title: The lower, the better? : fractional polynomials meta-regression of blood pressure reduction on stroke risk.
abstract: OBJECTIVE
  Lowering systolic blood pressure (BP) (SBP) by 10 mmHg or diastolic BP by 5 mmHg using any of the main classes of BP lowering drugs reduces stroke by about a third. The objective of the present study is to determine whether there is a limit to the extent to which BP should be lowered.
  
  
  METHODS
  From the individual 17 primary-prevention trials of single drug therapy included in a recent meta-analysis, we abstracted reductions in SBP (SBP reduction in the treatment group minus that in the control group [mmHg]) and data regarding incidence of stroke to generate relative risks (RRs). We performed "flexible" (not "linear") unrestricted maximum likelihood meta-regression, using fractional polynomials, of the reduction in SBP on the risk of stroke.
  
  
  RESULTS
  The best-fitting model offered a gain in deviance of 5.71 with respect to the reference linear model, according to the expected inverse J-shaped (nadir at a 13.7-mmHg reduction in SBP) dose-response relation between reductions in SBP and logarithmic RRs for stroke.
  
  
  CONCLUSIONS
  More than 13.7-mmHg SBP reduction with single drug therapy could produce no longer additional reduction in the risk of stroke in a primary-prevention setting.
authors.affiliation: Department of Cardiovascular Surgery, Shizuoka Medical Center, 762-1 Nagasawa, Shimizu-cho, Sunto-gun, Shizuoka, 411-8611, Japan, kfgth973@ybb.ne.jp.
authors.forename: Hisato
authors.initials: H
authors.lastname: Takagi
authors.forename: Takuya
authors.initials: T
authors.lastname: Umemoto
mesh_terms: D000959:Antihypertensive Agents / Q000627:therapeutic use*; D001794:Blood Pressure / Q000187:drug effects*; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000453:epidemiology / Q000503:physiopathology; D015994:Incidence; D015233:Models, Statistical; D011322:Primary Prevention / Q000379:methods*; D016032:Randomized Controlled Trials as Topic; D012044:Regression Analysis; D012307:Risk Factors; D020521:Stroke / Q000453:epidemiology / Q000503:physiopathology / Q000517:prevention & control*; D016896:Treatment Outcome
chemical_list: D000959:Antihypertensive Agents