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Evidence TablesAge

ReferenceStudy typeNumber of patientsPatient characteristicsInterventionComparisonLength of follow-upOutcome measuresSource of funding
Johnson G, Carson P, Francis GS et al. Influence of prerandomization (baseline) variables on mortality and on the reduction of mortality by enalapril. Veterans Affairs Cooperative Study on Vasodilator Therapy of Heart Failure (V-HeFT II). V-HeFT VA Cooperative Studies Group. Circulation. 1993; 87(6:Suppl):Suppl-9. Ref ID: 184RCT

VHEFT II post hoc subgroup analysis
N=804Inclusion criteria: male patients between 18–75 yrs old with chronic CHF. Patients had to have demonstrable cardiac dysfunction confirmed by radionuclide ejection fraction <45%, a cardiothoracic ratio ≥ 0.55, or a left ventricular internal diameter at end diastole (LVIDD) >2.7 cm/m2 determined by two-dimensionally directed M-mode echo. Patients also had to demonstrate reduced exercise tolerance in a maximal –exercise bicycle ergometer test (peak oxygen consumption <25 mL·kg-1·min-1 at termination of the test for dyspnoea or fatigue.)
Exclusion criteria: myocardial infarction or cardiac surgery in the preceding 3 months; angina pectoris limiting exercise or requiring long-term nitrates; hypertension requiring treatment other than diuretics, ß blockers, or calcium antagonist; serious obstructive valvular disease; obstructive lung disease (FEV1:FVC >0.60); other life threatening conditions or failure to give consent.
Patient characteristics:
Age: enalapril 60.6; Iso/hydral 60.5
Sex: all male
NYHA classification (%):
  1. enalapril 6.0; Iso/hydral 5.5
  2. enalaparil 49.6; Iso/hydral 52.4
  3. enalapril 44.2; Iso/hydral 41.6
  4. enalapril 0.2; Iso/hydral 0.5
Duration of CHF (years): enalapril 3.1; Iso/hydral 3.7, p<0.05
Ejection fraction (%): enalapril 28.6; Iso/hydral 29.4
Enalapril 20mg plus 2 placebos

Run-in period:
All patient had at least 4 weeks to establish optimal therapeutic dosages of digoxin and a diuretic agent, and any conflicting or nonstudy drugs were discontinued.
Hydralazine 300mg + isosrbide dinitrate 160mg + one placebo.

See intervention for details of run-in period for all patients
2 yrsAll cause mortality.Veterans Affairs Cooperative Studies Program
Effect Size
All cause mortality:
  • ≤ 55 years:
    • Enalapril: no deaths./no. at risk: 27/86; annual mortality rate (AMR): 11.1
    • Iso/hydral: no deaths./no. at risk: 31/89; AMR: 13.2
    • Risk ratio (enalapril vs. iso/hydral): 0.83
    • 95% CI 0.49–1.38
  • >55- ≤60 years:
    • Enalapril: no deaths./no. at risk: 29/86; AMR: 11.7
    • Iso/hydral: no deaths./no. at risk: 34/87; AMR: 14.6
    • Risk ratio (enalapril vs. iso/hydral): 0.78
    • 95% CI 0.47–1.28
  • >60- ≤65 years:
    • Enalapril: no deaths./no. at risk: 32/117; AMR: 9.7
    • Iso/hydral: no deaths./no. at risk: 43/114; AMR: 13.3
    • Risk ratio (enalapril vs. iso/hydral): 0.72
    • 95% CI 0.45–1.13
  • >65 years:
    • Enalapril: no deaths./no. at risk: 44/114; AMR: 14.4
    • Iso/hydral: no deaths./no. at risk: 45/111; AMR: 15.7
    • Risk ratio (enalapril vs. iso/hydral): 0.91
    • 95% CI 0.60–1.38
Authors’ Conclusion: ‘in no patient subgroup was the mortality with enalapril treatment significantly higher than the mortality with hydralazine/isosorbide dinitrate treatment.’

  • Increasing the number of subgroups analysed reduced the power to detect a significant effect within these groups. (increased risk of type II error) and also increased the chances of a significant finding (type I error)

From: Appendix E, Clinical Evidence Tables

Cover of Chronic Heart Failure
Chronic Heart Failure: National Clinical Guideline for Diagnosis and Management in Primary and Secondary Care: Partial Update [Internet].
NICE Clinical Guidelines, No. 108.
National Clinical Guideline Centre (UK).
Copyright © 2010, National Clinical Guideline Centre.

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