Anesthesia technique, mortality, and length of stay after hip fracture surgery

Abstract

Importance: More than 300,000 hip fractures occur each year in the United States. Recent practice guidelines have advocated greater use of regional anesthesia for hip fracture surgery.

Objective: To test the association of regional (ie, spinal or epidural) anesthesia vs general anesthesia with 30-day mortality and hospital length of stay after hip fracture.

Design, setting, and patients: We conducted a matched retrospective cohort study involving patients 50 years or older who were undergoing surgery for hip fracture at general acute care hospitals in New York State between July 1, 2004, and December 31, 2011. Our main analysis was a near-far instrumental variable match that paired patients who lived at different distances from hospitals that specialized in regional or general anesthesia. Supplementary analyses included a within-hospital match that paired patients within the same hospital and an across-hospital match that paired patients at different hospitals.

Exposures: Spinal or epidural anesthesia; general anesthesia.

Main outcomes and measures: Thirty-day mortality and hospital length of stay. Because the distribution of length of stay had long tails, we characterized this outcome using the Huber M estimate with Huber weights, a robust estimator similar to a trimmed mean.

Results: Of 56,729 patients, 15,904 (28%) received regional anesthesia and 40,825 (72%) received general anesthesia. Overall, 3032 patients (5.3%) died. The M estimate of the length of stay was 6.2 days (95% CI, 6.2 to 6.2). The near-far matched analysis showed no significant difference in 30-day mortality by anesthesia type among the 21,514 patients included in this match: 583 of 10,757 matched patients (5.4%) who lived near a regional anesthesia-specialized hospital died vs 629 of 10,757 matched patients (5.8%) who lived near a general anesthesia-specialized hospital (instrumental variable estimate of risk difference, -1.1%; 95% CI, -2.8 to 0.5; P = .20). Supplementary analyses of within and across hospital patient matches yielded mortality findings to be similar to the main analysis. In the near-far match, regional anesthesia was associated with a 0.6-day shorter length of stay than general anesthesia (95% CI, -0.8 to -0.4, P < .001). Supplementary analyses also showed regional anesthesia to be associated with shorter length of stay, although the observed association was smaller in magnitude than in the main analysis.

Conclusions and relevance: Among adults in acute care hospitals in New York State undergoing hip repair, the use of regional anesthesia compared with general anesthesia was not associated with lower 30-day mortality but was associated with a modestly shorter length of stay. These findings do not support a mortality benefit for regional anesthesia in this setting.

Figure 1

Overview of Study Design, Showing the Near-Far Match, the Across-Hospital Match, and the Unadjusted, Unmatched Comparison Our study incorporated 3 matched comparisons. The primary analysis was a “near-far” instrumental variable match that included 10 757 pairs of patients who differed in terms of their residential proximity to hospitals specializing in regional or general anesthesia for hip fracture but were similar in terms of all other observable characteristics. Supplementary analyses included a within-hospital match that paired patients receiving regional vs general anesthesia within the same hospital and an across-hospital match that paired patients receiving regional vs general anesthesia across different hospitals.

Figure 2

Geographic Distribution of Patients Included in the Near-Far Matched Sample Orange circles correspond to patients residing in areas located relatively closer to hospitals that specialized in general anesthesia; blue circles correspond to patients residing in areas located relatively closer to hospitals that specialized in regional anesthesia. The interior borders represent zip code area boundaries.