A total of 23 individuals were recruited from the Positive Health Program HIV Clinic and 29 individuals were recruited from the REACH Cohort. No participants were excluded due to cognitive impairment. As shown in , the cohort characteristics consisted largely of middle-aged black and white men who had relatively high levels of education. The majority were men who have sex with men and injection drug users, and 69% had undetectable viral load at enrollment. Median follow-up time was 85 (IQR 72–90) days. Data on Med-eMonitor adherence was missing for two participants due to lack of interest in participating after enrollment, and HIV RNA was missing for another participant due to a missed study visit. Complete data was available for all other participants. Additionally, no devices were lost, stolen, or broken. At least one transmission error occurred in all but two participants, and errors consisted of the lack of a detected cradle connection, lack of a dial tone, a modem initialization error, and a busy signal. These errors, however, were typically transient, and a median of 92.4% (IQR 72.8%–98.4%) of data was transmitted daily during the follow-up period.
Cohort characteristics (N=52)
Adherence values are shown in . Median adherence was 97.1% (IQR 99.7–105.5%) for unannounced pill count, 96.8% (IQR 70.2–123.4%) for unadjusted Med-eMonitor, and 89.8% (IQR 77.1–102.5%) for adjusted Med-eMonitor. Unannounced pill count adherence was similar to unadjusted Med-eMonitor adherence, although it trended toward a difference (Wilcoxon signed rank test, p=0.07), and was significantly higher than adjusted Med-eMonitor adherence (p=0.01). Unannounced pill count adherence was not significantly correlated with unadjusted Med-eMonitor adherence (Spearman r=0.20; p=0.17), but was significantly correlated with adjusted Med-eMonitor adherence (r=0.29; p=0.04).
Monthly adherence levels over the three-month study period
provide scatter plots presenting each participant’s three-month average unannounced pill count adherence with his or her three-month average unadjusted and adjusted Med-eMonitor adherence, respectively. The discrepancies seen on the left side of these plots likely indicate non-use of the Med-eMonitor device, whereas discrepancies on the right side likely reflect extra openings without removal of pills (also known as curiosity events). Fewer right-sided discrepancies are seen with the adjusted Med-eMonitor data compared to the unadjusted Med-eMonitor data, as confirmed dosing should remove most curiosity events.
Scatter plots of unannounced pill count versus adjusted (Figure 2a) and unadjusted (Figure 2b) Med-eMonitor adherence. Data from the same participant are aligned vertically and are ordered from lowest to highest unannounced pill count adherence.
Fifty-three percent of participants had one or more interruptions of at least 48 hours according to both unadjusted and adjusted Med-eMonitor data. Among participants with any interruptions of at least 48 hours, the median duration of interruptions was 93.6 (IQR 57.6–151.2) hours for unadjusted data and 103.2 (IQR 67.2–158.4) hours for adjusted data. For the subset of participants who were also in the REACH cohort, the mean adherence level by unannounced pill count was 5% higher in the three months of the study period compared to the prior three months, with this difference nearing statistical significance (91.0% +/− SD 12.4% versus 94.6% +/− SD 7.8%; paired t-test, p=0.06). Median values, however, were more similar (96.0% [IQR 88.9%–99.2%] versus 97.1% (IQR 99.7–105.5%], respectively; Wilcoxon signed rank test, p=0.26).
presents the distribution of adherence by unannounced pill count and unadjusted and adjusted Med-eMonitor, revealing wider variation in both types of Med-eMonitor adherence measurements compared to the unannounced pill count.
Distribution of adherence by unannounced pill count, unadjusted Med-eMonitor and adjusted Med-eMonitor.
The number of participants with viral suppression remained constant during the three-month study period (N=36). HIV RNA suppression was significantly correlated with unannounced pill count adherence (Spearman r=−0.35, p=0.01), trended toward significance with unadjusted Med-eMonitor adherence (r=−0.24; p=0.10), and was not significantly correlated with adjusted Med-eMonitor adherence (r=−0.18, p =0.22).
As shown in , subjects generally found the Med-eMonitor device acceptable and useful; however, not all features were as appealing as others. For example, 79% stated that the device made it easy to remember when to take their pills, while 65% found the chimes annoying. Although not statistically significant, all three adherence measures were associated with a higher likelihood of using the Med-eMonitor again (OR 8.43 for unannounced pill count, p=0.71; OR 4.8 for unadjusted Med-eMonitor, p=0.52; and OR 68.8 for adjusted Med-eMonitor, p=0.29).
Acceptability of the Med-eMonitor device