Running average analysis of clinical trial ambulatory blood pressure data

A method is presented for analyzing ambulatory blood pressure monitoring (ABPM) time series data obtained from well-controlled clinical trials. The method uses running averages based on fixed time-of-day intervals (rather than a fixed number of neighboring measurements). These "interval running averages" effectively estimate average blood pressure during the specified time intervals, adjusting for unequal spacing between measurements, embedded missing data, varying measurement times-of-day, and doses of study medication taken during ABP monitoring. Blood pressure changes from baseline may be computed using the interval running averages in order to separate treatment effects from patients' normal daily blood pressure cycles. To ensure valid estimation of treatment effects over time, study medication dosing times should be rigorously controlled in the trial design and conduct. Interval running average curves may be presented graphically, and from them summary statistics may be computed for purposes of statistical analysis. By allowing for the inherent complications of ABP data collection, the effect of antihypertensive treatment in well-controlled clinical trials can be discerned.