Table 4.

Intervention pretesting.

Trial	Pretesting methods	Changes in the intervention implemented as a result of the pretesting exercise
TEXT MEa [9,19,32]	n=16; sampling: convenient; additional details: The aim of the pilot testing was to evaluate the messages and the system to deliver them. Participants received the relevant messages for 1 week. At the conclusion of the pilot study, participants received a questionnaire asking for the potential impact of the messages to change behavior, the process of receiving messages (eg, timing, personalization, and frequency), and for any further feedback	Refinement of the message bank and software system
Text4Heartb [21,29]	n=20; sampling: convenient; additional details: The aim of the pilot testing was to test the healthy eating messages. Participants received 1 text message per day (28 in total) and had access to the supporting website; 4 weeks later, participants were contacted by text and email to complete a follow-up Web-based survey. Website usage statistics including the frequency, login period, and page views were also tracked	No changes made to healthy eating message content or tone (viewed as acceptable), self-efficacy included as underlying theoretical construct; higher level of tailoring (messages personalized with name, time of day to receive messages, and primary behavior targeted), website log-on system simplified
Islam [22,33]	n=30; sampling: purposive; additional details: intervention pretested in patients with type 2 diabetes selected from a diabetes clinic of a tertiary hospital	Timing of text messages was set to be delivered from 10 am to 5 pm
Heartc [24-26,30]	n=10; sampling: convenience; additional details: Pilot testing of the intervention was integrated into the full randomized controlled trial (during the study, the first 10 study participants were closely monitored for 6 weeks to ensure that they received the messages and to resolve technical issues)	All SMSd messages were made available on a website for participants to review retrospectively if they chose and correction of grammatical errors identified by participants
StARe [8,18]	n=19; sampling: purposive; additional details: The full intervention package was tested in the 3 languages most commonly used in Cape Town (English, Afrikaans, and isiXhosa). Participants were contacted on a weekly basis by a researcher for a semi-structured interview on their experience of the intervention and the SMS text message delivery system	Change timing of the message and allowing users to change language

^aTEXT ME: Tobacco, Exercise and Diet Messages.

^bText4Heart: Text message and Internet-based comprehensive cardiac rehabilitation intervention.

^cHeart: Heart Exercise And Remote Technologies.

^dSMS: short message service.

^eStAR: Mobile Phone Text Messages to Support Treatment Adherence in Adults With High Blood Pressure.