healthmedicinet

Ethic approval

This study was undertaken with ethic approval from the Peking University biomedical
ethics committee, Duke University Institutional Review Board for Clinical Investigations
and School of Population Health Research Ethics Committee at the University of Queensland.

Study sample

Study subjects were recruited from five different Chinese medical schools, Duke University
in U.S., and the University of Queensland in Australia. All those schools were chosen
for convenience based on established collaboration within the network of the Center
of Excellence at the George Institute. Chinese students were majoring in clinical
medicine, enrolled in 2
^d
, 4
^th
and 7
^th
year at Peking University Health Science Center (PUHSC) in Beijing, School of Medicine,
Xi’an Jiaotong University (XJTU) in Xi’an, China Medical University (CMU) in Shenyang,
Ningxia Medical University (NMU) in Ningxia, and Changzhi Medical College (CMC) in
Changzhi. American students were majoring in clinical medicine, enrolled in the Doctor
of Medicine (MD) or MD/PhD (MSTP) program at Duke University, School of Medicine in
Durham, North Carolina, U.S.. Australian students were majoring in clinical medicine,
enrolled in 1
^st
, 2
^d
, 3
^rd
or 4
^th
year at the School of Medicine, the University of Queensland.

In terms of eligibility criteria, the participants had to have been enrolled before
October 2012. This was because by the time the survey was administered, students enrolled
by October 2012 would be in their 2
^d
or greater year at their school. Students were considered eligible if they were enrolled
in their 2
^d
, 4
^th
, or 7
^th
year. These cohorts were selected to represent students from pre-clinical, new-clinical,
and post-clinical populations from five different Chinese medical universities. The
three cohorts of students began schooling in 2006, 2009 and 2011.

Based on a sample size calculation from the pilot study, the target sample size was
150 students from each grade, or 450 students in total, from the five medical universities
in China. This was based on an estimate that 55 % students were considered to have
positive attitudes towards preventive counselling from the pilot study (??=?0.05,
absolute permissible error?=?5 %, relative error?=?10 % response rate?=?70 %). The
sample size was calculated as: N?=?U
_(1-?)^??2
/ Relative error
²
. We included all medical students from Duke University and from the University of
Queensland. The total number of enrollments between October 2012 and November 2012
was 425 students from Duke University, 500 students from the University of Queensland,
and 1568 students from the five Chinese medical schools. The non-response rates in
the Duke University, University of Queensland, and five Chinese medical universities
were 54.4, 50.5, and 79.2 %, respectively.

Survey tool and distribution

This study examined the prevalence of healthy lifestyles among medical students and
its association with attitudes towards preventive counseling of NCDs using a 32-item,
self-reported online survey that took medical students approximately 15 min to complete.

The web-based survey consisted of four sections: 1. general health status; 2. personal
health behaviors including physical activity, diet, mental health, smoking, alcohol
consumption, health goals and health care seeking behaviors; 3. health care opinions
and attitudes; 4. personal information. Many of the questions were adapted from validated
sources, including the U.S. Centers for Disease Control (CDC) Behavioral Risk Factor
Surveillance System (BRFSS) 13], CDC National Health Interview Survey 14], NHIS Tobacco Questions: 1997–2010 15], and International Physical Activity Questionnaire (IPAQ) 16]. The inclusion of questions in the survey was based on consultations with the research
team at the George Institute in China, a leader in the field of medical students’
lifestyles. The authors also referred to the study “Healthy Doctor?=?Healthy Patient”,
by Professor Erica Frank from the University of British Columbia 17]. There were also questions that have been developed by the research team.

Before the formal implementation of the survey, we conducted a paper-based pilot study
at Peking University Health Science Center in April 2012 to assess the acceptance
of the questionnaire and made modifications as needed. Also to assess the feasibility
of online survey and the response rate, an online pilot survey was administered to
students at Peking University Health Science Center in September 2012 and further
modifications were made as needed.

The final questionnaire was distributed in Chinese to Chinese medical students and
in English to American and Australian medical students. Care was taken to ensure the
consistence between the Chinese version and English version of the questionnaire.
If the source of the questions were from validated English questionnaires, the questions
were translated to Chinese and back translation was done to ensure the consistence
of the meaning. And vice versa, if the source of questions were in Chinese, they were
translated to English and back translation was done. Students were sent an email with
a link to the questionnaire and were instructed to complete it within 2 weeks. In
an additional effort to maximize the response rate, each medical school administrator
followed up emails by sending four reminder emails, 4 weeks apart, between October
2012 and November 2012. Students who completed the survey received monetary compensation
for their time and effort.

The standard of healthy lifestyles (Exposure Variables)

The four domains of exposure variables were diet, exercise, smoking, and alcohol consumption.
Those complying with dietary recommendations in the U.S. and Australia consumed more
than five servings of vegetables and/or fruits per day 18]. In comparison, participants in China who reported consuming at least 200 grams of
fruits and 300 grams of vegetables per day were considered to be in compliance with
dietary recommendations 19], 20]. Participants who reported at least 150 min or more of moderate-to-vigorous physical
activity per week were considered to be in compliance with exercise recommendations
21]. Participants were considered smokers if they reported having smoked at least 100
cigarettes in their lifetime and were currently still smoking cigarettes 22]. Alcohol consumption was divided into binge drinking and heavy drinking. Heavy drinkers
were those who consumed, on average, at least one drink per day for women and at least
two drinks per day for men in month 23]. Binge drinkers were those who reported drinking more than four drinks for women
and more than five drinks for men in one sitting at any time during the past month.
Participants who met dietary and exercise recommendations and who reported being non-smokers
15], non-heavy drinkers, and non-binge drinkers, were considered to have an overall healthy
lifestyle.

Outcome measures

The primary outcome measure of this study was the association between the healthy
lifestyles and the attitudes towards preventive counselling.

Statistical analysis

Univariate logistic regression analyses were performed to obtain an odds ratio (OR),
95 % confidence interval (95%CI) and P-value, to assess the association between healthy behaviors and attitudes towards
preventive counseling among medical students at Duke University, the University of
Queensland, and five medical schools in China. In addition, data was pooled according
to country in order to compare findings from the U.S, Australia and China.

Differences in health behaviors and attitudes towards preventive counseling, due to
level of education and level of professional development, may exist among students
from different cohorts. Therefore, data was stratified by year to avoid effect modification.
Prevalence estimates were obtained for all participants on self-reported body mass
index, healthy behaviors (i.e., diet, exercise, smoking, and alcohol), and attitudes
towards preventative counseling for each of these domains.

Multivariate logistic regression analyses were adjusted for gender to evaluate the
association between healthy behaviors and attitudes towards preventative counseling
between males and females. The main exposure variables (independent variables) were
physical activity, balanced diet, weight control, stress management, smoking behavior
and alcohol consumption. The main outcome variables (dependent variables) were students’
attitudes toward preventative counseling, which included basic knowledge of chronic
diseases, stratified by year of training, country, and adjusted for gender; perceived
adequacy of training; school’s promotion of each healthy habit; and so on. Collinearity
between the domain variables was assessed by simple tabulation and any collinearity
problems were noted in the tables. All analyses were performed using SPSS17.0 24].