Multiple approaches to assessing the effects of delays for hip fracture patients in the United States and Canada.
OBJECTIVE
To examine the determinants of postsurgery length of stay (LOS) and inpatient mortality in the United States (California and Massachusetts) and Canada (Manitoba and Quebec).


METHODS
Patient discharge abstracts from the Agency for Health Care Policy and Research Nationwide Inpatient Sample and from provincial health ministries.


METHODS
Descriptive statistics by state or province, pooled competing risks hazards models (which control for censoring of LOS and inpatient mortality data), and instrumental variables (which control for confounding in observational data) were used to analyze the effect of wait time for hip fracture surgery on postsurgery outcomes. DATA EXTRACTIONS: Data were extracted for patients admitted to an acute care hospital with a primary diagnosis of hip fracture who received hip fracture surgery, were admitted from home or the emergency room, were age 45 or older, stayed in the hospital 365 days or less, and were not trauma patients.


RESULTS
The descriptive data indicate that wait times for surgery are longer in the two Canadian provinces than in the two U.S. states. Canadians also have longer postsurgery LOS and higher inpatient mortality. Yet the competing risks hazards model indicates that the effect of wait time on postsurgery LOS is small in magnitude. Instrumental variables analysis reveals that wait time for surgery is not a significant predictor of postsurgery length of stay. The hazards model reveals significant differences in mortality across regions. However, both the regressions and the instrumental variables indicate that these differences are not attributable to wait time for surgery.


CONCLUSIONS
Statistical models that account for censoring and confounding yield conclusions that differ from those implied by descriptive statistics in administrative data. Longer wait time for hip fracture surgery does not explain the difference in postsurgery outcomes across countries.
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John M. Olin School of Business, Washington University in St. Louis, MO 63130-4899, USA.
Hamilton
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D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D002140:California; D015986:Confounding Factors, Epidemiologic; D005260:Female; D006302:Health Services Research; D006620:Hip Fractures / Q000150:complications / Q000401:mortality* / Q000601:surgery*; D017052:Hospital Mortality; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data*; D008297:Male; D008350:Manitoba; D008404:Massachusetts; D010351:Patient Discharge / Q000706:statistics & numerical data; D016016:Proportional Hazards Models; D011792:Quebec; D015203:Reproducibility of Results; D012307:Risk Factors; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome; D014850:Waiting Lists