Ankle fracture follow up using the Chertsey Outcome score for Trauma. Floor and ceiling effect of the scale

Abstract

Background: Patient reported outcome measures (PROMs) are increasingly used by orthopaedic surgeons in order to measure their results. The Chertsey Outcome Score for Trauma (COST) is a recently validated PROM, which treats trauma as pathology, is not site or pathology specific. It measures the rehabilitation of the patients after an injury, using the pre-injury status as the default state of the patients. The aim of the present study was to focus on a narrow group of patients with similar ankle fracture injuries, investigate if there is any floor or ceiling effect of the scale and examine its use during the ankle fracture at the immediate post-injury rehabilitation period.

Materials and methods: All patients who had isolated ankle fractures treated either operatively or conservatively between March 2018 and December 2019, were included in the study. A COST and a FADI questionnaire was completed prior to their follow-up at 2, 6 and 12 weeks post injury/operation. Demographic data were also collected.

Results: A total of 527 COST questionnaires from 314 different patients (aged 51.4 ± 18.4 years) were included in the study. The average COST score was 40.28 ± 18 and the average FADI score was 60.1 ± 21.8. The VAS score reached 3.57 ± 2.2. There was no significant floor and ceiling effect for the COST score. The COST score had good correlation with the FADI score (Spearman's Rho=0.69) and good internal consistency (Cronbach's Alpha=0.85).

Conclusion: No significant floor or ceiling effect was identified for the COST score, during the short and medium term follow up period following an ankle fracture, treated with either conservative or operative management. The scale was found to be valid and with good internal consistency.

Keywords: COST; Internal consistency; PROM; Patient reported outcome measure; Rehabilitation; Validity.