Review of patient-reported outcome instruments measuring health-related quality of life and satisfaction in patients with type 2 diabetes treated with oral therapy

Objective: Treatments and their mode of administration may represent a burden for patients and can therefore impact their health-related quality of life (HRQL) or treatment/health satisfaction. Patients with type 2 diabetes mellitus (T2DM) can be treated with oral hypoglycemic agents (OHAs), injectable medications (such as insulin), or a combination of agents. This review aimed to identify patient-reported outcome (PRO) instruments measuring HRQL and/or satisfaction that could differentiate between oral medications based on medication related attributes such as efficacy, tolerability, weight loss, dosing frequency and pill burden.

Research design and methods: Medline, Embase, PsycINFO, Cochrane Library and the Patient-Reported Outcome and Quality of Life Questionnaires (PROQOLID) biomedical databases were searched to identify instruments and document their development methodology, content and psychometric properties (i.e. validity, reliability), responsiveness and ability to detect changes between treatments.

Results: Nineteen instruments were retained based on their potential to differentiate between OHAs. Ten instruments assessed HRQL, amongst which the Audit of Diabetes Dependent Quality of Life, Diabetes 39, Diabetes Health Profile and Impact of Weight on Quality of Life displayed good psychometric properties in T2DM populations and comprehensive HRQL content. Nine instruments assessed satisfaction. Both the Oral Hypoglycemic Agent Questionnaire (OHAQ) and Diabetes Medication Satisfaction (DiabMedSat) Questionnaire have highly relevant content regarding drug attributes. The OHAQ is specific to oral treatment and the DiabMedSat includes HRQL items. The Diabetes Treatment Satisfaction Questionnaire is a standard instrument that is extensively used and provides conclusive results in studies of patients with T2DM.

Conclusions: Very few of the existing PRO instruments are specific to OHAs. Despite satisfaction instruments being recommended to differentiate between OHAs in studies of T2DM based on medication attributes, we find that none of the existing instruments appear to be useful in detecting differences between treatments, therefore limiting their use in clinical and observational research.