Known-groups validity and responsiveness to change of the Patient Experience with Treatment and Self-management (PETS vs. 2.0): a patient-reported measure of treatment burden.

Purpose: The purpose of this study was to test the known-groups validity and responsiveness to change of the Patient Experience with Treatment and Self-management (PETS, vs. 2.0), a measure of treatment burden.
Methods: The PETS and other standard measures were mailed at baseline and 12-month follow-up to adults living with multiple chronic conditions in southeast Minnesota (USA). A sample of 365 people (mean age = 62.1 years) completed both surveys. Baseline, 12-month, and changes in PETS burden scores were examined. Clinical anchors used to test validity included number of diagnoses (2-4 vs. 5+), mental health diagnosis (yes/no), medication adherence and health literacy (suboptimal/optimal), and changes in self-efficacy, global physical, and global mental health (worsening/improving). Independent-samples t-tests were used to compare scores.
Results: PETS scales showed good internal consistency (αs ≥ 0.80). There were few differences across number of diagnoses, but having a mental health diagnosis was associated with higher baseline PETS burden scores (Ps < .05). Suboptimal medication adherence and health literacy over time were associated with worse 12-month PETS burden scores (Ps < .05). Compared with improvements, declines over time in self-efficacy, global physical health, and global mental health were each associated with worsening change scores on PETS impact summary, medical expenses, and bother due to medication reliance and medication side effects (Ps < .05).
Conclusion: Among multi-morbid adults, the PETS demonstrated evidence of known-groups validity and responsiveness to change across both objective (e.g., mental health diagnoses) and subjective anchors (e.g., changes in self-efficacy, global physical, and global mental health).