Cross-cultural validation of the Short Questionnaire to Assess Health-enhancing physical activity (SQUASH)

Physical inactivity has become one of the biggest public health problems of the
21st century . It is an important risk factor for cardiovascular disease and
diabetes mellitus. In the Netherlands only 61% of the population meets the
minimum recommendation of 30 minutes moderate intensity physical activity (PA)
daily, in ethnic minorities this percentage is much lower. For instance, only
18% of the Turkish Dutch meet this recommendation. Hence, the lack of PA may be
a major contributing factor to disparities in health that are observed among
these populations. Therefore, targeted health promotion interventions are
conducted within these groups that focus on increasing PA level with the aim to
decrease these health disparities.

Health promotion interventions can be evaluated with several instruments. An
important instrument to establish PA level is the self-reported PA
questionnaire. It provides crucial information about participation in specific
physical activities. Currently the SQUASH is the standard instrument used in
the Netherlands to assess PA level. It is for instance used by Universities,
but also in the POLS study (permanent onderzoek naar de leefsituatie) of
Statistics Netherlands and in the Lokale en Nationale Monitor Volksgezondheid
(GGD). From these studies important results about compliance with the
guidelines of health-enhancing PA in the total Dutch population are derived.

Empirical research has showed that the SQUASH is a valid instrument to measure
PA among the ethnic Dutch population. However, this does not mean that the
SQUASH is necessarily valid in ethnic minority groups as well. To establish the
effect of interventions for minority groups there is an urgent need for
reliable and valid measures of PA in ethnic minority groups in the Netherlands.
At this moment no such measures are available.

There are several reasons why the SQUASH might not be a valid instrument in
ethnic minority groups. In general the cross-cultural validity between
different ethnic groups is under threat because of three different types of
bias:
- construct bias: the dissimilarity of constructs across cultures. For
instance, the meaning of *leisure time* (in items on physical activity in
leisure time) may be different across ethnic groups. Or the interpretation of
the intensity of specified levels of PA may differ across ethnic groups. Or the
meaning of PA may differ across ethnic groups.
- method bias: refers to the specific measures of the instrument that
influences all items in the same degree, for instance in some cultures it is
more important to give polite answers than to give honest answers. Also,
subjects with a low PA level have less structured PA patterns and have more
difficulty with recalling activities. As ethnic minorities have a lower PA
level than the ethnic Dutch this may lead to method bias. Furthermore PA
intensity is very subjective, sedentary people with a low fitness level might
overestimate PA intensity, while people with a high fitness level might
underestimate PA intensity.
- item bias: errors of measurement at item level, for instance by inadequate
cross-cultural adaptation of items.

These forms of bias have to be tackled for at least the main ethnic groups
before a questionnaire can be used universally.

Primary Objective:
With this study we aim to cross-culturally validate the SQUASH questionnaire
(self-reported habitual physical activity) using an independent, objective
measurement of physical activity, i.e. an Actiheart device (heart rate and
accelerometer).

Secondary Objectives:
We also aim to give insight in different types of bias per ethnic minority
group.
Are the three main forms of bias (construct, method and item) prevalent in
different ethnic groups or do differences in bias between ethnic groups exist?

The study will be set up as a prospective validation study. It will employ both
quantitative (SQUASH questionnaire and exercise test) and qualitative
(cognitive interviews) study methods. The study will include 500 HELIUS
participants and will take approximately 1 year to complete.

There is no direct benefit for the participants. Due to the physical activity
testing potential benefit may be derived as a result of raised awareness of
physical activity recommendations.
Participants will be asked to wear an "Actiheart" device for 7 days. This
device is worn on the chest. It is small and unobtrusive and can be worn under
clothing. The Actiheart is fully watertight and can be worn while bathing or
swimming.
The use of sub-maximal exercise testing is not expected to present any risk for
participants. Sub-maximal fitness testing has been commonly used by studies in
mixed populations, including physically inactive participants.