The Study
Chlorthalidone Alone or in Fixed Combination with Slow-Release Metoprolol in the Management of Arterial Hypertension: A Long-Term Study of 545 Patients
This study gave different blood pressure pills to two groups of people and saw which group’s blood pressure dropped more. Because the doctors didn’t know who got which pill and people were randomly assigned, we can be pretty sure the pills caused the change—not something else.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Doctors tested if taking two blood pressure pills together works better than just one pill for people with high blood pressure.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 560 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Adding the second pill nearly doubled the number of people whose blood pressure got under control, but adding a third pill didn't help much more — suggesting two pills are enough for most.
- 2One pill (chlorthalidone) helped 46% of people; adding a second pill (metoprolol) helped 83% of people.
- 3For those who didn't respond to one pill, adding the second pill helped 80% of them.
- 4Adding a third pill helped only 62%.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of International Medical Research
Year
1989
Authors
E. Bichisao, L. Merlini, O. Gambini, D. Alberti, G. Pollavini
Related Content
Claims (5)
In adults with high blood pressure, taking 25 mg of chlorthalidone daily for 8 weeks lowers diastolic blood pressure below 95 mmHg in 45.6% of patients; adding 200 mg of slow-release metoprolol daily raises this proportion to 82.5%.
In adults with high blood pressure, taking 25 mg of chlorthalidone daily for 8 weeks lowers plasma potassium levels due to its diuretic effect, and this lowering can be reversed by adjusting the dose or combining it with other medications.
Among adults with high blood pressure that did not respond to a single medication, adding chlorthalidone and slow-release metoprolol together for 8 weeks brought diastolic blood pressure below 95 mmHg in 79.5% of patients.
Among adults with high blood pressure, taking chlorthalidone and metoprolol together caused mild or moderate side effects in 5.9% of people over eight weeks.
Adding a third blood pressure medication to two already taken by adults with essential hypertension increases the proportion reaching diastolic blood pressure control from 79.5% to 61.8%, indicating reduced benefit and possible unnecessary treatment in some individuals.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.