Prevalence of coronary heart disease and cardiovascular risk factors in a sample of older Australians: Australian Longitudinal Study of Ageing

Australasian Journal on Ageing, Vol 23 No 1 March 2004, Research 25–32 25

Blackwell Publishing, Ltd.ResearchPrevalence of CHD in older Australians

Prevalence of coronary heart disease and cardiovascular risk factors in a sample of older Australians: Australian Longitudinal Study of Ageing

Josephine Harris, Lynne Giles, Paul FinucaneFlinders University Department of Rehabilitation and Aged Care, Repatriation General Hospital, Daw Park, South Australia, Australia

Gary AndrewsFlinders University Centre for Ageing Studies, Bedford Park, South Australia, Australia

Objectives: To describe the prevalence of coronary heart disease (CHD) and characterise cardiovascular risk factors in elderly Australians.Methods: At entry into the Australian Longitudinal Study of Ageing (ALSA), 1075 participants aged 70 years and over provided cardiovascular data by questionnaire, clinical assessment and laboratory measurements.Results and Conclusion: A total of 201 participants (18.7%) were defined as having CHD, 138 participants (12.9%) had diabetes and 652 (61.3%) had systolic hypertension. Prevalent CHD was associated with male sex, older age, lower high-density lipoprotein (HDL) cholesterol, low diastolic blood pressure and use of antihypertensive medication. While many ‘traditional’ cardiovascular risk factors were not significantly associated with CHD in this cross-sectional analysis, follow-up of this sample will allow a longitudinal assessment of their relationship with CHD in older Australians.

IntroductionAlthough mortality from coronary heart disease (CHD) inAustralia is declining, it remains the second most commoncause of death, and the leading cause in those aged 85 yearsand over [1]. Risk factors for CHD are well defined in youngerpeople [2], but their importance in old age remains less certain.While numerous studies, including the Australian Dubbostudy [3,4], suggest that recognised risk factors predict CHDevents in some elderly populations [5–11], findings have beencomplex and conflicting, particularly in the very old andregarding total mortality [12–20]. The profile of cardiovascu-lar risk factors may change as people age; for example, totalcholesterol levels and blood pressure (especially diastolic)decline in late life [21–26]. Some suggest that such changesmay reflect the onset of comorbid disease rather than ageingper se [21,26–28]. A better understanding of coronary risk

factors in advanced age would allow the more appropriate useof preventive strategies.

As has been previously described [29], the Australian Longit-udinal Study of Ageing (ALSA) is a study of the determinantsof health and well-being in people aged 70 years and over. Thestudy will ultimately contribute to our understanding of riskfactors for CHD in elderly Australians, adding to the informa-tion gained from the Dubbo study [3,4,12,30–32]. Whileongoing longitudinal analysis will provide the most usefuldata, the present report examines the prevalence of CHD andthe risk profile at baseline. The association between risk factorsand prevalent CHD is also examined, although we recognisethat association does not necessarily imply a causal relationship.

Methods

Study sampleThe study sample consisted of 3263 people aged 70 yearsand over, randomly drawn from the electoral roll of residentsof Adelaide, South Australia. The sample was stratified byage, sex and local government area, with deliberate over-sampling of males to allow a sufficiently large number of oldermales to be tracked longitudinally. Persons living in either theirown homes or in residential care were included. A total of 558(17%) people were excluded because they were deceased(201), had left the area (161), could not speak English (89),could not be located at the given address (71) or the stated agewas incorrect (36). Of the remaining 2705 people, 1477 (55%)agreed to participate in the study. Spouses of the participantswere invited to participate; 597 of 879 (68%) so volunteeredand 457 who were aged 70 years and over were included in thisanalysis. Other household members aged 70 years or over werealso invited to participate and 13 of 24 (54%) agreed. In total,1947 people aged 70 years and over were interviewed. Ofthese, 1075 people (55%) consented to both a clinical assess-ment and to blood sampling. This analysis is based on those1075 participants. Baseline data collection was conductedfrom September 1992 to February 1993.

Identification of cardiac disease and its risk factorsParticipants were interviewed using a structured questionnairecontaining 733 questions, 18 of which sought symptoms ofangina pectoris or myocardial infarction (MI); the Rose ques-tionnaire [33]. In addition, participants were asked if they hadever suffered a ‘heart attack’. Participants were considered tohave CHD if they reported symptoms of angina pectoris or hadsymptoms or a history of MI.

Correspondence to: Josephine Harris, Department of Cardiology, Repatriation General Hospital. Email: [email protected]

H a r r i s J , G i l e s L , F i n u c a n e P e t a l .

26 Australasian Journal on Ageing, Vol 23 No 1 March 2004, Research 25–32

Risk factors for CHD were identified by a combination of clin-ical and laboratory assessments. Participants were questionedabout their smoking habits and were classified as currentsmokers, ex-smokers, or never-smokers. They were identifiedas having diabetes mellitus if they reported this on directquestioning and/or if they had a fasting blood glucose level≥7 mmol/L. Body mass index (BMI) was calculated as weight(kg)/height2 (m), and participants were then classified ashaving a BMI <22, 22–27 (used as the ‘normal’ reference group),>27–30, or >30. Blood pressure readings were taken in thedominant arm from a sitting position at 3, 4 and 5 min. Thesystolic and diastolic pressure readings were separatelyaveraged. The average systolic blood pressure (SBP) for eachparticipant was classified as <115, 115–140 (the ‘normal’reference group), 141–160, 161–180, or >180 mmHg. Theaverage diastolic blood pressure (DBP) for each participantwas classified as <70, 70–90 (the reference group), 91–100, or>100 mmHg. The pulse pressure (calculated as systolic minusdiastolic pressure, with the average from the three readingsused) was classified as <55, 55–65, 66–80 or >80 mmHg. Dataon medication use were collected and two medication categor-ies were created: (i) use of antihypertensives (medication thatmay have lowered the blood pressure reading, including somecardiac medications not usually used for hypertension such asnitrates) and; (ii) use of medication for hypertension or ‘bloodpressure’, as reported by the participant.

Blood for lipid analysis was sampled after a 10 h fast; total cho-lesterol, high-density lipoprotein cholesterol (HDL-C) and trigly-cerides were measured. Total cholesterol and triglycerides weremeasured enzymatically on a Hitachi 717 analyser; HDL-C wasmeasured after precipitation with Mg++/phosphotungstate.Low-density lipoprotein cholesterol (LDL-C) was calculatedusing the Friedewald formula [34] when the triglyceride levelwas less than 4.5 mmol/L. For each participant, total choles-terol was classified as ≤4, 4.1–5.5, 5.6–6.5, 6.6–7.5, or>7.5 mmol/L. The HDL-C was classified as <1, 1–1.5, 1.6–2,or >2 mmol/L, whereas LDL-C was classified as ≤2, 2.1–3.7,3.8–4.7, 4.8–5.7, or >5.7 mmol/L. Triglycerides were classifiedas <2 or ≥2 mmol/L.

Ethical approval for the present study was granted by the Com-mittee for Clinical Investigation at Flinders Medical Centre,Adelaide, South Australia.

Statistical analysisThe average of the 1992 and 1993 estimated resident popula-tion in each stratum (age, sex and local government area) wasused to calculate the probability of selection into the sample foran older Adelaide resident. These selection probabilities werethen adjusted for non-participation and sample weights werederived. The sample weights were applied in all analyses, sothat the results could be generalised to the older residents in theAdelaide Statistical Division in 1992–1993 [35].

The age and sex distributions of the respondents who con-sented to venepuncture and clinical assessment were compared

to the respondents who declined these components, using chi–squared tests of association or independent samples t-tests asappropriate.

Simple descriptive statistics were calculated for the cardio-vascular risk factors. A test for linear trend with increasing agewas carried out separately for males and females for the lipidand blood pressure measurements.

The association of CHD with age group and sex was assessedusing chi–squared tests of association. Simple logistic regres-sions of CHD on each putative risk factor were then carriedout. Age group and sex were included in each analysis.

To identify any potential problems from multicollinearity, thecorrelation between each pair of risk factors was calculatedusing Spearman’s rank correlation coefficient. Multiple logisticregression of CHD was then conducted. Variables wereincluded in the initial multiple logistic regression model if theP-value in the corresponding simple logistic regression was lessthan 0.2 and the variable was not highly correlated withanother. Backwards elimination of variables from this initialmodel was then carried out to determine a final set of predic-tors. Variables were retained in the final set if their overall P-value was less than 0.05. All analyses were performed usingSPSS for Windows Version 10.

Results

Study sampleOf the 1075 people who consented to clinical assessment andvenepuncture, 625 (58%) were female. The mean age of par-ticipants was 76.5 ± 5.2 years. The sample included 191 par-ticipants (18%) aged 80–84 years and 93 (9%) aged 85 yearsand over. Co-opted spouses or other household members madeup 26% of the sample. There was a significant difference in theage of the consenters and decliners, with those who declinedclinical assessment and venepuncture being slightly older(77.9 ± 6.4 years; t = 4.97 on 1956 d.f.; P < 0.001). The sexprofile of those participants who consented to clinicalassessment and venepuncture was also significantly differentfrom those who declined (declined 63% female vs consented58% female; χ2 = 5.7 on 1 d.f.; P = 0.017).

Prevalence of coronary heart disease risk factorsTable 1 summarises the prevalence rates of the major risk factorsfor CHD in our study population. Of the 138 participants whosatisfied historical or laboratory criteria for diabetes mellitus,66 (47.8%) were not previously known to have diabetes. Overall,303 participants (28.2%) were taking medication for hyperten-sion; only 38 (3.5%) were taking lipid lowering medication.Table 2 shows the mean levels of the lipid and blood pressuremeasurements in each age bracket for males and females.Significant changes with age were seen in men with total andLDL-C, triglycerides and DBP. In women, significant changeswere seen in LDL-C and a slight increase in SBP with age wasalso noted.

P r e v a l e n c e o f C H D i n o l d e r A u s t r a l i a n s


Prevalence of coronary heart disease by age group and sexSymptoms of angina pectoris were elicited from 41 (3.7%)participants, comprising 23 (5.1%) males and 18 (2.9%)females. Symptoms and/or history of MI were reported by 183participants, comprising 97 (21.6%) males and 86 (13.8%)females. Some persons reported symptoms of both anginaand MI, so that, overall, 201 (18.7%) participants had CHD.This affected 107 (23.8%) males and 94 (15.0%) females. Theassociation between CHD and sex was statistically significant

(χ2 = 13.1 on 1 d.f.; P < 0.001). The association between CHDand age group was also statistically significant (χ2 = 14.7 on 3d.f.; P = 0.002), with a trend for higher prevalence of CHD inthe older age groups. The prevalence of CHD in different agecohorts and in both sexes is shown in Figure 1.

Predictors of coronary heart diseaseThe separate simple logistic regressions are shown in Table 3.After controlling for age group and sex, the results showed that

Table 1: Distribution of coronary heart disease (CHD) risk factors in participants

Risk factor

Male Female Overall

n % n % n %

Smoking statusNever 130 28.9 423 67.8 553 51.5Past 279 62.0 147 23.5 426 39.7Current 41 9.1 54 8.6 95 8.8

Diabetes mellitusNot diagnosed nor BGL ≥7 mmol/L 377 83.8 560 89.5 937 87.1Diagnosed or BGL ≥7 mmol/L 73 16.2 65 10.5 138 12.9

Body mass index<22 45 10.1 118 19.4 163 46.122–27 235 53.0 250 41.1 485 15.5>27–30 110 24.9 140 23.0 250 23.8>30 53 12.0 101 16.6 154 14.6

Systolic blood pressure (mmHg)<115 24 5.3 13 2.2 37 3.5115–140 162 36.3 214 34.6 376 35.3141–160 149 33.3 231 37.4 380 35.7161–180 68 15.2 116 18.8 184 17.3>180 44 9.9 44 7.1 88 8.3

Diastolic blood pressure (mmHg)<70 59 13.1 122 19.7 181 16.970–90 323 71.9 409 66.1 732 68.591–100 55 12.2 74 12.0 129 12.1>100 12 2.7 14 2.3 26 2.4

Pulse pressure (mmHg)<55 109 24.3 107 17.2 216 20.155–65 115 25.6 132 21.2 247 23.066–80 121 26.9 221 35.5 342 31.9>80 104 23.2 163 26.2 267 24.9

Total cholesterol (mmol/L)≤4 23 5.1 8 1.4 31 2.94.1–5.5 210 46.6 165 26.5 375 35.05.6–6.5 143 31.9 232 37.4 375 35.16.6–7.5 62 13.7 153 24.7 215 20.1>7.5 12 2.7 62 10.0 74 6.9

LDL cholesterol (mmol/L)≤2 9 2.0 12 2.0 21 2.02.1–3.7 230 52.3 248 40.6 478 45.53.8–4.7 152 34.6 236 38.5 388 36.94.8–5.7 42 9.4 82 13.4 124 11.7>5.7 7 1.6 34 5.6 41 3.9

HDL cholesterol (mmol/L)<1 132 29.4 40 6.5 172 16.11–1.5 260 57.9 331 53.3 591 55.21.6–2 50 11.2 189 30.4 239 22.3>2 7 1.6 61 9.8 68 6.4

Triglycerides (mmol/L)<2 340 75.6 464 74.7 804 75.1≥2 110 24.4 157 25.3 267 24.9

Medication for hypertensionNo 336 74.7 436 69.7 772 71.8Yes 114 25.3 189 30.3 303 28.2

Antihypertensive medicationNo 259 57.6 339 54.2 598 55.6Yes 191 42.4 286 45.8 477 44.4

Total numbers in each category may be slightly less than the total sample number of 1075 due to occasional missing values. BGL, blood glucose level; HDL, high-density lipoprotein; LDL, low-density lipoprotein.



lower SBP (P = 0.03), lower DBP (P = 0.011), lower HDL-C(P < 0.001), higher triglycerides (P < 0.001), and use of antihyper-tensive medication (P < 0.001) were significantly associatedwith CHD.

The variables entered into the initial multiple logisticregression model were SBP, DBP, HDL-C, triglyceridesand use of antihypertensive medication. Sex and agegroup were also included in the analyses as control variables.No variables entered into the multiple logistic regressionwere correlated >0.4, other than a modest correlationbetween SBP and DBP where r = 0.46 on Spearman’srank correlation coefficients. Pulse pressure was notincluded because of its correlation with SBP (r = 0.78).The results are shown in Table 4. Apart from older ageand male sex, the variables independently associated witha significantly higher risk of prevalent CHD were: lowerHDL-C, low DBP (<70 mmHg) and taking antihyper-tensive medication. Low DBP (<70 mmHg) was associatedwith twice the odds of CHD compared to those particip-ants with normal DBP (70–90 mmHg). Taking antihyper-tensive medication (including for cardiac indications)was associated with prevalent CHD with an odds ratio of3.83. There was a response gradient for HDL-C, with thehighest HDL-C category associated with the lowest risk ofCHD.

The analyses were repeated excluding medication from the ini-tial set of variables. Both HDL-C and DBP were again retainedin the final model.

Figure 1: Prevalence of coronary heart disease (CHD) by age group and sex: ( ) male; (�) female

Table 2: Lipid and blood pressure variables for each age group

Variable and age group Male (mean ± SD) Test for linear trend Female (mean ± SD) Test for linear trend

Total cholesterol (mmol/L) – P = 0.007 – P = 0.11270–74 5.6 ± 1.0 – 6.3 ± 1.0 –75–79 5.6 ± 1.0 – 6.1 ± 1.1 –80–84 5.3 ± 0.9 – 6.5 ± 1.5 –85+ 5.2 ± 1.0 – 5.9 ± 1.2 –

Triglycerides (mmol/L) – P = 0.041 – P = 0.72970–74 1.8 ± 1.0 – 1.6 ± 0.8 –75–79 1.7 ± 1.5 – 1.6 ± 0.9 –80–84 1.4 ± 0.6 – 1.9 ± 0.9 –85+ 1.4 ± 0.8 – 1.6 ± 1.0 –

LDL cholesterol (mmol/L) – P = 0.016 – P = 0.03970–74 3.7 ± 0.9 – 4.0 ± 0.9 –75–79 3.7 ± 0.9 – 3.9 ± 1.0 –80–84 3.5 ± 0.9 – 4.2 ± 1.1 –85+ 3.3 ± 0.9 – 3.7 ± 1.1 –

HDL cholesterol (mmol/L) – P = 0.235 – P = 0.86570–74 1.1 ± 0.3 – 1.5 ± 0.4 –75–79 1.2 ± 0.3 – 1.4 ± 0.4 –80–84 1.2 ± 0.4 – 1.4 ± 0.4 –85+ 1.2 ± 0.4 – 1.5 ± 0.5 –

SBP average (mmHg) – P = 0.728 – P = 0.04070–74 145.9 ± 22.7 – 145.3 ± 18.5 –75–79 149.2 ± 23.8 – 152.6 ± 19.0 –80–84 150.6 ± 19.5 – 149.8 ± 22.9 –85+ 147.0 ± 24.0 – 152.4 ± 25.0 –

DBP average (mmHg) – P = 0.023 – P = 0.07370–74 80.3 ± 10.9 – 79.5 ± 10.5 –75–79 80.1 ± 9.4 – 80.0 ± 12.1 –80–84 78.8 ± 9.7 – 75.5 ± 11.1 –85+ 76.0 ± 12.0 – 77.9 ± 12.6 –

Pulse pressure average (mmHg) – P = 0.096 – P < 0.00170–74 65.6 ± 18.2 – 65.8 ± 15.9 –75–79 69.1 ± 20.3 – 72.8 ± 14.7 –80–84 71.8 ± 17.2 – 74.3 ± 18.3 –85+ 71.0 ± 20.9 – 74.5 ± 19.2 –

DBP, diastolic blood pressure; HDL, high-density lipoprotein; LDL, low-density lipoprotein; SBP, systolic blood pressure.



DiscussionOur study describes both the prevalence of clinical CHD andof traditional cardiovascular risk factors in a sample of morethan a 1000 Adelaide residents aged 70 years or over andexamines the association between them.

The CHD prevalence of 23.8% in males and 15.0% in femalesfound in the present study is less than that found in the Dubbostudy where the corresponding rates in the 70–79 years agegroup were 29.8% and 23.5%, and in the over 80 years group

22.7% and 25.4%, respectively [31]. The difference in theprevalence of CHD in women may relate to different diag-nostic criteria for CHD. We relied on history and the Rosequestionnaire, but did not perform electrocardiograms (ECG)or access medical records. Alternatively, there may be a truedifference between the two populations, with our sample livingin a more urban area and including people in residential care.Studies of older people in other countries have estimated theprevalence of CHD at between 20 and 30% in both men andwomen, again including ECG criteria [36,37]. However, a British

Table 3: Summary of simple logistic regressions for risk factors for coronary heart disease

Variable n† P-value Odds ratio 95% Confidence interval

Smoking statusNever 553 0.211 1.00 –Past 426 0.85 0.60–1.22Current 94 0.56 0.29–1.09

Diabetes mellitusNot self-reported and BGL <7 mmol/L 936 0.651 1.00 –Self-reported or BGL ≥7 mmol/L 138 0.90 0.56–1.44

Body mass index22–27 485 0.319 1.00 –<22 163 0.80 0.49–1.33>27–30 250 0.94 0.63–1.41>30 154 1.37 0.86–2.18

SBP (mmHg)115–140 376 0.030 1.00 –<115 37 2.05 0.97–4.33141–160 380 0.75 0.52–1.09161–180 184 0.76 0.48–1.21>180 88 0.53 0.28–1.03

DBP (mmHg)70–90 732 0.010 1.00 –<70 181 1.67 1.13–2.4891–100 129 0.61 0.35–1.08>100 26 0.82 0.27–2.44

Pulse pressure (mmHg)<55 216 0.092 1.00 –55–65 247 1.12 0.70–1.7966–80 342 0.71 0.44–1.13>80 267 1.17 0.74–1.85

Total cholesterol (mmol/L)≤4 31 0.201 1.00 –4.1–5.5 375 1.65 0.59–4.575.6–6.5 375 1.44 0.51–4.056.6–7.5 215 1.91 0.66–5.51>7.5 74 2.79 0.89–8.74

LDL cholesterol (mmol/L)≤2 21 0.241 1.00 –2.1–3.7 478 0.89 0.29–2.763.8–4.7 388 0.84 0.27–2.624.8–5.7 124 1.28 0.39–4.19>5.7 41 1.73 0.47–6.41

HDL cholesterol (mmol/L)<1 172 <0.001 1.00 –1–1.5 591 0.74 0.50–1.111.6–2 239 0.29 0.16–0.52>2 68 0.17 0.05–0.53

Triglycerides (mmol/L)<2 804 <0.001 1.00 –≥2 267 1.88 1.34–2.64

Medication for hypertensionNo 772 0.150 1.00 –Yes 303 0.76 0.53–1.10

Antihypertensive medicationNo 598 <0.001 1.00 –Yes 477 3.64 2.60–5.09

† n may sum to less than 1075 due to missing values. DBP, diastolic blood pressure; HDL, high-density lipoprotein; LDL, low-density lipoprotein; SBP, systolic blood pressure.



study using reported CHD rates estimated the prevalence ofCHD at 15% in men and 13% in women aged 65 years andover [38]. That study also used the Rose questionnaire andestimated the prevalence of angina on Rose criteria as 16% inwomen and 11% in men. This is somewhat higher than our find-ings (2.9 and 5.1%, respectively) and those of the EstablishedPopulations for Epidemiologic Studies of the Elderly (EPESE),which estimated Rose angina prevalence to be 4–6% in womenand 3–4% in men [39].

In their study of older people, Dewhurst et al. [38] estimatedthe sensitivity and specificity of the Rose questionnaire for thediagnosis of angina, as compared to a doctor’s diagnosis, at 79and 98%, respectively. Little difference in sensitivity and spe-cificity was found between men and women, but the predictivevalue differed (100% in men and 78% in women). Althoughwidely used in epidemiological studies for the diagnosis ofCHD, others have questioned its validity as a diagnosis ofmyocardial ischaemia, especially in women and in clinical popu-lations. For example, Garber et al. [40] compared the Rosequestionnaire with thallium scintigraphy results in patientswho reported chest pain. They found the sensitivity to besimilarly low in males and females (43.8% and 40.7%, respect-ively) but the specificity differed (76.7% compared to 55.7%).Madhavan et al. [41] found that in treated hypertensivepatients the Rose questionnaire had high specificity comparedto self-reported history of diagnosed angina (92%), but a sens-itivity of only 54%. Rose angina was not significantly associ-ated with ECG findings, nor did it predict subsequent clinicalevents. However, the Atherosclerosis Risk in CommunitiesStudy [42] found that Rose angina was moderately associatedwith disease (as assessed by ultrasound measurement ofcarotid wall thickness) and cardiovascular risk factors, andhence concluded that the questionnaire’s use in epidemiolog-

ical studies was valid. We have combined its use with particip-ants’ reports of their medical diagnoses but were unable todetect asymptomatic CHD.

We found that mean total cholesterol levels were higher infemales than in males in all age groups but declined in both sexeswith advancing age, especially in males. Prospective community-based studies from the USA [23] and Europe [22,24] reportedsimilar trends. While the Dubbo study reported higher meancholesterol levels [30] than those in our study, other studiesof elderly participants have found mean cholesterol levels tobe lower than [37], or similar to [24,43], our findings. BothHDL-C and triglyceride levels in our study were similar to thosereported in the Dubbo study [30]. The mean SBP readings inour study were slightly lower than those in the Dubbo study[30], although were in the borderline to mildly hypertensiverange, despite 44% of participants being on antihypertensivemedication. The mean DBP readings were similar in men inboth studies, with a possible trend toward decline in DBP withage. Readings for DBP averaged slightly higher in the Adelaidewomen.

We used the American Diabetes Association (ADA) criteria[44] for diagnosis of diabetes based on fasting plasma glucose,as well as using a history of diabetes. It has been reported thatthese ADA recommendations may underestimate the pre-valence of diabetes compared to criteria which include an oralglucose tolerance test (OGTT), especially in high-risk popu-lations [45,46]. However, an OGTT was not performed in ourstudy. A recent population based study using an OGTT [47]estimated the prevalence of diabetes in Australians aged 75years and over to be 23.5% in men and 22.7% in women,compared to estimates of 16.2% and 10.5% in our study ofmen and women aged 70 years and over, respectively.

Table 4: Summary of multiple logistic regressions for risk factors for coronary heart disease

Risk factor

Including medication variable Excluding medication variable

P-value OR 95% CI P-value OR 95% CI

Age group (years)70–74 0.001 1.00 – 0.001 1.00 –75–79 – 2.21 1.48–3.30 – 2.08 1.41–3.0680–84 – 1.90 1.18–3.05 – 1.86 1.18–2.9585+ – 1.96 1.06–3.63 – 1.97 1.09–3.54

SexMale 0.002 1.00 – 0.029 1.00 –Female – 0.57 0.40–0.81 – 0.68 0.48–0.96

DBP (mmHg)70–90 0.003 1.00 – 0.016 1.00 –<70 – 2.00 1.31–3.07 – 1.74 1.16–2.6191–100 – 0.64 0.35–1.16 – 0.69 0.39–1.24>100 – 0.95 0.31–2.93 – 0.83 0.27–2.48

HDL cholesterol (mmol/L)<1 <0.001 1.00 – <0.001 1.00 –1–1.5 – 0.83 0.54–1.25 – 0.73 0.49–1.091.6–2 – 0.34 0.19–0.63 – 0.27 0.15–0.49>2 – 0.19 0.06–0.61 – 0.17 0.06–0.54

Antihypertensive medicationNo <0.001 1.00 – – – –Yes – 3.69 2.60–5.23 – – –

CI, confidence interval; DBP, diastolic blood pressure; HDL, high-density lipoprotein.



While the Australian Longitudinal Study of Ageing sought tobe as representative as possible of the older Adelaide popula-tion, by drawing its randomised stratified sample from theelectoral roll and conducting weighted analysis, it did supple-ment this group with spouses and other household members.This reflects the aim of the study to be a holistic study ofageing, examining social and other health parameters.Although this analysis does not examine such social informa-tion, we did choose to include these (non-randomly selected)spouses and household members where they were 70 years orover, increasing the numbers and hence power of the study.However, this may make the study less representative of theolder Adelaide population. Also, the enrolment rate of 55%was suboptimal, and only 55% of the study participantsagreed to clinical assessment and venepuncture, as needed forthis analysis. Our subsample was younger and had fewerwomen than the overall study group. While our analysis wascorrected for age and sex, these response rates may havecaused some selection bias. However, our sample closelymatched the South Australian population aged 70 years ormore in 1992, whose average age was 77.2 ± 5.9 years with60% female [48].

Our analysis of the association between cardiovascular riskfactors and prevalent CHD revealed that the prevalence wasrelated to older age and male sex, and that those with CHDwere more likely to be taking antihypertensive medication; anexpected finding given that this includes medications taken forCHD. While the effect of medication may partly explain theassociation of CHD with low DBP, the association was inde-pendent of medication use and may reflect other factors suchas past MI leading to myocardial dysfunction and lowerblood pressure, particularly as we relied on the blood pressurereading rather than a history of hypertension. Others havefound hypertension to be associated with CHD, even on cross-sectional analysis, using a definition that included use of anti-hypertensives [31]. As in that study and others [36,37,49],we found HDL-C to be inversely associated with CHD pre-valence. Other traditional cardiovascular risk factors such assmoking were not found to be significantly and independentlyassociated with prevalent CHD in our population. Our particip-ants with CHD are survivors of the condition and may havemodified their behaviour accordingly, or had their risk profileaffected by illness, including CHD itself. Conversely, we recog-nise the limitations of cross-sectional data and the potential forselection bias, in addition to the survival bias discussed above.Any significant association does not necessarily imply a causalrelationship.

In conclusion, our study has estimated the prevalence of CHDin older Adelaide residents and has described the blood pres-sure and lipid levels of the population, as well as the prevalenceof other risk factors for CHD. While low HDL-C, use of anti-hypertensive medication and, perhaps paradoxically, low DBPwere associated with prevalent CHD, we anticipate that futurelongitudinal analysis will provide more meaningful informa-tion on predictors of CHD in this population.

AcknowledgementsThis research was supported by grants from the SouthAustralian Health Commission, Rotary Health Foundationand National Institutes of Health Grant AG 08523–02.

Key Points

• The prevalence of CHD in these Adelaide residentsaged 70 years and over (at entry into the AustralianLongitudinal Study of Ageing) was 23.8% in malesand 15.0% in females, based on reported historyand the Rose questionnaire.

• Mean SBP readings were in the borderline to mildlyhypertensive range, with 61.3% of participantshaving a reading of >140 mmHg.

• A total of 12.9% reported a history of diabetes orhad a fasting glucose level of ≥7 mmol/L.

• Prevalent CHD was significantly and independentlyassociated with male sex, older age, DBP<70 mmHg, low HDL cholesterol and use ofmedication which lowers blood pressure (forhypertension or cardiac indications).

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Prevalence of coronary heart disease and cardiovascular risk factors in a sample of older Australians: Australian Longitudinal Study of Ageing