title: Initiation of nonselective alpha1-antagonist therapy and occurrence of hypotension-related adverse events among men with benign prostatic hyperplasia: a retrospective cohort study.
abstract: BACKGROUND
  Treatment of benign prostatic hyperplasia (BPH) with nonselective alpha1 antagonists such as terazosin, doxazosin, and prazosin results in blood pressure reduction due to vasodilation.
  
  
  OBJECTIVE
  Using claims data from a large Medigap plan, we examined the effect of initiating nonselective alpha1-antagonist therapy on the incidence of hypotension-related adverse events likely to be associated with vascular alpha-adrenoreceptor antagonism in patients with BPH.
  
  
  METHODS
  Medical and prescription claims data were obtained from the MEDSTAT Group for 53,824 men with a diagnosis code for BPH during the study period (January 1995-December 1997). We examined the rate of possible hypotension-related adverse events (diagnosis codes for hypotension, syncope, dizziness, fractures, and other injuries) per 10,000 person-days for men who began therapy with alpha1 antagonists and for a random sample of nonusers, stratified by prior use of other antihypertensive agents.
  
  
  RESULTS
  After adjusting for baseline differences in event rates, those who initiated alpha1-antagonist therapy (n = 1564) had a significantly greater increase in hypotension-related adverse-event rates in the 4 months after initiation (vs the 4 months before initiation) than randomly selected nonusers (n = 8641) (increase of 1.82 vs decrease of 0.02 events per 10,000 person-days among those not taking antihypertensive agents; increase of 0.94 vs 0.69 events per 10,000 person-days among those taking other antihypertensive agents; P < 0.01). This increase began earlier and lasted longer among patients taking other antihypertensive agents. Those who discontinued their alpha1 antagonist had a higher rate of hypotensive events at baseline than those who did not (5.09 vs 3.19 events per 10,000 person-days among those using other antihypertensive agents; 3.62 vs 2.27 events per 10,000 person-days among those not using other antihypertensive agents; P < 0.05).
  
  
  CONCLUSIONS
  Initiation of nonselective alpha1-antagonist therapy for the treatment of BPH increases the risk of a cluster of clinical events consistent with vascular alpha-adrenoreceptor antagonism. This effect is seen during a 4-month period around the initiation date. Prior initiation of other antihypertensive medication increases this effect. Urologists should consult with a patient's primary care physician about use of other antihypertensive agents before initiating nonselective alpha1-antagonist therapy for BPH.
authors.affiliation: Department of Epidemiology, University of Iowa, Iowa City 52242, USA. echrischilles@uiowa.edu
authors.forename: E
authors.initials: E
authors.lastname: Chrischilles
authors.forename: L
authors.initials: L
authors.lastname: Rubenstein
authors.forename: J
authors.initials: J
authors.lastname: Chao
authors.forename: K J
authors.initials: KJ
authors.lastname: Kreder
authors.forename: D
authors.initials: D
authors.lastname: Gilden
authors.forename: H
authors.initials: H
authors.lastname: Shah
mesh_terms: D000058:Accidental Falls; D000317:Adrenergic alpha-Antagonists / Q000009:adverse effects*; D000368:Aged; D000959:Antihypertensive Agents / Q000009:adverse effects*; D015331:Cohort Studies; D015897:Comorbidity; D003920:Diabetes Mellitus / Q000453:epidemiology; D003967:Diarrhea / Q000453:epidemiology; D004244:Dizziness / Q000209:etiology; D017292:Doxazosin / Q000009:adverse effects; D004359:Drug Therapy, Combination; D050723:Fractures, Bone / Q000209:etiology; D006331:Heart Diseases / Q000453:epidemiology; D006801:Humans; D006973:Hypertension / Q000453:epidemiology; D007022:Hypotension / Q000139:chemically induced* / Q000453:epidemiology; D008297:Male; D009369:Neoplasms / Q000453:epidemiology; D011224:Prazosin / Q000009:adverse effects / Q000031:analogs & derivatives; D011470:Prostatic Hyperplasia / Q000188:drug therapy*; D012189:Retrospective Studies; D020521:Stroke / Q000453:epidemiology; D013575:Syncope / Q000209:etiology
chemical_list: D000317:Adrenergic alpha-Antagonists; D000959:Antihypertensive Agents; C041226:Terazosin; D017292:Doxazosin; D011224:Prazosin