Effects of Empagliflozin on Fluid Overload, Weight, and Blood Pressure in CKD.

SIGNIFICANCE STATEMENT: SGLT2 inhibitors reduce risk of kidney progression, AKI, and cardiovascular disease, but the mechanisms of benefit are incompletely understood. Bioimpedance spectroscopy can estimate body water and fat mass. One quarter of the EMPA-KIDNEY bioimpedance substudy CKD population had clinically significant levels of bioimpedance-derived "Fluid Overload" at recruitment. Empagliflozin induced a prompt and sustained reduction in "Fluid Overload," irrespective of sex, diabetes, and baseline N-terminal pro B-type natriuretic peptide or eGFR. No significant effect on bioimpedance-derived fat mass was observed. The effects of SGLT2 inhibitors on body water may be one of the contributing mechanisms by which they mediate effects on cardiovascular risk. BACKGROUND: CKD is associated with fluid excess that can be estimated by bioimpedance spectroscopy. We aimed to assess effects of sodium glucose co-transporter 2 inhibition on bioimpedance-derived "Fluid Overload" and adiposity in a CKD population. METHODS: EMPA-KIDNEY was a double-blind placebo-controlled trial of empagliflozin 10 mg once daily in patients with CKD at risk of progression. In a substudy, bioimpedance measurements were added to the main trial procedures at randomization and at 2- and 18-month follow-up visits. The substudy's primary outcome was the study-average difference in absolute "Fluid Overload" (an estimate of excess extracellular water) analyzed using a mixed model repeated measures approach. RESULTS: The 660 substudy participants were broadly representative of the 6609-participant trial population. Substudy mean baseline absolute "Fluid Overload" was 0.4±1.7 L. Compared with placebo, the overall mean absolute "Fluid Overload" difference among those allocated empagliflozin was -0.24 L (95% confidence interval [CI], -0.38 to -0.11), with similar sized differences at 2 and 18 months, and in prespecified subgroups. Total body water differences comprised between-group differences in extracellular water of -0.49 L (95% CI, -0.69 to -0.30, including the -0.24 L "Fluid Overload" difference) and a -0.30 L (95% CI, -0.57 to -0.03) difference in intracellular water. There was no significant effect of empagliflozin on bioimpedance-derived adipose tissue mass (-0.28 kg [95% CI, -1.41 to 0.85]). The between-group difference in weight was -0.7 kg (95% CI, -1.3 to -0.1). CONCLUSIONS: In a broad range of patients with CKD, empagliflozin resulted in a sustained reduction in a bioimpedance-derived estimate of fluid overload, with no statistically significant effect on fat mass. TRIAL REGISTRATION: Clinicaltrials.gov: NCT03594110 ; EuDRACT: 2017-002971-24 ( https://eudract.ema.europa.eu/ ).

Investigating modifications to participant information materials to improve recruitment into a large randomized trial.

BACKGROUND: Large randomized trials are the best method to test the efficacy and safety of treatments expected to have moderate effects. We observed a significant decline in potential participants' response to mailed invitations to participate in such trials over a 10-year period and investigated possible reasons behind this and potential modifications to the invitation process to mitigate it. METHODS: Participants who declined to participate in the HPS2-THRIVE trial were asked to give a reason. Formal focus groups were conducted to explore the reasons that potential participants might have for not participating. In addition, two embedded randomized comparisons around the timing of provision of the full participant information leaflet (PIL) and its style were conducted during recruitment into this large randomized trial. HPS2-THRIVE is registered at ClinicalTrials.gov (NCT00461630). RESULTS: The commonest reason given for declining invitations related to mobility and transportation (despite the offer of travel expenses). Both the focus groups and potential participants who declined their invitation indicated concern about side-effects of the treatment (as presented in the PIL) as a reason for declining the invitation. Neither delaying provision of the full PIL until the potential participant attended the trial clinic, nor modifying the style of the PIL improved the proportion of potential participants entering the trial: odds ratio (OR) 1.05 (95% confidence interval (CI) 0.94-1.17) and 1.10 (95% CI 0.94-1.28), respectively. However, modifying the style of the PIL did increase the proportion of participants attending screening appointments (OR 1.17, 95% CI 1.03-1.33). CONCLUSIONS: Many reasons given for not participating in trials are not tractable to individual trials. However, modification of the PIL does show potential to modestly improve participation. If further trials could identify similar simple interventions that were beneficial, their net effects could substantially improve trial participation and facilitate recruitment into large trials.