Objective Versus Self-Reported Adherence to Airway Clearance Therapy in Cystic Fibrosis

Abstract

BACKGROUND: Historically, studies of adherence to airway clearance therapy in cystic fibrosis (CF) have relied on self-reporting. We compared self-reported airway clearance therapy adherence to actual usage data from home high-frequency chest wall compressions (HFCWC) vests and identified factors associated with overestimation of adherence in self-reports. METHODS: Pediatric patients who perform airway clearance therapy with a HFCWC vest were eligible to participate. Objective adherence data were obtained from the HFCWC device, which records cumulative utilization time. Two readings at least 5 weeks apart were collected. Objective adherence was recorded as a ratio of mean-to-prescribed daily use (%). Self-reported adherence data were collected with a caregiver survey at enrollment. Adherence rates were categorized as low (< 35% of prescribed), moderate (36 -79% of prescribed), and high (> 80% of prescribed). An overestimation was present when self-reported adherence was at least one category higher than objective adherence. RESULTS: In the final sample (N ‫؍‬ 110), mean adherence by usage data was 61%. Only 35% of subjects (n ‫؍‬ 38) were highly adherent, and 28% (n ‫؍‬ 31) were low adherent. In contrast, 65% of subjects (n ‫؍‬ 72) reported high adherence and only 8% (n ‫؍‬ 9) reported low adherence (P < .001). Nearly half of self-reports (46%) overestimated adherence. In a multiple regression analysis, overestimation was associated with multiple airway clearance therapy locations (odds ratio 7.13, 95% CI 1.16 -43.72, P ‫؍‬ .034) and prescribed daily use > 60 min (odds ratio 3.85, 95% CI 1.08 -13.76, P < .038). Among subjects with prescribed daily airway clearance therapy > 60 min, the odds of overestimating adherence increased 3-fold (odds ratio 3.04, 95% CI 1.17-7.87, P ‫؍‬ .02) in a lower-income (< $50,000/y) environment. CONCLUSIONS: Self-reports overestimated actual adherence to airway clearance therapy, and the overestimation increased with treatment occurring in multiple households and prescribed therapy duration. Among participants with prescribed airway clearance therapy > 60 min, overestimation increased with lower income. Objective measures of adherence are needed, particularly for lower-income children and those receiving treatments in multiple locations.

Adherence to inhaled therapies over 4 years in people with cystic fibrosis

“…Adherence to all aspects of the CF daily regimen, including airway clearance therapy and dietary recommendations, has been studied using various methods. [1][2][3][4] Indeed, a significant disparity between self-reported and objectively measured adherence exists, 5 rendering assessment of adherence and comparison between different studies rather challenging. 6 Respiratory disease accounts for most deaths in CF, 7 and inhaled medication is used to reduce exacerbations and improve lung function and quality of life.…”

Objective measurement of lung volume recruitment therapy: laboratory and clinical validation

“…As noted, previous literature in other self-report versus objective measurement conditions would make this possibility unlikely. 26 27 The LVR counter used in this project is an in-house-developed prototype and as such does not provide a clear pathway to commercial and clinical translation of our findings; however, we suggest that this paper illustrates clear translational opportunities. Clinically, objective data provide opportunities for home monitoring of therapy, may suggest poor usage and may prompt clinicians to identify barriers to treatment, and similarly, patterns of use may provide important information about users’ beliefs and treatment choices, both positive and negative.…”

“…Greater discordance in the direction of the diary suggests overestimation of self-reported LVR usage, a common finding in other chronic conditions when self-report measures have been compared with objective measures of use. 26 27 In one study, 47% of people with cystic fibrosis reported performing more airway clearance therapy sessions than objectively recorded data would suggest across a 5-week period. 26 In contrast, medication adherence literature would indicate better concordance, with 72% of studies reporting ‘high’ concordance; high concordance is defined as <10% difference between self-reported diary and other measures of adherence.…”

“… 26 27 In one study, 47% of people with cystic fibrosis reported performing more airway clearance therapy sessions than objectively recorded data would suggest across a 5-week period. 26 In contrast, medication adherence literature would indicate better concordance, with 72% of studies reporting ‘high’ concordance; high concordance is defined as <10% difference between self-reported diary and other measures of adherence. 27 Differences in concordance rates between self-reported and objective measures may be related to the type of intervention (eg, ease and time required to perform), duration of follow-up period and participant awareness of monitoring.…”

“…Some studies have tracked self-reported adherence to prescribed LVR therapy using diaries 6 20 or patient recall. 21 However, self-reporting has been shown to overestimate adherence to airway clearance techniques 26 and prescribed medication 27 in other chronic disease populations. Prescribed LVR dosage in the literature varies from two to four times per day 2 3 5 6 9 19–22 with inconsistent relationships reported between self-reported ‘dose’ and outcomes.…”