title: Chronic kidney disease itself is a causal risk factor for stroke beyond traditional cardiovascular risk factors: a nationwide cohort study in Taiwan.
abstract: BACKGROUND
  Cardiovascular disease (CVD) is a leading cause of mortality and morbidity in patients with chronic kidney disease (CKD). In Taiwan, CVD is dominated by strokes but there is no robust evidence for a causal relationship between CKD and stroke. This study aimed to explore such causal association.
  
  
  METHODS
  We conducted a nationwide retrospective cohort study based on the Taiwan National Health Insurance Research Database from 2004 to 2007. Each patient identified was individually tracked for a full three years from the index admission to identify those in whom any type of stroke developed. The study cohort consisted of patients hospitalized with a principal diagnosis of CKD and no traditional cardiovascular risk factors at baseline (n = 1393) and an age-matched control cohort of patients hospitalized for appendectomies (n = 1393, a surrogate for the general population). Cox proportional hazard regression and propensity score model were used to compare the three-year stroke-free survival rate of the two cohorts after adjustment for possible confounding factors.
  
  
  RESULTS
  There were 256 stroke patients, 156 (11.2%) in the study cohort and 100 (7.2%) in the control cohort. After adjusting for covariates, patients with primary CKD had a 1.94-fold greater risk for stroke (95% CI, 1.45-2.60; p<0.001) based on Cox regression and a 1.68-fold greater risk for stroke (95% CI, 1.25-2.25; p = 0.001) based on propensity score. This was still the case for two cohorts younger than 75 years old and without traditional cardiovascular risk factors.
  
  
  CONCLUSIONS
  This study of Taiwanese patients indicates that CKD itself is a causal risk factor for stroke beyond the traditional cardiovascular risk factors. Primary CKD patients have higher risk for stroke than the general population and all CKD patients, irrespective of the presence or severity of traditional cardiovascular risk factors, should be made aware of the stroke risk and monitored for stroke prevention.
authors.affiliation: Division of Nephrology, Department of Internal Medicine, Buddhist Dalin Tzu Chi General Hospital, Chiayi, Taiwan.
authors.forename: Yi-Chun
authors.initials: YC
authors.lastname: Chen
authors.forename: Yu-Chieh
authors.initials: YC
authors.lastname: Su
authors.forename: Ching-Chih
authors.initials: CC
authors.lastname: Lee
authors.forename: Yung-Sung
authors.initials: YS
authors.lastname: Huang
authors.forename: Shang-Jyh
authors.initials: SJ
authors.lastname: Hwang
mesh_terms: D000328:Adult; D000368:Aged; D002318:Cardiovascular Diseases / Q000150:complications*; D002908:Chronic Disease / Q000453:epidemiology; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D006801:Humans; D007674:Kidney Diseases / Q000150:complications* / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors; D020521:Stroke / Q000150:complications* / Q000453:epidemiology*; D013624:Taiwan / Q000453:epidemiology