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National Indigenous Reform Agreement: PI 09-Antenatal care, 2014

Identifying and definitional attributes

Metadata item type:Help on this termIndicator
Indicator type:Help on this termIndicator
Short name:Help on this termPI 09-Antenatal care, 2014
METeOR identifier:Help on this term525833
Registration status:Help on this termIndigenous, Archived 24/11/2014
Description:Help on this term

There are two measures for this indicator, both to be reported by Indigenous status:

(1a): Number of women who gave birth, where an antenatal visit was reported in the first trimester, as a proportion of women who gave birth,

and

(1b): Number of women who gave birth, where five or more antenatal visits were reported, as a proportion of women who gave birth.

Rationale:Help on this term

The primary care needs of all Australians are met effectively through timely and quality care in the community.

Good antenatal care is associated with positive health outcomes for mothers and babies.
Indicator set:Help on this termNational Indigenous Reform Agreement (2014) Indigenous, Archived 24/11/2014
Outcome area:Help on this termIndigenous children are born and remain healthy Indigenous, Endorsed 21/07/2010
Quality statement:Help on this termNational Indigenous Reform Agreement: PI 09-Antenatal care, 2014 QS Indigenous, Archived 17/02/2016

Collection and usage attributes

Computation description:Help on this term

Crude rates are calculated for Indigenous Australians.

Age-standardised rates are calculated for Indigenous and non-Indigenous Australians.

Rate ratios and rate differences are calculated for Indigenous: non-Indigenous.

For variability bands: Variability bands are to be calculated for rates using the standard method (see definition below).

For trends: percentage change and statistical significance of change is to be calculated (required for CRC reporting).

Presentation:

Number, rate per 100 (percentage), rate ratios, rate differences and variability bands.

First trimester is defined as before 14 weeks of pregnancy.

Excludes non-residents of external territories and where the state/territory of residence was not stated.

Excludes records with missing data for gestation at first antenatal visit.

Definitions:

Standard method for variability band computation:

Rates derived from administrative data counts are not subject to sampling error but may still be subject to natural random variation, especially for small counts. A 95% confidence interval for an estimate is a range of values which is very likely (95 times out of 100) to contain the true unknown value. Where the 95% confidence intervals of two estimates do not overlap it can be concluded that there is a statistically significant difference between the two estimates. This is the standard method used in AIHW publications for which formulas can be sourced from Breslow and Day (1987) in the publication ‘Statistical methods in cancer research’. Typically in the standard method, the observed rate is assumed to have natural variability in the numerator count (e.g. deaths, hospital visits) but not in the population denominator count. Also, the rate is assumed to have been generated from a Normal distribution ("Bell curve"). Random variation in the numerator count is assumed to be centred around the true value, i.e. there is no systematic bias.

Computation:Help on this term

Crude rate: 100 x (Numerator ÷ Denominator).

Age-standardised rate: calculated using the direct method, using five year age groups from 15-19 years to 40-44 years using the Australian female population who gave birth in the current reporting period as the standard. Age-standardisation should be done in accordance with the NIRAPIMG agreed principles for direct age-standardisation (see Comments section. Note that Principle 1 and Principle 4 are not applicable for this indicator).

Rate ratio: Indigenous rate divided by non-Indigenous rate.

Rate difference: Indigenous rate minus non-Indigenous rate.

Variability band: to be calculated using the standard method for estimating 95% confidence intervals as follows:

Crude rate:

Crude rate (NIRA 2013)

Where CR = crude rate for either Measure 1a or Measure 1b

n = crude rate denominator for either Measure 1a or Measure 1b.

Age-standardised rate:

Age standardised rate 18 pt

Where wi = the proportion of the standard population in age group i

di = the numerator for either Measure 1a or Measure 1b  in age group i

ni = the denominator for either Measure 1a or Measure 1b respectively (see Denominator below) in the population in age group i

Percentage change: Calculated by multiplying the average annual change over the period by the number of data points less 1. This is then divided by the rate for the first year in the series and multiplied by 100.

The average annual change in rates, rate ratios and rate differences are calculated using linear regression which uses the least squares method to calculate a straight line that best fits the data and returns an array that best describes the line. The simple linear regression line, Y = a + bX, or ‘slope’ estimate was used to determine the average annual change in the data over the period. The formula used to calculate the slope estimate and standard error of the slope in Microsoft Excel is:

LINEST (known_y’s, known_x’s, true) entered as an array formula (Ctrl, Shift, Enter).

Statistical significance of change: The 95% confidence intervals (CIs) for the standard error of the slope estimate (average annual change) are used to determine whether the apparent increases or decreases in the data are statistically significant at the p<0.05 level. The formula used to calculate the CIs for the standard error of the slope estimate is:

95% CI(x) = x ± 1.96 x SE(x)

where x is the average annual change (slope estimate). If the upper and lower 95% confidence intervals do not include zero, then it can be concluded that there is statistical evidence of an increasing or decreasing trend in the data over the study period.

 

Numerator:Help on this term

Measure (1a): number of women who gave birth where an antenatal visit was reported in the first trimester (up to and including 13 completed weeks), for at least one live or stillborn baby.

Measure (1b): number of women who gave birth where five or more antenatal visits were reported for pregnancy of 32 or more weeks gestation, for at least one live or stillborn baby.

Numerator data elements:Help on this term
Data Element / Data SetPregnancy—estimated duration (at the first visit for antenatal care), completed weeks N[N]
Data Source
AIHW National Perinatal Data Collection (NPDC)
Guide for use
Data source type: Administrative by-product data
Data Element / Data SetFemale—number of antenatal care visits, total N[N]
Data Source
AIHW National Perinatal Data Collection (NPDC)
Guide for use
Data source type: Administrative by-product data
Data Element / Data SetFemale (pregnant)—estimated gestational age, total weeks NN
Data Source
AIHW National Perinatal Data Collection (NPDC)
Guide for use
Data source type: Administrative by-product data
Denominator:Help on this term

Measure (1a): total number of women who gave birth, for at least one live or stillborn baby (where gestation at first antenatal visit is known).

Measure (1b): total number of women who gave birth at 32 weeks or more gestation, for at least one live or stillborn baby (where number of antenatal visits is known).
Denominator data elements:Help on this term
Data Element / Data SetFemale (pregnant)—estimated gestational age, total weeks NN
Data Source
AIHW National Perinatal Data Collection (NPDC)
Guide for use
Data source type: Administrative by-product data
Data Element / Data SetPregnancy—estimated duration (at the first visit for antenatal care), completed weeks N[N]
Data Source
AIHW National Perinatal Data Collection (NPDC)
Guide for use
Data source type: Administrative by-product data
Data Element / Data SetFemale—number of antenatal care visits, total N[N]
Data Source
AIHW National Perinatal Data Collection (NPDC)
Guide for use
Data source type: Administrative by-product data
Disaggregation:Help on this term

Current period (2011):

For Indigenous only (numbers and crude rates):

  • National and state/territory (including sub-total for jurisdictions reported for baseline year) and remoteness area.

Time series – 2007, 2008, 2009, 2010 (the data for these years have been previously supplied), 2011 (required for 2014 reporting):

For Indigenous and non-Indigenous (numbers, age-standardised rates, rate ratio, rate difference, percentage change, variability bands and statistical significance of change):

  • National and state/territory (including sub-total for jurisdictions reported for baseline year) and remoteness area, by Indigenous status.
Disaggregation data elements:Help on this term
Data Element / Data SetPerson—area of usual residence, statistical area level 2 (SA2) code (ASGS 2011) N(9)
Data Source
AIHW National Perinatal Data Collection (NPDC)
Guide for use
Data source type: Administrative by-product data
Data Element / Data SetPerson—Indigenous status, code N
Data Source
AIHW National Perinatal Data Collection (NPDC)
Guide for use
Data source type: Administrative by-product data
Comments:Help on this term

Most recent data available for 2014 CRC report is 2011.

There were no data elements in the Perinatal national minimum data set (NMDS) for antenatal care prior to July 2010, however some information is obtained as part of the National Perinatal Data Collection (NPDC).

Information is included in the NPDC and the Perinatal NMDS for all live births and still births of at least 400 grams birthweight or at least 20 weeks gestation.

Data on gestation at first visit (1a) are only available to report for NSW, Qld, WA, SA, ACT and NT for births from January 2010, and for Victoria and Tasmania for births from 1 July 2010; and data on number of antenatal visits (1b) are only available to report for Qld, SA and NT for 2014 reporting.

Analysis by state/territory is based on usual residence of the mother.

Comparability between data currently collected for births before July 2010 may be limited by different definitions of first antenatal visit.

Maternal age is the age at the time of giving birth.

To report trends, the COAG Reform Council will separately request percentage change and statistical significance testing for this indicator directly from the data provider (AIHW).

Variability bands accompanying perinatal data should be used for the purposes of comparisons over time and for national estimates at a point in time for Indigenous/non-Indigenous comparisons.

Baseline year for NIRA target (Halve the child mortality gap within a decade) is 2008; baseline year for this indicator is 2007; target year is 2018.

NIRAPIMG agreed Principles for reporting directly age-standardised rates for administrative data

Overarching principle: Before undertaking age-standardisation, analysts must investigate the data being used to understand the age-specific distribution and any limitations that may impact on the results.

Principle 1: The standard population used should be the Australian Estimated Resident Population as at 30 June 2001 from the 2001 Census until population estimates from the 2011 Census become available.

The population used as the denominator for the calculation of Indigenous age-standardised rates should be SERIES B of Indigenous experimental estimates and projections 2006 to 2021 based on the 2006 Census until population estimates from the 2011 Census become available.

Principle 2: If the denominator is less than 30 in any one age group, then do not attempt to produce age-standardised rates.

Age-groups may be collapsed to obtain a denominator of 30 or more (provided that this is in accordance with principle 3 and 4).

Principle 3: If the total number of Indigenous events (e.g. deaths, hospital separations) is less than 20, then do not attempt to produce age-standardised rates.

Combining several years of data, or aggregating jurisdictions should be considered to obtain a total of 20 or more events.

If this does not meet the purpose (i.e. data are required for time series or jurisdictional comparisons), or does not result in greater than 20 events in total, then other measures and contextual information should be reported instead of age-standardised rates which could include total number of events, crude rates, age-specific rates, age-specific rate ratios and median age at death.

Principle 4: Age-standardised rates should be calculated using the five year age groupings of 0-4 years to 75 years and over (provided Principles 2 and 3 for denominator and numerator are met).

10-year age groups may be used to overcome small numbers (20 year age groups are too wide and should not be used).

Principle 5: Additional contextual information (most importantly age-specific rates and ratios) should be provided in addition to age-standardised rates when:

a) the age-standardised rates and rate ratios lie largely outside the range of the age-specific rates and rate ratios.

b) the pattern of age-specific rates of the Indigenous and non-Indigenous populations differ substantially (e.g. deaths from a certain cause concentrate on younger ages for Indigenous population while for non-Indigenous they may occur at older ages).

c) the age-specific rates depart from the assumption of a uniform increase in death with age (e.g. injury which peaks in the young adult to middle-ages and certain cancers amenable to treatment for some age groups).

d) the condition of interest is largely confined to a specific age range (e.g. sexually transmitted infections (STIs) and women who give birth). In such instances, age-standardisation could be restricted to include the age groups within this age range only.

Principle 6: For conditions restricted to a specific age group (e.g. conditions originating in the perinatal period and sudden infant death syndrome (SIDS)), it is recommended to report the age-specific rate for the age-group of interest instead of the age-standardised rate.

Representational attributes

Representation class:Help on this termPercentage
Data type:Help on this termReal
Unit of measure:Help on this termPerson
Format:Help on this termNN[N].N

Indicator conceptual framework

Framework and dimensions:Help on this termEffective/Appropriate/Efficient

Data source attributes

Data sources:Help on this term
Data SourceAIHW National Perinatal Data Collection (NPDC)
Frequency
Calendar years ending 31 December each year
Data custodian

Australian Institute of Health and Welfare


Accountability attributes

Reporting requirements:Help on this termNational Indigenous Reform Agreement.
Organisation responsible for providing data:Help on this termAustralian Institute of Health and Welfare.
Further data development / collection required:Help on this term

Specification: Interim, pending the development and implementation of standard data definitions.

A standard data item for gestation at first presentation for antenatal care has been developed and included in the Perinatal NMDS from 1 July 2010.

A standard data items for number of antenatal visits has been developed and included in the Perinatal NMDS from 1 July 2013.

Source and reference attributes

Steward:Help on this termNational Indigenous Reform Agreement Performance Information Management Group

Relational attributes

Related metadata references:Help on this term

Supersedes National Indigenous Reform Agreement: PI 09-Antenatal care, 2013 Indigenous, Archived 13/12/2013

Has been superseded by National Indigenous Reform Agreement: PI 09-Antenatal care, 2015 Indigenous, Archived 18/11/2015

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