4363.0 - National Health Survey: Users' Guide, 2014-15

ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 31/07/2017

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BLOOD PRESSURE

Definition

This topic refers to the diastolic and systolic measures of blood pressure, which were measured by the interviewers during the interview.

Population

Information was obtained for persons aged 18 years and over, who agreed to have their measurements taken, in the 2014-15 NHS. Data was imputed (for further information see Imputation section) for those who did not have their measurements taken. This differs to the 2011-13 AHS where information was obtained for all persons aged 5 years and over who agreed to have their measurements taken.

Methodology

Information about blood pressure was published in the National Health Survey: First Results, 2014-15 based on a sample of 14,564 people aged 18 years and over.

B lood pressure measurements were taken towards the end of the survey and were voluntary. Respondents were invited to sit down and extend and relax their left arm, with their palm facing upwards. Interviewers were given a choice of three different sized cuffs to select from depending on respondent size. All measurements were taken on the left arm, unless there was a prohibitive reason such as an injury. Interviewers undertook two blood pressure readings using an automated blood pressure monitor in which systolic and diastolic pressures were displayed. If there was a significant difference (greater than 10 mmHg) between the readings, for either the diastolic or systolic readings, the CAI instrument would prompt for a third reading.

The follow blood pressure ranges were used to categorise blood pressure for persons aged 18 years and over.

Blood pressure ranges


Category	Range mmHg

Normal	<120/80
Normal - high	From 120/80 to <140/90
High	From 140/90 to <160/110
Very high	From 160/100 to <180/110
Severe	From 180/110

Note: if either the systolic or diastolic reading was placed in a higher blood pressure level category, then the respondent was placed in that higher category.

The derived systolic and diastolic data items involve a combination of up to two readings. Unless there was only one reading, the first reading was generally not used. The majority of participating respondents had two readings taken, and in these cases the second reading was used for the measures of systolic and diastolic pressure. When a third reading was required to be taken, the second and third readings were averaged unless the third reading differed by 20 mmHg or more. If all readings had a variation of 20 mmHg or greater the derived measurement items were recorded as invalid readings.

Data items

The questionnaire, data items and related output categories for this topic are available in pdf/Excel spreadsheet format from the Downloads page of this product.

Interpretation

Points to be considered in interpreting data for this topic include the following:

Non-response rates for physical measurements were higher in 2014-15 than in the 2011-13 AHS. In 2014-15, 24.3% of respondents aged 18 years and over did not have their blood pressure measured. For these people, blood pressure was imputed. Blood pressure data presented in the 2014-15 NHS includes both measured and imputed data.
An investigation was undertaken to determine whether the characteristics of the people who were measured differed from those who were not measured. This investigation looked at variables such as smoking status, self-assessed health, employment status, marital status, country of birth, self perceived body mass, level of exercise and whether or not has high cholesterol (as a long-term health condition) and found no differences. While there were some differences in age, sex and part of state, these were taken account of in the weighting process. As a result of this investigation, results for all physical measurement data (BMI, waist circumference and blood pressure) from 2014-15 are of suitable quality and are directly comparable to 2011-13 and earlier years.

Comparability with 2011-12

In 2011-12, measured blood pressure was collected in both the NHS and the NNPAS surveys (i.e. the AHS Core). In the 2014-15 NHS, blood pressure data comprises both measured and imputed data. Results for blood pressure data from 2014-15 are considered to be of suitable quality and are directly comparable to the 2011-13 AHS and earlier years.

When making comparisons between 2014-15 and 2011-12 data it is recommended that:

The 18 years and over population is used, as the 2014-15 NHS only collected blood pressure data for this population.
Where possible, comparisons are made using the Australian Health Survey: Updated Results, 2011-12 (cat. no. 4364.0.55.003) and Microdata: Australian Health Survey, Core Content - Risk Factors and Selected Health Conditions, 2011-12 (cat. no. 4324.0.55.003) for the most accurate information. It should be noted that the 2014-15 NHS only collected blood pressure measurements for persons aged 18 years and over and so any comparisons with 2011-12 data should use this population.
For comparison of 2014-15 data with items which were only collected in the 2011-12 NHS, the Australian Health Survey: First Results, 2011-12 (cat. no. 4364.0.55.001) and Microdata: Australian Health Survey, National Health Survey, 2011-12 (cat. no. 4324.0.55.001) are used.