title: Factors associated with preference for sildenafil citrate and tadalafil for treating erectile dysfunction in men naïve to phosphodiesterase 5 inhibitor therapy: post hoc analysis of data from a multicentre, randomized, open-label, crossover study.
abstract: OBJECTIVE
  To determine if baseline characteristics, treatment efficacy, psychosocial outcomes or tolerability were associated with patient preference for sildenafil citrate (sildenafil) or tadalafil for treating erectile dysfunction (ED) in men naive to phosphodiesterase 5 inhibitor therapy.
  
  
  METHODS
  In an open-label, crossover study of sildenafil (25, 50 or 100 mg) and tadalafil (10 or 20 mg), dosed as needed, after a 4-week baseline assessment, 367 men with ED were randomly assigned to sildenafil followed by tadalafil or vice versa (8-week dose optimization and 4-week assessment phase for each treatment period). Patients completing both periods chose which treatment they preferred for an 8-week extension phase. Bivariate logistic regression and stepwise logistic regression were used to determine if any baseline characteristics or post-baseline measurements were associated with the patients' treatment preference. Baseline variables examined were age, race, ED aetiology/duration, body mass index, smoking status, alcohol consumption, vital signs, comorbid medical conditions, and baseline scores for the International Index of Erectile Function (IIEF) domains, Psychological and Interpersonal Relationship Scales (PAIRS) domains, and Sexual Encounter Profile (SEP) diary questions. Post-baseline variables examined were therapy sequence, dosage, and differences in IIEF and PAIRS domains, SEP scores, in number/timing of sexual attempts and in the severity of side-effects (overall patient perception).
  
  
  RESULTS
  Of 291 patients completing both treatments and indicating a preference, 85 (29%) preferred sildenafil and 206 (71%) preferred tadalafil. Variables were individually analysed using bivariate analysis; one baseline characteristic (presence/absence of hyperlipidaemia) and 13 post-baseline measurements were significantly associated with the patients' treatment preference. Variables were analysed as a group using stepwise logistic regression; a set of six post-baseline factors was identified as significantly associated with patient preference. Dosage choice, reductions in the PAIRS time concerns domain, IIEF intercourse satisfaction domain improvements, smaller side-effect severity scores, more sexual attempts, and increased SEP4 scores (satisfaction with erection hardness) during the tadalafil or sildenafil treatment periods were all significantly associated with preference for tadalafil or sildenafil.
  
  
  CONCLUSIONS
  We identified no baseline characteristics that prospectively distinguish patients who will prefer tadalafil or sildenafil. Patient differences in time concerns, dosage choice, intercourse satisfaction, treatment tolerability, number of sexual attempts and satisfaction with erection hardness were the set of factors most significantly associated with treatment preference, and the preference observed for tadalafil (71%) or sildenafil (29%) might be substantially accounted for by differences in these factors during the tadalafil and sildenafil treatment periods.
authors.affiliation: Pyrah Department of Urology, St. James University Hospital, Becket Street, Leeds, UK. ian.eardley@leedsth.nhs.uk
authors.forename: Ian
authors.initials: I
authors.lastname: Eardley
authors.forename: Francesco
authors.initials: F
authors.lastname: Montorsi
authors.forename: Graham
authors.initials: G
authors.lastname: Jackson
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Mirone
authors.forename: Melanie L-S
authors.initials: ML
authors.lastname: Chan
authors.forename: Kate
authors.initials: K
authors.lastname: Loughney
authors.forename: G Matthew
authors.initials: GM
authors.lastname: Vail
authors.forename: Anthony
authors.initials: A
authors.lastname: Beardsworth
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002243:Carbolines / Q000008:administration & dosage / Q000627:therapeutic use*; D018592:Cross-Over Studies; D007172:Erectile Dysfunction / Q000188:drug therapy*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D017060:Patient Satisfaction; D010410:Penile Erection / Q000187:drug effects; D010726:Phosphodiesterase Inhibitors / Q000009:adverse effects / Q000627:therapeutic use*; D010879:Piperazines / Q000009:adverse effects / Q000627:therapeutic use*; D011446:Prospective Studies; D011687:Purines / Q000009:adverse effects / Q000627:therapeutic use; D012720:Severity of Illness Index; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000009:adverse effects / Q000627:therapeutic use*; D011795:Surveys and Questionnaires; D000068581:Tadalafil; D016896:Treatment Outcome
chemical_list: D002243:Carbolines; D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D000068581:Tadalafil; D000068677:Sildenafil Citrate