The study intervention involved using SMS to remind patients to consume their medication. We evaluated patients’ medication adherence behavior and satisfaction with and demand for an SMS reminder service after the intervention. The SMS intervention significantly decreased the incidence of delayed and missed doses among participants in the intervention group, who showed a 29.0% decrease in the incidence regarding missed doses and 32.4% for the decrease in the incidence of delayed doses. These findings were similar to those reported by da Costa [8], who evaluated the effectiveness of and patient satisfaction with an SMS service that reminded women in Brazil who were diagnosed with AIDS to consume anti-viral drugs. Other studies have reported similar results, indicating that SMS reminders help patients consume their medications on time and reduce the incidence of delayed doses [12, 13].
In the current study, the rates for the decreases in the incidence of delayed doses for the participants in the control and intervention groups were 46.4 and 78.8%, respectively; these figures were 61.1 and 90.1%, respectively, for decreases in the incidence of missed doses. This indicates that participants in the control group also experienced significant improvement in medication adherence. This could result from the Hawthorne effect or increased efficacy in self-managing their illnesses [14]. Previous studies have shown that in the healthcare field text message reminders were effective in increasing patient attention to treatment, decreasing the incidence of missed doses, and enhancing medication adherence [8, 15].
We followed up with participants after only 7 days; however, long-term adherence is more difficult to maintain than is short-term adherence. Hanauer et al. used e-mail and SMS reminders to support diabetes management and identified decreases in SMS use after 2 months and 3 months [16]. Another study of SMS in adults with diabetes showed no change in blood glucose measurement activity throughout the 1-year study period [17]. Therefore, SMS messaging may be more appropriate for use with medications, such as some antibiotics, taken in the short term, compared with long-term medications used to treat chronic diseases.
SMS improves medication adherence
We used weighted logistic regression to examine the factors that influence improvement in the incidence of delayed and missed medication doses. The results showed that the SMS intervention significantly decreased the incidence of delayed and missed doses. This was consistent with a previous finding that indicated SMS interventions enabled patients to consume their medication on time [18]. Regarding age (Table 4), participants aged 65 years or older were significantly less likely to experience decreases in the incidence of missed doses compared with those aged 20–34 years (OR = 0.6, 95% CI = 0.4–0.9). According to related literature, senior patients are often more resistant to behavioral change and are likely to stop taking medication based on personal decisions [19]. In addition, senior patient may be less familiar with cell phones compared with younger patients, increasing their likelihood of ignoring text message reminders, thus limiting decreases in the incidence of missed doses. However, comparing Tables 3 and 4 shows that when senior participants neglected or delayed taking medication, after they received SMS reminders they had a higher likelihood of taking medication than did those who missed taking the medication. This suggests that if senior participants delayed taking medication, when they received reminders they had a higher likelihood of improving their adherence than did those who lacked a strong intention to take their medication and missed taking it despite the reminder. Military personnel, civil servants, teachers, and students demonstrated similar behaviors. These results were similar with those of a previous study [20].
Regarding occupation, military personnel, civil servants, teachers, and students were less likely to experience decreases in the incidence of missed doses compared with unemployed participants. This could be because the military personnel, civil servants, teachers, and students in our study were typically young or middle-aged adults who demonstrated relatively better health compared with unemployed participants; therefore, these participants might consider long-term medication use unnecessary.
Regarding medical history, participants with hypertension, heart disease, stroke, or thyroid disease were less likely to experience decreases in the incidence of delayed or missed doses compared with participants who lacked such diseases. This finding was consistent with that reported by a previous study [20]. This study indicated that hypertensive patients tended to have confidence in their ability at self-control and were likely to adjust their medication consumption behavior arbitrarily, leading to poor adherence [20]. Therefore, SMS interventions may not reduce the incidence of delayed or missed doses among specific patient groups. A previous study also emphasized that patients with chronic diseases may have less motivation to consume medication regularly if their condition did not seem to improve, was incurable, or yielded side effects because of long-term medication use [21]. Thus, SMS interventions may fail to significantly alter the medication consumption behavior of patients with chronic diseases.
Satisfaction with and demand for the SMS intervention
Numerous observational studies have focused on satisfaction with and demand for SMS interventions [22–25]. In the current study, according to the results of participants’ satisfaction with the SMS intervention, the item “frequency of the SMS” received the lowest satisfaction score of 3.1 points. Participants reported that “the frequency of text messages sent was too high,” “text messages did not need to be sent often,” and “the number of messages was excessive.” These responses indicate that although the SMS intervention could help remind participants to consume medicines, it could also induce negative perceptions. Regarding participant demand for the SMS intervention, most participants (44.2%) wished to receive a reminder 30 minutes before the time medication should be consumed (Table 5). However, 93.2% of participants disliked when a message was resent after the time medication should be consumed to ensure that they would immediately consume a missed dose. Approximately 91.6% of the participants were willing to recommend the SMS intervention to their family and friends, suggesting that the SMS reminder intervention was effective. Of the participants who stated that the SMS reminders did not reduce delays or missed doses, most were women (72.2%), married, and housekeepers. We speculate that because these participants had more flexible time to care for themselves and may already have been adhering to their medication satisfactorily, they did not perceive that the SMS intervention enhanced their medication adherence.
Previous studies that have adopted SMS interventions for increasing medication adherence all showed that patients in the intervention group experienced higher treatment effectiveness compared with control groups. This could be because SMSs pose a minimal interruption to patients’ lives and are low in cost [8]. Compared with other approaches, SMS is simpler and more satisfying for users. Additionally, because the SMS reminder service can prompt patients to be responsible for their own health, it serves a vital function in healthcare services.
Limitations
Medication adherence problems are typically related to use of long-term medications for chronic diseases. In the current study, participants were monitored for only 7 days. Such a short-term follow-up might not properly interrogate the relationship between long-term medication adherence and use of SMS. Because we did not design the study to specify the medications used by participants, we could not evaluate the effects and outcome of their medication treatment. Additionally, the daily SMS system sent more than one reminder to participants who took several kinds of medications based on various medication schedules, which resulted in inconveniencing these participants. Many studies have shown that medication adherence outcome data that are purely reliant on self-reporting have a high likelihood of reporting bias [26, 27]. Because overstimulation might exist in both the intervention and control groups, the current study included two groups (intervention vs. control) that completed pretests and post-tests to reduce the effects of reporting bias.