Reducing salt intake by urine chloride self-measurement in non-compliant patients with chronic kidney disease followed in nephrology clinics: a randomized trial.

BACKGROUND: Adherence to low salt diets and control of hypertension remain unmet clinical needs in chronic kidney disease (CKD) patients. METHODS: We performed a 6-month multicentre randomized trial in non-compliant patients with CKD followed in nephrology clinics testing the effect of self-measurement of urinary chloride (69 patients) as compared with standard care (69 patients) on two primary outcome measures, adherence to a low sodium (Na) diet (<100 mmol/day) as measured by 24-h urine Na (UNa) excretion and 24-h ambulatory blood pressure (ABPM) monitoring. RESULTS: In the whole sample (N = 138), baseline UNa and 24-h ABPM were143 ± 64 mmol/24 h and 131 ± 18/72 ± 10 mmHg, respectively, and did not differ between the two study arms. Patients in the active arm of the trial used >80% of the chloride strips provided to them at the baseline visit and at follow-up visits. At the third month, UNa was 35 mmol/24 h (95% CI 10.8-58.8 mmol/24 h; P = 0.005) lower in the active arm than the control arm, whereas at 6 months the between-arms difference in UNa decreased and was no longer significant [23 mmol/24 h (95% CI -5.6-50.7); P = 0.11]. The 24-h ABPM changes as well as daytime and night-time BP changes at 3 and 6 months were similar in the two study arms (Month 3, P = 0.69-0.99; Month 6, P = 0.73-0.91). Office BP, the use of antihypertensive drugs, estimated Glomerular Filtration Rate (eGFR) and proteinuria remained unchanged across the trial. CONCLUSIONS: The application of self-measurement of urinary chloride to guide adherence to a low salt diet had a modest effect on 24-h UNa and no significant effect on 24-h ABPM.

Urine chloride self-measurement to monitor sodium chloride intake in patients with chronic kidney disease.

Background Excessive sodium intake is a risk factor for hypertension, cardiovascular disease and the risk for kidney failure in chronic kidney disease (CKD) patients. Methods We tested the diagnostic performance and the feasibility of an inexpensive method based on urine chloride strips for self-monitoring sodium intake in a series of 72 CKD patients. Results Twenty-four hour urinary chloride as measured by the reactive strips and 24 h urinary sodium were interrelated (r=0.59, p<0.001). Forty-nine out of 72 patients (78%) had a 24 h urinary sodium >100 mmol/24 h, i.e. the upper limit recommended by current CKD guidelines. The strip method had 75.5% sensitivity and 82.6% specificity to correctly classify patients with urine sodium >100 mmol/24 h. The positive and the negative predictive values were 90.2% and 61.3%, respectively. The overall accuracy (ROC curve analysis) of urine chloride self-measurement for the >100 mmol/24 h sodium threshold was 87% (95% CI: 77%-97%). The large majority of patients (97%) perceived the test as useful to help compliance with the prescribed dietary sodium and considered the test as simple and of immediate application (58%) or feasible but requiring attention (39%). Conclusions A simple and inexpensive test for urine chloride measurement has a fairly good performance for the diagnosis of excessive sodium intake. The test is feasible and it is perceived by CKD patients as helpful for enhancing compliance to the dietary sodium recommendations. The usefulness of this test for improving hypertension control in CKD patients will be tested in a clinical trial (Clinicaltrials.gov RF-2010-2314890).

Lung ultrasound to detect and monitor pulmonary congestion in patients with acute kidney injury in nephrology wards: a pilot study.

INTRODUCTION: Lung congestion and frank pulmonary edema are established complications of acute kidney injury (AKI) and early detection and monitoring of lung congestion may be useful for the clinical management of AKI patients. METHODS: We compared standardized clinical criteria (including lung crackles and peripheral edema grading) and simultaneous chest ultrasound (US) to detect lung congestion in a series of 39 inpatients with AKI. RESULTS: At baseline, twelve patients (31%) were clinically euvolemic and twelve presented clear-cur cardiovascular congestion (31%) by clinical criteria. Fifteen patients (38%) were hypovolemic. The median number of US-B lines in patients with cardiovascular congestion was much higher (50, inter-quartile range 27-99) than in euvolemic (14, IQR 11-37) and hypovolemic patients (7, IQR 3-16, P < 0.001). Remarkably, a substantial proportion of asymptomatic euvolemic (66%) and hypovolemic (46%) patients had lung congestion of moderate to severe degree (> 15 US-B lines) by lung US. Crackles severity and the number of US-B lines over time were inter-related (Spearman's ρ = 0.38, P < 0.01) but the agreement (Cohen k statistics) between the two metrics was unsatisfactory. Forty-eight percent of patients had lung congestion of moderate to severe degree by lung US and this estimate by far exceeded that by clinical criteria (32%). CONCLUSIONS: This pilot study shows that chest US has potential for the detection of lung congestion at a pre-clinical stage in AKI. The results of this pilot study form the basis for a clinical trial testing the usefulness of this technique for guiding lung congestion treatment in patients with AKI.

Office, standardized and 24-h ambulatory blood pressure and renal function loss in renal transplant patients.

OBJECTIVES: Hypertension is a risk factor for renal function loss in kidney transplant patients but there are still no longitudinal studies focusing on the relationship between ambulatory blood pressure (BP) monitoring (ABPM) and the glomerular filtration rate (GFR) evolution over time in these patients. METHODS: In a cohort of 260 renal transplant patients, we investigated the longitudinal relationship between repeated office BP measurements and simultaneous GFR measurements (on average 35 paired measurements per patient) and the relationship between baseline ABPM with the same outcome measure (by linear mixed models). Furthermore, we tested the prediction power of baseline ABPM and standardized BP measurements for a combined renal end point (GFR loss >30%, end-stage kidney disease or death) over a 3.7 years follow-up. RESULTS: Longitudinal office BP measurements were inversely related with simultaneous GFR measurements and the same was true both for baseline daytime and night-time BP. (all P < 0.001). Baseline 24-h ABPM [hazard ratio (5 mmHg):1.11; 95% confidence interval 1.03-1.19] and night-time SBP [hazard ratio (5 mmHg):1.10; 95% confidence interval 1.03-1.17] predicted the combined renal end point and the predictive model based on night-time SBP provided a data-fit superior than that by daytime SBP. CONCLUSION: In renal transplant patients, daytime and night-time SBP predict the risk of GFR loss overtime, and among the various BP metrics, night-time BP is the strongest indicator of the risk of renal function loss. Optimization of BP control and interventions targeting night-time BP may afford renal benefits in transplant patients, a hypothesis that remains to be tested in a clinical trial.

Nocturnal Hypertension and Altered Night-Day BP Profile and Atherosclerosis in Renal Transplant Patients.

BACKGROUND: The clinical relevance of ambulatory blood pressure monitoring (ABPM) for risk stratification in renal transplant patients still remains poorly defined. METHODS: We investigated the association between clinic and ABPM with an established biomarker of atherosclerosis (intima-media thickness [IMT] by echo-color Doppler) in a large, inclusive survey (n = 172) in renal transplant patients at a single institution. RESULTS: Forty-two patients (24%) were classified as hypertensive by ABPM criteria and 29 (17%) by clinic blood pressure (BP) criteria. Average daytime and nighttime BP was 126 ± 12/78 ± 9 mm Hg and 123 ± 13/74 ± 10 mm Hg, respectively. Forty-five patients (26%) were classified as hypertensive by the daytime criterion (>135/85 mm Hg) and a much higher proportion (n = 119, 69%) by the nighttime criterion (>120/70 mm Hg). Sixty-two patients (36%) had a night-day ratio of 1 or greater, indicating clear-cut nondipping. The average nighttime systolic BP (r = 0.24, P = 0.001) and the night-day systolic BP ratio (r = 0.23, P = 0.002) were directly related to IMT, and these associations were much more robust than the 24-hour systolic BP-IMT relationship (r = 0.16, P = 0.04). Average daytime BP and clinic B were unrelated to IMT. In a multiple regression analysis adjusting for confounders, the night-day systolic BP ratio maintained an independent association with IMT (ß = 0.14, P = 0.04). CONCLUSIONS: In renal transplant patients, the prevalence of nocturnal hypertension by far exceeds the prevalence of hypertension as assessed by clinic, daytime, and 24-hour ABPM. Nighttime systolic BP and the night-day ratio but no other BP metrics are independently associated with IMT. Blood pressure during nighttime may provide unique information for the assessment of cardiovascular risk attributable to BP burden in renal transplant patients.