Importance of Objective Adherence Measurement

The efficacy of interventions to improve adherence, such as that just described, cannot be tested and evaluated reliably without good methods for objectively measuring adherence. Traditional methods of measuring adherence for the assessment of chronic disease have been self-report (interviews, questionnaires, diaries). Analyzed self-report unreliably points to bias and censoring (in an attempt to please the researcher/clinician) and forgetfulness, resulting in inflated patient adherence. The discrepancy between adherence measured by objective monitoring and self-report has been shown to overestimate true adherence up to 30%. The advent of electronic event monitoring has circumvented these issues, giving rise to a new standard of adherence measures.

Over the past decade, electronic monitoring devices for objectively measuring pill bottle openings (MEMS cap, Aprex Corp., Fremont, CA), asthma inhaler actuation and technique (MDELog, Medtrac Technologies, Lakewood, CO), and CPAP use (CPAP Systems, Respironics, Pittsburgh, PA) have become widespread for clinical adherence researcher. Electronic adherence monitors work by recording the time and date of a medication event, which is defined as a set of actions taken that is critical to the taking of the medication.

For example, in the case of asthma inhaler use, the MDILog is a small battery-powered monitor that encases the inhaler canister and time-stamps the event of each actuation, or “puff.” Electronic monitoring not only provides an objective and accurate measure of absolute adherence, but also provides the benefits of measuring the daily patterns of medication use, assessing dose-response relationships, and evaluating adherence promotion interventions.

Adherence Measurement

Several studies using objective adherence data from asthma inhaler use and CPAP use have shown that interventions based on the above theories can improve patient adherence. Some of these interventions include clinician-to-patient feedback, group education sessions, and individual education and support. For CPAP, interventions have manifested into clinical practice for better management of the disease. Recent studies found that long-term adherence can be predicted in the first few days of treatment, and that patient education and support at the initiation of treatment improves adherence. These important findings from the CPAP adherence monitor have resulted in improved management of patients using CPAP. Other ancillary drugs used on an as-needed basis include oral corticosteroids and antibiotics. Prednisone, a corticosteroid, is effective in decreasing airway inflammation. This drug is usually initiated during a crisis and then the dose is gradually tapered and discontinued, although some patients may require a daily dose to lessen the inflammatory response of the airways. Antibiotics, also usually initiated during a crisis (specifical infection) and then discontinued after a course of ten days to three weeks, may also be prescribed daily for prophylaxis for upper respiratory infections.