Validation of use of wireless monitors to measure levels of mobility during hospitalization

Accurate methods of measuring levels of mobility during hospitalization are lacking. We validated the use of wireless monitors to measure three levels of mobility during hospitalization: (1) lying, (2) sitting, and (3) standing or walking. Hospitalized medical patients 65 years or older who did not have delirium or dementia and could walk in the 2 weeks before admission were eligible. Wireless monitors, which recorded average position every 20 seconds, were attached to the thigh and ankle of consented patients. Direct behavioral observation by trained observers who recorded mobility level was used as the gold standard. Forty-seven male patients (mean age 73.9 years), with a mean length of stay of 5.3 days, generated 187 two-hour direct behavioral observation periods. Wireless monitors were highly correlated with direct behavioral observations. The median kappa was 0.92 and the kappa across all observations was 0.88, indicating excellent agreement. This study demonstrates that wireless monitors validly measure mobility levels among older hospitalized patients.