SHEP - Targeting systolic BP <160 mm Hg in patients with isolated systolic hypertension

in

SHEP Cooperative Research Group. Prevention of stroke by antihypertensive drug treatment in older persons with isolated systolic hypertension. JAMA 1991;265:3255-64.

Bottom line: In patients with isolated systolic HTN with SBP ~170, reducing SBP <160 mm Hg with a chlorthalidone-based regimen reduced the risk of CVD (NNT 19), including individual components such as stroke (NNT 46) over 4.5 years. This benefit was countered by an increase in adverse events, including bothersome adverse events (NNH 14), syncope (NNH 112) and electrolyte abnormalities.

 

Patients (n=4736)

  • Included: SBP 160-219 mm Hg & DBP <90 mm Hg
  • Excluded: Existing "major CV disease"
  • Typical study patient
    • Age 72 y
    • Female 57%
    • Previous CVD: Stroke 1.4%, MI 5%
    • BP 170/77 mm Hg

Interventions

  • I: Chlorthalidone 12.5-25 mg/d +/- atenolol 25-50 mg/d to achieve BP goal
    • If baseline SBP 160-179 mm Hg: Goal to reduce BP by >20 mm Hg
    • If baseline SBP 180+ mm Hg: Goal SBP <160 mm Hg
  • C: Placebo & attempt to reach same BP goals as above

Results @ mean 4.5 years

  • Achieved SBP at year 5: 144 vs 155 mm Hg (mean difference 11 mm Hg)
  • Receiving BP meds by year 5: 90% vs 44%
  • Death: 9.0% vs 10.2%, relative risk (RR) 0.87 (0.73-1.05)
  • Efficacy
    • CV disease (CV death, MI, stroke/TIA, coronary revascularization, aneurysm, endarterectomy): 12.2% vs 17.5% (NNT 19), RR 0.68 (0.58-0.79)
      • Total stroke (primary outcome): 4.1% vs 6.3% (NNT 46), RR 0.63 (0.49-0.82)
      • Non-fatal MI or coronary death: 4.4% vs 5.9% (NNT 72), RR 0.73 (0.57-0.94)
    • "LV failure": 2.0% vs 4.3% (NNT 44), RR 0.46 (0.33-0.65)
  • Safety
    • Any adverse event: 91.8% vs 86.4% (NNH 19)
    • Any intolerable adverse event: 28.1% vs 20.8% (NNH 14)
    • Key adverse events (not a comprehensive list)
      • Falls: 12.8% vs 10.4% (NNH 42)
      • Loss of consciousness/passing out: 2.2% vs 1.3% (NNH 112)
      • Na <130: 4.1% vs 1.3% (NNH 36)
      • K <3.2: 3.9% vs 0.8% (NNH 33)

Internal validity

  • Low risk of allocation, performance, detection & attrition bias
    • Central allocation
    • Double-blind
    • Protocolized, stepped approach to treatment