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Determining the Impact of Text Messaging for Sexual Health Promotion to Young People

Gold, Judy BBioMedSci (Hons)*†; Lim, Megan S. C. PhD*†; Hocking, Jane S. PhD; Keogh, Louise A. PhD; Spelman, Tim GradCert (Stats)*; Hellard, Margaret E. PhD*†§

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Sexually Transmitted Diseases: April 2011 - Volume 38 - Issue 4 - p 247-252
doi: 10.1097/OLQ.0b013e3181f68d7b
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In the past 2 decades, the use of new technologies—mobile phones, internet, and the like—has exploded. New communication technologies have the potential to play an important role in sexual health education and prevention, particularly among young people, who are at high risk of sexually transmitted infections (STIs)1 and have the highest rate of internet use and mobile phone ownership in the population.2 Short messaging service (SMS), also know as text messaging, is a particularly promising method of health promotion as it does not rely on fixed equipment, messages can be sent to multiple recipients simultaneously with immediate delivery and the cost of sending messages is low.3

In recent years, SMS has been used to successfully deliver clinical care and preventative health interventions related to disease self-management, smoking cessation, diet, and physical activity.4,5 Within the sexual health field, SMS has been used by health practitioners for communication between clinics and patients, partner notification, contraception reminders, and health promotion and education; however, evidence of its effectiveness has been limited.3 A randomized controlled trial conducted in 2006–2007 found those receiving SMS and email messages about sexual health improved their knowledge, and that females receiving messages were more likely to seek an STI test than those who did not receive any messages.6 We report the results of a second study that aimed to determine the impact of using SMS on a population level on sexual health knowledge and behavior.



This project was designed as a health promotion intervention with baseline and follow-up behavioral surveys to determine the interventions' effect on sexual health knowledge and behavior.


Each year the Burnet Institute holds a market stall at the Melbourne Big Day Out music festival and conducts a cross-sectional behavioral survey to monitor sexual behavior and drug use among young people attending the event.7,8 Individuals are eligible to participate if they are between 16 and 29 years and have sufficient English skills to complete a self complete questionnaire. Participants completing the survey in 2008 were asked to provide their mobile phone number to receive SMS about sexual health after the event. The questionnaire collected information regarding demographics, sexual health knowledge and behavior, and alcohol and drug use and served as the baseline measure for the project. Participants receive refreshments, a showbag containing sexual health information and condoms, and are entered into a draw to win an mp3 player and CD vouchers.


Text messages about STIs (asymptomatic nature, urine testing, simple treatment, and prevalence), their consequences (chlamydia causing infertility) and condom use were developed by authors J.G., M.L., and M.H. and tested and refined with Burnet Institute staff and students in the target age group. Messages were designed to address the known low level of sexual health knowledge, STI testing, and condom use among this age group,8–12 as well as perceived barriers to STI testing.13 We did not subscribe to a single behavioral change theoretical model, but based our intervention primarily on Weinstein's Precaution Adoption Process model14,15 and incorporated elements from Ajzen's Theory of Planned Behavior16 and Bandura's concept of self-efficacy.17

Messages were designed to be short, catchy, and informative, and where possible, tied into particular events (e.g., Valentines Day, Mother's Day). A total of 12 messages were sent out approximately fortnightly, between February and July 2008 (Table 1). Participants could opt out of receiving the SMS by texting back “stop” or similar to the study mobile phone number.

Text Messages Broadcast


Two weeks after the last broadcast SMS, participants were sent an SMS inviting them to complete an online follow-up survey. The survey contained similar questions to the baseline questionnaire, with some additional questions to evaluate the messages. Tickets to the following year's Big Day Out music festival and CD vouchers were offered as prizes to encourage participation. Up to 5 reminder SMS and 2 email reminders were sent to those not completing the online survey.


Participants who reported never having had sex at baseline were excluded from analysis. McNemar's test was used to determine changes in sexual health knowledge, STI testing, and condom use between baseline and follow-up.

To account for differences in sexual activity among those who were lost to follow-up (either due to actively withdrawing from receiving the messages or by not completing the follow-up survey), the retained sample was weighted upwards to represent the full initial sample. Multivariate logistic regression was used to first identify baseline factors which predicted loss to follow-up. These factors were then used to design weighting strata, in which those subjects lost to follow-up were matched with groups of retained subjects they most closely resembled in terms of the baseline predictors isolated by the multivariate analysis. The number of individuals within each weighting stratum completing the follow-up survey was then divided by the number of individuals within each stratum at baseline; the inverse of this formed the weight for individuals in this group. Both unweighted and weighted analyses were performed.


Approval was sought from and granted by the Department of Human Services Human Research Ethics Committee and the Monash University Standing Committee on Ethics in Research Involving Humans.


Participant Characteristics

Overall 2377 valid baseline surveys were completed; 250 (11%) never had sex and were excluded from further analysis. Of the remaining 2127 surveys, 1771 (83%) provided a valid mobile phone number and were thus enrolled to receive the intervention. Over the 4 months of the intervention, 319 of the original 1771 (18%) withdrew from receiving the SMS and 587 (40%) of those invited (n = 1452) completed the follow-up survey (Fig. 1).

Figure 1.:
Participant summary.

Baseline Survey Results

The median age was 22 years, with just over half (56%) female. The majority of participants were born in Australia, resided in metropolitan Melbourne and had completed high school (Table 2).

Participant Characteristics at Baseline

Just over a third (39%) reported ever having had an STI test, with 13% reporting an STI test within the past 6 months. Most reported a regular sexual partner in the past 12 months, and just over half reported a casual sexual partner in the same time frame. Around a third reported a new sexual partner in the past 3 months. Just over half reported always using condoms with casual and/or new partners (Table 2).

Follow-up Survey Results

Of the 587 who completed the online follow-up survey, 469 (80%) reported they found the SMS interesting or entertaining, 401 (68%) reported they learnt something from the SMS and 132 (23%) reported they found them annoying. Almost three-quarters (n = 428, 73%) reported they showed the SMS to others, most commonly friends (68%) and partners (38%). Nineteen percent reported they would not be willing to receive similar SMS in the future.

Three factors were found to be significantly associated with being lost to follow-up—male gender (odds ratio [OR]: 1.6, 95% confidence interval [CI]: 1.3–1.9, P < 0.01), not having completed high school (OR: 1.4, 95% CI: 1.0–1.9, P = 0.03), and not attending a doctor in the 12 months before the baseline survey (OR: 1.6, 95% CI: 1.2–2.1, P < 0.01). These factors were used to derive weighting strata on which the retained sample of participants who completed the follow-up survey was weighted upwards to represent the full 1771 sexually active participants at baseline.

Both unweighted and weighted analyses found a significant increase in sexual health knowledge among males and females at follow-up compared to baseline (Table 3). At follow-up, more than 55% of males and more than 70% of females correctly answered 5 or more of 6 sexual health questions correctly, compared to fewer than 30% of males and 45% of females at baseline.

Comparison Between Survey Response at Baseline and Follow-up, Unweighted and Weighted Analyses Using McNemar's Test

Weighted analysis indicated a significant increase in STI testing among both males and females within the past 6 months. In all, 23% of females reported an STI test within the past 6 months at follow-up, compared to 18% at baseline. For males, 10% reported an STI test within the past 6 months at follow-up compared to 8% at baseline (Table 3).

A significantly lower proportion of males reported multiple, casual, or new partners at follow-up compared to baseline. A higher proportion reported always using condoms with casual partners, with a lower proportion reporting always using condoms with new partners (Table 3).

A significantly higher proportion of females reported multiple sexual partners at follow-up compared with baseline, but a lower proportion reported casual or new partners. There was a significant decrease in the proportion reporting always using condoms with casual or new partners at follow-up compared to baseline (Table 3).


This project demonstrated that SMS are a feasible, popular and effective method of sexual health promotion to young people with a relatively low withdrawal rate, the demonstrated improvement in sexual health knowledge and STI testing and the positive feedback received.

We successfully enrolled over 1700 young people from a community venue to receive sexual health-related text messages. Over a 4-month intervention period fewer than 20% of those enrolled actively withdrew from receiving the messages. This indicates the success of this approach in retaining an audience over time. With 3 exceptions,6,18,19 previous trials of SMS for health promotion have recruited 200 or fewer individuals.20–28 Retention rates in previous trials ranged from 39% to 100%18–28; however, most interventions ran for a shorter time period than this project.18,20,21,23–25,27

There was a significant increase in knowledge in male and female participants after receiving the SMS compared to baseline. Many other approaches, such as sex education and peer-led programs have also led to demonstrated improvements in sexual health knowledge among young people.29,30 The advantage of using SMS over these approaches is that it is a very resource efficient to implement, can reach a large number of individuals simultaneously, does not require a physical setting, and requires very little input or disruption to the individual. Additionally, the text messages can, and were, shared with others, furthering their reach and potential impact.

Around 70% of young men and 90% of young women in Australia see a general practitioner each year,31 yet fewer than 8% are tested for chlamydia.11 We observed a significant increase in the proportion reporting a recent STI test after the SMS intervention compared to baseline. Few other interventions have reported increased uptake of STI testing—1 multimedia awareness campaign has been shown to have increased testing in Australia,32 whereas the 2 other studies measuring the use of mass media to promote chlamydia testing resulted in very small numbers being tested for chlamydia.33,34 Encouraging uptake of chlamydia testing via SMS may be useful in assisting the implementation of a proposed national chlamydia screening program for young people.35

The findings relating to changes in partner numbers and condom use are somewhat difficult to interpret. The apparent reduction in the number of casual and new sexual partners reported at follow-up compared to baseline may reflect seasonal trends in partner numbers because of holiday periods36 or a chance finding rather than impact of the messages themselves, which did not specifically address partner numbers and STI risk. Alternatively, receiving regular reminders about sexual health, particularly STIs, may act indirectly to prompt individuals to alter their partner seeking behavior. Similarly, the apparent reduction in consistent condom use with new sexual partners, and among females with casual partners, could be a chance finding or may reflect participants believing they have a decreased risk of STIs because they have been tested for an STI or have reduced their partner numbers. Certainly, choices and decisions about sexual partners and condom use are complex, and are influenced by many more social and environmental factors than just information and intentions.

This project has some limitations. The response rate to the follow-up survey was below 50%, perhaps because we required participants to have internet access and to manually type in the link from the SMS to access the survey (unlike the baseline survey, which was completed on-site). The changing modes of data collection may have also influenced results.37 Those who were lost to follow-up were significantly different from those who completed the follow-up survey, which may indicate either differential access or interest in completing the follow-up survey and/or differential impact of the intervention. It is possible that this intervention is less effective among certain subpopulations that may be considered harder to reach (i.e., males, those with a lower level of education and those who do not regularly attend health services). This project was not a randomized controlled trial, and it is possible the observed project outcomes may be due to other factors apart from the SMS intervention, such as ongoing school and media sexual health education and promotion and peer and other social and environmental influences. However, the consistent results relating to sexual health knowledge and STI testing with the earlier randomized controlled trial6 increases confidence that the observed changes were due to the intervention. The question related to STI testing did not specifically exclude pap smears, which may account for the high proportion of females who report having ever had an STI test. Finally, all data were self-reported which may not be accurate.38

The major strength of this project was that it was able to confirm the findings of the earlier randomized controlled trial regarding increasing knowledge and health seeking behavior,6 but on a larger scale and outside of the artificial parameters of a scientific trial.

Although using SMS for sexual health promotion is unlikely to replace ongoing, more comprehensive sexual health education programs, it appears to be an effective and useful addition to the arsenal to target young people, especially those outside of institutional settings, for sexual health promotion.


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