3.1. Study Design and Population
This three-group experimental study (two interventions, one control) investigated middle-aged women (30 - 59) with borderline high cholesterol (200 - 239 mg/dL) at two Kermanshah urban health centers during September 2019. Based on prior research and considering the average changes in cholesterol levels in the three study groups — group 1 (SMS intervention): 22.2 ± 10.89, group 2 (group discussion): 19.2 ± 13.65, and group 3 (control): 16.4 ± 15.4 — with a statistical power of 80% and a confidence level of 95%, the minimum required sample size was calculated to be 55 participants per group using PASS 11 software (
8).
The study attempted to mitigate the influence of confounding variables (age, BMI, and literacy) by creating combined variable categories for adjustment across the various groups. The minimization method was employed for random assignment. The two urban health centers with the greatest population reach were used as the source for sample recruitment. Potential participants were identified from the Integrated Health System (SIB), comprising individuals who had undergone fasting blood sugar (FBS) and cholesterol tests for cardiovascular risk assessment. From the initial pool of 172 individuals contacted, 165 participants were ultimately selected for the study after a thorough review of the inclusion and exclusion criteria. Participants were randomly assigned to one of three groups using permuted block randomization [block sizes of (e.g. 6, 9)], with allocation concealment ensured by sealed, opaque envelopes (
Figure 1).
Flowchart of screening, randomization, and intervention
To participate in this study, individuals had to be between 30 and 59 years old, own a mobile phone, and be able to read text messages. Participants also needed to have borderline high cholesterol levels, specifically between 200 and 239 mg/dL. Individuals were excluded if they had a history of heart disease, diabetes, high blood pressure, hypothyroidism, or were currently taking cholesterol-lowering medication.
3.2. Data Collection and Questionnaire
A demographic questionnaire was used to collect data on age, height, weight, BMI, education level, mobile phone ownership, underlying disease status, and medication use. Dietary habits were assessed via the Dietary Habits Assessment Questionnaire. This 11-item questionnaire assessed participants’ consumption of dairy products, type of oil used, and intake of vegetables, fruits, and legumes with dichotomous (e.g. yes/no) response options. The validity and reliability of this questionnaire have been confirmed (
9).
The short form of the International Physical Activity Questionnaire (IPAQ) contains 7 questions about physical activity in the past seven days. Physical activities were categorized into three levels of intensity: Vigorous, moderate, and light in this study. These categories were determined based on the sum of each activity over a 7-day period. Activities with a sum exceeding 3000 units were classified as vigorous, those ranging from 600 to 3000 units were classified as moderate, and those below 600 units were classified as light. The units are based on the metabolic equivalent (MET) values assigned to different activities in the IPAQ, multiplied by the duration and frequency of the activities. The IPAQ is also a valid questionnaire and its validity and reliability have been confirmed in Iran (
10).
Cholesterol levels were measured using the Sinova D280 autoanalyzer (Sinova Medical Device Co., Ltd., China), which is a reliable and accurate instrument that is widely used in clinical laboratories. To ensure the accuracy and precision of the results, blood samples (2 to 3 cc) were taken from the participants after 12 hours of fasting and analyzed under the same laboratory conditions.
After the educational objectives were defined, the educational content for the three sessions was developed. To ensure content validity, the materials were reviewed by three university professors and two nutrition specialists. Based on their feedback, necessary revisions were made to the content. In the SMS intervention group, participants received three text messages per week, delivered between 6:00 - 6:30 pm every week, with the goal of increasing awareness, providing reminders, and offering encouragement. The content of these messages was limited to 160 characters and focused on topics related to hyperlipidemia, diet, and physical activity. To ensure engagement, participants were instructed to send a confirmation reply (e.g. a specific code) upon receiving each message. Messages were derived from American Heart Association (AHA) guidelines and Iranian Ministry of Health protocols, covering hyperlipidemia awareness (e.g. "Limit saturated fats to reduce cholesterol"), nutrition tips (e.g. "Use olive oil instead of animal fats"), and physical activity prompts (e.g. "Aim for 30 min of daily walking").
Participants in the group discussion were assigned to three groups, each containing 15 - 20 individuals. These groups met bi-weekly at 10 am for three educational sessions lasting 45 - 60 minutes. Pamphlets covering the material of each educational session were provided to participants. Following the distribution of the pamphlets, the researcher gave a short presentation summarizing the key information and then facilitated a discussion among the participants. Attendance was recorded for each session, with an average participation rate of around 95%. Sessions followed an interactive, participant-centered approach, including group discussions on personal challenges in managing cholesterol and motivational techniques (e.g. weekly goal-setting).
These three sessions provided a comprehensive overview of blood lipids, covering key aspects from understanding the different types of lipids and their roles in the body to practical strategies for managing them through diet and exercise. The first session introduced dyslipidemia, the various types of fats, their impact on cardiovascular health, and the importance of a balanced diet as represented by the food pyramid. The second session delved into the specifics of nutrition for individuals with high blood lipids, outlining foods to include and avoid, and explaining how elevated lipid levels affect the heart and blood vessels, increasing the risk of CVDs. Finally, the third session emphasized the crucial role of physical activity in managing blood lipids, detailing how regular exercise can lower levels and improve cardiovascular health, while also providing guidance on choosing appropriate types, intensity, and duration of physical activity. In this study, following data collection, the control group was given an educational booklet comprising the instructed content.