Knee OsteoarthritisNCT06574191
The Effects of Patient and Visit Characteristics on Health Outcomes in Knee Osteoarthritis
A study testing Topical Diclofenac gel 1% in people with Knee Osteoarthritis, run by University of California, Davis at 1 site in United States.
Trial summary
The goal of this clinical trial is to understand the patient and clinic visit characteristics that affect health outcomes for individuals with knee osteoarthritis (OA) pain using topical diclofenac gel. Read more about this study
- Who is it for?
- Ages 50 years and older
- Conditions the study is for
- Knee Osteoarthritis
- What is being tested?
- Topical Diclofenac gel 1%
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 220 participants
- Where
- 1 siteUnited States
- Study dates
- 29 Jan 2025to 27 Jan 2028
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 50 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- English-speaking
- 50 years of age or older
- Radiographically confirmed knee OA of K/L grade 2 or higher within the past 2 years
- Knee pain at least 15 days/month.
- Average worst daily pain 3/10 or higher over a two-week period.
Who cannot join
- Medical contraindication to taking NSAIDs such as: history of coronary artery bypass graft, myocardial infarction, coronary artery stent placement, or stroke within the past 6 months; systolic heart failure with ejection fraction <45%; chronic kidney disease stage ≥4; severe gastrointestinal bleed or stomach ulcer within the past 6 months; current pregnancy; cirrhosis; currently taking blood thinners (aspirin 81 mg daily is okay); allergy to NSAIDs or aspirin; or any other medical contraindication to using topical NSAIDs.
- Inflammatory arthritis
- Partial or total knee replacement of the index knee
- Recent therapeutic injection of the index knee (less than 12 weeks)
- Planned knee/lower limb surgery during the two-month study period
- Active cancer treatment not in remission or life expectancy less than 6 months
Show all 10Show fewer
- Inability to provide informed consent (e.g. dementia)
- Current use of topical or oral NSAIDs more than 3 days per week.
- Inability to receive text messages or emails to complete questionnaires between study visits.
- Unable to follow the study protocol.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
University of California Davis Health
Sacramento, California, 95817
Michelle Dossett, MD, PhD, MPH, 916-734-5367, mdossett@ucdavis.edu
About this study
The goal of this clinical trial is to understand the patient and clinic visit characteristics that affect health outcomes for individuals with knee osteoarthritis (OA) pain using topical diclofenac gel. The main questions it aims to answer are:
- What baseline patient characteristics predict response to topical diclofenac?
- Does patient physiology during the study visit predict response to topical diclofenac?
- Do study visit characteristics predict response to topical diclofenac?
Read more
Participants will:
- attend 2 study visits to complete study questionnaires and have blood drawn
- apply topical diclofenac to their knee for 8 weeks
- complete biweekly questions about knee pain and diclofenac use between study visits
Read the detailed description
220 older adults with symptomatic knee OA will attend a single research clinic visit (one of four different types of study visits) with a study clinician. The investigators will video record the visits and measure participant heart rate and skin conductance during the visit. Participants will complete baseline questionnaires immediately prior to the study visit. All participants will receive diclofenac gel (a topical over-the-counter non-steroidal anti-inflammatory drug [NSAID]), a guideline recommended treatment for knee OA-related pain at the end of the first study visit. Participants will identify an "index" knee (worst pain, right or left) that they will treat and follow during the study. Between study visit 1 and the 8-week follow-up visit, participants will receive an every other week text message asking them to report on pain and diclofenac use to better understand changes in pain over time. Final questionnaires will be completed at the second study visit at week 8.
- Conditions
- Knee Osteoarthritis
- Being tested
- Topical Diclofenac gel 1%
- Medical subject headings
- Osteoarthritis, Knee
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Topical Diclofenac gel 1%Drug
Topical NSAID
| Study group | Role | What they receive |
|---|---|---|
| Diclofenac | Experimental | All study participants receiving topical diclofenac gel 1%. Participants will be instructed to apply 4 grams of the gel to the index knee at least once per day, and up to 4 times per day, for 8 weeks. Receives: Drug: Topical Diclofenac gel 1% |
What is being measured
The primary outcome is the main question the study is designed to answer.
Knee Pain
Western Ontario and McMaster Universities Arthritis Index (WOMAC) pain score from the index knee at 8 weeks. Score range 0-20. Higher scores signify worse pain.
Measured: 8 weeks
Knee Function
Western Ontario and McMaster Universities Arthritis Index (WOMAC) physical function score from the index knee at 8 weeks. Score range 0-68. Higher scores signify worse function.
Measured: 8 weeks
Secondary outcomes (6)
Global Impressions
Baseline-adjusted end of visit global impression ratings from study visit video recordings. Each global impression is measured on a 1-9 scale. Global impressions include engagement (clinician and patient), friendliness (clinician and patient), relaxed (clinician and patient), empathic (clinician), reciprocity (dyad), business-like (clinician), dominant (clinician), rushed/hurried (clinician), bored/uninterested (clinician), confident (patient), and pleased (patient). We will construct a Global Impression Summative Scale Score if a preliminary round of psychometric evaluation determines that a combination of the individual construct scores can be constructed that has adequate internal consistency and unidimensionality.
Measured: 30 minutes
Non-verbal Behaviors
Baseline-adjusted end of visit non-verbal behaviors from study visit video recordings. Each non-verbal behavior is measured as counts (number of times) or total length of time within a discrete period of time (i.e., 2 minutes) from the video. Nonverbal behaviors that will be counted or timed for both parties include: gaze duration and number, smile duration and number, number of nods, self-touch, and gestures. We will also assess the number of clinician backchannel responses while patients spoke, the number of instances of shared laughter between the dyads, and the length of time that both the patient and clinician spoke. We will construct a Non-verbal Behavior Summative Score if a preliminary round of psychometric evaluation determines that a combination of the individual construct scores can be constructed that has adequate internal consistency and unidimensionality.
Measured: 30 minutes
Skin conductance index measure
Concordance in skin conductance response (measured in micro Siemens) from electrodes attached to the patient's and clinician's fingers over the course of the study visit will be calculated using an established approach (Marci CD, 2007; PMID 17299296) to create a single index value for the visit. The natural logarithm of this value will be taken to reduce skew. A value greater than 0 means more than 50% concordance in the data, a value less than zero means less than 50% concordance in the data.
Measured: 30 minutes
Change in patient skin conductance response
Change in patient skin conductance response from beginning to end of the initial study visit in micro-Siemens as measured by skin electrodes. Change score will be calculated as mean skin conductance response for the first 2 minutes of the study visit minus the mean value for the last 2 minutes of the study visit.
Measured: 30 minutes
Heart rate variability index measure
Concordance in heart rate variability, measured from electrodes attached to the patient and clinician, over the course of the study visit, will be calculated using established approaches (see references below). Concordance is quantified by the degree to which heart rate variability of the patient and clinician are "in-phase" or "anti-phase" linked (i.e., coordinated changes in the same or opposite direction) along the study visits.
https://pubmed.ncbi.nlm.nih.gov/29683720/ https://pubmed.ncbi.nlm.nih.gov/21910541/ https://pubmed.ncbi.nlm.nih.gov/24708502/ https://pubmed.ncbi.nlm.nih.gov/35315937/
Measured: 30 minutes
Change in patient RMSSD (root mean square of successive differences)
The RMSSD component (proxy for high frequency heart rate variability) will be measured in the patient over the course of the study visit. Change score will be calculated as mean RMSSD value for the first 5 minutes of the study visit minus the mean value for the last 5 minutes of the study visit.
Measured: 30 minutes
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted27 Aug 2024
- Study start29 Jan 2025
- Primary completion27 Jan 2028 (estimated)
- Study completion27 Jan 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Knee OsteoarthritisStudies of the same condition, open and under way.
- More trials run by University of California, DavisThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 220 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of California, Davis
- Sponsor type
- University, hospital or other
- Collaborators
- National Institute on Aging (NIA), Beth Israel Deaconess Medical Center
- Responsible party
- Sponsor
- Investigators
- Michelle Dossett, MD, PhD, Principal investigator, University of California, Davis
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06574191
- Sponsor's protocol ID
- 2054088
- Other IDs
- R01AG078283
- Status last verified
- Mar 2026
- First submitted
- 15 May 2024
- Last updated
- 30 Mar 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: De-identified questionnaire and COMT genotype data will be available upon reasonable written request after publication and upon completing a data transfer agreement. Raw video and physiologic data will not be shared due to participant confidentiality/privacy.
Study at a glance
From the registry record, last updated by the sponsor on 30 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Effects of Patient and Visit Characteristics on Health Outcomes in Knee Osteoarthritis
- ClinicalTrials.gov ID
- NCT06574191
- Acronym / sponsor ID
- 2054088
- Conditions
- Knee Osteoarthritis
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 220 participants (estimated)
- Lead sponsor
- University of California, DavisUniversity, hospital or other
- Collaborators
- National Institute on Aging (NIA), Beth Israel Deaconess Medical Center
- Study start
- 29 Jan 2025 (actual)
- Primary completion
- 27 Jan 2028 (estimated)
- Study completion
- 27 Jan 2028 (estimated)
- First posted
- 27 Aug 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The goal of this clinical trial is to understand the patient and clinic visit characteristics that affect health outcomes for individuals with knee osteoarthritis (OA) pain using topical diclofenac gel. The main questions it aims to answer are:
- What baseline patient characteristics predict response to topical diclofenac?
- Does patient physiology during the study visit predict response to topical diclofenac?
- Do study visit characteristics predict response to topical diclofenac?
Participants will:
- attend 2 study visits to complete study questionnaires and have blood drawn
- apply topical diclofenac to their knee for 8 weeks
- complete biweekly questions about knee pain and diclofenac use between study visits
Detailed description
220 older adults with symptomatic knee OA will attend a single research clinic visit (one of four different types of study visits) with a study clinician. The investigators will video record the visits and measure participant heart rate and skin conductance during the visit. Participants will complete baseline questionnaires immediately prior to the study visit. All participants will receive diclofenac gel (a topical over-the-counter non-steroidal anti-inflammatory drug [NSAID]), a guideline recommended treatment for knee OA-related pain at the end of the first study visit. Participants will identify an "index" knee (worst pain, right or left) that they will treat and follow during the study. Between study visit 1 and the 8-week follow-up visit, participants will receive an every other week text message asking them to report on pain and diclofenac use to better understand changes in pain over time. Final questionnaires will be completed at the second study visit at week 8.
Study design
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Diclofenac | Experimental | Drug: Topical Diclofenac gel 1%All study participants receiving topical diclofenac gel 1%. Participants will be instructed to apply 4 grams of the gel to the index knee at least once per day, and up to 4 times per day, for 8 weeks. |
Who may qualify
- Ages
- 50 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- English-speaking
- 50 years of age or older
- Radiographically confirmed knee OA of K/L grade 2 or higher within the past 2 years
- Knee pain at least 15 days/month.
- Average worst daily pain 3/10 or higher over a two-week period.
Key exclusion criteria (10 listed)
- Medical contraindication to taking NSAIDs such as: history of coronary artery bypass graft, myocardial infarction, coronary artery stent placement, or stroke within the past 6 months; systolic heart failure with ejection fraction <45%; chronic kidney disease stage ≥4; severe gastrointestinal bleed or stomach ulcer within the past 6 months; current pregnancy; cirrhosis; currently taking blood thinners (aspirin 81 mg daily is okay); allergy to NSAIDs or aspirin; or any other medical contraindication to using topical NSAIDs.
- Inflammatory arthritis
- Partial or total knee replacement of the index knee
- Recent therapeutic injection of the index knee (less than 12 weeks)
- Planned knee/lower limb surgery during the two-month study period
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Topical Diclofenac gel 1%Topical NSAID | Drug | Diclofenac |
Primary outcome
Knee Pain
Time frame: 8 weeks
Western Ontario and McMaster Universities Arthritis Index (WOMAC) pain score from the index knee at 8 weeks. Score range 0-20. Higher scores signify worse pain.
Knee Function
Time frame: 8 weeks
Western Ontario and McMaster Universities Arthritis Index (WOMAC) physical function score from the index knee at 8 weeks. Score range 0-68. Higher scores signify worse function.
6 secondary outcomes
Global Impressions
Time frame: 30 minutes
Non-verbal Behaviors
Time frame: 30 minutes
Skin conductance index measure
Time frame: 30 minutes
Change in patient skin conductance response
Time frame: 30 minutes
Heart rate variability index measure
Time frame: 30 minutes
Change in patient RMSSD (root mean square of successive differences)
Time frame: 30 minutes
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 30 Mar 2026.
- Individual participant dataSharing planned: Yes. De-identified questionnaire and COMT genotype data will be available upon reasonable written request after publication and upon completing a data transfer agreement. Raw video and physiologic data will not be shared due to participant confidentiality/privacy.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Michelle Dossett, MD, PhD principal investigator
University of California, Davis
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Topical Diclofenac gel 1% in people with Knee Osteoarthritis, run by University of California, Davis at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 10 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 30 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Maya Porter (916-734-4216, mtporter@ucdavis.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Knee Pain (time frame: 8 weeks). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 30 Mar 2026; AzTrials last refreshed its copy on 8 Nov 2026.