Increasing the response rate of text messaging data collection: a delayed randomized controlled trial.
OBJECTIVE
To test the effectiveness of multiple interventions on increasing the response rate of text messaging for longitudinal data collection.


METHODS
Our cohort included 283 caregivers of children aged 6-12 months who were participating in an anemia program in rural China. Using text messages to collect data on anemia medication adherence, we conducted a delayed randomized controlled trial to test multiple interventions (an additional four reminders; a ¥5.0 (US$0.79) credit reward for replying; and a feedback text message). After a 6-week pilot study with week 7 as the baseline measurement, we randomly allocated all participants into two groups: group 1 (n = 142) and group 2 (n = 141). During weeks 8-11, we introduced the interventions to group 1, and in weeks 12-15 the intervention was introduced to both groups. We compared the response rates between groups and explored factors affecting the response rate.


RESULTS
During weeks 8-11, the response rates in group 1 increased and were significantly higher than in group 2 (p<0.05). During weeks 12-15, the response rate increased significantly in group 2 (p>0.05) and slightly decreased in group 1. Younger participants or participants who had children with lower hemoglobin concentration were more likely to reply (p = 0.02). Sending four reminders on the second day contributed to only 286 (11.7%) extra text messages.


DISCUSSION
Our study showed that multiple interventions were effective in increasing response rate of text messaging data collection in rural China.


CONCLUSIONS
Larger multi-site studies are needed to find the most effective way of using these interventions to allow usage of text messaging data collection for health research.
['Li|Ye|Y|', 'Wang|Wei|W|', 'Wu|Qiong|Q|', 'van Velthoven|Michelle Helena|MH|', 'Chen|Li|L|', 'Du|Xiaozhen|X|', 'Zhang|Yanfeng|Y|', 'Rudan|Igor|I|', 'Car|Josip|J|']
D000328:Adult D000740:Anemia D017028:Caregivers D002681:China D003625:Data Collection D005260:Female D006801:Humans D007223:Infant D007407:Interviews as Topic D008297:Male D010865:Pilot Projects D012424:Rural Population D060145:Text Messaging D013997:Time Factors
randomized controlled trial nutrition surveys program evaluation