Sept. 29, 2022 -- Health communications delivered by text message are effective, cheap, and highly cost-effective for some behaviors, such as smoking cessation – but they may not work for sexually transmitted infection (STI) prevention. That was the conclusion of researchers who sent regular texts to young people who recently had an STI, aiming to encourage safer sex behaviors, but found that in fact the messages did not reduce rates of chlamydia and gonorrhea reinfection. 

Results of the study, led by the London School of Hygiene and Tropical Medicine (LSHTM) and published in The BMJprompted the researchers to call for better evaluation of health communication interventions, particularly since the World Health Organization currently recommends digital health communication for sexual and reproductive health. 

Their findings were based on a trial in which 6248 people aged 16 to 24 years with a recent diagnosis of, or treatment for, chlamydia, gonorrhea, or non-specific urethritis were recruited from 92 sexual health clinics across the U.K. between April 1, 2016, and November 23, 2018. Rates of STIs are highest in this age group. Full data were available for 4675 (75%) participants, and characteristics such as age, ethnicity, education, and sexual orientation were similar between the groups at the start of the trial. In both groups, about 65% of participants were female, 78% white, and 85% heterosexual.

The researchers randomly assigned 3,123 participants to receive a series of text messages "to improve sex behaviors" (the “safetxt” intervention) and compared them with 3,125 control participants who received a monthly text message for 1 year asking for any change to postal or email address. 

Texts Based on Behavioral Psychology

'Safetxt' messaging was based on the COM-B (capability, opportunity, motivation, and behavior) model for influencing behavior, developed by co-author Susan Michie, advisor to the Government's Behavioral Insights Team and recently appointed chair of a WHO technical advisory group on behavioral  insights.   

Whereas the control group received only a neutral monthly test, the safetxt group received four texts daily for days 1 to 3, one or two daily for days 4 to 28, two or three weekly for month 2, and 2 to 5 monthly for months  3 to 12. The messages encouraged participants to inform partners about their infection, use condoms, and seek STI testing before having unprotected sex with a new partner. 

Messages were tailored according to participants' sex or gender and sexual orientation and were deliberately non-blaming and non-stigmatizing. All those who said they had sex with men received messages about how others had negotiated condom use. Women and men who had sex with women were sent messages about emergency contraception. Men who reported having sex with men were sent messages about HIV post-exposure prophylaxis. Women who only had sex with women were not sent messages about condom use. 

More Reinfections in the Intervention Group

The researchers expected that safetxt would reduce the risk of chlamydia and gonorrhea reinfection at 1 year by improving three key safer sex behaviors: partner notification at one month, condom use, and testing for STIs before having unprotected sex with a new partner. In fact, their findings revealed more reinfections occurred in safetxt group than in the control group.

Results showed that at 4 weeks, 86% of participants in the intervention group versus 84% in the control group had notified the last partner they had sex with before they tested positive that the partner needed to get treatment. Also, 42% of participants in the intervention group versus 40% in the control group reported using a condom at last sexual encounter. At 1 year, 34% of participants in the intervention group versus 31% in the control group reported using a condom at their last sexual encounter, and 54% of participants in the intervention group versus 49% in the control group reported using a condom at a first sexual encounter with their most recent new partner.

At 12 months, the study participants were asked to take a test at home for chlamydia and gonorrhea infections and send the sample to the researchers. They found that chlamydia or gonorrhea reinfection had occurred in 693 of 3,123 (22.2%) in the safetxt group versus 633 of 3,125 (20.3%) in the control group.

Texts Could Have Increased Risk

Thus despite "some increase... in self-reported precautionary behaviors such as condom use," the team said, "the number of STIs was not reduced" – indeed, they admitted, the intervention "could have increased risk.” Possible reasons for this, they suggested, were reduced feelings of stigma at having an STI, and reduced sense of isolation in being “not the only one” with an STI, in both cases leading to lower precautionary behavior.

They noted too that although the intervention did not target sexual partnerships, the proportion of participants who reported having a new partner or two or more partners at one year was also higher in the intervention group.

"Our text message intervention was grounded in psychological theory, incorporating the best evidence on health behavior change, but it did not have the effects we anticipated," the authors said. "In light of our results, WHO should revise its endorsement of digital behavior change communication for strengthening health systems, to specify which topics and content WHO endorses."