Subgroup analysis (2004-12-21)

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A recently published trial shows a logical approach for establishing the validity of a subgroup comparison. There has been a lot of published research that shows that heart disease is different and more deadly among black patients. Some possible explanations of these differences involve the renin-angiotensin system in bioavailability of nitric oxide. In a study that seemed to show no overall differences in efficacy for a drug treatment, hydralazine plus isosorbide dinitrate, for treating congestive heart failure, there was nevertheless the suggestion that this treatment might be effective when analysis was restricted to just the black patients in the study. This study, however, was not designed to look for race-specific effects, so the results had to be treated as preliminary. The authors of one review state  that "prospective trials involving large numbers of black patients are needed to further clarify their response to therapy." With this justification, a new randomized trial, recruiting just black patients, was begun. This study did indeed show that the two drugs were effective among these black patients, and became one of the first examples of a therapy recommended solely for a specific racial subgroup.

The concept of using race or ethnicity in medical decisions is controversial, because of the potential for misuse and abuse of this information. There is also debate about whether there is enough genetic variations among different racial and ethnic groups to justify treating them as distinct group. The authors of one paper skirt this issue by using the phrase "patients who self-identify as black".

Further reading

  1. Is research into ethnicity and health racist, unsound, or important science? Bhopal R. British Medical Journal 1997: 314(7096); 1751-6. [Medline]
  2. Combination of isosorbide dinitrate and hydralazine in blacks with heart failure. Taylor AL, Ziesche S, Yancy C, Carson P, D'Agostino R, Jr., Ferdinand K, Taylor M, Adams K, Sabolinski M, Worcel M, Cohn JN. N Engl J Med 2004: 351(20); 2049-57. [Medline] [Abstract] [Full text] [PDF]
  3. Racial differences in response to therapy for heart failure: analysis of the vasodilator-heart failure trials. Vasodilator-Heart Failure Trial Study Group. Carson P, Ziesche S, Johnson G, Cohn JN. J Card Fail 1999: 5(3); 178-87. [Medline]
  4. Medicine’s Race Problem. Satel S, Hoover Institution. Accessed on 2004-12-21.