The PROMISE trial is a randomized, double-blind, placebo controlled cross-over trial
where individuals are participating for 36 weeks. The trial consists of a 6-week run-in
period, followed by two 12-week study periods, separated by a 6-week washout period.
First, during a run-in period, each participant will be converted from their ACEi/ARB
dose to irbesartan 150 mg once daily. Individuals who already used irbesartan 150mg once
daily before trial participation will remain on this dose during the run-in period. After
six weeks, blood and 24-hour urine samples will be collected (baseline visit) and
participants will be randomized to patiromer or placebo (start of study period A). The
participant, research team, and treating physician will be blinded to treatment
allocation (patiromer or placebo), while irbesartan will remain open-label.
At one week after start of study period A and B, participants will perform a home blood
pressure measurement and visit a local lab to verify the plasma potassium level (safety
visit), in combination with a scheduled phone consultation. The following actions may be
taken: 1) If plasma potassium is >5.0 mmol/L or eGFR is >25% lower than baseline, the
dose of irbesartan will be reduced to 150 mg/d and remain so during the remainder of the
study period; 2) If systolic blood pressure is <110 mmHg, the participant has symptoms of
hypotension, and plasma potassium is <5.0 mmol/L, antihypertensive co-medication may be
adjusted, if applicable. If there is no antihypertensive co-medication that can be
adjusted, the irbesartan dose will be reduced to 150 mg/d during the remainder of the
study period.
At six weeks after start of the study period, there will be an in-hospital study visit.
Blood samples will be collected, and office blood pressure will be measured. Any of the
same two actions as described above may be taken in case of hyperkalaemia, severe acute
kidney function decline or hypotension, respectively.
At the end of each 12-week study period, blood and 24-hour urine samples will be
collected, and home (as well as office) blood pressure will be measured to establish the
study endpoints. In addition, the study medication (patiromer/placebo) will be stopped
and irbesartan dose will be reduced (or maintained) at 150 mg once daily. After a 6-week
washout period, the second baseline will take place (measurements identical to the first
baseline), which marks the start of study period B. During study period B, participants
who had been randomized to patiromer in period A will now receive placebo and vice versa.
The measurements during study period B will be identical to period A. At 12 weeks after
the start of study period B, the protocol is completed and patients will return to their
original medication.
The investigators chose a cross-over study design to be able to use participants as their
own control; this will enhance statistical power and reduce the number of required
participants. Based on previous studies, it is known that 6 weeks are sufficient to reach
stable albuminuria and blood pressure after an ARB dose change. Therefore, even if
halfway the 12-week study period a dose reduction is made, there is enough time for
albuminuria and blood pressure to stabilize before the end of the study period (i.e.,
when the primary endpoint is established). A 6-week washout period is inserted to avoid
carry-over effects.