Measuring quality of life in macular disease: What use are utilities?

Validity of EuroQOL-5D, time trade-off, and standard gamble for age-related macular degeneration in the Singapore population

BACKGROUND/AIMS

Utility values of age-related macular degeneration (AMD) in Asian patients are unknown. This study aims to assess utility values and construct validity of the EuroQOL-5D (EQ-5D), time trade-off (TTO), and standard gamble (SG) instruments in the Singapore multi-ethnic AMD population.

METHODS

Cross-sectional, two-centre, institution-based study. Visual acuity (VA), clinical AMD severity, and utility scores on the EQ-5D, TTO, and SG were obtained from 338 AMD patients. VA was analysed in terms of the better-seeing eye (BEVA), worse-seeing eye (WEVA), and weighted average of both eyes (WVA). We evaluated SG on the perfect health-death (SG(death)) and binocular perfect vision-binocular blindness (SG(blindness)) scales. Construct validity was determined by testing a priorihypotheses relating the EQ-5D, TTO, and SG utility scores to VA and clinical AMD severity.

RESULTS

The mean utilities on the EQ-5D, TTO, SG(death), and SG(blindness) were 0.89, 0.81, 0.86, and 0.90, respectively. EQ-5D scores correlated weakly with BEVA, WEVA, and WVA (Pearson's correlation coefficients -0.291, -0.247, and -0.305 respectively, P<0.001 for all). SG(death) and SG(blindness) demonstrated no correlation with BEVA, WEVA, or WVA (Pearson's correlation coefficients, range -0.06 to -0.125). TTO showed weak association only with WEVA and WVA (correlation coefficients -0.237, -0.228, P<0.0001), but not with BEVA (correlation coefficient -0.161). Clinical AMD severity correlated with EQ-5D and SG(death), but not with TTO and SG(blindness) (P=0.004, 0.002, 0.235, and 0.069, respectively).

CONCLUSIONS

AMD has a negative impact on utilities, although utility scores were high compared with Western cohorts. EQ-5D, TTO, and SG showed suboptimal construct validity, suggesting that health status utilities may not be sufficiently robust for cost-utility analyses in this population.

Metric properties of the MacDQoL, individualized macular-disease-specific quality of life instrument, and newly identified subscales in French, German, Italian, and American populations

OBJECTIVES

The aims of this analysis were to confirm the UK results in other countries and to explore the possibility of subscales of the 25-Item Macular disease Dependent Quality of Life (MacDQoL) questionnaire.

METHODS

Two clinical studies were pooled. Principal components analyses (Varimax) were conducted on baseline data from each country and from all combined. Factorial structures were compared between countries, and Cronbach alpha values were used to identify item clusters. Four groups of patients were created according to visual acuity (VA) in the best eye (BE < 10/20; BE ≥ 10/20) and worst eye (WE < 10/100; WE ≥ 10/100). These groups were used to investigate (analysis of variance) the sensitivity of MacDQoL to VA impairment and to compare it with the NEI-VFQ-25 generic visual function questionnaire.

RESULTS

A total of 797 patients (mean age 76.8 years; 55.8% women) had wet age-related macular degeneration (AMD). Strong correlations between the MacDQoL items (r > 0.48) and factor loadings > 0.49 on a forced one-factor analysis supported the use of an average weighted impact score. Four constructs (Cronbach alpha > 0.8) were derived, represented by the labels: Essential tasks, Family/social life, Activities/capabilities, and Embarrassment. The structure did not differ among the four countries involved, except one item (Finance), which has been excluded. Patients with BE VA <10/20 and WE VA <10/100 produced significantly worse overall scores than those with BE VA >10/20 and WE VA >10/100 (MacDQoL P < 0.0001; NEI-VFQ-25 P < 0.0001).

CONCLUSIONS

The analysis confirmed the metric properties of the MacDQoL. The MacDQoL offers a broad individualized measure of the impact of MD on quality of life.

Improving treatment satisfaction and other patient-reported outcomes in people with type 2 diabetes: the role of once-daily insulin glargine

Insulin therapy becomes essential for many people with type 2 diabetes. After starting insulin, people with diabetes that is poorly controlled with oral agents typically report improved well-being and treatment satisfaction. However, healthcare professionals and people with type 2 diabetes are often reluctant to begin insulin treatment, citing concerns such as time/resources needed to educate patients, increased risks of hypoglycaemia and fear of injections, which lead them to focus on intensifying conventional oral therapy. Insulin glargine, which offers people with diabetes a once-a-day injection regimen with low risk of hypoglycaemia, is more likely to overcome such initial barriers than other more complex insulin regimens. Once-daily insulin glargine, in combination with modern glucose-dependent oral agents that do not need to be chased with food to prevent hypoglycaemia, does not require the fixed mealtimes and set amounts of carbohydrates necessary with twice-daily injection mixes and older sulphonylureas. We know that it is such dietary restrictions that cause the most damage to quality of life (QoL). To avoid damaging QoL unnecessarily and to ensure optimal satisfaction with treatment, it is important to evaluate the effects of treatment on QoL, treatment satisfaction and other patient-reported outcomes (PROs) using questionnaires validated for this purpose, such as the widely used Diabetes Treatment Satisfaction Questionnaire and the Audit of Diabetes-Dependent Quality of Life measure. A systematic electronic literature search identified reports of studies evaluating PROs associated with insulin glargine in comparison with other treatments. The studies show that insulin glargine is usually associated with greater improvements in treatment satisfaction and other PROs compared with intensifying oral therapy or alternative insulin regimens.

Quality of life in age-related macular degeneration: a review of the literature

BACKGROUND

The Age-related Macular Degeneration Alliance International commissioned a review of the literature on quality of life (QoL) in macular degeneration (MD) with a view to increasing awareness of MD, reducing its impact and improving services for people with MD worldwide.

METHOD

A systematic review was conducted using electronic databases, conference proceedings and key journal hand search checks. The resulting 'White Paper' was posted on the AMD Alliance website and is reproduced here.

REVIEW

MD is a chronic, largely untreatable eye condition which leads to loss of central vision needed for tasks such as reading, watching TV, driving, recognising faces. It is the most common cause of blindness in the Western world. Shock of diagnosis, coupled with lack of information and support are a common experience. Incidence of depression is twice that found in the community-dwelling elderly, fuelled by functional decline and loss of leisure activities. Some people feel suicidal. MD threatens independence, especially when comorbidity exacerbates functional limitations. Rehabilitation, including low vision aid (LVA) provision and training, peer support and education, can improve functional and psychological outcomes but many people do not receive services likely to benefit them. Medical treatments, suitable for only a small minority of people with MD, can improve vision but most limit progress of MD, at least for a time, rather than cure. The White Paper considers difficulties associated with inappropriate use of health status measures and misinterpretation of utility values as QoL measures: evidence suggests they have poor validity in MD.

CONCLUSION

There is considerable evidence for the major damage done to QoL by MD which is underestimated by health status and utility measures. Medical treatments are limited to a small proportion of people. However, much can be done to improve QoL by early diagnosis of MD with good communication of prognosis and continuing support. Support could include provision of LVAs, peer support, education and effective help in adjusting to MD. It is vital that appropriate measures of visual function and QoL be used in building a sound evidence base for the effectiveness of rehabilitation and treatment.