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NCT00931528 · OUTCOME

Percentage of Patients Maintaining Spontaneous (Off-drug) Erectile Function (EF) at Weeks 28-30 After Initiation of Radiation Therapy (RT)

Tadalafil in Preventing Erectile Dysfunction in Patients With Prostate Cancer Treated With Radiation Therapy · Source last updated 2018-02-14

Results reported by the registry submitting party. Population, time horizon, units and missing values must be read together.

Measure
NUMBER
Unit
percentage of participants
Interval / dispersion
95% Confidence Interval
Time frame
Baseline and 30 weeks from the start of radiation therapy

What was measured

EF is measured by Question 1 of the International Index of Erectile Function (IIEF). The IIEF is a validated 15-item for measuring patient-reported erectile function. Question 1 asks "How often were you able to get an erection during sexual activity?" Responses ranged from 0=no sexual activity, to 5=Almost always or always. Higher scores indicated better functioning. All patients have erectile function prior to initiation of RT, indicated by a score of 3, 4, or 5 on IIEF Q1. Patients with a lower IIEF Q1 score at weeks 28-30 than at baseline will have less erectile function and be categorized as nonresponders. Patients with similar or improved erectile function will be categorized as responders (maintaining). Patient-related predictors of at erectile function at this time point are also reported with this outcome measure.

Analysis population: All randomized eligible patients with IIEF at both baseline and 30 week time point.

Groups in this outcome

Tadalafil

Beginning ≤ 7 days after the start of radiotherapy, patients receive oral tadalafil once daily for 24 weeks.

Placebo

Beginning ≤ 7 days after the start of radiotherapy, patients receive oral placebo once daily for 24 weeks.

Group identifiers and denominators belong to this outcome only. They may differ in another outcome or in safety reporting.

Analysis denominator · Participants

GroupSource count
Tadalafil80
Placebo61

Reported measurements

Source class 1
Values in percentage of participants · Interval/dispersion: 95% Confidence Interval
GroupValueSpreadLowerUpperComment
Tadalafil79Not reported7088Not reported
Placebo74Not reported6385Not reported

Source statistical analyses

Group order, estimate direction, methods and comments are retained. No treatment ranking is inferred.

  1. ci Lower Limit
    1
    ci Num Sides
    TWO_SIDED
    ci Pct Value
    95
    ci Upper Limit
    9
    group Description
    Sample size calculations were based on the hypothesis that the use of tadalafil would statistically significant increase the proportion of patients maintaining spontaneous erectile function compared to the use of placebo. Based on a 2-sided Fisher exact test with alpha=0.05, 91 patients/arm would provide 80% statistical power to detect an increase from 20% to 40% in spontaneous erectile response at weeks 28-30. Although designed for the Fisher exact test, Chi-square was used and reported.
    group Ids
    1. OG000
    2. OG001
    non Inferiority Type
    SUPERIORITY_OR_OTHER
    p Value
    0.49
    param Type
    Difference in percentages
    param Value
    5
    statistical Method
    Chi-squared
  2. group Description
    Logistic regression using generalized estimating equations was performed modeling the probability of non-responders. Only treatment arm (Placebo vs. Tadalafil), age (\> 65 vs. other), RT method (External RT vs. brachytherapy), and significant pretreatment characteristics \[N stage (NX vs. N0)\] were retained in the model. (Dropped: ethnicity, Zubrod, T stage, prostate-specific antigen (PSA).) The results for each explanatory variable are reported separately. Treatment arm is reported here.
    group Ids
    1. OG000
    2. OG001
    non Inferiority Type
    SUPERIORITY
    p Value
    0.2386
    statistical Method
    Regression, Logistic
  3. group Description
    Logistic regression using generalized estimating equations was performed modeling the probability of non-responders. Only treatment arm (Placebo vs. Tadalafil), age (\> 65 vs. other), RT method (External RT vs. brachytherapy), and significant pretreatment characteristics \[N stage (NX vs. N0)\] were retained in the model. (Dropped pretreatment characteristics: ethnicity, Zubrod, T stage, PSA.)The results for each explanatory variable are reported separately. RT method is reported here.
    group Ids
    1. OG000
    2. OG001
    non Inferiority Type
    SUPERIORITY
    p Value
    0.7908
    statistical Method
    Regression, Linear
  4. group Description
    Logistic regression using generalized estimating equations was performed modeling the probability of non-responders. Only treatment arm (Placebo vs. Tadalafil), age (\> 65 vs. other), RT method (External RT vs. brachytherapy), and significant pretreatment characteristics \[N stage (NX vs. N0)\] were retained in the model. (Dropped pretreatment characteristics: ethnicity, Zubrod, T stage, PSA.) The results for each explanatory variable are reported separately. Age is reported here.
    group Ids
    1. OG000
    2. OG001
    non Inferiority Type
    SUPERIORITY
    p Value
    0.0467
    statistical Method
    Regression, Logistic
  5. group Description
    Logistic regression using generalized estimating equations was performed modeling the probability of non-responders. Only treatment arm (Placebo vs. Tadalafil), age (\> 65 vs. other), RT method (External RT vs. brachytherapy), and significant pretreatment characteristics \[N stage (NX vs. N0)\] were retained in the model. (Dropped pretreatment characteristics: ethnicity, Zubrod, T stage, PSA.) The results for each explanatory variable are reported separately. N Stage is reported here.
    group Ids
    1. OG000
    2. OG001
    non Inferiority Type
    SUPERIORITY
    p Value
    0.0068
    statistical Method
    Regression, Logistic
Complete source fields
analyses
  1. ci Lower Limit
    1
    ci Num Sides
    TWO_SIDED
    ci Pct Value
    95
    ci Upper Limit
    9
    group Description
    Sample size calculations were based on the hypothesis that the use of tadalafil would statistically significant increase the proportion of patients maintaining spontaneous erectile function compared to the use of placebo. Based on a 2-sided Fisher exact test with alpha=0.05, 91 patients/arm would provide 80% statistical power to detect an increase from 20% to 40% in spontaneous erectile response at weeks 28-30. Although designed for the Fisher exact test, Chi-square was used and reported.
    group Ids
    1. OG000
    2. OG001
    non Inferiority Type
    SUPERIORITY_OR_OTHER
    p Value
    0.49
    param Type
    Difference in percentages
    param Value
    5
    statistical Method
    Chi-squared
  2. group Description
    Logistic regression using generalized estimating equations was performed modeling the probability of non-responders. Only treatment arm (Placebo vs. Tadalafil), age (\> 65 vs. other), RT method (External RT vs. brachytherapy), and significant pretreatment characteristics \[N stage (NX vs. N0)\] were retained in the model. (Dropped: ethnicity, Zubrod, T stage, prostate-specific antigen (PSA).) The results for each explanatory variable are reported separately. Treatment arm is reported here.
    group Ids
    1. OG000
    2. OG001
    non Inferiority Type
    SUPERIORITY
    p Value
    0.2386
    statistical Method
    Regression, Logistic
  3. group Description
    Logistic regression using generalized estimating equations was performed modeling the probability of non-responders. Only treatment arm (Placebo vs. Tadalafil), age (\> 65 vs. other), RT method (External RT vs. brachytherapy), and significant pretreatment characteristics \[N stage (NX vs. N0)\] were retained in the model. (Dropped pretreatment characteristics: ethnicity, Zubrod, T stage, PSA.)The results for each explanatory variable are reported separately. RT method is reported here.
    group Ids
    1. OG000
    2. OG001
    non Inferiority Type
    SUPERIORITY
    p Value
    0.7908
    statistical Method
    Regression, Linear
  4. group Description
    Logistic regression using generalized estimating equations was performed modeling the probability of non-responders. Only treatment arm (Placebo vs. Tadalafil), age (\> 65 vs. other), RT method (External RT vs. brachytherapy), and significant pretreatment characteristics \[N stage (NX vs. N0)\] were retained in the model. (Dropped pretreatment characteristics: ethnicity, Zubrod, T stage, PSA.) The results for each explanatory variable are reported separately. Age is reported here.
    group Ids
    1. OG000
    2. OG001
    non Inferiority Type
    SUPERIORITY
    p Value
    0.0467
    statistical Method
    Regression, Logistic
  5. group Description
    Logistic regression using generalized estimating equations was performed modeling the probability of non-responders. Only treatment arm (Placebo vs. Tadalafil), age (\> 65 vs. other), RT method (External RT vs. brachytherapy), and significant pretreatment characteristics \[N stage (NX vs. N0)\] were retained in the model. (Dropped pretreatment characteristics: ethnicity, Zubrod, T stage, PSA.) The results for each explanatory variable are reported separately. N Stage is reported here.
    group Ids
    1. OG000
    2. OG001
    non Inferiority Type
    SUPERIORITY
    p Value
    0.0068
    statistical Method
    Regression, Logistic
classes
  1. categories
    1. measurements
      1. group Id
        OG000
        lower Limit
        70
        upper Limit
        88
        value
        79
      2. group Id
        OG001
        lower Limit
        63
        upper Limit
        85
        value
        74
denoms
  1. counts
    1. group Id
      OG000
      value
      80
    2. group Id
      OG001
      value
      61
    units
    Participants
description
EF is measured by Question 1 of the International Index of Erectile Function (IIEF). The IIEF is a validated 15-item for measuring patient-reported erectile function. Question 1 asks "How often were you able to get an erection during sexual activity?" Responses ranged from 0=no sexual activity, to 5=Almost always or always. Higher scores indicated better functioning. All patients have erectile function prior to initiation of RT, indicated by a score of 3, 4, or 5 on IIEF Q1. Patients with a lower IIEF Q1 score at weeks 28-30 than at baseline will have less erectile function and be categorized as nonresponders. Patients with similar or improved erectile function will be categorized as responders (maintaining). Patient-related predictors of at erectile function at this time point are also reported with this outcome measure.
dispersion Type
95% Confidence Interval
groups
  1. description
    Beginning ≤ 7 days after the start of radiotherapy, patients receive oral tadalafil once daily for 24 weeks.
    id
    OG000
    title
    Tadalafil
  2. description
    Beginning ≤ 7 days after the start of radiotherapy, patients receive oral placebo once daily for 24 weeks.
    id
    OG001
    title
    Placebo
param Type
NUMBER
population Description
All randomized eligible patients with IIEF at both baseline and 30 week time point.
reporting Status
POSTED
time Frame
Baseline and 30 weeks from the start of radiation therapy
title
Percentage of Patients Maintaining Spontaneous (Off-drug) Erectile Function (EF) at Weeks 28-30 After Initiation of Radiation Therapy (RT)
type
PRIMARY
unit Of Measure
percentage of participants

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Preserved source evidence · Not medical advice