A structured questionnaire was administered from March, 2018 to July, 2018 at participant homes in participants’ free time using a cross-sectional multi-stage random sampling method in order to select 749 samples among 12 communes out of 5 districts in the Phnom Penh municipality of Cambodia.

The study design was reviewed by the Khon Kaen University ethics committee and was approved for human research (Reference No. HE582071). Data collection was conducted by administering the questionnaire in a face-to-face interview. All participants gave written informed consent to participate in the study. If the participant was unable to read the consent form, the researcher read it aloud for them.

Multi-stage random sampling was used to select the samples in this study. Phnom Penh capital city was selected and 5 districts were randomly selected from the total of 12 districts of Phnom Penh capital city. Then 2 or 3 communes were randomly selected from each selected district, for a total of 12 communes to be selected. Each household in each commune was listed and assigned a number and a systematic random sampling procedure was used to select 748 households from the total 44,436 households. Finally, one member aged 18-59 of each household was randomly selected if the household had more than one member in this age category.

The inclusion criteria for the study were that participants over 18 years of age, and were able to understand the questionnaire. Exclusion criteria were any serious health problems (causing them to be bedbound), diarrhea at the time of data collection (defecating more than 3 times per day), pregnancy, mental illness, deformity and lower limb amputation.

The sample size for this study was calculated using an established formula ¹⁴ and the estimated sample size was 749.

The outcome measure used in this study is soft drink consumption, for which a threshold of ≥3 times per week was chosen. This threshold was used as it has been previously associated with being overweight/obese, and having metabolic syndrome ^{15– 17} .

A structured questionnaire was developed based on the research questions and relevant literature. The questionnaire consisted of two parts: part 1, demographic and socioeconomic characteristics, including gender, age, marital status, educational attainment, occupation, number of family members and personal monthly income; part 2, lifestyle and behavior characteristics, including tobacco use, alcohol consumption, food habits, soft drink consumption, physical activity and sedentary behavior.

As the questionnaires were developed for data collection, a pre-test of the questionnaire was conducted in 30 participants from different areas from the target group. Reliability was calculated using Cronbach’s alpha coefficient, and was 0.857. Then the questionnaire was developed and tested for content validity by five experts. Finally, a forum of researchers edited and rearranged the questionnaire based on the results of the field test, with the aim to ensure the validity and reliability of the tool.

Dependent variable . Participants consuming soft drinks more than three times per week was the dependent variable used in this study. Participants were asked “How many times per week have you drunk a soft drink in the last month?” Participant answers were classified into two groups: those who drank soft drinks less than 3 times per week (“no” = 0) and 3 times per week of more (“yes” = 1).

Predictor variables . Age, household income and expenditure, and the number of individuals in the household were coded as continuous variables. Categorical variables comprised gender (male or female), marital status (single, married or divorced), level of education (no formal education, primary, secondary, high school, associated degree, Bachelor’ degree, Master’s degree or higher), occupation (farmer, unemployed, NGO employee, self-employed, student, government officer, home maker, unskilled worker, or other) and the people they were cohabiting with (spouse, parents, relatives, none, friend, or other).

Data were imported to Stata version 13 (College Station, Texas, USA) for analysis. Continuous and categorical data were inspected using descriptive statistics to determine the frequencies and percentages (categorical variables) and means, medians and standard deviations (continuous variables) of each socio-economic and demographic characteristic collected. Bivariate logistic regression was used to estimate the association between each socioeconomic factor and the outcome measure of soft drink consumption. Crude odds ratios (CORs) were computed using 95% confidence intervals (CIs) and variables with significance of p<0.25 were entered into the final model. In this final model, multivariate logistic regression was used to estimate the association between socioeconomic factors and soft drink consumption. Adjusted odds ratios (AORs) were then computed using the 95% CI. Significance was considered at a threshold of p<0.05.

A total of 749 participants from 5 districts and 12 communes were recruited into the study. The socio-demographic characteristics of respondents are summarized in Table 1. In total, 50.2% of participants were women and 49.80% were men, and the mean age of participants (± standard deviation) was 32.26±11 years. The marital status of participants was 53.94% married, 43.52% single and 2.54% divorced. The most frequent level of participants’ highest educational attainment was high school (31.91%), followed by Bachelor’s degree (26.44%) and primary school level (15.22%). The most frequent occupations were private company workers (28.97%), self-employed (21.36%) and students (20.16%), with only 0.67% of the participants being farmers and 0.93% unemployed. More than half of the participants (57.41%) had a household size of less than 5 members, and participants most frequently reported living with their spouse (47.93%), parents (25.37%) and relatives (12.95%). Monthly income ranged from US$40 to $5,100 with a mean (±SD) of US$495±686.7. Monthly expenditure ranged from US$20 to $3,750 USD with mean of US$288.5±394.1 (see Table 1).

The overall prevalence of soft drink consumption was 44.73% (95%CI: 41.16-48.30%). Educational attainment, gender, age, occupation, household composition, household size, and income were found to have associations with soft drink consumption (p<0.25) in the bivariate analysis ( Table 2).

The final model found only four factors associated with soft drink consumption: gender, age, household size and income. Men (AOR: 1.49, 95%CI: 1.10-2.00; p = 0.009), those aged 31-59 years (AOR: 1.93, 95%CI: 1.98-4.62; p <0.001), those in smaller households (AOR: 1.38, 95%CI: 1.44-3.19; p = 0.036), and those earning <US$300/month (AOR: 1.59, 95%CI: 1.10-2.31; p = 0.003) were more likely to consume soft drinks at least three times a week ( Table 3).

Figshare: Underlying Data 1, https://doi.org/10.6084/m9.figshare.12612998.v1 ²⁴

This project contains the following underlying data:

Figshare: Extended data, https://doi.org/10.6084/m9.figshare.12612992.v1 ²⁵

This project contains the following extended data:

Data are available under the terms of the Creative Commons Zero "No rights reserved" data waiver (CC0 1.0 Public domain dedication).