Measurement properties of pulmonary function measurement and patient-reported outcome measures in patients with multiple rib fracture without flail segment; validation study alongside the multicenter FixCon trial

Abstract Background The reliability and validity of pulmonary function, pain and health related quality of life (HR-QoL) as outcome measures for patients with rib fractures, remain uncertain. Our objective was to evaluate measurement properties in patients with multiple rib fractures by comparing them with generic HR-QoL instruments (EuroQoL-5D-5L [EQ-5D-5L], Short Form-12 [SF-12]). Methods A multicenter RCT in adults ( n = 180) was performed. Spirometry was performed at 30 days, 3, 6, and 12 months after trauma. Patients completed five questions on pain, EQ-5D-5L, SF-12, and two anchor questions on improvement in pulmonary function and thoracic complaints since previous measurement. Reliability, construct validity, responsiveness and floor and ceiling effects were evaluated for all follow-up time-points. Results EQ-5D and SF-12 (sub)scales showed adequate internal consistency. Construct and longitudinal validity were adequate for all (sub)scales, except for construct validity of the SF-12 Physical Component Summary. Ceiling effects were present for all pain questions from 30 days onwards, for EQ-5D-5L utility score (US) from 3 months onwards. Responsiveness analysis indicated that spirometry values showed trivial (tidal volume), small (inspiratory capacity, FEV1), or moderate (FVC) degree of change from 30 days to 12 months. All five pain levels, EQ-5D-5L and SF-12 (sub)scales showed moderate to large degree of change form 30 days to 12 months. Conclusions Spirometry and pain are valid instruments for monitoring functional recovery in patients after sustaining multiple rib fractures. Responsiveness was confirmed for pain and spirometry (FVC). EQ-5D-5L and SF-12 are valid, reliable, and responsive. Pain and HRQoL are therefore suitable instruments for measuring treatment effects over time.