Process Measures
In total, 76.8% (344/448) of the intervention participants responded to the feedback questionnaire. Most respondents reported that the SMS text message support program was useful (298/344, 86.6%); easy to understand (336/344, 97.7%); and appropriate in terms of language, number of messages, and program length (Summary of utility and perceived acceptability of SMS text message support among 334 intervention participants. Response options were “Strongly agree,” “Agree,” “Neutral,” “Disagree,” and “Strongly disagree” for the first 6 items and final item. We report the proportion for “Agree” and “Strongly agree.” For the first 3 questions regarding message characteristics, we report the percentage of participants who answered.Found messages usefulMessages were easy to understand 298/344 (86.6%)336/344 (97.7%)Messages motivated changeDiet more healthy because of messagesExercise increased because of messagesMessages reminded them to take their medicines217/344 (63.1%)209/344 (60.8%)168/344 (48.8%)204/344 (59.3%)Read at least three-fourths of messagesDeleted messagesSaved messagesShowed messages to family or friendsForwarded messages to family or friends318/344 (92.4%)47/344 (13.7%)273/344 (79.3%)187/344 (54.4%)41/344 (11.9%)Message language was appropriateNumber of messages per week was appropriateProgram length was appropriateTime of day messages received was appropriate311/344 (90.4%)300/344 (87.2%)295/344 (85.8%)258/344 (75.0%)