Clinical measurement of physical activity appears to be an independent predictor of whether or not patients with chronic obstructive pulmonary disease (COPD) will end up being hospitalized, according to a new study conducted by researchers in Connecticut. The study also corroborates an earlier investigation that linked higher levels of inactivity with an increased incidence of hospitalizations among patients with COPD.
The results of the study will be presented at the ATS 2013 International Conference.
“Physical inactivity is common in patients with COPD and appears to predict poor outcome, including more frequent hospitalizations, compared to COPD patients who have higher levels of exercise,†said study lead author Sheila Zanoria, MD, resident at the University of Connecticut Health Center in Farmington, Conn. “This remains true even when accounting for other factors that may be present.
“Our study evaluated levels of physical activity and other respiratory measurements, including the six-minute walk distance (6MWD),which measures the distance a patient is able to walk in six minutes,†she said. “Then we examined the relationship between those baseline measurements and the subsequent hospitalization rate among the same patients over a four- to five-year follow-up period.
“Ideally, we hoped to identify specific measurements that could be used proactively to help identify which patients are most at risk for hospitalization,†Dr. Zanoria added.
The retrospective study looked at baseline data collected from 60 COPD patients in 2008 and compared that data with the number of hospitalizations that occurred during the follow-up period. Initial baseline data were collected from each patient during a period of seven consecutive days. During that time, each patient wore a tri-axial accelerometer, a device worn at the waist and used to measure physical activity in units called vector magnitude units, or VMUs. VMUs are typically measured continually and then summed up every minute to provide usable data.
During the same seven-day period, researchers also evaluated patients’ exercise capacity using the 6MWD, supplemental oxygen use and forced expiratory volume in one second measurement, or FEV1, which measures the amount of air a patient is able to exhale in one second.
