Design of the Month


The following quotation is taken from the Guardian of 3 September 2007.

A once-a-day pill to lower blood pressure should be given routinely to people with diabetes, a team of doctors said yesterday, after a trial showed it can prolong life by preventing heart disease, strokes and other medical complications.

Investigators followed 11,000 people with type 2 diabetes for 4½ years and found that the pill, a combination of two blood pressure lowering drugs, reduced the risk of serious illness and death from cardiovascular disease, even in patients without high blood pressure.

Researchers based at the University of Sydney announced the findings yesterday at a meeting of the European Society of Cardiology in Vienna to coincide with a report published online in the Lancet.

Patients for the trial were recruited from 215 medical centres across 20 countries. Each was given either a placebo or a daily pill combining 4mg of a blood vessel relaxant called perindopril with 1.25mg of a diuretic called indapamide. Half of the patients had high blood pressure.

At the end of the trial, doctors found that deaths from cardiovascular disease were 4.6% in the placebo group and 3.8% among those taking the pill, a relative reduction of 18%.

Deaths from any cause also fell, from 8.5% among the placebo group to 7.3% of those taking the blood pressure pill, a drop of 14%. Side effects of the pill include coughing and changes in blood metabolites, though the doctors said drop-out rates were similar among both placebo and pill-taking patients.

  1. Was this an observational study, a case-control study, a designed experiment, a study using historial controls or a cohort study?
  2. What does the word controlled mean in this context? Was this trial controlled?
  3. What does the word randomized mean in this context? Was this trial randomized?
  4. How could blocking have been used in this trial?
  5. What ethical issues were involved?

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