# Reference values for the quality of life after traumatic brain injury questionnaire and its overall scale from the adult German general population

## TL;DR

This study provides reference values for a quality of life questionnaire for traumatic brain injury patients, based on the German general population, to help clinicians assess and treat affected individuals.

## Contribution

The study introduces population-based reference values for the QoLIBRI and QoLIBRI-OS questionnaires in Germany, enabling personalized clinical evaluation.

## Key findings

- The QoLIBRI and QoLIBRI-OS showed good psychometric properties in the general population.
- Reference values were derived and stratified by sex, age, and education for clinical use.
- A web-based application was developed to compare TBI patient scores with population norms.

## Abstract

One of the central outcomes to which attention should be paid after sustaining a traumatic brain injury (TBI) is health-related quality of life (HRQoL). The present study aims at providing reference values for the Quality of Life after Brain Injury (QoLIBRI) and its overall scale (QoLIBRI-OS) using data from the German general population.

A total of 3,502 individuals from the general German population completed an online survey containing adapted versions of both instruments designed for individuals without TBI. Psychometric properties, including reliability and validity analyses, were examined. Comparisons of construct assessment were conducted using 353 sex-, age-, and education-matched dyads from the general population sample and individuals after TBI.

Both instruments demonstrated satisfactory psychometric properties in the general population sample. The construct assessment between the general population and the TBI samples was considered sufficiently comparable to derive reference values. A patient is considered to have an impaired HRQoL if their QoLIBRI or QoLIBRI-OS score falls below the 16th percentile of their reference group, which is defined by sex, chronic health condition status, age, or education.

We provided reference values in form of an open access web-based application. Clinicians can use the provided reference values to directly compare the QoLIBRI and QoLIBRI-OS scores of individuals after TBI with those of the general population. This allows them to identify impaired HRQoL domains and develop personalized treatment plans.

The online version contains supplementary material available at 10.1186/s41687-026-01014-3.

Health-related quality of life (HRQoL) is one of the outcomes requiring attention after sustaining a traumatic brain injury (TBI). The Quality of Life after Brain Injury (QoLIBRI) and its short version, the overall scale (QoLIBRI-OS), are reliable patient-reported outcome measures for assessing TBI-specific HRQoL. This study informs clinical decision-making for individuals after TBI in Germany by providing reference values from the general population, which allows for the easy evaluation and interpretation of questionnaire scores and helps identify areas in need of treatment. The reference values are presented as percentiles, stratified by sex, age, and education, and are available in the form of an open-access web application. With this application, clinicians can directly compare the QoLIBRI/QoLIBRI-OS scores of affected individuals with those of the general population.

The online version contains supplementary material available at 10.1186/s41687-026-01014-3.