Research Article: One-Year Readmission Risk and Mortality after Hip Fracture Surgery: A National Population-Based Study in Taiwan

Date Published: July 21, 2017

Publisher: JKL International LLC

Author(s): Tien-Ching Lee, Pei-Shan Ho, Hui-Tzu Lin, Mei-Ling Ho, Hsuan-Ti Huang, Je-Ken Chang.


Early readmission following hip fracture (HFx) is associated with high morbidity and mortality. We conducted a survival analysis of patients with readmission within 1 year after HFx to elucidate the trend and predictors for readmission. We used Taiwan National Health Insurance Database to recruit HFx patients who underwent operations between 2000 and 2009. Patients < 60 years; with pathological fractures; involved in major traffic accidents; with previous pelvis, femur, and hip operations; or who died during the index admission were excluded. We used the Chi-square test, logistic regression, Kaplan-Meier method, and Cox proportional hazards model to analyze variables, including age, gender, hospital stay duration, index admission time, and comorbidity on readmission. 5,442 subjects (61.2% female) met the criteria with mean age of 78.8 years. Approximately 15% and 43% HFx patients were readmitted within 30 days (early) and between 30 days and 1 year (late) after discharge, respectively. Highest readmission incidence was observed within the first 30 days. Most common causes of readmission in early and late groups were respiratory system diseases and injuries, respectively. Cox model showed male, old age, hospital stay > 9 days, Charlson Comorbidity Index ≥ 1, index admission during 2000–2003, and internal fixation of HFx were independent predictors of readmission. One-year mortality of the early and the late readmission groups was 44.9% and 32.3%, much higher than overall mortality which was 16.8%. Predictive factors for readmission within 1 year included male, old age, comorbidities, and longer hospital stay. One-year mortality in readmitted patients was significantly higher. HFx patients with these factors need careful follow-up, especially within 30 days after discharge.

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A total of 5,442 subjects who underwent an operation because of hip fracture met the criteria and were included into the study. The median and mean length of hospital stay during the index admission was 9 days (interquartile range, 7-11 days) and 10.1 days (standard deviation, 6.3 days). Among these patients, 3,333 (61.2%) were female and 2,109 (38.8%) were male, with a mean age of 78.8 years. Of these, 2,266 (41.6%) patients underwent internal fixation and the remaining 3,176 (58.4%) underwent joint replacement; 817 (15.0%) and 2,354 (43.3%) were readmitted within 30 days (early readmission) and between 30 days and 1 year (late readmission) after discharge of index admission, respectively. The average length of index hospital stay was 12.6 days (standard deviation, 9.4 days) in the early readmission group and 11.2 days (standard deviation, 7.7 days) in the late readmission group. The distribution of variables in these two groups is shown in Table 1. The Kaplan-Meier curves (Fig. 1A-1F) reveal the time-to-readmission events within 1 year following hip fractures, with comparisons of different variables including gender, age, length of hospital stay, comorbidity, time of index admission, and type of operation. Analysis revealed that these variables showed similar patterns for time-to-readmission events. A rapid ascending curve was observed in the first 30 days for all patients with hip fracture. According to Figure 1 and Table 1, higher readmission rate was shown in subjects of male gender, of an older age, with the following conditions as length of hospital stay more than nine days, comorbidity (CCI) larger or equal to one, earlier study period of index admission for operation, or with internal fixation of hip fractures at any time over one year after discharge.

In this nationwide population-based retrospective study of 5,442 patients who underwent surgery for hip fractures and were discharged from hospital over a period of 1 year, 817 (15.0%) and 2354 (43.3%) were readmitted within 30 days and between 30 days and 1 year following discharge, respectively. The overall readmission rate, calculated using a time-to-event analysis, is similar to those of previous studies, which have reported readmission rates between 11.8% and 34% within 28 or 30 days after discharge [16, 17, 19, 20]. The predictive factors for readmission included male gender, an older age, an earlier period of index admission, a higher number of comorbidities, and a longer hospital stay, in both the early and the late readmission groups. The Kaplan-Meier curves (Fig. 1A-1F) show the time to readmission over the first year following discharge and give the complete picture of how different groups fared over time with respect to readmission [21]. During the first 30 days, a higher risk of readmission was noted. The higher risk observed during the earlier phases of follow-up could be due to postoperative delirium [22], post-hemorrhagic anemia [23], poor appetite [24], and poor general condition. This needs to be verified in further studies.

In this population-based study of 5442 patients who underwent surgical treatment for hip fractures, we found the predictive factors for readmission included male gender, older age, a higher number of comorbidities, and a longer hospital stay in both early and late readmission groups. A higher risk of readmission is observed during the first 30 days of follow-up. We suggest that patients with predictive factors need careful follow-up, especially within 30 days following operation for hip fracture.




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