Is poor symptom perception a predictor of poor adherence to controller medication among adults with asthma

The purpose of this study is to investigate the relationship between asthma symptom perception, illness perception, and adherence to controller medications, and to identify explanatory variables for symptom perception accuracy and adherence rates. Teel's (1997) Symptom Interpretation Model (SIM) guided the study. One-hundred-twenty adults with asthma who were taking Advair as a controller medication, were enrolled in this cross-sectional descriptive study. Ninety-seven subjects, all patients of asthma/allergy specialty clinics, completed the four-week study protocol. Subjects completed daily diaries that assessed subjective symptom perception on two 10-point numeric rating scales (NRS), based on intensity and emotional response to symptoms, and measured peak expiratory flow rates (PEFR) twice daily. Individual perceptual accuracy scores (PAS-intensity and PAS-emotion) were determined by correlations of the NRS scores with the PEFRs. Baseline measures included demographics, illness perception (Illness Perception Questionnaire - Revised), positive and negative affect (PANAS); and a single-item indicator of perceived asthma severity. Adherence was measured by the Medication Adherence Report Scale (MARS) and by Percent Advair (percent of doses taken/doses prescribed).;Results of an independent t-test comparing adherence rates of good versus poor perceivers (PAS-intensity) was not significant with either the Percent Advair or the MARS. However, results based on the PAS-emotion did demonstrate a significant difference between good and poor perceivers with Percent Advair as the dependent variable (t = -2.019, p = .047). The mean scores for Percent Advair, the pre-study MARS and the post-study MARS were consistently lower among the good perceivers than the poor perceivers. Multiple regression analyses reveal that years with asthma, illness identity (personal control and treatment efficacy, consequences, and timeline-cyclical subscales of the IPQ-R) and peak flow variability are significant explanatory variables for perceptual accuracy (PAS-intensity).;PAS-intensity and the IPQ-R consequence subscale emerged as explanatory variables for adherence when percent Advair was the criterion variable. When the MARS was used as the criterion for adherence, years with asthma, perceived asthma severity, personal control/treatment efficacy, age and positive affect emerged as explanatory variables.;Illness identity appears to inform perceptual accuracy and adherence rates as assessed. Clinical assessment of a patient's illness identity may help tailor interventions appropriate to the individual's needs.