Results:

Of the 1,987 records identified, removing duplicates and studies ineligible for inclusion, a total 16 RCTs were included. Five of the studies used personalization messaging, eight used two-way communication, and eight used daily text message frequency. The median intervention duration was 12 weeks, and self-report was the most commonly used method to assess medication adherence. In the pooled analysis, a total of 2,747 patients were included (median age was 39 years and 50.3% were female). Text messaging was significantly associated with improved medication adherence (OR, 2.11; 95% confidence interval [CI], 1.52-2.93; p < 0.001). Study characteristics including intervention duration, chronic disease characteristics of the population, or text message characteristics (personalization, two-way communication, or daily text message frequency) did not appear to significantly influence the effect size. In a sensitivity analysis, findings remained robust to change in inclusion criteria based on study quality (OR, 1.67; 95% CI, 1.21-2.29; p = 0.002). There was moderate heterogeneity (I² = 62%) across clinical trials. After adjustment for publication bias, the point estimate was reduced, but remained positive for an intervention effect (OR, 1.68; 95% CI, 1.18-2.39). The effect observed translates into adherence rates improving from 50% (assuming this baseline rate in patients with chronic disease) to 67.8%, or an absolute increase of 17.8%.