This study demonstrated that a simple SMS text message substantially increased adherence to RDT results. Compared to those who were not sent a reminder message, the probability of adhering to the correct malaria treatment advice increases by 10–15 percentage points among those who were sent the reminder. Previous estimates of the magnitude in the effect size of SMS interventions to increase adherence to drug treatments range from 8-17% [12–14, 18] —the estimates in this study are very much in line with those studies. Together, these studies suggest that for many health-related behaviours, individuals may benefit from additional reinforcement to help them to follow through with intended or prescribed behaviours.
Unlike previous SMS intervention studies in which the message often persuaded the participant to do something that the individual already stated that s/he wanted to do (e.g. use sunscreen, take medication, or save money), in this study the message reinforces a previously given medical advice, which likely contradicted the planned behaviour of the participants. Indeed, the vast majority of the participants tested were found to have negative results (96%). These individuals, having just purchased treatment medicines, were essentially asked to change behaviour and not do something they usually would do—take an anti-malarial drug—to treat a suspected episode of malaria. This suggests that reminder messages can help individuals break from their default behaviours in addition to helping them follow through with intended behaviours.
To further understand how the SMS intervention may have influenced participants’ choices, participants in the treatment group were asked to describe which aspect of the SMS message they found helpful. The majority of respondents (52%) said that the SMS reminded them of their test result, while another 30% said that it reminded them of the correct treatment course. Only about 10% mentioned the usefulness of having a link to an advice nurse and only 10 participants actually contacted the advice nurse for consultation regarding unresolved febrile symptoms or to confirm that they should not take the anti-malarial medication. Hence, it appears that the reinforcement of the medical advice reiterated by the SMS was the most helpful to participants in choosing which drugs to take for their condition.
Given the ubiquity of cell phones throughout Nigeria and the relatively low cost of sending an SMS compared to the cost of anti-malaria drugs, the SMS intervention is cost-effective from a societal point of view. The average cost of the anti-malaria treatment course purchased within the study sample was 350 Naira (US$2.50). This cost reflects only the retail price of treatments and does not include the large-scale international subsidy for ACT, which is about $4.00 a course. Based on the results of this study, a similar SMS intervention would save $0.25 per episode in direct treatment costs alone. If the proportion of participants who bought ACT and international subsidy were taken into consideration, then the cost savings would average $0.43 per episode. Rough estimates of the cost of sending an SMS manually is about 10 cents including labour and service costs, suggesting that the SMS intervention is a cost-saving one. If the SMS messages were automated the cost be would even lower.
This study provides further evidence that reminding or nudging people can alter health-related behaviours. However, these results should be interpreted in light of several caveats. For various reasons, randomization was not perfectly balanced, although application of regression controls helped to adjust for these factors. Because the pilot study was conducted in primarily urban areas, this sample is unlikely to be representative of the state or of the country. Results reflect a wealthier and more educated population and health behaviours may differ, including responses to SMS messages, for poorer populations located in rural areas. An expanded version of this study is currently underway to assess the extent to which SMSs increase RDT adherence in other states, in areas with higher entomological inoculation rates, and in more representative populations. Further, because adherence to treatment advice is a self-reported measure, some reporting bias may be present if the SMS message also prompted individuals to self-report “better” outcomes. To the extent that the SMS increased reporting bias, the intervention effect size could be over-estimated. However, because results for malaria drugs and non-malaria drugs showed differential drug-taking behaviour, such self-reporting bias may be minimal. Finally, the SMS contained the exact same information that was provided by the advice nurse. For this reason, the SMS may have served as a general reminder of the testing experience, and in the present study the effect of a general reminder from the effect of the precise message contained within the SMS could not be differentiated. Future interventions would need to test different wording of the message to see which word choices increase adherence the most.
Currently, innovations in integrating RDTs into malaria case management in the private sector are well underway. Though this pilot study was limited to customers seeking care for malaria in the private sector healthcare market in Nigeria, RDT roll out is likely to expand in all sectors, and the results of this pilot study could have broader implications. The results suggest that SMS may be a tool to increase adherence to RDT results and could be used by many different health care practitioners (such as community health workers or hospital nurses) to support patients in following appropriate treatment advice. Coupling the RDT roll out with reinforcement messaging could help bring ACT use in line with actual malaria cases.