Study design:
This particular research activity was conducted using the secondary evaluation of four community-based, longitudinal public-use data sets in order to determine the relationship of baseline kidney function and long-term risk of cardiovascular disease (CVD) and all-cause mortality. As such, the researchers included the AtherosclerosisRisk in Communities Study (ARIC), the Cardiovascular Health Study (CHS), the Framingham Heart Study (FHS), and the Framingham Offspring Study (Offspring) as data pool that were analysed accordingly as studies that have meticulous ascertainment of CVD events during theirfollow-up periods.
Background/Objectives:
The completion of the research activity was grounded on the attainment of the following research objectives that likewise state the purpose of the study:
Population number and social demographic parameters:
Since the study was completed based on previously conducted research activities, the sampling population was directly sampled from the techniques used by the cohorts. The population included the following:
The 15th examinationin FHS and the second examination in Offspring were consideredto be the baseline period for our current analysis.
Sampling frame and sampling strategy:
The researchers excluded 575 subjects who had data missing on age, race,gender, or creatinine or were of nonwhite/nonblack race; 36subjects with glomerular filtration rate (GFR) <15 ml/min per 1.73 m2; 93 subjects whodid not provide permission to release data; three subjects withoutfollow-up data; 556 subjects with missing baseline CVD data;and 4278 subjects with preexisting CVD. The final study population consisted of 22,634 subjects. Since a totalof 602 subjects had missing single data points, such as systolicBP and total cholesterol, single imputationwas performed on the basis of age, gender, and race stratifiedmeans. Although analyses were performed using both the imputed and non-imputeddata, the final models were based on the imputed results.
Inclusion criteria and exclusion criteria:
Baseline characteristics included the following criteria:
- age
- gender
- race
- education level
- smoking
- ]alcohol intake
- baseline CVD
- diabetes
- hypertension
- antihypertensive agents
- lipid-lowering agents
- diabetes medications
- height
- weight
- body mass index (BMI)
- systolic and diastolic BP
- left ventricular hypertrophy (LVH) by electrocardiogram
- total cholesterol
- HDL cholesterol
- creatinine
- glucose
Screening tests, clinical parameters and laboratory parameters:
In order to meet the criteria set by the researchers to the selected population representatives and participants of the study, the following screening tests, clinical parameters and laboratory parameters were utilized:
BaselineCVD included a history of congestive heart failure in CHS, FHS,and Offspring (not coded in ARIC) and a history of angioplastyand coronary bypass procedures in ARIC and CHS (not availablein the Framingham cohorts).
Results:
Upon careful analyses and evaluation of the data that were utilized in the research activity, the following information was presented as results and findings of the study:
· The mean serum creatinine for both whites and blacks was 0.9mg/dl. The mean estimated GFR was 88.6 ml/min per 1.73 m2 forwhites and 99.9 ml/min per 1.73 m2 for blacks.
· CKD was presentin 1664 subjects. The CKD group was composed of 1505 (8.1%)white and 159 (3.8%) black subjects; 19% of patients with CKDwere from ARIC, 47% were from CHS, 25% were from FHS, and 9%were from Offspring.
· In patients with CKD, the mean estimatedGFR was 51.9 ml/min per 1.73 m2 for whites and 49.6 ml/min per1.73 m2 for blacks. But because of the large study sample, all studyvariables were significantly different between the white andblack subgroups.
· The prevalence of traditional CVD risk factors was higher inpatients with CKD as compared with those without CKD.
· Patientswith CKD were older and more likely to include those with ahistory of hypertension and diabetes.
Conclusion and discussion:
The study suggested that the presence of CKD isan independent risk factor for adverse outcomes in a large, pooled, community-based cohort of patients without CVD. Therisk associated with CKD appears to be stronger in blacks thanin whites. Moreover, evidence that patientswith CKD should be considered at high risk for CVD and mortalityoutcomes. Lastly, patients with CKD are potential candidatesfor aggressive risk factor reduction.
Limitations:
Because the public-use databasedoes not provide center information in ARIC and CHS due confidentiality concerns, the researchers were not able to adjust for differencesor clustering of outcomes as a result of center effects. As such theyseveral socioeconomic variables (education, race, smoking, andalcohol use) were used to control for such centrality effects.
Moreover, the definition of CKD in the study was singularly based on serum creatinine assessment which could have likely introduced misclassificationbias. It should also be taken into consideration that these studies evaluated subjects when they were at their baseline and presumably free of acute illnesses that mayaffect serum creatinine.
Despite the large study population, there were relativelyfew blacks with CKD which were selected as samples. However, the relationship betweenblacks with CKD and adverse outcomes was highly significant.
Furthermore, the study likewise lack data on several more recently identified risk factorsfor CVD that may be especially prominent in patients with kidneydisease such as C-reactive protein, homocysteine,and albuminuri.
Finally, the researchers were not able to adjust forchanges in medication use during follow-up or to assess theimpact that several newer therapies like statins and renin-angiotensin-aldosteronesystem blockade, which may have had on CVD outcomes indicated in the cohorts.
Credit:ivythesis.typepad.com
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