Relation of baseline presence and severity of renal disease to long-term mortality in persons with known stroke
Introduction
Mounting evidence indicates that even relatively minor impairments in chronic renal function, are common in the setting of cardiovascular disease, and predictive of vascular events including stroke [1]. Indeed, the independent association between chronic kidney disease (CKD) and stroke occurrence has now been reported in several studies [2], [3]. However, beyond the link between baseline renal dysfunction and incident vascular disease, mild to moderate CKD has been related to generally poorer clinical outcomes following an index vascular event [4]. Yet, several studies in a variety of clinical settings reflect poor surveillance for, and management of, renal disease in these at-risk patients [5]. Early identification of undiagnosed CKD may facilitate initiation of therapy aimed at limiting further renal function deterioration or optimizing vascular risk reduction, thereby boosting clinical outcomes among persons with established cerebrovascular disease [6].
Even several years after an index stroke, stroke survivors remain at significantly greater risk of dying compared to the general population [7]. Although several prognosticators of longer term survival after stroke have been identified [7], the impact of CKD has been relatively understudied. The few available studies have either utilized unreliable renal function measures like serum creatinine [8], [9], [10], or measured only impaired kidney function (i.e. low estimated glomerular filtration rate {eGFR}) [10], [11], or abnormal filtration barrier (i.e. proteinuria) [12], but not both as recommended by expert consensus guidelines [6], [13].
The objective of this study was to evaluate the independent association of various indices of baseline CKD, as well as baseline CKD severity, with risk of all-cause mortality and cardiovascular disease-specific mortality among persons with a known history of stroke in the United States.
Section snippets
Subjects and methods
This study utilized data from a nationally representative sample of the civilian, non-institutionalized US population. This data was collected by the Centers for Disease Control and Prevention's third National Health and Nutrition Examination Surveys [NHANES III] conducted at 89 survey locations between January 1, 1988, and December 31, 1994. This survey utilized a complex multistage cluster design and over-sampled persons 60 years and older, non-Hispanic black individuals, and Mexican American
Sample characteristics
The socio-demographic and clinical characteristics of the study sample can be found in Table 1. Among the sample of individuals with a known stroke 77.3% were aged 65 years or older and 55.8% were female. About 34.9% had an eGFR of less than 60 mL/min/1.73 m2, albuminuria was present in 24.5% of the sample. The mean duration since stroke occurrence among those with a stroke was 8.4 years. Mean mortality follow-up duration was 78.8 months.
Serum creatinine distribution
Supplementary Table 1 in Appendix A presents the mean
Discussion
In this nationally representative cohort, we found that over an average period of about 6.5 years following baseline assessment, stroke survivors with a reduced baseline GFR were generally more likely to die, when compared to stroke survivors with normal baseline GFR, after accounting for major confounders. Furthermore, we observed that risk of death in this cohort increased independently with greater baseline CKD severity, in a linear fashion, with even mild to grades of CKD severity being
Acknowledgments
Resource Centers for Minority Aging Research and Center for Health Improvement for Minority Elders (BO).
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