Is use of mechanical ventilation a reasonable proxy indicator for coma among Medicare patients hospitalized for acute stroke?

OBJECTIVE: To ascertain whether use of mechanical ventilation on admission to the hospital is a proxy indicator of coma (i.e., very severe stroke) among acute stroke patients.
METHODS: A secondary analysis of data from a medical record review on a nationally representative sample of 2,824 Medicare patients, ages 65 years or older, who were hospitalized for stroke in 1982-1983 or 1985-1986 in 297 acute care hospitals in 30 areas within five geographically dispersed states.
RESULTS: Use of mechanical ventilation on the first day of hospitalization was significantly associated with level of consciousness on admission: < 2 percent of noncomatose patients versus 17.5 percent of comatose (p < .001). With a high specificity and high likelihood ratio for a positive test, use of mechanical ventilation on the first day of hospitalization ruled-in coma. It was also significantly associated with severity of illness, prognostic indicators (i.e., admission through the emergency room, admission to intensive care, and having a "do-not-resuscitate" order written during the hospital stay), and with in-hospital death. Adjusting for patient demographics, stroke type, comorbidity, and process of care, early initiation of mechanical ventilation remained significantly associated with both coma and in-hospital death.
CONCLUSIONS: A stroke patient's use of mechanical ventilation on the first day of hospitalization is a valid proxy indicator of level of consciousness.