Validity and reliability of the pediatric quality of life inventory™ 4.0 generic core scales to measure health-related quality of life in pediatric outpatients after thermal injuries

Background Health-related quality of life (HRQoL) is a patient-centered outcome in pediatric burn care, yet no burn-specific, validated German-language instrument is available for this population. This study evaluated the feasibility and measurement properties of the German PedsQL™ 4.0 Generic Core Scales (GCS) in pediatric outpatients after thermal injuries. Methodology In this retrospective observational study, the authorized German PedsQL™ 4.0 GCS was implemented in a pediatric burn clinic. Data from October 2022 to January 2026 were analyzed across 16 age-, respondent-, and recall-specific forms. Feasibility, internal consistency (model-based omega total), structural validity (ordinal confirmatory factor analysis of parent-proxy reports), floor and ceiling effects, known-groups validity, and responsiveness were assessed. Patients were the unit of analysis; analysis windows (0–30 and ≥ 31 days after the patient-specific index) were distinct from questionnaire recall versions. Results Of 1,194 questionnaire opportunities, 951 (79.6%) were completed; language barriers accounted for 42.0% of non-completions. Parent-proxy and child self-report index samples comprised 382 and 134 patients. The parent-proxy Total Score averaged 80.73, with Emotional functioning the lowest (73.61). Of 96 form-by-scale coefficients, 75 were estimated; Emotional functioning point estimates exceeded 0.70 in all forms, although precision was frequently limited, whereas the Total Score was estimable in seven forms (0.814–0.945), and Physical, Social, and Cognitive/School values below 0.70 occurred only in 8–12-year or adolescent forms. No model achieved adequate global fit (correlated four-factor model, n = 244: CFI = 0.865; RMSEA = 0.120). Ceiling effects reached 55.2% for Social and 42.0% for Cognitive/School functioning, without relevant floor effects. Known-groups differences were confined to parent-proxy Physical Summary (adjusted p = 0.030; δ = −0.238). In 122 paired patients, Total and Physical Summary Scores increased by 4.98 (95% CI 2.80–7.16) and 6.63 (3.45–9.82) points, with no consistent evidence of Social improvement. Conclusions The German PedsQL™ 4.0 GCS was feasible for routine use and showed generally adequate internal consistency in several larger form-by-scale analyses. Group-level monitoring requires attention to form, domain, sample size, and structural-fit limitations. Structural validity was only partially supported and examined in parent-proxy reports alone; content validity and invariance were not evaluated. Ceiling effects require cautious interpretation.