Comparison of measures of comorbidity for predicting disability 12-months post-injury

• Published in: BMC health services research 2013-01, Vol.13 (1), p.30-30, Article 30
• Main Authors: Gabbe, Belinda J, Harrison, James E, Lyons, Ronan A, Edwards, Elton R, Cameron, Peter A
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Age; Aged; Aged, 80 and over; Arthritis; Back pain; Bone and Bones - injuries; Cardiovascular disease; Care and treatment; Chronic illnesses; Codes; Coding standards; Comorbidity; Comparative analysis; Confidence Intervals; Diabetes; Disability; Disability Evaluation; Disability outcomes; Female; Glasgow Outcome Scale; Heart attacks; Hospitals; Humans; Injuries; International Classification of Diseases; Liver diseases; Logistic Models; Lung diseases; Male; Medical research; Medicine, Experimental; Middle Aged; Mortality; Orthopaedic injury; Orthopedics; Outcome Assessment, Health Care - methods; Patient outcomes; Prediction; Predictive Value of Tests; Preventive medicine; Prospective Studies; Risk Adjustment; Trauma; Variables; Wounds and injuries; Wounds and Injuries - rehabilitation; Young Adult
• ISSN: 1472-6963; 1472-6963
• DOI: 10.1186/1472-6963-13-30

Understanding the factors that impact on disability is necessary to inform trauma care and enable adequate risk adjustment for benchmarking and monitoring. A key consideration is how to adjust for pre-existing conditions when assessing injury outcomes, and whether the inclusion of comorbidity is needed in addition to adjustment for age. This study compared different approaches to modelling the impact of comorbidity, collected as part of the routine hospital episode data, on disability outcomes following orthopaedic injury. 12-month Glasgow Outcome Scale - Extended (GOS-E) outcomes for 13,519 survivors to discharge were drawn from the Victorian Orthopaedic Trauma Outcomes Registry, a prospective cohort study of admitted orthopaedic injury patients. ICD-10-AM comorbidity codes were mapped to four comorbidity indices. Cases with a GOS-E score of 7-8 were considered "recovered". A split dataset approach was used with cases randomly assigned to development or test datasets. Logistic regression models were fitted with "recovery" as the outcome and the performance of the models based on each comorbidity index (adjusted for injury and age) measured using calibration (Hosmer-Lemshow (H-L) statistics and calibration curves) and discrimination (Area under the Receiver Operating Characteristic (AUC)) statistics. All comorbidity indices improved model fit over models with age and injuries sustained alone. None of the models demonstrated acceptable model calibration (H-L statistic p