Epidemiological notes Susan Vaughan

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1 Epidemiological notes Susan Vaughan BHF: or BCIS Audit 2009: Heart disease includes different types of conditions that have different treatment modalities. For the purposes of trends and quantifying the burden of it, the following grouping is used: Ischaemic Heart Disease (IHD) ICD10 I20-25 incl. Angina (ICD10 20) Acute myocardial Infarction (AMI): ICD10 21 Other IHD: ICD Valvular:ICD10 I34-39 Heart Failure: ICD10 I50 Atrial Fibrillation: ICD10 48 The burden of CHD in terms of morbidity is not easily quantified due to the need to link hospital activity with deaths and to track back to identify re-admissions. There is uncertainty in disease coding and the variations in referral rates from GPs, the variations in hospital policies for admission e.g. rural hospitals may admit more due to distances confound this further. A more reliable indicator of the relative burden from IHD is the premature mortality as per the death rates in those aged under 75 years. For men 18% are caused by IHD (cancers 35% and for women, 9% (94% cancers). Scotland overall has the consistently highest rate in the UK (fig.1) despite the 44% decrease in rates over the last 10 years. Figure 1: Age-standardised death rates from IHD per 10,000 population by country in males aged 35-74y 1

2 Mortality rate (EASR) per,000 population England Wales Scotland UK Year Source: Taken from BHF statistics database, Coronary Heart Disease Statistics 2010 Amongst the North of Scotland, higher rates relative to the national average apply to Western Isles and Orkney. However, the rates for the Island boards are based on a low number of events and without confidence intervals, comparison should be made with caution. For example, the rates for Orkney have been consistently lower than the national average for each year from 2000 to 2009 except for 2007 when the rate was 54% higher (standardised rates from ISD with no confidence limits). In contrast, the rates for the Western Isles have been more consistently higher (for 6 years out of the 10 year period). Figure 2: Age-standardised death rates from IHD per 10,000 population by local authority areas in males aged 35-74y: 3 year average for

3 120 Scotland Mortality rate (EASR) for males per,000 population Shetland Aberdeenshire Moray Highland Argyll & Bute Aberdeen City Orkney Western Isles Local Authority Source: Taken from BHF statistics database, Coronary Heart Disease Statistics 2010 However, despite the overall decrease in trends for mortality, there is evidence that the trend is levelling off in younger adults i.e. those aged under 55 years. The BHF statistics show this on an overall basis in the UK for both men and women aged 35-44years. In Scotland the lack of decline has specifically been seen in the age band 35-55years in the most deprived groups of men and women. However, this is also true of other causes of mortality and there is evidence of a dissociation of changes in risk factors and mortality from IHD. It is possible that this might reflect the latency in changes in risk and affect on mortality or/and changes in the social pattern of secondary management of IHD and invasive cardiac procedures. Reference: Leyland AH & Lynch JW 2009 BMJ 339;b f17e

4 Inequalities in premature mortality from IHD are widening (over the last 10 years) but so are those from cancer. The overall decreases in rates in Scotland between 2000 and 2009 were 45% for IHD and 12% for cancers, whilst the decreases in rates in the most deprived population groups were 36% for IHD and 3% for cancers. (Figures 3 & 4) Figure 3 Age-sex standardised mortality rates in 45 to 74year age group from IHD in Scotland between 2000 and 2009: overall rates and rates in the most deprived groups. Under 75 deaths from Coronary Heart Disease, SIMD 15% most deprived areas and Scotland Overall, 2000 to European Age-Standardised Rate per, Year Scotland overall CVD Scotland vs. 15% Most Deprived From Scottish Govt. health inequalities update (March 31 st 2011) Figure 3 Age-sex standardised mortality rates in 45 to 74year age group from cancers in Scotland between 2000 and 2009: overall rates and rates in the most deprived groups. Under 75 deaths from Cancer, SIMD 15% most deprived areas and Scotland Overall, 2000 to European Age-Standardised Rate per, Year Scotland overall Most deprived 15% (SIMD) From Scottish Govt. health inequalities update (March 31 st 2011) 4

5 Invasive treatment trends for IHD includes (1) an increase in the PCI/CABG for populations which historically have been lower than the national average due to accessibility to PCI centres (2) a year on year increase in PCIs although UK wide this has now reduced to an almost steady rate from 2006 to 2009 at an annual increase of 2.5% (Ref. BCIS audit 2009 ( The Scottish rate in 2009 of 1385pmp is similar to England s rate of 1336 pmp. (Ref. BCIS audit) Taking into account the higher relative IHD mortality in Scotland, it could be expected that this will increase at a greater rate than the average annual UK 2.5% A great deal of variation exists across Scotland in terms of coronary revascularisation rates, which do not necessarily reflect proximity to a PCI centre or relative morbidity. For Argyll & Bute and Moray where PCI centres are distant, the rates are in recent years been similar (Argyll & Bute) or much higher (Moray) than the national average (ISD OC5 tables). On a Health Board basis, this variation also exists when both standardisation for population composition and relative mortality proxy for morbidity) are taken into account (table 1). Again there should be caution in interpretation without confidence intervals and trend data. Table 1 Mortality and age adjusted operation ratios based using national rates as the expected rates for coronary revascularisation (PCI + CABG) by Health Board of residence Ayrshire & Arran Borders Dumfries & Galloway Fife Forth Valley Grampian Greater Glasgow & Clyde Highland Lanarkshire Lothian Orkney Shetland Tayside Western Isles Males Females Scotland Data source: from SMR01 data as per ISD OC2 tables Although we know in Highland that coronary revascularisation rates are higher in the more deprived areas, it fails to completely bridge the inequality gap between mortality of the most deprived and that of the least deprived. (Ref. I. Douglas, March 2011 Health Intelligence & Knowledge Team, NHS Highland) dge/documents/recent%20publication%20and%20resources/evidencing%20the% 20gap_FINAL.pdf) Therefore, targeting of areas with most need may contribute to reducing the inequality in mortality without increasing the rate per se significantly for the whole population. Neither the national nor the constituent Health Boards position is not known in respect to inequalities in coronary revasularisation rates. 5

6 In terms of the prevalence of disease with the caveat that measurement is always prone to factors which vary from area to area, the conditions affecting older age groups will give rise to a greater burden due to the ageing of the populations. These conditions are Heart Failure, Valvular Disease and Atrial Fibrillation. Estimated numbers in NoS and for NHSH using population projections and published agespecific prevalence rates are given in Table 2: Table 2 Estimated numbers of the population with Heart Failure, Valvular Heart Disease or Atrial fibrillation Heart Failure 1 Valvular Heart &over 65& over &over 65& over &over 65& over NoSPHN 4,368 14,417 18,784 4,885 15,593 20,478 5,408 17,793 23,201 NHSH 1,143 3,537 4,679 1,278 3,880 5,159 1,405 4,561 5,966 NoSPHN 10,919 14,752 25,671 12,212 15,956 28,168 13,520 18,206 31,726 NHSH 2,857 3,619 6,476 3,196 3,971 7,167 3,513 4,667 8,180 Atrial Fibrillation 3 NoSPHN 3,918 7,264 11,182 4,382 7,857 12,239 4,851 8,965 13,816 NHSH 1,025 1,782 2,807 1,147 1,955 3,102 1,261 2,298 3,558 GROS Population Projections; 2008-based 1 BHF Table 2.12, Sciotland Iung B & Vahanian A 2011 Nat. tev. Cardiol Murphy N et al 2007 Heart