The Saudi Health Interview Survey was a cross-sectional national multistage survey of individuals aged 15 years or older performed between April and June 2013. KSA was divided into 13 regions. Each region was divided into subregions and blocks. All regions were included and a probability proportional to size was used to randomly select subregions and blocks. Households were randomly selected from each block. A roster of household members was conducted and an adult aged 15 or older was randomly selected to be surveyed. If the randomly selected adult was not present, our surveyors made an appointment to return, and a total of three visits were made before the household was considered as a nonresponse. The sample was nationally representative for all Saudi nationals 15 years or older. [14–16]
The Saudi Ministry of Health and its Institutional Review Board (IRB) approved the study protocol. The University of Washington IRB deemed the study as IRB exempt, since the Institute for Health Metrics and Evaluation received de-identified data for this analysis. All respondents consented and agreed to participate in the study. If the randomly selected respondent was between the ages of 15–17 years old, then the parent(s) or legal guardian of that individual consented as well.
The survey included questions on socio-demographic characteristics, tobacco consumption, diet, physical activity, health care utilization, and self-reported chronic conditions.
Smoking status was assessed using 15 questions. Ever smoking was assessed by asking respondents about smoking any tobacco products, such as cigarettes, cigars or pipes, or Shisha. To assess current smoking, respondents were asked for current use and current daily smoking of tobacco products. Smokers were also asked about the amount of their tobacco use.
The current or previous smokers were asked for their ages when they first started smoking daily.
The ever smokers were asked for quitting attempts and receipt of advice to stop smoking during the past 12 months.
Smokeless tobacco status was assessed by asking for ever and current use of smokeless tobacco products, such as snuff, chewing tobacco, Swaika, or Medwakh. To assess exposure to secondhand smoke, respondents were asked on how many of the past 7 days someone smoked in their home when they were present at home, and similar questions were asked for their workplace or school.
We used measured weight and height to calculate body mass index (BMI) as weight (kg)/height (m2). Participants were classified into four groups: 1) underweight for a BMI less than 18.5; 2) normal weight for a BMI within 18.5–25.0; 3) overweight for a BMI within 25.0–30.0; or 4) obese if their BMI was greater than or equal to 30. We used the International Physical Activity questionnaire to classify respondents into four groups of physical activity : (1) met vigorous physical activity, (2) met moderate physical activity, (3) insufficient physical activity to meet vigorous or moderate levels, and (4) no physical activity. For analytic purposes, we used no (minimal) physical activity against all other groups. We computed the servings of fruits and vegetables consumed per day from the detailed dietary questionnaire as the sum of the average daily servings.
The respondents were asked to rate their health as excellent, very good, good, fair, or poor and compare it with 12 months ago as better, worse, or about the same.
To assess diagnosed hypertension, diabetes, and hypercholesterolemia status, respondents were asked four separate questions to understand whether they have ever been told by a doctor, nurse, or other health professional that had pre-diabetes mellitus (otherwise known as pre-diabetes, borderline diabetes, impaired fasting glucose, impaired glucose tolerance, or impaired sugar tolerance), diabetes mellitus, hypercholesterolemia, or hypertension. Women diagnosed with diabetes or hypertension during pregnancy were not counted as having these conditions. Similarly, the same type of questions was used to determine previous diagnosis of stroke, myocardial infarction, atrial fibrillation, cardiac arrest, congestive heart failure, chronic obstructive pulmonary disease, asthma, renal failure, and cancer. We considered a person to be diagnosed with a chronic condition if they reported being diagnosed with any of these conditions.
We used a backward elimination multivariate unconditional logistic regression model to measure association between the outcome variables of current smoking, daily shisha consumption, heavy smoking (more than 16 cigarettes per day), and successful attempts to quit smoking and covariates, including sex, age, marital status, education, diet, physical activity, self-rated health, and reported chronic conditions. Of the 10,735 completed interviews, all had age and sex data, but we excluded 29 observations for missing smoking status, 122 observations for missing daily shisha consumption, 398 observations for missing obesity values, 266 for missing self-reported hypercholesterolemia status, 115 for missing self-reported diabetes status, 32 for missing self-reported other chronic conditions, 212 for missing fruit and vegetables consumption, 33 for missing marital status, and 20 for missing educational level. In total, 10,293 observations were used in our regression analyses.
Data were weighted to account for the probability of selection and age and sex poststratification based on census data for age and sex distribution of the Saudi population. We used Stata 13.1 for windows (StataCorp LP, TX, USA) for the analyses and to account for the complex sampling design.