Home Nebulized Therapy for Patients with COPD: Discussion
One hundred percent compliance is probably an unrealistic target for most patients. It is therefore better to consider a level of compliance that will maintain the patient in good health, which is the required outcome of treatment. Eighty to 100% has been suggested as a standard for full compliance. In this investigation, patients were considered to be “poor compliers” if they took <70% of the overall treatment prescribed for them during the 4-week period. The physicians involved in the study (P.J.R., G.M.C.) considered that therapeutic efficacy of the nebulizer therapy would be compromised beyond this point.
Studies of compliance in asthma and COPD show a noticeable variation in adherence to medical advice, with results ranging from 48 to 103%. Much of this variation can be attributed to differences in experimental design, the way in which compliance is assessed, and the number of times treatment must be taken. Frequency of drug administration has been reported to affect compliance with treatment, greater frequency being associated with poorer compliance. For this reason, patients instructed to use the nebulizer more than four times a day were considered poorly compliant if they took <60% of prescribed treatment. However, the results of this study showed no correlation between compliance and dose frequency. This may be due to the fact that nebulizers might be regarded to some extent as “as occasion requires” treatment. This study showed that levels of compliance in COPD patients are low and correspond to those found in other chronic illnesses. The mean compliance found was 57% with 36 patients (44%) being compliant with their prescribed regimen and 46 (56%) being poorly compliant, taking <70% of their treatment. Compliance levels were unrelated to demographic variables such as age, gender, duration of illness, and socioeconomic group, as widely reported elsewhere.
If patients increase their compliance in response to severity of symptoms and the impact on their quality of life, we would expect percent compliance to correlate with the score on the SGRQ1. This was not the case; percent compliance was not related to quality of life measurements at the start of the study, suggesting that the patient’s experience in the 4 weeks prior to the study had no effect on the patient’s subsequent use of the nebulizer. This contrasts with the finding by Turner et al that nebulizer-adherent patients complain of more breathlessness than nonadherent patients. There are two possible explanations for the finding that percent compliance correlates with the total score, symptom score, and the impact score on the SGRQ2: first, that patients who experience more respiratory symptoms and a greater impact of their illness 011 their lifestyle tend to be poorer compliers during a period of observation; second, poor compliance leads to a greater impairment in quality of life. While no causality can be implied, the second explanation is consistent with the results of the SGRQ1 finding that patients’ use of the nebulizer is not related to the symptoms they experience or the impact that COPD has on their quality of life.