title: Time-Varying Association of Individual BP Components with eGFR in Late-Stage CKD.
abstract: OBJECTIVE
  The association of individual BP components with changes in eGFR in patients with late-stage CKD is unknown. The objectives of our study were to examine the associations of systolic BP, diastolic BP, and pulse pressure with continuous temporal changes in eGFR and an eGFR decline ≥30% in late-stage CKD.
  
  
  METHODS
  We performed a retrospective cohort study (2010-2015) of patients with CKD in a multidisciplinary CKD clinic with an eGFR≤30. The associations of repeat measures of BP (systolic BP, diastolic BP, and pulse pressure) with eGFR were examined using general linear mixed models. The associations of BP components and eGFR decline ≥30% were examined with time-varying Cox models.
  
  
  RESULTS
  In total, 1203 patients were followed for a median of 548 days (interquartile range, 292-913), with an average of 6.7 visits and BP measures per patient. Mean baseline systolic BP, diastolic BP, pulse pressure, and eGFR were 139.2 mmHg, 73.2 mmHg, 64.9 mmHg, and 16.8 ml/min, respectively. Systolic BP and diastolic BP measures over time were statistically significantly associated with changes in eGFR (P<0.001), whereas pulse pressure was not. Patients with extremes of systolic BP (<105 or >170) and high diastolic BP (>90) measures were at a higher risk of GFR decline ≥30% (systolic BP <105: hazard ratio, 1.51; 95% confidence interval, 0.98 to 2.34; systolic BP >170: hazard ratio, 1.62; 95% confidence interval, 1.05 to 2.49; referent systolic BP =121-130; diastolic BP =81-90: hazard ratio, 1.40; 95% confidence interval, 0.99 to 1.86; diastolic BP >90: hazard ratio, 1.83; 95% confidence interval, 1.21 to 2.77; referent diastolic BP =61-70). The findings were consistent after multiple sensitivity analyses. Pulse pressure was not significantly associated with risk of eGFR decline.
  
  
  CONCLUSIONS
  In patients referred to a multidisciplinary care clinic with late-stage CKD, only extremes of systolic BP and elevations of diastolic BP were associated with eGFR decline.
authors.affiliation: Division of Nephrology.|Insititute for Clinical Evaluative Sciences, Ottawa, Canada.|Ottawa Hospital Research Institute, Ottawa, Canada; and.
authors.forename: Manish M
authors.initials: MM
authors.lastname: Sood
authors.affiliation: Division of Nephrology.|School of Epidemiology, Public Health and Preventative Medicine, Universality of Ottawa.
authors.forename: Ayub
authors.initials: A
authors.lastname: Akbari
authors.affiliation: Department of Family Medicine, University of Ottawa, Ottawa, Canada.|Insititute for Clinical Evaluative Sciences, Ottawa, Canada.|Ottawa Hospital Research Institute, Ottawa, Canada; and.|School of Epidemiology, Public Health and Preventative Medicine, Universality of Ottawa.
authors.forename: Doug
authors.initials: D
authors.lastname: Manuel
authors.affiliation: Division of Nephrology.
authors.forename: Marcel
authors.initials: M
authors.lastname: Ruzicka
authors.affiliation: Division of Nephrology.
authors.forename: Swapnil
authors.initials: S
authors.lastname: Hiremath
authors.affiliation: Division of Nephrology.
authors.forename: Deborah
authors.initials: D
authors.lastname: Zimmerman
authors.affiliation: Division of Nephrology.
authors.forename: Brenden
authors.initials: B
authors.lastname: McCormick
authors.affiliation: Insititute for Clinical Evaluative Sciences, Ottawa, Canada.|Ottawa Hospital Research Institute, Ottawa, Canada; and.|School of Epidemiology, Public Health and Preventative Medicine, Universality of Ottawa.
authors.forename: Monica
authors.initials: M
authors.lastname: Taljaard
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure; D018450:Disease Progression; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007668:Kidney / Q000503:physiopathology*; D016013:Likelihood Functions; D016014:Linear Models; D008297:Male; D008390:Markov Chains; D008875:Middle Aged; D009010:Monte Carlo Method; D017711:Nonlinear Dynamics; D016016:Proportional Hazards Models; D051436:Renal Insufficiency, Chronic / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013997:Time Factors
keywords: Blood Pressure Determination; CKD; Humans; Proportional Hazards Models; Renal Insufficiency, Chronic; Retrospective Studies; Risk; Systole; blood pressure; diastolic blood pressure; eGFR; glomerular filtration rate; linear mixed model; pulse pressure; repeat measures; systolic blood pressure; time-varying Cox proportional hazards model