George Bakris of the University of Chicago and colleagues assessed the effect of the two drug combinations on 11,506 patients with hypertension.
After three years, they recorded 113 cases of chronic kidney disease in the amlodipine group compared with 215 cases in the hydrochlorothiazide group
The researchers found that treatment with amlodipine was associated with 1.7% fewer cases of chronic kidney disease than with hydrochlorothiazide.
The researchers commented: ‘This trial shows that in patients with hypertension at high risk for cardiovascular events, combination treatment with benazepril plus amlodipine reduces progression of chronic kidney disease more effectively than does benazepril plus hydrochlorothiazide.'
The trial was terminated early because of this superior efficacy.
But writing in an editorial commenting on the study, Hiddo Heerspink and Dick de Zeeuw of the University of Groningen in the Netherlands raised questions about the design of the trial.
The premature termination of the study reduced the statistical power of the analysis, they said. They also queried the use of a composite endpoint including serum creatinine changes and end-stage renal disease.
Such issues need to be examined before concluding that one drug combination is better than another, they argued.