LABORATORY REACTIVITY MODELS AS PREDICTORS OF AMBULATORY BLOOD-PRESSURE AND HEART-RATE

We attempted to validate the usefulness of the laboratory reactivity paradigm by examining responses to three distinct lab tasks and an overall lab average as predictors for ambulatory blood pressure. Subjects were 126 university students. We assessed ambulatory blood pressure, heart rate and perceived distress during an 8-hr working day. In the lab, all subjects responded to three standardized 5-min tasks: isometric handgrip, mental arithmetic, and a structured discussion of a recent interpersonal conflict situation. The analyses used absolute task levels, change scores, a composite index of reactivity, and a mean value for all obtained lab measures. Task levels correlated significantly with means of the ambulatory cardiovascular indices; the scores ranged from 0.35 to 0.49 for SBP, from 0.45 to 0.58 for DBP, and from 0.57 to 0.65 for HR. Only the DBP change score associated with the discussion task correlated with the ambulatory mean. The correlations between lab task levels and ambulatory measures were strongest for the discussion task and the composite score; the task level for the math task was consistently the weakest predictor of ambulatory activity. When lab resting values were forced into a step-wise multiple regression as step one, only the response to the discussion added significantly (3% each for SBP and DBP) to the variance in ambulatory pressure that was not already explained by resting values. The overall lab mean for SBP was a better predictor of the ambulatory mean than was any combination of resting values and reactivity indices.