Randomized Controlled Trial of Daily Text Messages to Support Adherence to Preexposure Prophylaxis in Individuals at Risk for Human Immunodeficiency Virus: The TAPIR Study

Abstract

Background: Adherence is critical for efficacy of tenofovir disoproxil fumarate/emtricitabine (FTC) as preexposure prophylaxis (PrEP).

Methods: Between February 2013 and February 2016, 398 men who have sex with men and transgender women were randomized 1:1 to receive individualized texting for adherence building (iTAB) or standard care (SoC) for 48 weeks. The primary endpoint was dried blood spot (DBS) tenofovir diphosphate (TFV-DP) concentrations at both week 12 and the last on-drug visit of >719 fmol/punch (ie, adequate adherence). Secondary outcomes included DBS TFV-DP concentrations of >1246 fmol/punch (ie, near-perfect adherence) and plasma FTC >350 ng/mL (consistent with dosing within the past 24 hours).

Results: Concentrations >719 fmol/punch of TFV-DP were found in 88.6% of participants at week 12 and 82.5% at week 48. For the primary endpoint, the study arms did not differ (72.0% in iTAB and 69.2% in SoC; P > .05). For the secondary composite endpoint of >1246 fmol/punch the iTAB arm was superior to SoC (33.5% vs 24.8%; P = .06), reaching statistical significance when adjusting for age (odds ratio, 1.56 [95% confidence interval, 1.00-2.42]; P < .05). At week 48, iTAB was superior to SoC for near-perfect adherence (51.0% vs 37.4%; P = .02). At week 12, iTAB was superior to SoC for dosing in past 24 hours by plasma FTC (47.5% vs 33.3%; P = .007), but not at weeks 24, 36, and 48 (all P > .05).

Conclusions: Automated text messaging is a low-burden tool that improves durability of near-perfect PrEP adherence.

Clinical trials registration: NCT01761643.

Figure 1.

Consort diagram. Abbreviations: HIV, human immunodeficiency virus; LTFU, lost to follow up.

Figure 2.

Adherence by tenofovir diphosphate at week 12 and 48. Includes only subjects who complete study week. Numbers in cells represent percentage of subjects with a value greater than the stated cut point at the study week alone. *P < .05. Abbreviations: iTAB, individualized texting for adherence building; SoC, standard of care; Wk, study week.

Figure 3.

Proportion with plasma emtricitabine concentration >24-hour trough (>350 ng/mL). *P < .05. Abbreviations: iTAB, individualized texting for adherence building; SoC, standard of care; Wk, study week.