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). Data Sources/Study Setting. Patient discharge abstracts from the Agency for Health Care Policy and Research Nationwide Inpatient Sample and from provi ncial health ministries. Study Design. Descriptive statistics by state or province, pooled competing risks hazards models (which control for censoring of LOS and inpatient mor tality data), and instrumental variables (which control for confounding in observational data) were used to analyze the effect of wait time for hip fr acture surgery on postsurgery outcomes. Data Extractions. Data were extracted for patients admitted to an acute car e hospital with a primary diagnosis of hip fracture who received hip fractu re surgery, were admitted from home or the emergency room, were age 45 or o lder, stayed in the hospital 365 days or less, and were not trauma patients . Principal Findings. The descriptive data indicate that wait times for surge ry are longer in the two Canadian provinces than in the two U.S. states. Ca nadians also have longer postsurgery LOS and higher inpatient mortality. Ye t the competing risks hazards model indicates that the effect of wait time on postsurgery LOS is small in magnitude. Instrumental variables analysis r eveals that wait time for surgery is not a significant predictor of postsur gery length of stay. The hazards model reveals significant differences in m ortality across regions. However, both the regressions and the instrumental variables indicate that these differences are not attributable to wait tim e 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.