Table 3 Quality assessment checklist used for included studies (modified from Ara et al.) [24]

 Relevant population

How closely do the patient characteristics in the study match to the patient population we have described in our inclusion criteria (PICO)

 Relevant health states

Timing of data collection, e.g. pre-surgery, post-surgery, follow-up intervals. The use of any medications that is likely to have an independent effect on HSUVs (either detrimental or beneficial)

 Sample size

This was not considered as exclusion criteria, but the precision of the estimate was assessed

 Response rates to the measure used

Are response rates reported and if so, are the rates likely to be a threat to the validity of the estimated HSUVs for the health states?

 Loss to follow-up

How large is the loss to follow-up and are these likely to threaten the validity of the estimates?

 Missing data

What are the levels of missing data and how are they dealt with?

Are there details on the causes of the missing data?

Again, could this threaten the validity of the estimates?

 Appropriate use of valuation method

If valuation methods are used (TTO, SG, DCE, VAS) they are used appropriately?

Does the valuation method provide preference based values anchored at 1 as equivalent to full health and 0 as equivalent to dead?

Are adequate details of the valuation method provided to allow judgement on appropriateness?

 Appropriate use of GPMB

Are adequate details of the PBM method provided (e.g. details given on the version used, the social tariff applied)

Was the GPBM delivered as intended? (e.g. wording and response options not changed)

Is the measure used for the group it was intended (e.g. is an adult GPBM being used for children? Is EQ-5D-Y used with the adult tariff?)

 Appropriate health-state description (vignette)

If a health state is valued using a vignette, can the accuracy of the vignette be established? e.g. the process by which it was derived is described