Not all roads lead to Rome - a review of quality of life measurement in diabetes

Aims Quality of life (QoL) is recognized widely as an important health outcome in diabetes, where the burden of selfmanagement places great demands on the individual. However, the concept of QoL remains ambiguous and poorly defined. The aim of our review is to clarify the measurement of QoL in terms of conceptualization, terminology and psychometric properties, to review the instruments that have been used most frequently to assess QoL in diabetes research and make recommendations for how to select measures appropriately.

Methods A systematic literature search was conducted to identify the ten measures most frequently used to assess QoL in diabetes research (including clinical trials) from 1995 to March 2008.

Results Six thousand and eight-five abstracts were identified and screened for instrument names. Of the ten instruments most frequently used to assess ‘QoL’, only three actually do so [i.e. the generic World Health Organization Quality of Life (WHOQOL) and the diabetes-specific Diabetes Quality of Life (DQOL) and Audit of Diabetes-Dependent Quality of Life (ADDQoL)]. Seven instruments more accurately measure health status [Short-Form 36 (SF-36), EuroQoL 5-Dimension (EQ-5D)], treatment satisfaction [Diabetes Treatment Satisfaction Questionnaire (DTSQ)] and psychological well-being [Beck Depression Inventory (BDI), Hospital Anxiety and Depression Scale (HADS), Well-Being Questionnaire (W-BQ), Problem Areas in Diabetes (PAID)].

Conclusions No single measure can suit every purpose or application but, when measures are selected inappropriately and data misinterpreted, any conclusions drawn are fundamentally flawed. If we value QoL as a therapeutic goal, we must ensure that the instruments we use are both valid and reliable. QoL assessment has the proven potential to identify ways in which treatments can be tailored to reduce the burden of diabetes. With careful consideration, appropriate measures can be selected and truly robust assessments undertaken successfully.

Predicting outcomes in the Dose Adjustment For Normal Eating (DAFNE) trial

Background: In the UK, DAFNE training in flexible intensive insulin therapy significantly reduced the negative impact of diabetes on quality of life (QoL) and improved blood glucose (BG) control without significantly increasing severe hypoglycaemia or body mass index (BMI). Analyses were conducted to predict who would benefit most from the generally highly successful DAFNE training and who might experience undesirable effects (e.g. weight gain).

Methods: Multiple regression was used to predict change in outcomes (6-months post-DAFNE) using baseline data: demographic, biomedical, ADDQoL (measure of the impact of diabetes on QoL), extended DTSQ (Diabetes Treatment Satisfaction Questionnaire), and other psychological measures including diabetes-specific well-being and locus of control.

Findings: Greatest improvement in ADDQoL scores was achieved by those reporting less dietary freedom and less treatment satisfaction at baseline (R2=0.21). BG improvement was predicted by higher baseline BG, lower perceived frequency of hypoglycaemia, greater expectations of DAFNE, and greater BMI (R2=0.30). Increase in BMI was predicted by less dietary freedom, DAFNE training centre, and less ‘satisfaction with insulin’ at baseline (R2=0.23).

Conclusions/Discussion: DAFNE has important benefits to offer. Lifting dietary restrictions had substantial benefits for QoL. BG improvement was predicted by baseline BG but also by expectations (perhaps reflecting greater optimism or determination). Prediction of weight gain was more complex. The influence of training centre will have involved implicit messages conveyed by Educators before and during DAFNE. While DAFNE was successful overall, outcomes are likely to be maximised for individuals if their expectations and personal goals are considered by DAFNE Educators.

Patient-reported outcomes in trials of incretin-based therapies in patients with type 2 diabetes mellitus

Incretin-based therapies have a glucose-dependent mode of action that results in excellent glucose-lowering efficacy with very low risk of hypoglycaemia, and weight neutrality [dipeptidyl peptidase-4 (DPP-4) inhibitors] or weight loss [glucagon-like peptide-1 (GLP-1) receptor agonists], in people with type 2 diabetes mellitus (T2DM). Patient-reported outcomes (PROs) complement physician evaluations of efficacy and tolerability and offer insights into the subjective experience of using modern diabetes treatments. We conducted a systematic search of clinical trials of the GLP-1 receptor agonists liraglutide, exenatide and long-acting exenatide, one of which included the oral DPP-4 inhibitor sitagliptin as a comparator. No other PRO data for DPP-4 inhibitors were identified. This review summarizes PRO data from eight clinical trials, the majority of which used the Diabetes Treatment Satisfaction Questionnaire (DTSQ) and/or Impact of Weight on Quality of Life-Lite (IWQOL-Lite) to evaluate patient experience. People with T2DM were highly satisfied with modern incretin-based therapies compared with traditional therapies. Treatment satisfaction (including perceptions of convenience and flexibility) was high and generally higher with GLP-1 agonists in association with their greater glucose-lowering efficacy and tendency to facilitate weight loss. Weight-related quality of life (QoL) also improved in people using incretin therapies. The glycaemic improvements achieved with GLP-1 receptor agonists, coupled with the low incidence of hypoglycaemia and ability to cause weight loss, seemed to offset potential concern about injections. It is plausible that superior patient-reported benefits found in clinical trials may translate into improved, clinically meaningful, long-term outcomes through increased treatment acceptability. Long-term, prospective data are needed to ascertain whether this is the case in practice.

Generic and diabetes-specific well-being in the AT.LANTUS follow-on study : further psychometric validation of the W-BQ28 indicates its utility in research and clinical practice in type 2 diabetes in the UK

Aims  To undertake further psychometric validation of the W-BQ28 to determine its suitability for use in adults with Type 2 diabetes in the UK using data from the AT.LANTUS follow-on study.

Methods  A total of 353 people with Type 2 diabetes participated in the AT.LANTUS Follow-on study, completing measures of well-being (W-BQ28), treatment satisfaction (DTSQ) and self-care (SCI-R). Confirmatory factor analyses was used to confirm the W-BQ28 structure and internal consistency reliability was assessed. Additional statistical tests were conducted to explore convergent, divergent and known-groups validity. Minimal important differences were calculated using distribution and anchor-based techniques.

Results  Structure of the W-BQ28 (seven four-item subscales plus 16-item generic and 12-item diabetes-specific scales) was confirmed (comparative fit index = 0.917, root mean square error of approximation (RMSEA) = 0.057). Internal consistency reliability was satisfactory (four-item subscales: alpha = 0.73–0.90; 12/16-item scales: α = 0.84–0.90). Convergent validity was supported by expected moderate to high correlations (rs = 0.35–0.67) between all W-BQ28 subscales (except Energy); divergent validity was supported by expected low to moderate correlations with treatment satisfaction (rs = −0.03–0.52) and self-care (rs = 0.02–0.22). Known-groups validity was supported with statistically significant differences by sex, age and HbA1c for expected subscales. Minimal important differences were established (range 0.14–2.90).

Conclusions  The W-BQ28 is a valid and reliable measure of generic and diabetes-specific well-being in Type 2 diabetes in the UK. Confirmation of the utility of W-BQ28 (including establishment of minimal important differences) means that its use is indicated in research and clinical practice.

Psychometric validation of the Self-Care Inventory-Revised (SCI-R) in UK adults with type 2 diabetes using data from the AT.LANTUS follow-on study.

Background:
Achieving optimal outcomes in type 2 diabetes (T2DM) involves several demanding self-care behaviours, e.g. managing diet, activity, medications, monitoring glucose levels, footcare. The Self-Care Inventory-Revised (SCI-R) is valid for use in people with T2DM in the US. Our aim was to determine its suitability for use in the UK.