Background The purpose of this study is to evaluate serum bicarbonate as a risk factor for renal outcomes, cardiovascular events and mortality in patients with chronic kidney disease (CKD). Study Design Observational cohort study. Setting & Participants 3939 participants with CKD stages 2-4 who enrolled in the Chronic Renal Insufficiency Cohort (CRIC) between June 2003 - December 2008. Predictor Serum bicarbonate. Outcomes Renal outcomes, defined as end-stage renal disease (either initiation of dialysis or kidney transplantation) or 50% reduction in eGFR; atherosclerotic events (myocardial infarction, stroke, peripheral arterial disease); congestive heart failure events; and death. Measurements Time to event. Results The mean eGFR was 44.8 ± 16.8 (SD) mL/min/1.73 m2, and the median serum bicarbonate was 24 (IQR, 22-26) mEq/L. During a median follow-up of 3.9 years, 374 participants died, 767 had a renal outcome, and 332 experienced an atherosclerotic event and 391 had a congestive heart failure event. In adjusted analyses, the risk of developing a renal endpoint was 3% lower per mEq/L increase in serum bicarbonate (HR, 0.97; 95% CI, 0.94-0.99; p=0.01). The association was stronger for participants with eGFR> 45ml/min/1.73m2 (HR, 0.91; 95%CI, 0.85-0.97; p=0.004). The risk of heart failure increased by 14% (HR, 1.14; 95%CI, 1.03-1.26; p=0.02) per mEq/L increase in serum bicarbonate over 24 mEq/L. Serum bicarbonate was not independently associated with atherosclerotic events (HR, 0.99; 95%CI, 0.95-1.03; p=0.6) and all-cause mortality (HR, 0.98; 95%CI, 0.95-1.02; p=0.3). Limitations Single measurement of sodium bicarbonate. Conclusions In a cohort of participants with CKD, low serum bicarbonate was an independent risk factor for kidney disease progression, particularly for participants with preserved kidney function. The risk of heart failure was higher at the upper extreme of serum bicarbonate. There was no association between serum bicarbonate and all-cause mortality or atherosclerotic events.

The association between apparent treatment resistant hypertension (ATRH) and clinical outcomes is not well studied in chronic kidney disease (CKD). We analyzed data on 3367 hypertensive participants in the Chronic Renal Insufficiency Cohort (CRIC) to determine prevalence, associations, and clinical outcomes of ATRH in non-dialysis CKD patients. ATRH was defined as blood pressure (BP) ≥140/90 mm Hg on ≥3 antihypertensives, or use of ≥4 antihypertensives with BP at goal at baseline visit. Prevalence of ATRH was 40.4%. Older age, male gender, black race, diabetes, and higher BMI were independently associated with higher odds of having ATRH. Participants with ATRH had a higher risk of clinical events compared to participants without ATRH - composite of myocardial infarction (MI), stroke, peripheral arterial disease (PAD), congestive heart failure (CHF), and all-cause mortality HR [95% CI]: (1.38 [1.22,1.56]); renal events (1.28 [1.11, 1.46]); CHF (1.66 [1.38, 2.00]); and all-cause mortality (1.24 [1.06,1.45]). The subset of participants with ATRH and BP at goal on ≥ 4 medications also had higher risk for composite of MI, stroke, PAD, CHF, and all-cause mortality HR [95% CI] (1.30 [1.12, 1.51]) and CHF (1.59 [1.28, 1.99]) compared to those without ATRH. ATRH was associated with significantly higher risk for CHF and renal events only among those with eGFR ≥30 ml/min/1.73 m2. Our findings show that ATRH is common and associated with high risk of adverse outcomes in a cohort of patients with CKD. This underscores the need for early identification and management of patients with ATRH and CKD.

Background Early and late readmissions may have different causal factors and thus require different strategies for prevention. Objective Determine whether predictors of readmission change within the 30-day window post-discharge. Design Retrospective cohort study Setting Academic medical center Participants Medicine discharges, 1/1/2009-12/31/2010 Exposures (1) Factors related to the index hospitalization: acute illness burden, inpatient care process factors, and clinical indicators of instability at discharge; (2) Unrelated factors: chronic illness burden, and social determinants of health. Outcomes (1) Early readmissions, 0-7d post-discharge; (2) Late readmissions, 8-30d post-discharge. Results 13,334 discharges, representing 8,078 patients were included in the analysis, 1,046 readmissions (7.8%) occurred in the early period and 1,586 readmissions (11.9%) occurred in the late period. Early readmissions were associated with markers of acute illness burden, including length of hospital stay (Odds Ratio(OR) 1.02, 95%CI 1.00-1.03), and whether a rapid response team assessment was called (OR1.48, 95%CI 1.15-1.89); some markers of chronic illness burden, including being on a medication that indicates organ failure (OR1.19 95%CI 1.02-1.40); and some social determinants of health, including barriers to learning (OR 1.18 95%CI 1.01-1.38); and were less likely if a patient was discharged from the hospital between 800AM-1259 PM (OR0.76, 95%CI 0.58-0.99). Late readmissions were associated with markers of chronic illness burden, including being on a medication that indicated organ failure (OR1.27, 95%CI 1.10-1.46) or hemodialysis (OR1.75, 95%CI 1.29-2.37); and social determinants of health, including barriers to learning (OR1.22, 95%CI 1.07-1.40), and having unsupplemented Medicare or Medicaid (OR1.20, 95%CI 1.04-1.38). Limitations Single center, only ascertains readmissions at our institution Conclusions The 30 days following hospital discharge may not be homogeneous. Causal factors and readmission prevention strategies may be different for the early vs. late periods. Primary Funding Source Health Resources and Services Administration training grant [T32 HP12706].