Measuring barriers to adherence: validation of the problematic experiences of therapy scale

Abstract

Purpose: To present the psychometric properties of the Problematic Experiences of Therapy Scale (the PETS), a brief measure to assess self-reported perceived barriers to adherence to physical rehabilitative therapy. Methods: Participants (study 1: n ¼ 128, study 2: n ¼ 227) taking part in trials of rehabilitative exercises completed the PETS and adherence questions at 12 weeks. Participants in study 2 were also asked about maintained adherence at 6-month follow-up. Results: Principal component analysis identified a four-factor structure relating to symptoms, uncertainty, doubts and practical problems. Cronbach's alphas ranged between 0.84 and 0.96 for study 1 and study 2. Correlations between factors varied, ranging between À0.22 and À0.53 for study 1, and 0.12 and 0.36 for study 2. Adherence was associated with all subscales at 12 weeks, and with the symptoms and doubts subscales at 6-months. Conclusions: The PETS is a valid and reliable measure that can be used to assess participants' perceived reasons for non-adherence to a home-based rehabilitative therapy. It can be easily incorporated into treatment trials and as subscales were associated with reported adherence and maintained adherence, it provides potentially valuable indicators of reported barriers to adherence or might be used in clinical practice to facilitate conversations about adherence.ä Implications for Rehabilitation Low levels of adherence are commonly reported among people with chronic conditions who are required to undertake self-managed, home-based rehabilitation, yet patientperceived barriers to adherence are rarely measured. The Problematic Experiences of Therapy Scale (the PETS) is a brief self-report measure that assesses the extent to which respondents perceive that they have been prevented from carrying out an intervention by common and plausible reasons. A patient-centered approach to reasons for non-adherence could facilitate conversations about adherence and identify areas in which the respondent may benefit from additional support or interventions to aid adherence.

Predictors of adherence to home-based physical therapies: a systematic review

“…It is important to note the variation in how concepts of adherence and non-adherence are operationalised in existing literature [17]. Participants are sometimes considered non-adherent to HBPT regimens if they fail to achieve either a certain proportion, or absolute value, of recommended exercise frequency should be considered the cut-off between adherence and non-adherence.…”

“…Self-managed HBPTs in particular, often demonstrate the lowest levels of patient adherence amongst physical therapy modalities [14,15]. Nonetheless, for adherent patients, HBPT can be superior to standard care [16].It is important to note the variation in how concepts of adherence and non-adherence are operationalised in existing literature [17]. Participants are sometimes considered non-adherent to HBPT regimens if they fail to achieve either a certain proportion, or absolute value, of recommended exercise frequency should be considered the cut-off between adherence and non-adherence.…”

“…Furthermore, HBPT is often characterised by a number of features that make it particularly susceptible to non-adherence [19]. These features include the unsupervised nature of treatment, necessitation of lifestyle modification, not providing immediate symptomatic-relief, doubts and uncertainty about the therapy, and potential provocation of symptoms [17,25].Whilst two recent systematic reviews in this field have investigated intervention-related factors associated with adherence to HBPTs [26,27], the included studies do not always directly investigate Running head: Adherence to home-based physical therapies relationships between adherence and specific potential predictors. One of these reviews did investigate both intervention and specific individual factors [26].…”

A randomised controlled study of the effectiveness of breathing retraining exercises taught by a physiotherapist either by instructional DVD or in face-to-face sessions in the management of asthma in adults

“…5. The factor structure of the Problematic Experiences of Therapy Scale (PETS) 43 was checked using exploratory factor analysis as it has not previously been used in an asthma population.…”

“…Participants' perceptions of any adherence problems were measured using the PETS. 43 The PETS was developed to measure patient perceptions of barriers to adherence to home-based rehabilitation. The four validated PETS subscales were included (problems due to symptoms -three items; problems due to uncertainty about the therapy -three items; problems due to doubts -three items; and practical problems -five items), along with a new theoretically derived subscale to measure problems due to lack of support (three items).…”