Trent 2015.

Methods	Design: pilot RCT Location: Baltimore, MD (USA) Time frame: October 2011 to February 2012 Sample size estimation and outcome of focus: 100 minimum recruitment as practical milestone for feasibility and acceptability (pilot study); focus on injection appointment adherence
Participants	General with N: 100 urban adolescent girls Source: urban academic general pediatric and adolescent medicine practice Inclusion criteria: age 13 to 21 years; willing to be randomized; currently using DMPA; have cellular phone with text messaging capability for personal use Exclusion criteria: no cell phone with text messaging capability for personal use; cognitive impairment prevented use of cell phone texting
Interventions	Study focus: improve appointment adherence for contraceptive injections Theory or model: Geser’s sociological framework for understanding innovative potential of cell phone technology Intervention: standard care plus daily text appointment reminders starting 72 hours before clinical visit; monthly healthy self‐management messages (condom use, weight control, side effect management, STI testing reminder); call for missed appointment or no reply to appointment reminder (or other text message) Comparison: standard counseling and clinic appointment reminders to home phone; call from nurse case manager after missing re‐injection appointment
Outcomes	Primary: appointment adherence (3 contraceptive injection appointments) Follow‐up: 9 months
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Investigator communication: computer‐generated randomization sequence
Allocation concealment (selection bias)	Low risk	Investigator communicated randomization concealed prior to assignment. Research staff opened packet with randomization status and pertinent information for next steps.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Investigator communication: principal investigator blinded to enrollment status Presume no blinding of participant or provider; not feasible due to type of intervention
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Appointment adherence (for injections) via electronic tracking database
Incomplete outcome data (attrition bias) All outcomes	High risk	Loss to follow‐up: 31% did not complete cycle 3; intervention 34% (33/50); control 28% (36/50)