Subthreshold diode micropulse photocoagulation for the treatment of clinically significant diabetic macular oedema

Abstract

<h3>Background and objectives</h3> Patients with chronic kidney disease (CKD) are often volume expanded and hypertensive. Few controlled studies have assessed the effects of a sodium-restricted diet (SRD) in CKD. <h3>Design, setting, participants, &amp; measurements</h3> We conducted a randomized crossover trial to evaluate the effect of SRD (target &lt;2 g sodium per day) versus usual diet on hydration status (by bioelectrical impedance spectroscopy) and blood pressure (BP) between May of 2009 and May of 2013. A total of 58 adults with stage 3–4 CKD were enrolled from two academic sites: University of Michigan (<i>n</i>=37) and University of North Carolina at Chapel Hill (<i>n</i>=21); 60% were men, 43% were diabetic, 93% were hypertensive, and mean age was 61 years. Participants followed SRD or usual diet for 4 weeks, followed by a 2-week washout period and a 4-week crossover phase. During the SRD, dieticians provided counseling every 2 weeks, using motivational interviewing techniques. <h3>Results</h3> Whole-body extracellular volume and calf intracellular volume decreased by 1.02 L (95% confidence interval [95% CI], −1.48 to −0.56; <i>P</i>&lt;0.001) and −0.06 L (95% CI, −0.12 to −0.01; <i>P</i>=0.02), respectively, implying decreased fluid content on the SRD compared with usual diet. Significant reductions in urinary sodium (−57.3 mEq/24 h; 95% CI, −81.8 to −32.9), weight (−2.3 kg; 95% CI, −3.2 to −1.5), and 24-hour systolic BP (−10.8 mmHg; 95% CI, −17.0 to −4.6) were also observed (all <i>P</i>&lt;0.01). Albumin-to-creatinine ratio did not change significantly and mean serum creatinine increased slightly (0.1 mg/dl; 95% CI, −0.01 to 0.2; <i>P</i>=0.06). No period or carryover effects were observed. Results were similar when analyzed from phase 1 only before crossover, although <i>P</i> values were modestly larger because of the loss of power. <h3>Conclusions</h3> In this randomized crossover trial, implementation of SRD in patients with CKD stage 3–4 resulted in clinically and statistically significant improvement in BP and hydration status. This simple dietary intervention merits a larger trial in CKD to evaluate effects on major clinical outcomes.