Trial · NCT02500602

CAP: Doxazosin in the Treatment of Co-Occurring PTSD and Alcohol Use Disorders

NCT02500602, Phase 2, Completed, VA Office of Research and Development; results first posted 2021-04-14

3 sourcestrials-2026-11-12-0.5.0

Cite this record

ConductScience Library. CAP: Doxazosin in the Treatment of Co-Occurring PTSD and Alcohol Use Disorders. Trials, record NCT02500602. Release trials-2026-11-12-0.5.0, 12 Nov 2026. https://conductscience.org/library/trials/NCT02500602

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Trial

As registered on ClinicalTrials.gov, in the graph's capture of the registry.

Title: CAP: Doxazosin in the Treatment of Co-Occurring PTSD and Alcohol Use Disorders
NCT number: NCT02500602
Status: Completed
Phases: Phase 2
Enrollment: 144 participants, actual
Lead sponsor: VA Office of Research and Development
Conditions: Posttraumatic Stress Disorder, Alcohol Use Disorders
Interventions: doxazosin, placebo
First posted: 2015-07-16
Last updated: 2021-05-13
Results first posted: 2021-04-14

Source ClinicalTrials.gov

Registered outcomes3

Each outcome the trial registered, primary first, in ClinicalTrials.gov's words.

List	Outcome	Time frame	Description
Primary	Clinician Administered PTSD Scale	12 Weeks	The primary PTSD outcome measure was the Clinician-Administered PTSD Scale for DSM-5 (CAPS-5; Weathers et al., 2013). The CAPS-5 is a semi-structured interview that measures the DSM-5 symptoms of PTSD and requires the presence of at least one intrusion symptom, one avoidance symptom, two cognition and mood symptoms, and two arousal symptoms for a period of 1 month or more to reach diagnostic threshold. There are 20 symptom items and responses that are rated on a 5-point scale ranging from 0 (absent) to 4 (extreme/incapacitating), with a total PTSD symptom severity score of the sum of the 20 symptom items ranging from 0-80, and lower scores indicating better outcomes (or less severe PTSD symptomology). The CAPS-5 was assessed at end of treatment (week 12).
Primary	PTSD Checklist (PCL-5)	12 Weeks	The secondary PTSD outcome measure was the PTSD Checklist-5 (PCL-5; Weathers et al., 2013b). The PCL-5 is 20-item self-report measure that assesses the DSM-5 symptoms of PTSD using a severity rating Likert scale ranging from 0 to 4 that indicates the degree of distress across symptoms (0 = not at all to 4 = extremely). The overall score range is 0-80 (and combines the score for all 20 symptoms), with lower scores representing better outcomes (less severe PTSD symptomology). The PCL-5 was assessed at end of treatment (week 12).
Primary	Time Line Follow Back (TLFB)	12 Weeks	The TLFB obtains retrospective self-report of substance use by using a calendar and memory prompts to stimulate recall (Sobell \& Sobell, 1992). Quantity and frequency assessments are made using this instrument (e.g., total number of standard drink units, percent of days using) as well as abstinence (yes/no). TLFB yields consistently high test-retest correlations and correlates well with other self-reports and collateral reports (Sobell et al., 2003). The TLFB assesses frequency and amount of substance use over a pre-determined timeframe. TLFB data were collected throughout the trial, and the values reported here represent the TLFB data at end of treatment (week 12).

Source ClinicalTrials.gov

Outcomes3

Each outcome the trial posted results for, in ClinicalTrials.gov's words.

Type	Outcome	Time frame	Units	Measured as
PRIMARY	Clinician Administered PTSD Scale	12 Weeks	score on a scale	MEAN
PRIMARY	PTSD Checklist (PCL-5)	12 Weeks	score on a scale	MEAN
PRIMARY	Time Line Follow Back (TLFB)	12 Weeks	percent	MEAN

Source ClinicalTrials.gov

Results by group8

Each measurement the trial posted, group by group, in the words and numbers it posted.

Outcome	Group	Category	Value	Spread	Units
Clinician Administered PTSD Scale	Doxazosin		34.2	Standard Deviation 9.6	score on a scale
Clinician Administered PTSD Scale	Placebo		32.5	Standard Deviation 8.7	score on a scale
PTSD Checklist (PCL-5)	Doxazosin		47.3	Standard Deviation 14.5	score on a scale
PTSD Checklist (PCL-5)	Placebo		46.9	Standard Deviation 15.2	score on a scale
Time Line Follow Back (TLFB)	Doxazosin	percentage of days drinking	53.7	Standard Deviation 34.8	percent
Time Line Follow Back (TLFB)	Placebo	percentage of days drinking	48.1	Standard Deviation 41.2	percent
Time Line Follow Back (TLFB)	Doxazosin	percent heavy days drinking	37	Standard Deviation 37.6	percent
Time Line Follow Back (TLFB)	Placebo	percent heavy days drinking	38.6	Standard Deviation 38	percent

Source ClinicalTrials.gov

Participant flow12

How many started, completed or left each group, period by period.

Period	Milestone	Group	Participants
Treatment Phase	STARTED	Doxazosin	74
Treatment Phase	STARTED	Placebo	70
Treatment Phase	COMPLETED	Doxazosin	68
Treatment Phase	COMPLETED	Placebo	69
Treatment Phase	NOT COMPLETED	Doxazosin	6
Treatment Phase	NOT COMPLETED	Placebo	1
Follow Up Phase	STARTED	Doxazosin	68
Follow Up Phase	STARTED	Placebo	69
Follow Up Phase	COMPLETED	Doxazosin	53
Follow Up Phase	COMPLETED	Placebo	47

1 to 10 of 12Source ClinicalTrials.gov

See all 12 participant flow

Adverse events56

Each adverse event the trial posted, group by group: the participants affected out of those at risk.

Type	Event	Organ system	Group	Affected	At risk	Events
other	Depression	Psychiatric disorders	Doxazosin	7	74	7
other	Depression	Psychiatric disorders	Placebo	5	70	5
other	Hypotension	Cardiac disorders	Doxazosin	0	74	0
other	Hypotension	Cardiac disorders	Placebo	4	70	4
other	Hypertension	Cardiac disorders	Doxazosin	4	74	4
other	Hypertension	Cardiac disorders	Placebo	0	70	0
other	Diarrhea	Gastrointestinal disorders	Doxazosin	5	74	5
other	Diarrhea	Gastrointestinal disorders	Placebo	3	70	3
other	Stomach Virus/Cramping/Nausea	Gastrointestinal disorders	Doxazosin	13	74	13
other	Stomach Virus/Cramping/Nausea	Gastrointestinal disorders	Placebo	6	70	6

1 to 10 of 56Source ClinicalTrials.gov

See all 56 adverse events

Adverse event totals6

The totals the trial posted for each group.

Total	Group	Affected	At risk
Total, all-cause mortality	Doxazosin	0	74
Total, all-cause mortality	Placebo	0	70
Total, other adverse events	Doxazosin	48	74
Total, other adverse events	Placebo	40	70
Total, serious adverse events	Doxazosin	12	74
Total, serious adverse events	Placebo	9	70

Source ClinicalTrials.gov

Papers1

The papers the trial lists on ClinicalTrials.gov.

PMID	Listed as
36883885	DERIVED

Source PubMed

Grants0

The grants NIH RePORTER links to the trial, newest funded first: NIH's, and some of AHRQ's, CDC's, FDA's and VA's. Each shows its title, principal investigators, organization and funder in its newest year.

None in this release.

Trial comparisons2

Comparisons of the trial's two groups, calculated by ConductScience from the counts it posted.

Comparison	Source
Doxazosin vs Placebo: deaths from any cause	Trial comparisons
Doxazosin vs Placebo: serious adverse events	Trial comparisons

Tests0

The ConductCognition tests this trial's registered outcomes name, as ScienceGraph matched them in trial-tests-2026-11-12-0.2.1.

None in this release.

Data dates

The day each source was copied for this release.

ClinicalTrials.gov: 2026-11-12; ClinicalTrials.gov
Results, from AACT: 2026-03-23; AACT
NIH grant links: 2026-11-13; NIH RePORTER

Sources 3

ClinicalTrials.gov's posted results, through CTTI's AACTFreely available. Acknowledgement requested
ClinicalTrials.govNo license stated
NIH RePORTER's clinical studies and project filesPublic domain

Each source's terms

ClinicalTrials.gov's posted results, through CTTI's AACTClinicalTrials.gov data via Aggregate Analysis of ClinicalTrials.gov (AACT), CTTI. CTTI makes its materials freely available and requests acknowledgement. https://aact.ctti-clinicaltrials.org/documentation/299
ClinicalTrials.govnone stated
NIH RePORTER's clinical studies and project filesPublic domain (NIH RePORTER)

ClinicalTrials.gov's data carry an international copyright outside the United States: https://clinicaltrials.gov/about-site/terms-conditions.

For software

Read this trial from software.

The record and each of its lists are JSON, twenty rows a page. No key.

GET https://conductscience.org/api/trials/v1/NCT02500602

GET https://conductscience.org/api/trials/v1/NCT02500602/events?page=2

API reference For AI assistants