# Biases in the measurement of health-related quality of life in the EQ-5D-5L among those with serious physical traumatic injuries: the ADVANCE cohort study

## TL;DR

This study finds that UK military personnel with serious physical injuries perceive health-related quality of life differently than uninjured peers, with differences depending on injury type.

## Contribution

Identifies measurement bias in HRQOL assessments for injured populations based on injury type and functional status.

## Key findings

- Personnel with limb amputation injuries showed higher likelihood of low HRQOL scores but similar perceived health ratings compared to uninjured peers.
- Injured individuals without limb loss reported both lower HRQOL scores and lower perceived health compared to uninjured personnel.
- Measurement bias was detected in mobility and mental health domains depending on injury type.

## Abstract

Physical traumatic injuries are likely to impact on a person’s Health-Related Quality of Life (HRQOL). We present data on HRQOL, from which EQ-5D-5L index scores are derived, and overall perceived health in UK Armed Forces personnel who sustained serious physical combat injuries and compare them to demographically similar personnel without such injuries (uninjured group). To ensure that perception of HRQOL is similar between groups, we also assess for measurement bias through Differential Item Functioning (DIF).

577 personnel in an injured group (including subgroups of limb amputation injuries (n = 160) and non-amputation injuries (n = 417)) and 564 personnel in the uninjured group who sustained no such injuries were assessed in the ADVANCE cohort study. Health index values were derived from the EQ-5D-5L, overall perceived health from the EQ-visual analogue scale, and mobility from a Six-Minute Walk Test (6MWT). DIF was identified using multiple indicator multiple causes modelling.

Compared to the uninjured group, personnel injured with associated limb loss had significantly higher likelihood of reporting low health index scores (Relative Risk Ratio (RRR) 7.18 (95% Confidence Interval (CI) 4.25, 12.29; relative to high health index scores)), however no difference in the probability of reporting low or moderate overall perceived health, relative to high, was observed. Those injured without limb loss had a significantly higher probability of reporting low health index values (RRR 3.58 (95%CI 2.57, 5.03)) and low overall perceived health (RRR 1.91 (95%CI 1.34, 2.66)). Measurement bias was observed in items regarding mobility and anxiety/depression for those injured with associated limb loss and self-care for those with injured without. Differences in 6MWT only partially explained the bias observed in the mobility item.

Personnel who experience serious traumatic injuries perceive aspects of HRQOL differently to personnel who experience no such injuries, with heterogenous biases expressed depending on presence of limb amputation. Researchers evaluating HRQOL in health interventions may need to account for this bias if comparing individuals with different traumatic injuries/conditions.

The online version contains supplementary material available at 10.1007/s11136-025-04158-9.

Physical traumatic injuries have the potential to impact an individual’s quality of life. However, quality of life remains difficult to measure. If we ask a person before and after sustaining a physical traumatic injury about their quality of life, would we expect their quality of life to remain the same? Would we expect their idea of what quality of life is to also remain the same, or to change depending on the nature of their injury? In this study, we explore the health-related quality of life among UK Armed Forces personnel who sustained serious physical traumatic injuries and a comparison group of individuals who were similar to the injured group, but didn’t experience injuries. We find that whilst the injured group report worse health-related quality of life overall, we also observed some differences in how individuals perceive quality of life in terms of mobility, self-care and mental health that depended on the type of injury they received. Findings from this study show how researchers, policy makers and organisations must consider how to measure quality of life accurately, especially when comparing different groups of people.

The online version contains supplementary material available at 10.1007/s11136-025-04158-9.