An exploratory study to test the impact on three "bolt-on" items to the EQ-5D.

Generic preference-based measures were criticized for being inappropriate in some conditions. One solution is to include "bolt-on" dimensions describing additional specific health problems. This study aimed to develop bolt-on dimensions to the EuroQol five-dimensional questionnaire (EQ-5D) and assess their impact on health state values. Bolt-on dimensions were developed for vision problems, hearing problems, and tiredness. Each bolt-on dimension had three severity levels to match the EQ-5D. Three "core" EQ-5D states across a range of severity were selected, and each level of a bolt-on item was added, resulting in nine states in each condition. Health states with and without the bolt-on dimensions were valued by 300 members of the UK general public using time trade-off in face-to-face interviews, and mean health state values were compared using t tests. Regression analysis examined the impact of the bolt-on variants and the level of the bolt-on items after controlling for sociodemographic characteristics. Bolt-on dimensions had an impact on health state values of the EQ-5D; however, the size, direction, and significance of the impact depend on the severity of the core EQ-5D state and of the bolt-on dimension. Regression analysis demonstrated that after controlling for possible differences in sociodemographic characteristics between the groups, there were no significant differences in health state values between the three bolt-on dimensions but confirmed that the impact depended on the severity of the EQ-5D health state and the levels of bolt-on dimensions. The impact of a bolt-on dimension on the EQ-5D depends on the core health state and the level of the bolt-on dimension. Further research in this area is encouraged.

Yang Y ，Rowen D ，Brazier J ，Tsuchiya A ，Young T ，Longworth L ... -  《-》

Use of generic and condition-specific measures of health-related quality of life in NICE decision-making: a systematic review, statistical modelling and survey.

Longworth L ，Yang Y ，Young T ，Mulhern B ，Hernández Alava M ，Mukuria C ，Rowen D ，Tosh J ，Tsuchiya A ，Evans P ，Devianee Keetharuth A ，Brazier J ... -  《-》

A Vision "Bolt-On" Item Could Increase the Discriminatory Power of the EQ-5D Index Score.

Recently, a vision "bolt-on" EuroQol five-dimensional questionnaire (EQ-5D) was developed and tentative utility values (i.e., a "value set") for this new descriptive system were estimated. To compare the discriminatory power of this bolt-on and standard utility-based EQ-5D health indices. Cross-sectional data on the (3-level) vision bolt-on EQ-5D were collected through face-to-face interviews with 500 and 336 individuals with and without visual impairment, respectively. To assess the discriminatory power of the vision bolt-on index relative to the standard EQ-5D index developed in the vision bolt-on valuation study, 16 pairs of mutually exclusive subgroups of individuals defined by the individuals' visual acuity and responses to the 14-item visual function questionnaire were compared pairwise. The absolute mean difference in the two index scores and the corresponding F statistic derived from the comparisons were used as measures of discriminatory power. The absolute mean difference in the bolt-on index score was larger than that in the standard EQ-5D index score in 14 of the 16 comparisons. The bolt-on index score exhibited a larger F-statistic value than did the standard EQ-5D index score in all known-group comparisons, with the F-statistic ratio ranging from 0.415 to 0.770. The vision bolt-on EQ-5D appears to be more discriminative than the standard EQ-5D in measurement of vision problems. Future studies should investigate the extent to which the vision bolt-on item can increase the sensitivity of the EQ-5D to vision change in interventional studies.

Luo N ，Wang X ，Ang M ，Finkelstein EA ，Aung T ，Wong TY ，Lamoureux E ... -  《-》

Testing the Psychometric Properties of 9 Bolt-Ons for the EQ-5D-5L in a General Population Sample.

We aimed to assess the psychometric performance and added value of 9 existing bolt-ons (breathing problems, cognition, hearing, self-confidence, skin irritation, sleep, social relationships, tiredness, and vision) for the EQ-5D-5L in a general population sample. The EQ-5D-5L, 9 bolt-ons, SF-6Dv1, Patient-Reported Outcomes Measurement Information System (PROMIS)-29+2, PROMIS Global Health, and Satisfaction with Life Scale were completed in an online cross-sectional survey among a general adult population sample in Hungary (n = 1587). The following psychometric properties were tested for the EQ-5D-5L + bolt-on(s): ceiling, divergent and convergent validity, structural validity, known-group validity, and explanatory power. Adding sleep (30%), tiredness (24%), or vision (21%) substantially reduced the ceiling of the EQ-5D-5L (41%). Cognition, sleep, social relationships, and tiredness correlated with corresponding PROMIS and SF-6D items (rs = ǀ0.32ǀ - ǀ0.73ǀ). All bolt-ons, except cognition and self-confidence, loaded on a different factor from the EQ-5D-5L dimensions. Breathing, hearing, skin irritation, and vision significantly improved known-group validity in relevant health condition groups. The sleep bolt-on improved known-group validity in 9 of 13 chronic health conditions. Tiredness had the largest impact on explaining EQ VAS score variance in 8 of 13 conditions. Hearing and vision improved the ability of the EQ-5D-5L to capture declining health with age, whereas self-confidence and social relationships were valuable for mental health assessment. This study established the validity of multiple bolt-ons for the EQ-5D-5L and highlights the usefulness of including relevant bolt-ons in population-based and patient surveys. Our findings inform the further development of these bolt-ons and the bolt-on item selection for clinical studies.

Rencz F ，Janssen MF 《-》

Selecting Bolt-On Dimensions for the EQ-5D: Examining Their Contribution to Health-Related Quality of Life.

Generic preference-based measures may miss dimensions important for the health-related quality of life (HRQOL) of patients. When this happens, a possible solution is to add bolt-ons. Finch et al. (Finch AP, Brazier JE, Mukuria C, Bjorner JB. An exploratory study on using principal component analysis and confirmatory factor analysis to identify bolt-on dimensions: the EQ-5D case study. Value Health 2017;10:1362-75) have recently shown that bolt-ons can be systematically identified using factor analysis. Nevertheless, because for each bolt-on option a complete re-evaluation may be required, methods to select between them are needed. To investigate the possibility of selecting bolt-ons using their ability to predict differences in HRQOL. It tests six factors (energy/vitality, satisfaction, relationships, hearing, vision, and speech), and 37 items loading on them, using the EuroQol five-dimensional questionnaire as a case study. Data were obtained from the Multi-Instrument Comparison study, an online survey on health and well-being measures carried out in six countries. Two tests were performed. In the first test, linear regressions were fitted to determine whether different bolt-ons helped explain variations in HRQOL as measured by the Health visual analogue scale. The upper anchor (100) of this scale represents excellent physical, mental, and social health, and the lower anchor (0) represents death. Bolt-on relevance was judged comparing the strength, direction, and statistical significance of unadjusted β coefficients. In the second test, linear regressions were fitted to further investigate whether different factors and items helped explain the negative effect of six chronic conditions on HRQOL. A reduction in the coefficients for the chronic condition dummies meant that the factor or item detected the effect. Energy/vitality, relationships, and satisfaction reported substantially larger coefficients than did speech, vision, and hearing. Also, items loading on energy/vitality, relationships, and satisfaction generally presented larger coefficients than did those loading on speech, vision, and hearing. The second test did not detect consistent decrements in the coefficients for chronic conditions when testing factors, but it generally did detect consistent decrements when testing items. The first test appeared useful for bolt-on selection. Further research is needed before using the second test.

Finch AP ，Brazier JE ，Mukuria C 《-》