10.22 Empagliflozin and renal function over time A study published in June 2016 in New England Journal of Medicine wanted to determine the long-term renal effects (measured by eGFR: estimated glomerular filtration rate)

of empagliflozin in patients with type 2 Diabetes. 7020 patients with type 2 Diabetes at 590 sites in 42 countries received at least one dose of a study drug. Patients were randomly assigned to receive either empagliflozin (at a dose level of either 10 mg or 25 mg) or a placebo once daily in addition to standard care. The difference between the study groups in the average rate of change in eGFR was estimated after a duration of 4 weeks.

a. The authors stated that there was a short-term decrease in the eGFR in the empagliflozin groups, with 95% confidence interval of weekly decreases of 0.62 ± 0.04 ml per minute per 1.73 m2 of body-surface area in the 10-mg group. Interpret the confidence interval.

b. The authors also provided a p-value that is <0.001 for the comparisons in eGFR means of the 10 mg dose empagliflozin group with the placebo group. Specify the hypotheses for this test of comparison of means, which was two-sided. Interpret the p-value obtained.