Plain English Summary
Background and study aims
Endometriosis is a common condition where tissue that behaves like the lining of the womb (endometrium) is found in other parts of the body. It affects 6-10% of women and causes severe pelvic pain. Endometriosis can be treated surgically or medically. However, symptoms often come back after surgery and the currently available medical treatments are hormones which have undesirable side effects and are contraceptive. Omega-3 purified fatty acid (PUFA) supplements may reduce endometriosis-associated pain, have minimal side effects and no effects on fertility. The aim of this small study is to assess the feasibility of conducting a larger study of PUFA for endometriosis-associated pain.
Who can participate?
Patients aged 18-50 with endometriosis
What does the study involve?
Participants are randomly allocated to receive soft gelatin capsules containing either omega-3 purified fatty acids (fish oil) or olive oil, and are advised to take two capsules per day, one in the morning and one in the evening for 8 weeks. Pain is measured at the start and end of the study and blood samples are collected to measure fatty acid levels.
What are the possible benefits and risks of participating?
PUFAs are a dietary supplement and may reduce endometriosis-associated pain. They have minimal side effects and no effects on fertility.
Where is the study run from?
Royal Infirmary of Edinburgh (UK)
When is the study starting and how long is it expected to run for?
October 2013 to May 2017
Who is funding the study?
University of Edinburgh (UK)
Who is the main contact?
1. Mrs Ann Doust (public)
2. Prof. Andrew Horne (scientific)
Mrs Ann Doust
University of Edinburgh
51 Little France Crescent
Edinburgh Eh16 4SA
+44 (0)131 242 9492
Prof Andrew Horne
47 Little France Crescent
PurFECT: PURified Fatty acids for Endometriosis Clinical Trial: a randomised controlled trial
Endometriosis (womb lining outside the womb) affects 6-10% of women and is associated with debilitating chronic pelvic pain. It costs the UK >£2.8 billion per year in loss of productivity. Endometriosis is managed surgically or medically. However, ~75% symptoms recur after surgery and available medical treatments (‘anti-hormones’) have undesirable side effects and are contraceptive. Omega-3 purified fatty acids (PUFA) have been shown in animal models to reduce factors that are thought to lead to endometriosis-associated pain, have minimal side effects and no effects on fertility. The trialists plan to perform a feasibility study to inform planning of a future multicentre trial to evaluate the efficacy of PUFA in the management of endometriosis-associated pain.
South East Scotland Research Ethics Committee 01, 02/02/2016, ref: 16/SS/0010
Randomised controlled double-blind feasibility study
Primary study design
Secondary study design
Randomised controlled trial
Patient information sheet
Not available in web format, please use the contact details to request a patient information sheet
Participants are randomised to receive either omega-3 purified fatty acids (fish oil) or olive oil soft gelatin (placebo) capsules, with a dose of 1000 mg each, and advised to take two capsules per day, one in the morning and one in the evening for 8 weeks. The outcomes are measured at baseline and at the end of the study (i.e., 8 weeks).
Primary outcome measure
1. The proportion of screened women who are eligible for the trial
2. The proportion of eligible patients randomised into the study
3. The proportion of randomised patients who take the supplement and complete questionnaires at final follow up
The outcomes will be measured at baseline and at the end of the study (i.e., 8 weeks).
Secondary outcome measures
The remaining outcomes will be used to refine the research methodology of a future large RCT:
1. Pain, measured using the Numerical Rating Score (NRS) collected via text message during the screening phase (-1 to -4 weeks) and last 4 weeks (weeks 5-8) of the treatment phase
2. Eicosapentaenoic acid, arachidonic acid and docosahexaenoic acid concentrations measured from peripheral venous blood samples at baseline and 8 weeks
3. Quality of life, measured using SF-12 at baseline and 8 weeks
4. Pain, measured using the Brief Pain Inventory (BPI) at baseline and 8 weeks
5. Pain catastrophizing, measured using the Pain Catastrophising Questionnaire (PCQ) at baseline and 8 weeks
5. Pain, measures using the PainDETECT™ questionnaire at baseline and 8 weeks
6. Sexual activity, measured using the Sexual Activity Questionnaire (SAQ) at baseline and 8 weeks
7. Fatigue, measured using the Brief Fatigue Inventory (BFI) at baseline and 8 weeks
8. General health, measures using the General Health Questionnaire -12 (GHQ-12) at baseline and 8 weeks
9. Work and productivity activity impairment, measured using the Work and Productivity Activity Impairment Questionnaire- Specific Health Problem version 2.0 (WPAI-SHP) at baseline and 8 weeks
10. Acceptability of proposed methods of recruitment, randomisation, treatments and questionnaires, measured using a questionnaire at 8 weeks
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
1. Aged 18-50 years
2. Known endometriosis diagnosed from previous laparoscopy
3. Pain of at least 3 months duration located in the true pelvis
4. Worst pain score ≥4 over 4 weeks as measured by Numerical Rating Score (NRS)
5. Ability to provide informed consent
Target number of participants
Total final enrolment
Participant exclusion criteria
1. Unable to take/allergic to fish/PUFA/peanuts/soyabean
2. Insulin dependent diabetes
4. Taking contraindicated medications (anticoagulants)
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
Royal Infirmary of Edinburgh
51 Little France Crescent
University Of Edinburgh
Funding Body Type
private sector organisation
Funding Body Subtype
Universities (academic only)
Results and Publications
Publication and dissemination plan
The target is to use the clinical study report for publication and presentation at scientific meetings.
IPD sharing statement
The current data sharing plans for the current study are unknown and will be made available at a later date.
Intention to publish date
Participant level data
To be made available at a later date
Basic results (scientific)
2018 protocol in: https://pilotfeasibilitystudies.biomedcentral.com/articles/10.1186/s40814-018-0274-8
2020 results in https://www.ncbi.nlm.nih.gov/pubmed/31951599 (added 20/01/2020)