Zanchetti 1993.

Methods	Multicenter study involving 2‐week placebo run‐in period, followed by double‐blind, placebo‐controlled treatment period of 4 weeks. ABPM was performed at the end of the placebo run‐in period and on the last day of treatment for a period of 24‐36 hours. Recordings were considered valid if had at least 1 valid BP measurement per hour and at least 24 hours of continuous BP recordings after removal of outlying values by an automatic procedure
Participants	Participants with mild‐to‐moderate essential hypertension defined as a sitting clinic DBP 95‐114 mmHg were randomized (126 participants). 81 had valid ABPM data and were included in the analysis
Interventions	Nifedipine GITS 30 mg (25 participants), nifedipine GITS 60 mg (28 participants), or placebo (28 participants), once daily for 4 weeks. Nifedipine 60 mg and placebo were used for this analysis
Outcomes	Antihypertensive efficacy
Notes	No information about time of dosing provided. Emailed first author with no response. Assumed 8 a.m. dosing; 'hour 0'
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No description of the process of randomization
Allocation concealment (selection bias)	Unclear risk	No description of the process
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	No description of the process
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No description of the process
Incomplete outcome data (attrition bias) All outcomes	High risk	Only participants with study defined "valid" BP measurements included in analysis
Selective reporting (reporting bias)	Low risk	All outcomes in methods were reported
Other bias	High risk	Bayer SpA, Milan involved in study group

ABPM: ambulatory blood pressure monitoring; DBP: diastolic blood pressure; SBP: systolic blood pressure; SD: standard deviation.