] It is not surprising in a disease condition like COPD, in which people are encouraged to increase their doses when feeling unwell, that they may decrease the doses when they feel well.[63] Patients with suboptimal adherence were also likely to put up with their medical problems before taking any action. Many patients participating in a primary care study were found to fight the disease and tended to use the least amount of the medication when possible.[46] Changes in adherence patterns with disease severity, symptoms, and therapeutic response have been reported among COPD patients.[20,21,26,36,55,64]

Two thirds of the study subjects had comorbidities, suggesting the possible relevance of these findings in patients with other chronic ailments. Depression is known to be a risk factor for nonadherence,[29,30] but we avoided any specific questions about depression in the questionnaire due to the sensitivity of the topic and concerns about patient nonresponse. The mean age of the current study population was > 70 years. The relatively greater adherence observed among the participants might have been the result of more organized behavior in old age. It is possible that the results are biased given the response rate of only 52.6%. However, it is likely that those who responded to the questionnaire had greater adherence than the nonrespondents. Extrapolation of the findings of this study to other COPD patients, especially younger ones, should be done with caution. The cross-sectional design of the study does not allow the drawing of any conclusions on the cause-effect relationship between nonadherence and health beliefs and experiences. Adherence was assessed by self-report and the validity of self-reports has been criticized.[65,66,67,68] Being an anonymous questionnaire, it is unlikely that any of the patients gave incorrect responses in an attempt to please the researchers. Items such as race, languages spoken, education, financial status, and social support were not included in the questionnaire because the associations between adherence and these factors have been found to be inconsistent across studies.

Predictors of adherent behavior and differences in health beliefs, experiences, and behaviors of adherent and less adherent patients with COPD were identified. Patients' acceptance of the disease process and recommended treatment, knowledge about and faith in the treatment, effective patient-clinician interaction, and routinization of drug therapy are critical for optimal medication adherence in COPD patients.


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