title: Behavioral support intervention for uncontrolled hypertension: a complier average causal effect (CACE) analysis.
abstract: BACKGROUND
  The complier average causal effect (CACE) analysis addresses noncompliance with intervention and missing end-point measures in randomized controlled trials.
  
  
  OBJECTIVE
  To conduct a CACE analysis for the Peer Coach and Office Staff Support Trial examining the intervention's effect among "compliers," defined as subjects who would have received an effective dose of the intervention had it been offered, and to compare with an intention-to-treat analysis.
  
  
  METHODS
  A randomized controlled trial of 280 African American patients aged 40-75 with sustained uncontrolled hypertension from 2 general internal medicine practices.
  
  
  METHODS
  Change in 4-year coronary heart disease (CHD) risk (primary) and in systolic blood pressure (SBP) (secondary) from the baseline to the end of the 6-month intervention.
  
  
  RESULTS
  Of 136 intervention subjects, 68% were compliers who had significantly more end points measured (86% vs. 34% for CHD risk; 99% vs. 57% for SBP) and lower baseline CHD risk (5% vs. 7.5%) and SBP (139 vs. 144 mm Hg) compared with noncompliers. In the intention-to-treat analysis, the effect of offering the intervention was nonsignificant for 4-year CHD risk (P=0.08) but significant for SBP (P=0.003). CACE analyses showed that receipt of an effective dose of the intervention resulted in a 1% greater reduction in 4-year CHD risk (P<0.05) and at least 8.1 mm Hg greater reduction in SBP compared with compliers in the control group (P<0.05).
  
  
  CONCLUSIONS
  Among compliers, an effective dose of peer coach and office-based support resulted in significant reductions in 4-year CHD risk and SBP. More intensive interventions are likely to be required for noncompliers.
authors.affiliation: *Department of Epidemiology and Biostatistics, University of Texas Health Science Center at San Antonio (UTHSCSA) †Center for Research to Advance Community Health ‡Department of Urology, University of Texas Health Science Center at San Antonio, San Antonio §School of Public Health, University of Texas Health Science Center at Houston, Houston ∥Cancer Therapy & Research Center, University of Texas Health Science Center at San Antonio, San Antonio, TX ¶Departments of Surgery and Public Health Sciences, Penn State College of Medicine, Hershey, PA #University Health System **Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Liang
authors.forename: Benjamin R
authors.initials: BR
authors.lastname: Ehler
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Hollenbeak
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Turner
mesh_terms: D000328:Adult; D001741:Black or African American / Q000706:statistics & numerical data*; D000368:Aged; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D001521:Behavior Therapy; D003327:Coronary Disease / Q000517:prevention & control*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance / Q000706:statistics & numerical data*; D010353:Patient Education as Topic; D010379:Peer Group; D012307:Risk Factors; D012944:Social Support; D014481:United States
chemical_list: D000959:Antihypertensive Agents