Download Unequal impact: Maori and non

Unequal impact: Maori and
non-Maori cancer statistics
International Group for Indigenous Health Measurement,
28-30 November, 2006
Canberra
Donna Cormack
Te Ropu Rangahau Hauora a Eru Pomare
Acknowledgements
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Te Ropu Rangahau Hauora a Eru Pomare (Bridget Robson)
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Gordon Purdie (Biostatistician), Department of Public Health
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Contracted by the Ministry of Health
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Acknowledge the individuals and organisations who contributed
Overview
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Background
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Context of the Cancer Chartbook: ‘Unequal Impact’
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Issues
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Results
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Summary
Context
“Maori are tangata whenua. Not people in the land or over the land, but
people of it” (Moana Jackson, 1993)
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We have rights to good health (health care and healthy environments)
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We have a right to determine our own health priorities and futures
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We have rights to monitor the impact of Crown policy, action and inaction
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We have rights to be counted as a population in our own right
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Meeting these rights requires comprehensive, detailed, accurate
information
Cancer control context
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Recent developments in cancer control policy
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Cancer Control Strategy launched in 2003
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Establishment of a Cancer Control Council
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New Zealand Cancer Control Strategy Action Plan: 2005-2010
Evidence of increasing ethnic gaps in cancer mortality over the 1980s and
1990s
Little detailed information available on cancer for Maori
Measurement issues
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Issues with the quality and completeness of data
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The implications of different standards
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‘Ever Maori’
Standardising to the Maori population
Assumptions and generalisations driving research questions and framing
of results
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‘late presentation’
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‘aggressive tumours’
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‘non-compliance’
Data issues
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Data Sources: Cancer Register and mortality data 1995-2001, and
hospital admissions 1996-2003, NZHIS
We know that Maori are undercounted in cancer registrations, hospital
admissions and deaths
‘Ever Maori’: count as Maori anyone ever recorded as Maori in any of the
data sources or on the NHI during the analysis period
Ethnicity data: Estimate Maori cancer registrations undercounted by
17%, deaths by 6%,
Classification of ethnicity: “Ever Maori’ method reduced undercount to
<1%, numbers of unassigned ethnicity decreased
Has been used in other analyses
Chartbook analyses
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Stage at diagnosis: from extent of disease data on cancer registration: %
localised, regional, distant, unknown.
Maori:non-Maori odds ratios for stage, adjusted for age, using logistic
regression
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Survival data: cancer-specific mortality, censored at death if died from
other causes or at 31 December 2001
Survival curves – Kaplan-Meier estimates (unadjusted)
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Hazard ratios – Maori/non-Maori relative risk of death after diagnosis;
proportional hazards model, adjusted for age and sex, and for stage;
also calculated by stage.
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Choice of standard population
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Differences in age structures: Maori (relatively young) and non-Maori
(relatively old)
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Segi’s world population and WHO world population both used in Aotearoa
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Maori population considerably younger and non-Maori considerably older
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Magnitude of age-standardised incidence and mortality rates generally
increased (Maori, Segi, WHO) while ratio ratios remained fairly similar
Rates standardised to Maori population reflect Maori realities more closely
than those adjusted to older standards
Maori
Non-Maori
Rate ratios
Maori
Segi
WHO
Maori
Segi
WHO
Maori
Segi
WHO
220.9
378.4
425.0
187.8
319.2
359.1
1.18
1.19
1.18
Results: leading cancer sites
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Leading cancer registration sites differ for Mäori and non- Mäori, in terms of
ranking and percentage of new cases or deaths
Most commonly occurring cancers:
- lung, stomach, cervix, testis and liver more common
- colorectal, melanoma, prostate, bladder and brain less common
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Leading causes of cancer death:
- cervix and liver more common for Mäori
- melanoma more common for non-Mäori
Leading cancer registration sites 1996-2001
Maori
Non-Maori
Number
% of new
cases
Number
% of new
cases
Trachea, bronchus & lung
1,437
19.4
Prostate
15,324
16.3
Female breast
1,147
15.9
Colorectal
14,410
15.3
Prostate
632
8.5
Female breast
11,762
12.5
Colorectal
514
6.9
Melanoma of skin
9,372
9.9
Stomach
329
4.4
Trachea, bronchus & lung
7,975
8.5
Leukaemias
276
3.7
Bladder
3,284
3.5
Cervix uteri
250
3.4
Non-Hodgkin’s lymphoma
3,256
3.5
Non-Hodgkin’s lymphoma
232
3.1
Leukaemias
3,133
3.3
Liver & intrahepatic bile ducts
183
2.5
Stomach
2,019
2.1
Pancreas
176
2.4
Kidney
1,835
1.9
Site
Site
Both sexes
Leading cancer death sites 1996-2001
Maori
Non-Maori
Number
% of
cancer
deaths
Number
% of
cancer
deaths
1,370
32.0
Trachea, bronchus & lung
7,107
17.3
Female breast
383
8.9
Colorectal
6,502
15.8
Colorectal
292
6.8
Female breast
3,435
8.3
Stomach
277
6.5
Prostate
3,111
7.6
Prostate
178
4.2
Non-Hodgkin’s lymphoma
1,656
4.0
Pancreas
168
3.9
Pancreas
1,651
4.0
Liver & intrahepatic bile ducts
153
3.6
Stomach
1,537
3.7
Leukaemias
137
3.2
Leukaemias
1,392
3.4
Non-Hodgkin’s lymphoma
111
2.6
Melanoma of skin
1,352
3.3
95
2.2
Brain
1,174
2.9
Site
Site
Both sexes
Trachea, bronchus & lung
Brain
Mapping cancer disparities
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Age-standardised incidence rate for all sites:
- 220.9 per 100 000 for Mäori
-187.8 per 100 000 for non-Mäori
- relative risk of 1.18 (95% CI 1.15-1.21)
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Age-standardised mortality rate for all sites:
- 127.9 per 100 000 for Mäori
- 66.3 per 100 000 for non-Mäori
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relative risk of 1.93 (95% CI 1.87-1.99)
Cancer-specific survival is lower for most types of cancer
Maori/non-Maori age-standardised cancer incidence &
mortality ratios 1996-2001
All sites
Lung
Breast
Prostate
Colon
Rectum Stomach
Cervix
Uterus
Testis
Mäori/non-Mäori Age-standardised Rate Ratio (log scale)
10.0
4.85
4.25
3.70
3.31
3.69
3.08
2.27
2.28
1.93
1.68
1.18
1.84
1.61
1.61
1.21
1.17
1.0
0.84
0.76
0.58
Deaths
Registrations
0.1
0.76
Hazard ratios
Relative risk of death (age-sex adjusted) after diagnosis
significantly higher for Mäori for:
Lung
1.34
Uterus
1.65
Breast
1.69
Kidney
1.52
Prostate
2.33
Oral cancers
2.07
Colorectal
1.67
Liver
1.39
Cervix
2.68
Oesophagus
1.74
Stomach
1.57
Bladder
2.37
Stage at diagnosis (extent of disease spread)
Maori are less likely to have stage recorded for cancers of the:
lung
breast
cervix
colorectal
stomach
uterus
oesophagus
brain
1.41
1.29
1.86
2.19
1.63
2.13
1.79
1.90
OR adjusted for age at diagnosis
Distribution of stage at diagnosis
Colorectal cancer 1996-2001
% 50
40
30
20
10
0
Localised
Regional
Mäori
Distant
non-Mäori
Unknown
Stage at diagnosis (staged cancers only)
• Adjusted for age & sex, Maori are significantly less likely to be
diagnosed at localised stage for:
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breast
trachea, bronchus & lung
colorectal
cervix
prostate
testis
kidney
lip, oral cavity & pharynx
melanoma
Stage at diagnosis (staged cancers only)
• Adjusted for age & sex, Maori are significantly more likely to be
diagnosed at distant stage for:
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colorectal
trachea, bronchus & lung
breast
cervix
prostate
melanoma
Impact on survival disparities
HR Age
adjusted
Lung
1.34
HR Age &
stage
adjusted
1.28
Breast
1.69
1.48
31%
Cervix
2.68
2.34
20%
Colorectal
1.67
1.34
50%
Prostate
2.33
1.70
47%
Kidney
1.52
1.36
31%
%
reduced
17%
Maori/non-Maori hazard ratios by
stage (adjusted for age)
Localised Regional Distant
Stomach
Unknown
1.98
1.70
1.77
1.68
Colorectal 2.00
1.56
1.11ns
1.54
Lung
1.76
1.55
1.20
1.29
Breast
1.87
1.34
1.34ns
1.76
Cervix
2.38ns
2.42
3.87
1.93
Prostate
0.97ns
1.23ns
1.55
1.92
ns=not significant at 5% level
Stage at diagnosis
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Differential stage at diagnosis accounts for part but not all of the disparity
in cancer-specific survival between Mäori and non- Mäori
At each stage, Mäori cancer-specific mortality after diagnosis is higher
than non- Mäori for many cancers
This indicates the likely existence of disparities in timely access to
definitive diagnostic procedures, staging procedures, and optimal
treatment/management of cancer
Assumptions and generalisations
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Challenges assumptions about explanations for disparities in cancer
experiences and outcomes
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late presentation or late diagnosis
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non-compliance or unequal treatment
Requires us to look more closely at the role of health systems and health
care processes
Summary
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Need to be able to measure and monitor cancer disparities
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‘Ever Maori’ can mitigate undercount
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Requires good quality, consistent, standardised data
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Kaupapa Maori approach can meet everyone’s needs
Need to be able to establish priorities for Maori cancer control
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Requires depth, breadth and detail of information
Need to think critically about the way we talk about Maori cancer
and cancer inequalities
Requires us to challenge assumptions underpinning research
questions and the framing and interpretation of results
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