Patient-physician discordance in assessment of adherence to inhaled controller medication: a cross-sectional analysis of two cohorts

Abstract

Objective: We aimed to compare patient's and physician's ratings of inhaled medication adherence and to identify predictors of patient-physician discordance.

Design: Baseline data from two prospective multicentre observational studies.

Setting: 29 allergy, pulmonology and paediatric secondary care outpatient clinics in Portugal.

Participants: 395 patients (≥13 years old) with persistent asthma.

Measures: Data on demographics, patient-physician relationship, upper airway control, asthma control, asthma treatment, forced expiratory volume in one second (FEV₁) and healthcare use were collected. Patients and physicians independently assessed adherence to inhaled controller medication during the previous week using a 100 mm Visual Analogue Scale (VAS). Discordance was defined as classification in distinct VAS categories (low 0-50; medium 51-80; high 81-100) or as an absolute difference in VAS scores ≥10 mm. Correlation between patients' and physicians' VAS scores/categories was explored. A multinomial logistic regression identified the predictors of physician overestimation and underestimation.

Results: High inhaler adherence was reported both by patients (median (percentile 25 to percentile 75) 85 (65-95) mm; 53% VAS>80) and by physicians (84 (68-95) mm; 53% VAS>80). Correlation between patient and physician VAS scores was moderate (r_s=0.580; p<0.001). Discordance occurred in 56% of cases: in 28% physicians overestimated adherence and in 27% underestimated. Low adherence as assessed by the physician (OR=27.35 (9.85 to 75.95)), FEV₁ ≥80% (OR=2.59 (1.08 to 6.20)) and a first appointment (OR=5.63 (1.24 to 25.56)) were predictors of underestimation. An uncontrolled asthma (OR=2.33 (1.25 to 4.34)), uncontrolled upper airway disease (OR=2.86 (1.35 to 6.04)) and prescription of short-acting beta-agonists alone (OR=3.05 (1.15 to 8.08)) were associated with overestimation. Medium adherence as assessed by the physician was significantly associated with higher risk of discordance, both for overestimation and underestimation of adherence (OR=14.50 (6.04 to 34.81); OR=2.21 (1.07 to 4.58)), while having a written action plan decreased the likelihood of discordance (OR=0.25 (0.12 to 0.52); OR=0.41 (0.22 to 0.78)) (R²=44%).

Conclusion: Although both patients and physicians report high inhaler adherence, discordance occurred in half of cases. Implementation of objective adherence measures and effective communication are needed to improve patient-physician agreement.

Keywords: asthma; discordance; logistic models; medication adherence.