Background

Despite recommendations, many middle-age adults neglect to check their blood cholesterol levels. Short message service (SMS, also known as texting) has been seldom studied for preventive education. We estimated how SMS can be a cost-effective method in encouraging people to check their blood cholesterol levels.

Methods

In a field trial, 3600 cell phone users (age > 30) were randomly assigned to the intervention (N: 1200) and the control groups (N: 2400). An SMS was sent to the intervention group for five rounds every two weeks, which targeted the cognitive and affective learning and finally advised the blood cholesterol level to be checked, if not checked during the past twelve months. Two weeks after the last round, both groups were asked for the time/level of their latest blood cholesterol, family history of early cardiac death and having a family member with coronary heart disease (CHD), and to report their attitude about whether annual blood sampling is worth the cost and time to prevent CHD. Moreover, the intervention group was asked if they remembered the SMS content. The cost-effectiveness was evaluated by estimating the "number needed to treat" (NNT) and calculating the cost of sending SMS to that number of people.

Results

In the intervention group, 629 individuals (72.0%) recalled the SMS content. The factors associated with cholesterol screening during the past two years were older age, diabetes, family history of coronary disease, higher education, female gender and being non-smoker. In both groups, women were significantly more aware of their blood cholesterol level (68.7% vs. 53.6%). The relative frequency of respondents who believed it was not worth checking their cholesterol annually was significantly lower in the intervention group (P < 0.001). The intervention group was significantly more likely to check its blood cholesterol levels (OR:1.22) after adjustment for age, diabetes, family history of CHD and smoking. The NNT was estimated ≈ 25 for the general population and ≈ 11 for those who received SMS and had a family member with CHD.

Conclusions

We would postulate that SMS could affect people's adherence to preventive programs. Relatives of patients admitted with a diagnosis of CHD should be prioritized for superior cost-effectiveness and logistical feasibility.