We describe the development of a two-way text messaging intervention tool for substance users who are non-adherent with HIV medications, and examine message flow data for feasibility and acceptability. The assessment and intervention tool, TxText, is fully automated, sending participants mood, substance use, and medication adherence queries by text message. Participants respond, the tool recognizes the category of response, and sends the personalized intervention message that participants designed in return. In 10months, the tool sent 16,547 messages (half initial, half follow-up) to 31 participants assigned to the TxText condition, who sent 6711 messages in response to the initial messages. Response rates to substance use (n=2370), medication (n=2918) and mood (n=4639) queries were 67, 69, and 64%, respectively. Responses indicating medication adherence, abstinence from substances, and good moods were more common than negative responses. The TxText tool can send messages daily over a 3month period, receive responses, and decode them to deliver personalized affirming or intervention messages. While we await the outcomes of a pilot randomized trial, the process analysis shows that TxText is acceptable and feasible for substance abusers with HIV, and may serve as a complement to HIV medical care.
Keywords: HIV adherence; Intervention; Substance abuse; Text messaging; mHealth.