UWL: Food, Appetite and Environment (2009)
Simons LA, Simons J, Friedlander Y, McCallum J. Cholesterol and other lipids predict coronary heart disease and ischaemic stroke in the elderly, but only in those below 70 years. Atherosclerosis. 2001; 159: 201-208.PubMed ID: 11689222
To test the hypothesis that cholesterol and other risk factors may be differentially predictive of coronary heart disease and stroke in older persons when they are segregated into different age groups.
- All non-institutionalized residents of the town of Dubbo, NSW
- 60 years and older (born before 1930).
None specifically mentioned.
Subjects were all participants in the Dubbo Study, an ongoing prospective study of cardiovascular disease in an elderly Australian cohort first examined in 1988 and 1989.
- Outcomes were analyzed in both sexes combined for the total cohort and for specific age groups
- Contributions of risk factors to coronary heart disease or ischaemic stroke were examined in cross-tabulations and Cox proportional hazards models
- Using Cox proportional hazards, outcomes were modelled for the total cohort and for age groups 60 to 69, 70 to 79, and 80+ years
- Point estimates and 95% confidence intervals for the Hazard Ratio were calculated from the regression coefficients.
Timing of Measurements
Coronary heart disease and ischaemic stroke outcomes were recorded during 129 months of follow-up (August 1988 to December 1999).
- Fasting venous blood obtained for assessment of total serum cholesterol and triglycerides, HDL-cholesterol, apolipoproteins A1 and B, and lipoprotein (a)
- LDL cholesterol calculated using Friedewald equation
- Hospitalization and death records were monitored continuously and postal surveys conducted every two years to confirm vital status.
Demographic, psychosocial and standard cardiovascular risk factor assessments.
- Initial N: 2,805 subjects
- Attrition (final N): 2,805 subjects, 1,235 men and 1,570 women
- Age: 738 men and 847 women (1,585 total) were aged 60 to 69 years; 410 men and 549 women (959 total) were aged 70 to 79 years; 87 men and 174 women (261 total) were aged 80+ years
- Location: Australia.
Age-specific Incidence Rates During 129 Months of Follow-up
|Age Category||CHD (Number and Rate)||Stroke (Number and Rate)|
60 to 69 years (738 men, 847 women)
|408, 26/100||111, 7/100|
|70 to 79 years (410 men, 549 women)||371, 39/100||158, 16/100|
|80+ years (87 men, 174 women)||120, 46/100||57, 22/100|
All ages (1,235 men, 1,570 women)
There were 899 coronary heart disease events (32 per 100) and 326 stroke events (12 per 100).
Total cholesterol, LDL cholesterol, serum apo-B, total and HDL cholesterol ratio, and apo-B and apo-A1 were significant predictors of coronary heart disease in the total cohort, but significant only in the subgroup of 60 to 69 years.
The respective hazard ratios were 1.21 (95% CI: 1.09 to 1.35), 1.21 (95% CI: 1.09 to 1.35), 1.25 (95% CI: 1.13 to 1.39), 1.25 (95% CI: 1.14 to 1.37) and 1.21 (95% CI: 1.10 to 1.38).
Similar findings were applicable with respect to ischaemic stroke in the age group of 60 to 69 years.
Total cholesterol predicted coronary heart disease in men above a threshold value of 7.06mmol per L and in women above 7.8mmol per L, but with stroke the prediction was incremental.
Other risk factors such as HDL cholesterol, triglycerides, lipoprotein (a), diabetes, hypertension and smoking predicted coronary heart disease, although only HDL and hypertension similarly predicted ischaemic stroke.
Our current findings, together with other published data, lead to the following conclusions:
- Total cholesterol levels exceeding 7.0mmol per L are predictive of coronary heart disease in elderly up to 70 years. There is ancillary evidence of event reduction through the use of statin drugs.
- Total cholesterol is predictive of ischaemic stroke in elderly up to 70 years of age. There is ancillary evidence of event reduction through use of statin drugs in those already manifesting coronary heart disease.
- Policies for cholesterol testing in subjects older than 70 years remain problematical and the benefit of cholesterol reduction in those more than 75 years of age remains to be demonstrated.
Authors note that study numbers were relatively small in the age group of 80+ years and stroke outcomes were only approximately one-third of the rate of coronary heart disease.
Quality Criteria Checklist: Primary Research
|1.||Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)||N/A|
|2.||Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?||Yes|
|3.||Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?||Yes|
|4.||Is the intervention or procedure feasible? (NA for some epidemiological studies)||N/A|
|1.||Was the research question clearly stated?||Yes|
|1.1.||Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?||Yes|
|1.2.||Was (were) the outcome(s) [dependent variable(s)] clearly indicated?||Yes|
|1.3.||Were the target population and setting specified?||Yes|
|2.||Was the selection of study subjects/patients free from bias?||Yes|
|2.1.||Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?||Yes|
|2.2.||Were criteria applied equally to all study groups?||Yes|
|2.3.||Were health, demographics, and other characteristics of subjects described?||Yes|
|2.4.||Were the subjects/patients a representative sample of the relevant population?||Yes|
|3.||Were study groups comparable?||Yes|
|3.1.||Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)||Yes|
|3.2.||Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?||Yes|
|3.3.||Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)||Yes|
|3.4.||If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?||Yes|
|3.5.||If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)||N/A|
|3.6.||If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?||N/A|
|4.||Was method of handling withdrawals described?||Yes|
|4.1.||Were follow-up methods described and the same for all groups?||Yes|
|4.2.||Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)||Yes|
|4.3.||Were all enrolled subjects/patients (in the original sample) accounted for?||Yes|
|4.4.||Were reasons for withdrawals similar across groups?||N/A|
|4.5.||If diagnostic test, was decision to perform reference test not dependent on results of test under study?||N/A|
|5.||Was blinding used to prevent introduction of bias?||Yes|
|5.1.||In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?||N/A|
|5.2.||Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)||Yes|
|5.3.||In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?||Yes|
|5.4.||In case control study, was case definition explicit and case ascertainment not influenced by exposure status?||N/A|
|5.5.||In diagnostic study, were test results blinded to patient history and other test results?||N/A|
|6.||Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?||N/A|
|6.1.||In RCT or other intervention trial, were protocols described for all regimens studied?||N/A|
|6.2.||In observational study, were interventions, study settings, and clinicians/provider described?||N/A|
|6.3.||Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?||N/A|
|6.4.||Was the amount of exposure and, if relevant, subject/patient compliance measured?||N/A|
|6.5.||Were co-interventions (e.g., ancillary treatments, other therapies) described?||N/A|
|6.6.||Were extra or unplanned treatments described?||N/A|
|6.7.||Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?||N/A|
|6.8.||In diagnostic study, were details of test administration and replication sufficient?||N/A|
|7.||Were outcomes clearly defined and the measurements valid and reliable?||Yes|
|7.1.||Were primary and secondary endpoints described and relevant to the question?||Yes|
|7.2.||Were nutrition measures appropriate to question and outcomes of concern?||Yes|
|7.3.||Was the period of follow-up long enough for important outcome(s) to occur?||Yes|
|7.4.||Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?||Yes|
|7.5.||Was the measurement of effect at an appropriate level of precision?||Yes|
|7.6.||Were other factors accounted for (measured) that could affect outcomes?||Yes|
|7.7.||Were the measurements conducted consistently across groups?||Yes|
|8.||Was the statistical analysis appropriate for the study design and type of outcome indicators?||Yes|
|8.1.||Were statistical analyses adequately described and the results reported appropriately?||Yes|
|8.2.||Were correct statistical tests used and assumptions of test not violated?||Yes|
|8.3.||Were statistics reported with levels of significance and/or confidence intervals?||Yes|
|8.4.||Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?||N/A|
|8.5.||Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?||Yes|
|8.6.||Was clinical significance as well as statistical significance reported?||Yes|
|8.7.||If negative findings, was a power calculation reported to address type 2 error?||N/A|
|9.||Are conclusions supported by results with biases and limitations taken into consideration?||Yes|
|9.1.||Is there a discussion of findings?||Yes|
|9.2.||Are biases and study limitations identified and discussed?||Yes|
|10.||Is bias due to study's funding or sponsorship unlikely?||Yes|
|10.1.||Were sources of funding and investigators' affiliations described?||Yes|
|10.2.||Was the study free from apparent conflict of interest?||Yes|