Explaining the Decline in Coronary Heart Disease Mortality in Ireland 19852000

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Explaining the Decline in Coronary Heart Disease
Mortality in Ireland 1985-2000

• KATHLEEN BENNETT1, ZUBAIR KABIR1, EMER SHELLEY3,
  BELGIN UNAL2, JULIA CRITCHLEY2, IVAN PERRY4,
  JOHN FEELY1, SIMON CAPEWELL2
• (1Department of Pharmacology and Therapeutics,
  Trinity Centre for Health Sciences, St Jamess
  Hospital, Dublin 8, Ireland, 2Department of
  Public Health, University of Liverpool, Whelan
  Building, Quadrangle, LIVERPOOL, L69 3GB,
  3Department of Health and Children, Hawkins
  House, Dublin 2, Ireland, 4 Department of
  Epidemiology and Public Health, University
  College Cork, Cork, Ireland, International
  Health Research Group, Liverpool School of
  Tropical Medicine)

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Background

• Coronary heart disease (CHD) mortality rates have
  been falling since the 1970s in
• the USA
• the UK and in
• most developed countries
• CHD mortality rates in Ireland
• still amongst the highest in Europe
• decreasing steadily since mid-1980s

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Figure 1 Trends in age standardised CHD
mortality rates 1968-2001 Men aged 35-74 years
(WHO 2004)
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Background

• The National Cardiovascular Health Strategy in
  Ireland, Building Healthier Hearts, aims to
  reduce cardiovascular mortality morbidity.
• Future strategies now require a better
  understanding of recent trends.

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Why have CHD death rates halved since the 1980s?

• Evidence based cardiology treatments?
• OR
• Risk factor reductions?

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Aim

• To explain fall in CHD mortality from 1985-2000
• IRISH IMPACT MODEL
• Compares population between 1985 2000
• Men Women
• All age groups 25- 84 years

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Building a comprehensive CHD model

• IMPACT Model Includes
• CHD treatments
• Immediate AMI Treatments
• Secondary Prevention
• Post AMI, post CABG, post Angioplasty
• Chronic Angina CABG, Angioplasty, Aspirin
• Unstable Angina Aspirin, Heparin, PG IIB/IIIA
• Heart failure
• Hypertension
• Statins for primary prevention
• CHD Risk factors (surveys, local studies)
• Smoking, Population blood pressure, Cholesterol,
  obesity, diabetes, inactivity

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Impact of individual treatment on population
mortality example

• Thrombolysis aspirin for AMI, Men aged 45-54
• Patients Treatment Absolute Deaths
• eligible uptake risk prevented
• reduction or postponed (DPP)
• a x b x c
  a x b x c
• 520 X 44 x 0.053
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• SOURCES
• Routine Local national ISIS2 RCT
• statistics audits Meta-analyses
• Epidemiological
• surveys

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ß Coefficients fall in CHD mortality per unit
decrease in risk factor (from meta-analyses
cohorts)

• Cholesterol lowering Law et al BMJ 1994
• 1mmol/l reduction popn mean cholesterol
• ? 45 reduction in CHD mortality
• Blood pressure Prospective Studies Collaboration,
  Lancet 2002
• 1 mm Hg ? Diastolic BP ? 2 ? CHD
• Smoking Sigfusson et al BMJ 1991
• 1 decrease smokers ? 1.1 ? CHD

  Unal, Critchley Capewell Circulation 2004
109(9) 1101-7
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Population risk factor change Impact on
Mortality example

• Change in smoking prevalence in men 45-54 (fell
  by 5, from 37 to 32, 1985-2000)
• CHD deaths Beta Risk Factor Deaths
• in 1985 coefficient reduction
  prevented 1985-2000
  or postponed (DPP)
• a x ß x c
  (a x ß x c)
• 330 x 0.6 x 0.14 28
  DPP
• SOURCES
• Routine RCTs Local
  national
• statistics Meta-analyses
  Epidemiological
• surveys

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RESULTS

• Using 1985 as base year, in 2000
• Expected number of deaths 8681
• Observed number of deaths 4918
• Fall in death numbers 3763
• 2440 fewer deaths in men 1323 in women
• ( 47 fall in men, 47 in women)
• IMPACT model explained approximately
• 92 of mortality fall

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2000
1985
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Limitations

• Data for early years limited
• Poor trend data for some risk factors
• Less information for women elderly
• Changing risk factor definitions/methodologies
• Assumptions about efficacy /effectiveness
• Therefore Sensitivity Analysis
• Validation essential

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CONCLUSIONS

• Ireland 1985-2000
• 47 CHD mortality fall
• Major contributions from medical therapies
• reductions in major risk factors
• ? Comprehensive CHD strategy important
• maximise effective treatments secondary
  prevention in eligible population
• actively promote primary prevention particularly
  healthy diet smoking reduction

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Acknowledgements

• Project funded by Irish Heart Foundation.