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Does comorbidity affect the outcome of surgery? Total hip replacement in the UK and Japan
1Department of Public Health and Policy, London School of Hygiene and Tropical Medicine, UK.
Insights
Comorbidity significantly impacts serious complications after total hip replacement (THR) in the UK, but not in Japan. The Index of Co-Existent Diseases (ICED) showed limited predictive validity in both countries for surgical outcomes.
Area of Science:
- Orthopedic Surgery
- Health Services Research
- Epidemiology
Background:
- Comorbidity significantly influences surgical outcomes.
- Accurate assessment of comorbidity is crucial for comparing clinical performance.
- The Index of Co-Existent Diseases (ICED) is a comorbidity measure requiring validation across different healthcare systems.
Purpose of the Study:
- To evaluate the impact of comorbidity on total hip replacement (THR) outcomes in the UK and Japan.
- To assess the predictive accuracy of the Index of Co-Existent Diseases (ICED).
- To explore methods for improving the predictive power of the ICED.
Main Methods:
- Logistic regression analysis of retrospective cohort data.
- Inclusion of patients undergoing total hip replacement (THR) in the UK (n=268) and Japan (n=249).
- Assessment of serious complications and changes in activities of daily living (ADL) and social activities.
Main Results:
- Comorbidity levels differed significantly between the UK and Japan.
- In the UK, higher comorbidity was associated with increased serious complications (P<0.001), unlike in Japan.
- The ICED demonstrated poor predictive power for surgical complications and functional status changes in both countries.
Conclusions:
- Comorbidity is a key factor in THR complications in the UK, necessitating its consideration in performance comparisons.
- The ICED's validity is limited in the UK and Japan compared to the USA.
- Further development of comorbidity assessment tools is required for the UK and Japan.
Objectives:
To assess the impact of comorbidity on the outcome of surgery in the UK and in Japan; to determine the predictive ability of a new measure of comorbidity, the Index of Co-Existent Diseases (ICED); and to see if its predictive power could be improved.
Design:
Logistic regression using data from two retrospective cohorts with prospective outcome data collection.
Setting:
Six hospitals (three teaching, three non-teaching) in the UK and 15 (12 teaching, three non-teaching) hospitals in Japan.
Study Participants:
Patients undergoing total hip replacement (THR) surgery in the UK (n = 268) and in Japan (n = 249).
Main Outcome Measures:
Serious complications before hospital discharge and change in three measures of general health status [basic activities of daily living (ADL); instrumental ADL; social activities].
Results:
The distribution of levels of comorbidity differed between the UK and Japan: none (26.1 versus 42.2%); mild (30.6 versus 43.0%); moderate (23.5 versus 12.0%); and severe (19.8 versus 2.8%). In the UK, the incidence of serious complications was higher in patients with moderate (27.0%) or severe (26.4%) comorbidity than in those with no (14.3%) or mild (13.4%) comorbidity (P<0.001). In contrast, no significant association was found in Japan. The relationship between comorbidity and change in health status was weak in the UK and non-significant in Japan. Logistic regression confirmed that comorbidity was a significant predictor of serious complications in the UK. The only other significant factor was surgical approach (anterior/antero-lateral; odds ratio 2.16, P<0.05). Attempts to improve the predictive power of the ICED by modifying its structure and by reclassifying complications was successful in achieving a linear (rather than dichotomous) relationship. The predictive power, however, was poor.
Conclusions:
Comorbidity is a significant determinant of serious complications following THR but not of changes in functional or health status. Comparisons of clinical performance using post-operative complications must take levels of comorbidity into account if they are to be meaningful. The ICED is of less validity in the UK and Japan than in its country of origin, the USA. Further work to develop better instruments for the UK and Japan is needed.