In Reply Our study evaluated the association between anesthesia technique and outcome among patients with hip fracture, observing an indeterminate effect of anesthesia technique on 30-day mortality and a shorter inpatient length of stay with regional anesthesia.
One of our analyses used geographic proximity to hospitals that used more regional anesthesia as an instrumental variable for receipt of regional anesthesia, the thought being that after adjustment for measured medical and socioeconomic characteristics, geographic proximity was not indicative of patients with particular unmeasured health problems.
Neuman MD, Rosenbaum PR, Silber JH. Anesthesia Technique and Outcomes After Hip Fracture Surgery—Reply. JAMA. 2014;312(17):1802. doi:10.1001/jama.2014.11232