A meta-analysis of 16 randomized clinical trials found that mobile telephone text messaging nearly doubled the odds of patients with chronic diseases adhering to their medication regimens.

The studies evaluated cardiovascular disease, diabetes, HIV, asthma, allergic rhinitis, epilepsy and other chronic diseases. Of the interventions, eight used a daily text messaging frequency and eight used two-way communication. The median duration of the interventions was 12 weeks.

Lead researcher Jay Thakkar, FRACP, of Westmead Hospital in Sydney, Australia, and colleagues published their results online in JAMA: Internal Medicine on Feb. 1.

“While promising, these results should be interpreted with caution given the short duration of trials and reliance on self-reported medication adherence measures,” they wrote. “Future studies need to determine the features of text message interventions that improve success, as well as appropriate patient populations, sustained effects, and influences on clinical outcomes.”

The researchers defined adherence as “the extent to which a patient correctly follows a prescribed therapy” and said it was a medically preferred term compared with compliance, which they said “reflects more unidirectional connotations.”

They cited data that found the healthcare system spends approximately $100 billion in excessive physician visits each year due to medication nonadherence. They hypothesized that mobile phone text messaging may be a practical and cheap way to deliver electronic reminders to patients. In 2014, there were approximately seven billion mobile telephone subscribers, according to the researchers.

For this analysis, the researchers included randomized clinical trials with at least four weeks of follow up that evaluated adult patients with chronic disease who received mobile telephone text message interventions to promote medication adherence.

The 16 trials that met the inclusion criteria had a total of 2,742 patients and a median sample size of 97 patients. The median age was 39 years, and 50.3 percent of patients were female.

The researchers noted that there were differences among the text message interventions. Twelve of the studies reported adherence as the proportion of patients who were adherent, while the other four reported adherence as the proportion of medication doses taken as prescribed.

A pooled analysis found text messages significantly improved medication adherence. The researchers noted that adherence rates improved from the 50 percent cited in previous research to 67.8 percent among patients who received the text messaging interventions.

The meta-analysis had a few limitations, according to the researchers, including that it may have been subject to publication bias. They also noted that the definitions of adherence differed in the studies and that many of the studies used self-reporting to determine outcomes, which may lead to recall bias and social desirability bias. In addition, the trials in the meta-analysis had short intervention durations and follow-up periods and none had data on adherence following the trial or after the intervention ended.

“The short duration of the trials suggests uncertainty about the duration of the effect, the time-effect relationship, and the continuation or decay of the effect after the intervention is withdrawn,” the researchers wrote. “While our meta-analysis identified a positive effect of text messaging on medication adherence in the short term, it is uncertain if this influence will translate into longer-term effects on adherence behavior or on clinical outcomes.”