Scottish Health Survey 2015 - volume 2: technical report

5 Waist Circumference

5.1 Introduction

There has been increasing interest in the distribution of body fat as an important indicator of increased risk of cardiovascular disease. The waist circumference is a measure of the distribution of body fat. Waist circumference is probably a more important predictor of health risk than the body mass index ( BMI), which is weight relative to height.

5.2 Exclusion criteria

Participants are excluded from the waist circumference measurement if they:

• Are pregnant
• Are chair bound
• Have a colostomy / ileostomy (This is a surgical opening drawing the intestine or colon to the surface of the skin in the lower abdominal area. Bodily waste is collected in a pouch outside the body). Participants may volunteer this information. Do not ask a Participant directly if they have a colostomy.

5.3 Equipment

You will need:

• A measuring tape calibrated in millimetres
• Milton wipes

5.4 Preparing the Participant

The Participant needs to be wearing light clothing. Never measure directly onto the skin. Explain to the Participant the importance of this measurement and that layers of clothing can substantially affect the reading. If possible the Participant needs to remove:

• All outer layers of clothing, such as jackets, heavy or baggy jumpers, cardigans and waistcoats
• Shoes with heels as this alters the natural position of the torso
• Tight garments intended to alter the shape of the body, such as corsets, lycra body suits and support tights/underwear (if the Participant is unable or unwilling to remove these then continue the measurement but record a note in CAPI)
• Belts (can be loosened if not removed)

Some Participants may be wearing religious or other symbols which they cannot remove and which may affect the measurement. Do not embarrass or offend the Participant by asking them to remove such items. Record in CAPI if the measurement is likely to be affected by this.

5.5 Procedure

1. Ensure that the Participant is standing erect in a relaxed manner and breathing normally. Weight should be evenly balanced on both feet and the feet should be about 25-30cm (1 foot) apart. The arms should be hanging loosely at their sides. This position will provide the most accurate and easy measurement of the waist.

2. Ask the Participant to point to his or her navel or tummy button.

3.Instruct the Participant to place the tape around their body, over their clothing, at the level of the navel. You should then click the popper in place and pull to tight the tape around the waist of the Participant overlying their navel (Section 6 WAIST AND HIP CIRCUMFERENCES - Use guidelines for 'Easy Check Circumference' tape measure). The tape should be snug but not tight. If the Participant is not able to pass the tape around his/her waist, you may have to hold onto one end of the tape measure at their navel, and walk around the Participant with the other end.

4. Check that the tape is not twisted and that it is horizontal all the way around the Participant. To do this you must look round the participant's back from his/her left side to check that it is level. This will be easier if you are kneeling or sitting on a chair to the side of the Participant.

5. Ask the Participant to breathe normally and to look straight ahead.

6. Take the measurement at the end of a normal breath by holding the tape flat against the body.

7. Record the measurement in CAPI in centimetres, to one decimal place.

8. Repeat steps 1-7 to record a second measurement. If the second reading differs significantly from the first, CAPI will report an error message. At this point check that you have entered the results into CAPI correctly. Otherwise take a third measurement, following the procedure above. Enter this result into CAPI. The computer will know which two results to use.

9. If the Participant wishes, record the waist measurement on their measurement record card.

5.6 Additional points

• The tape should be tight enough so that it doesn't slip but not tight enough to indent clothing.
• Some Participants will be wearing clothing where the waistband of the trousers/skirt sits on the waist. Do not ask them to move the clothing or take the measurement at a different position. Measure the waist circumference over the waistband and make a note of this in CAPI. If the waistband is not horizontal all the way around the body i.e. it may be lower at the front, always ensure that the tape is horizontal which may mean that it passes over the waist band in some places and not in others.
• We only want to record problems that will affect the measurement by more than would be expected when measuring over light clothing. As a rough guide only record a problem if you feel it affected the measurements by more than 0.5cm.
• Wipe the measurement tape with Milton wipes between households.