Continuous in-the-field measurement of heart rate: Correlates of drug use, craving, stress, and mood in polydrug users

Abstract

Background: Ambulatory physiological monitoring could clarify antecedents and consequences of drug use and could contribute to a sensor-triggered mobile intervention that automatically detects behaviorally risky situations. Our goal was to show that such monitoring is feasible and can produce meaningful data.

Methods: We assessed heart rate (HR) with AutoSense, a suite of biosensors that wirelessly transmits data to a smartphone, for up to 4 weeks in 40 polydrug users in opioid-agonist maintenance as they went about their daily lives. Participants also self-reported drug use, mood, and activities on electronic diaries. We compared HR with self-report using multilevel modeling (SAS Proc Mixed).

Results: Compliance with AutoSense was good; the data yield from the wireless electrocardiographs was 85.7%. HR was higher when participants reported cocaine use than when they reported heroin use (F(2,9)=250.3, p<.0001) and was also higher as a function of the dose of cocaine reported (F(1,8)=207.7, p<.0001). HR was higher when participants reported craving heroin (F(1,16)=230.9, p<.0001) or cocaine (F(1,14)=157.2, p<.0001) than when they reported of not craving. HR was lower (p<.05) in randomly prompted entries in which participants reported feeling relaxed, feeling happy, or watching TV, and was higher when they reported feeling stressed, being hassled, or walking.

Conclusions: High-yield, high-quality heart-rate data can be obtained from drug users in their natural environment as they go about their daily lives, and the resultant data robustly reflect episodes of cocaine and heroin use and other mental and behavioral events of interest.

Keywords: Ambulatory physiological monitoring; Cocaine; Craving; Heart rate; Heroin.

Conflict of interest statement

Author Disclosures

Conflict of Interest

No conflict declared.

Published by Elsevier Ireland Ltd.

Figures

Figure 1

Mean heart rate in the 120 minutes before and after event-contingent (i.e., participant-initiated) EMA entries reporting the use of heroin or cocaine (top panel, N=28) and after EMA entries reporting the use of 1 or 2 “dimes” of cocaine (bottom panel, N=20). For clarity, we do not show data from events in which both heroin and cocaine were used. Error bars indicate standard errors of the mean. In all cases, drug use occurred prior to the time of entry, indicated by a vertical line at time 0. The denominator degrees of freedom in this and all other EMA analyses reflect the number of participants who contributed data to more than one line in the graph, though the analyses include data from all participants who contributed data to any line in the graph.

Figure 2

Mean heart rate in the 30 minutes before and after random-prompt EMA entries in which participants are reporting either the presence or absence of cravings for heroin or cocaine. Data are shown for 40 participants. Other details are the same as in Figure 1.

Figure 3

Mean heart rate in the 30 minutes before and after random-prompt EMA entries in which participants reported the presence or absence of feeling relaxed, feeling happy, watching TV, walking, feeling stressed, and having recently been hassled. Data are shown for 40 participants. Other details are the same as in Figure 1.