Comparing Preference-based Outcome Measures for Overactive Bladder: EQ-5D-5L vs OAB-5D

A new journal article by OHE’s Michael Herdman and Nancy Devlin and colleagues was recently published in The Patient. The paper examines EQ-5D-5L outcomes from a clinical trial in patients with overactive bladder (OAB) and compares them to results on the OAB-5D, a condition-specific preference-based measure (PBM) of health.

Cost-utility analysis forms an integral part of health technology assessment (HTA) in a growing number of countries. Societal preferences for the health states associated with a given health condition before and after treatment are an essential component of such analyses and are often derived using preference-based measures of health such as EQ-5D.

Increasingly, condition-specific PBMs are becoming available, which may offer advantages over more generic PBMs such as EQ-5D. One such measure is the OAB-5D, which is derived from the Overactive Bladder Questionnaire (OAB-q) and which assesses health dimensions that are particularly pertinent to patients with OAB. There is little information available, however, about the comparative performance of the two PBMs in patients with OAB.

Our new paper compares outcomes on EQ-5D-5L with those on the OAB-5D using data from a clinical trial in which the two instruments were administered. The paper is authored by OHE’s Michael Herdman, and Nancy Devlin, in collaboration with researchers from Astellas Pharma Europe, the European Foundation for the study of Chronic Liver FailureAlliance Urology Specialists in the US, and the University of Bristol and Bristol Urological Institute, in the UK.

Data were from the BESIDE clinical trial, which compared outcomes in patients with OAB randomised to one of three different treatment regimens (combination treatment with solifenacin 5 mg plus mirabegron, solifenacin 5 mg, or solifenacin 10 mg). EQ-5D-5L and OAB-q (from which OAB-5D scores were derived) were administered at baseline and at weeks 4, 8, 12 and end of treatment. A particularly relevant aspect of the analysis is that EQ-5D-5L preference weights were calculated using the recently published EQ-5D-5L value set for England, making this one of the first published analyses to be carried out using the new value set.

In the 2,054 patients who received at least one dose of treatment over the study period, EQ-5D-5L Index mean score changes from baseline to end of treatment were observed to be larger with combination treatment (0.059) than with monotherapy (changes with solifenacin 5 mg and 10 mg of 0.040 and 0.044, respectively), but the differences were not statistically significant. Using the OAB-5D, on the other hand, it was found that differences in the size of improvements between arms were statistically significant (mean change of 0.107 for combination treatment vs 0.085 for 5 mg, and 0.087 for 10 mg; p ≤ 0.01), indicating that the condition-specific measure was more sensitive to treatment differences than the generic measure. The dimensions most improved overall were anxiety/depression, pain/discomfort, and usual activities on EQ-5D-5L, and urge, urine loss, and coping on OAB-5D.

In conclusion, the authors suggested that using both a generic and condition-specific PBMs in the same study could provide the optimal measurement strategy for cost-utility analysis in this population. Use of the condition-specific measure enhances measurement precision and sensitivity, and content relevance, whilst the generic measure permits comparisons with outcomes from other studies, treatments, and populations.

Herdman, M., Nazir, J., Hakimi, J., Siddiqui, E., Huang, M., Pavesi, M., MacDiamid, S., Drake, M.J., and Devlin, N. 2017. Assessing Preference-Based Outcome Measures for Overactive Bladder: An Evaluation of Patient-Reported Outcome Data from the BESIDE Clinical Trial. Patient, 10 (6):677-86. DOI | PubMed | RePEc

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