Postoperative Cognitive Dysfunction (POCD)NCT07598552
Early Cognitive Changes After Same-day Discharge Hip and Knee Arthroplasty
An observational study of Postoperative Cognitive Dysfunction (POCD) and Cognitive Change, run by Odense University Hospital at 1 site in Denmark.
Trial summary
The goal of this observational study is to explore early cognitive changes in patients aged 70 years or older undergoing same-day discharge after hip or knee replacement surgery. Read more about this study
- Who is it for?
- Ages 70 years and older
- Conditions the study is for
- Postoperative Cognitive Dysfunction (POCD), Cognitive Change, Total Knee Arthroplasty
- How many people
- 48 participants
- Where
- 1 siteDenmark
- Study dates
- 18 May 2026to 30 Nov 2026
- How long will I take part?
- 7 Days
- Phase
- Observational
- 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 70 years and older
- All sexes
- No healthy volunteers
- Older adult
Study population: Patients scheduled for hip or knee arthroplasty at Svendborg hospital, Denmark.
Who may be able to join
- Unilateral elective primary Total Hip Arthroplasty, Total Knee Arthroplasty, or Unicompartmental Knee
- Native Danish speaker
- Spinal anesthesia
Who cannot join
- Inability or unwillingness to provide informed consent
- Inability to comply with virtual study procedures or follow-up sessions, including because of visual or hearing impairment
- Known dementia or other diagnosed cognitive disorders or Brief Assessment of Impaired Cognition (BASIC)≤20
- Parkinson's disease or other neurological conditions causing functional impairment
- History of alcohol abuse (≥35 units per week)
- Daily use of anxiolytics or hypnotics
- Not discharged on the day of surgery
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Denmark1 site, 1 recruiting
- Recruiting
Odense University Hospital, Svendborg Hospital
Svendborg, 5700
Abdullahi Abdirisak Hirsi, MD, +4553376575, abdullahi.abdirisak.hirsi2@rsyd.dk
Martin Lindberg-Larsen, Professor, +4551435711, martin.lindberg-larsen@rsyd.dk
About this study
Official title: Early Cognitive Changes in Patients Aged 70 Years or Older After Same-day Discharge Hip and Knee Arthroplasty: A Prospective Cohort Study
The goal of this observational study is to explore early cognitive changes in patients aged 70 years or older undergoing same-day discharge after hip or knee replacement surgery. The main question it aims to answer is:
Does patients experience cognitive changes in cognitive test performance from before surgery to the first day after surgery?
Participants will:
- Complete a cognitive test battery virtually about 14 days before surgery, and on the first and seventh day after their operation.
- Record pain levels and pain medicine use during the first week after surgery
Read the detailed description
Introduction Background Postoperative cognitive dysfunction (POCD) is a prevalent complication in elderly patients and has significant clinical and socioeconomic consequences, delayed recovery, decreased quality of life, persistent neurocognitive disorders and increased morbidity and mortality within the first year of surgery . The pathogenesis remains poorly understood, partly due to varying diagnostic approaches and methodologies. Nevertheless, there is consensus that POCD is multifactorial influenced by factors such as advanced age, sleep disturbances, and inadequate perioperative pain management .
Sleep deprivation, in particular, can exacerbate hyperalgesia, impair cognition, and lead to increased respiratory and cardiac risks due to REM sleep rebound. Fast-track surgical protocols, which emphasize multimodal rehabilitation-including regional anesthesia, opioid-sparing analgesia, and early mobilization-have been shown to reduce postoperative pain, sleep disturbances, and the risk of delirium. These protocols have reduced the average length of hospital stays worldwide. In Denmark length of hospital stay after total hip arthroplasty (THA), total knee arthroplasty (TKA) and unicompartmental knee (UKA) is now only one day and an increasing number of patients are discharged on the day of surgery. Same-day discharge enable earlier return to a familiar environment and potentially enhanced pathophysiological recovery.
No studies have described early postoperative cognitive test performance in elderly patients undergoing same-day discharge hip and knee arthroplasty. This study therefore aims to address this knowledge gap by examining early cognitive changes in patients aged ≥70 years after same-day discharge hip and knee arthroplasty.
Aim The primary aim of this study is to report early cognitive changes measured with Symbol Digit Modality Test (SDMT) in patients over 70 years undergoing same-day discharge THA, TKA and UKA. Secondary, to report cognitive changes using the Stroop Color Test and verbal fluency test as well as patient's perceived cognitive function. As patients return home on the day of surgery in this contemporary same-day discharge arthroplasty setting, we hypothesize that early postoperative changes in cognitive performance will be limited compared with earlier fast-track studies with a longer median length of stay (LOS).
Methods
The cognitive tests:
The cognitive tests will be administered by research assistants with prior research experience.
Eligible participants will be recruited from the outpatient clinic. Testing will be performed virtually with the patients being at home. The patients will receive instructions to complete all sessions in the same quiet room and on the same device, to keep environmental stimuli (lighting, background noise, screen distance, seating, posture, and internet conditions) constant and thereby reduce within-subject variance and practice effects. The baseline test will be administered 14 days +- 3 days prior to surgery to avoid preoperative anxiety effects. Postoperatively, testing will be carried out on postoperative day 1 and day 7. More frequent testing is avoided to reduce practice effects.
Only patients receiving spinal anesthesia will be included to minimize confounding from general anesthesia and to reflect current fast-track practice. Spinal anesthesia is administered using a relatively short-acting blockade bupivacaine 5 mg/mL, 2.5 mL (12.5 mg) in THA, while for primary TKA and UKA, bupivacaine 5 mg/mL, 2 mL (10 mg) . Standard local infiltration analgesia (LIA) will be used with 150 mL ropivacaine 2 mg/mL in knee arthroplasties but not in hip arthroplasties . Peripheral nerve blocks are not used. Patients will also receive cloxacillin 2 gr, methylprednisolone 125 mg and 1 gr tranexamic acid intravenously immediately prior to skin incision.
Postoperative pain management and other medication Postoperative pain management will follow a standardized multimodal, opioid-sparing regimen. All patients will receive paracetamol (1 g × 4) in combination with ibuprofen 400 mg × 3 (7 days) for THA patients in and 400 mg × 4 (14 days) for TKA and UKA patients, unless contraindicated.
Opioids will be reserved as rescue medication, administered only on an "as needed" basis. Morphine 10 mg tablets will be used as first-line rescue analgesia, with oxycodone 5 mg as an alternative for patients who do not tolerate morphine.
Data Source:
A REDCap database has been established in collaboration with the Open Patient Data Explorative Network (OPEN) at Odense University Hospital (25). Patients scheduled for hip and knee arthroplasty at Svendborg hospital and included in the planned study will be enrolled in the database following informed consent. Patient's baseline database will be registered on comorbidities and medication use entered by trained research staff.
Statistics and sample size Although this is an exploratory study, the sample size was guided by considerations from both the literature and our pilot planning. Because the design is paired, each participant serves as their own control (baseline vs. postoperative assessment). For the SDMT we assumed a minimal clinically important difference (MCID) of 4 points , a within-subject correlation of 0.85 between baseline and postoperative scores, and a standard deviation of 7.5 . With a two-sided alpha of 0.05 and 80% power, this corresponds to approximately 14 participants with complete paired measurements per subgroup (THA, TKA, and UKA) if analyses are performed separately. To account for anticipated dropout/non-same-day discharge, we will aim to enroll 16 patients per subgroup to obtain 14 participants with complete paired measurements.
Continuous variables will be summarized as mean with standard deviation (SD) and range if approximately normally distributed; otherwise as median with interquartile range (IQR) and range. Categorical variables will be described using absolute and relative frequencies (n, %).
Patient involvement Patients who have previously undergone hip or knee arthroplasty were involved in the design process. Their feedback informed the research questions and outcome measures, ensuring relevance and patient-centeredness. During pilot testing, participating patients also provided input on the planned assessment procedures and overall feasibility, which further informed methodological adjustments.
- Conditions
- Postoperative Cognitive Dysfunction (POCD), Cognitive Change, Total Knee Arthroplasty, Unicompartmental Knee Arthroplasty
- Keywords
- Same-day discharge, Fast-track surgery, Hip arthroplasty, Knee arthroplasty, Unicompartmental knee arthroplasty, Cognitive function, SDMT, Stroop test, Verbal fluency, Older adults, recovery
- Medical subject headings
- Postoperative Cognitive Complications
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| Total Hip Arthroplasty | Patients aged 70 years or older undergoing elective unilateral total hip arthroplasty with planned discharge on the day of surgery. | |
| Total Knee Arthroplasty | Patients aged 70 years or older undergoing elective unilateral total knee arthroplasty with planned discharge on the day of surgery. | |
| Unicompartmental Knee Arthroplasty | Patients aged 70 years or older undergoing elective unilateral unicompartmental knee arthroplasty with planned discharge on the day of surgery. |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Symbol Digit Modalities Test (SDMT) score from baseline to postoperative day 1.
The SDMT is a validated neuropsychological tool that measures processing speed, attention, and visual scanning. The SDMT will be administered virtually as an oral 90-second test. The primary metric will be the SDMT score, defined as the number of correct digit substitutions completed within 90 seconds
Measured: From baseline, 14 days before surgery, and postoperative day 1.
Secondary outcomes (7)
Change in Symbol Digit Modalities Test (SDMT) score from baseline to postoperative day 7.
The SDMT is a validated neuropsychological tool that measures processing speed, attention, and visual scanning. The SDMT will be administered virtually as an oral 90-second test. The primary metric will be the SDMT score, defined as the number of correct digit substitutions completed within 90 seconds
Measured: From baseline, 14 days before surgery, and postoperative day 7.
Change in Stroop Color-Word Test score from baseline to postoperative day 1.
The Stroop Color-Word Test is a validated measure of selective attention and susceptibility to interference. The primary metrics will be completion time (seconds) and number of errors recorded for each session.
Measured: From baseline, 14 days before surgery, and postoperative day 1.
Change in Stroop Color-Word Test score from baseline to postoperative day 7.
The Stroop Color-Word Test is a validated measure of selective attention and susceptibility to interference. The primary metrics will be completion time (seconds) and number of errors recorded for each session.
Measured: From baseline, 14 days before surgery, and postoperative day 7.
Change in Verbal fluency assessment score from baseline to postoperative day 1.
Verbal fluency assessment is a validated test which assesses executive function, semantic memory, and language. In our test a semantic (animal naming) and a phonemic (letter S) fluency task were used, each administered for 60 seconds. Number of correct responses for each task will be registered.
Measured: From baseline, 14 days before surgery, and postoperative day 1.
Change in Verbal fluency assessment score from baseline to postoperative day 7.
Verbal fluency assessment is a validated test which assesses executive function, semantic memory, and language. In our test a semantic (animal naming) and a phonemic (letter S) fluency task were used, each administered for 60 seconds. Number of correct responses for each task will be registered.
Measured: From baseline, 14 days before surgery, and postoperative day 7.
Reporting patient-reported cognitive function on postoperative day 1.
A brief two-item subjective cognitive questionnaire will be administered to assess patient's perceived cognitive changes and to identify any discrepancy between subjective experience and objective neuropsychological test performance.
Measured: Postoperative day 1.
Change in patient-reported cognitive function from postoperative day 1 to postoperative day 7.
A brief two-item subjective cognitive questionnaire will be administered to assess patient's perceived cognitive changes and to identify any discrepancy between subjective experience and objective neuropsychological test performance.
Measured: From postoperative day 1 and postoperative day 7.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted20 May 2026
- Study start18 May 2026
- Primary completion31 Oct 2026 (estimated)
- Study completion30 Nov 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (23)Papers the sponsor has linked to this study.
- Other trials for Postoperative Cognitive Dysfunction (POCD)Studies of the same condition, open and under way.
- 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
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 48 participants (estimated)
- Target duration
- 7 Days
Sponsor and investigators
- Lead sponsor
- Odense University Hospital
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Abdullahi Abdirisak Hirsi, Odense University Hospital
- Investigators
- Martin Lindberg-Larsen, Professor, Principal investigator, Head of Research / Consultant Orthopaedic Surgeon at Odense University Hospital. Department of Clinical Research, University of Southern Denmark (SDU)
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07598552
- Sponsor's protocol ID
- 25/49880
- Status last verified
- Jun 2026
- First submitted
- 14 May 2026
- Last updated
- 22 Jun 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Individual participant data will not be publicly shared due to Danish data protection regulations and the nature of the clinical dataset. De-identified data may be made available from the investigators upon reasonable request and subject to applicable approvals.
Publications
Nissen SK, Fournaise A, Lauridsen JT, Ryg J, Nickel CH, Gudex C, Brabrand M, Andersen-Ranberg K. Cross-sectoral inter-rater reliability of the clinical frailty scale - a Danish translation and validation study. BMC Geriatr. 2020 Nov 3;20(1):443. doi: 10.1186/s12877-020-01850-y.
PubMed 33143651Strober LB, Bruce JM, Arnett PA, Alschuler KN, DeLuca J, Chiaravalloti N, Lebkuecher A, Di Benedetto M, Cozart J, Thelen J, Cadden M, Guty E, Roman CAF. A much needed metric: Defining reliable and statistically meaningful change of the oral version Symbol Digit Modalities Test (SDMT). Mult Scler Relat Disord. 2022 Jan;57:103405. doi: 10.1016/j.msard.2021.103405. Epub 2021 Nov 16.
PubMed 34923428Morrow SA, Drake A, Zivadinov R, Munschauer F, Weinstock-Guttman B, Benedict RH. Predicting loss of employment over three years in multiple sclerosis: clinically meaningful cognitive decline. Clin Neuropsychol. 2010 Oct;24(7):1131-45. doi: 10.1080/13854046.2010.511272. Epub 2010 Sep 8.
PubMed 20830649Harris PA, Taylor R, Thielke R, Payne J, Gonzalez N, Conde JG. Research electronic data capture (REDCap)--a metadata-driven methodology and workflow process for providing translational research informatics support. J Biomed Inform. 2009 Apr;42(2):377-81. doi: 10.1016/j.jbi.2008.08.010. Epub 2008 Sep 30.
PubMed 18929686Springborg AH, Jensen CB, Gromov K, Troelsen A, Kehlet H, Foss NB. Acute postoperative pain and catastrophizing in unicompartmental knee arthroplasty: a prospective, observational, single-center, cohort study. Reg Anesth Pain Med. 2025 Sep 4;50(9):706-711. doi: 10.1136/rapm-2024-105503.
PubMed 38839429Ahmed MT, Troyas C, Daramola AM, Isik OG, Cassim TZ, Goldberg TE, Banerji A, Sleigh J, Garcia PS. Characterization of Speech and Language Deficits in the Postanesthesia Care Unit: A Novel, Qualitative Cognitive Assessment. Anesth Analg. 2025 Mar 1;140(3):655-664. doi: 10.1213/ANE.0000000000006940. Epub 2024 Mar 25.
PubMed 39976622Andersen LO, Kehlet H. Analgesic efficacy of local infiltration analgesia in hip and knee arthroplasty: a systematic review. Br J Anaesth. 2014 Sep;113(3):360-74. doi: 10.1093/bja/aeu155. Epub 2014 Jun 17.
PubMed 24939863Pu X, Sun JM. General anesthesia vs spinal anesthesia for patients undergoing total-hip arthroplasty: A meta-analysis. Medicine (Baltimore). 2019 Apr;98(16):e14925. doi: 10.1097/MD.0000000000014925.
PubMed 31008923Jorgensen K, Nielsen TR, Nielsen A, Oxboll AB, Gerner SD, Waldorff FB, Waldemar G. Diagnostic accuracy of the Brief Assessment of Impaired Cognition case-finding instrument in a general practice setting and comparison with other widely used brief cognitive tests-a cross-validation study. Eur J Neurol. 2024 Oct;31(10):e16418. doi: 10.1111/ene.16418. Epub 2024 Jul 24.
PubMed 39045891Marceaux JC, Prosje MA, McClure LA, Kana B, Crowe M, Kissela B, Manly J, Howard G, Tam JW, Unverzagt FW, Wadley VG. Verbal fluency in a national sample: Telephone administration methods. Int J Geriatr Psychiatry. 2019 Apr;34(4):578-587. doi: 10.1002/gps.5054. Epub 2019 Jan 18.
PubMed 30588700Joffe Y, Liu J, Arias F, Tommet D, Fong TG, Schmitt EM, Travison T, Kunicki ZJ, Inouye SK, Jones RN. Adaptation, calibration, and validation of a cognitive assessment battery for telephone and video administration. J Am Geriatr Soc. 2025 Feb;73(2):482-491. doi: 10.1111/jgs.19275. Epub 2024 Nov 21.
PubMed 39569941Chapman JE, Helmstaedter C, Abbott DF, Pardoe HR, Vaughan DN, Jackson GD, Tailby C; Australian Epilepsy Project Investigators. Videoconference-integrated, computer-assisted cognitive testing improves the remote assessment of processing speed and attention. J Int Neuropsychol Soc. 2025 Aug;31(7-8):582-591. doi: 10.1017/S1355617725101124. Epub 2025 Oct 22.
PubMed 41122074Contino V, Abrams JH, Arumugam S, Sinha SK, Vellanky SS, Cremins MS, McCann GP. Spinal Anesthesia Using Ropivacaine Leads to Earlier Ambulation After Total Hip Arthroplasty. Orthopedics. 2021 May-Jun;44(3):e343-e346. doi: 10.3928/01477447-20210414-04. Epub 2021 May 1.
PubMed 34039195Lindberg-Larsen M, Varnum C, Jakobsen T, Andersen MR, Sperling K, Overgaard S, Hansen TB, Jorgensen CC, Kehlet H, Gromov K. Study protocol for discharge on day of surgery after hip and knee arthroplasty from the Center for Fast-track Hip and Knee Replacement. Acta Orthop. 2023 Mar 20;94:121-127. doi: 10.2340/17453674.2023.11636.
PubMed 36942664Kehlet H, Lobo DN. Exploring the need for reconsideration of trial design in perioperative outcomes research: a narrative review. EClinicalMedicine. 2024 Feb 29;70:102510. doi: 10.1016/j.eclinm.2024.102510. eCollection 2024 Apr.
PubMed 38444430
Study at a glance
From the registry record, last updated by the sponsor on 22 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Early Cognitive Changes in Patients Aged 70 Years or Older After Same-day Discharge Hip and Knee Arthroplasty: A Prospective Cohort Study
- ClinicalTrials.gov ID
- NCT07598552
- Acronym / sponsor ID
- 25/49880
- Conditions
- Postoperative Cognitive Dysfunction (POCD), Cognitive Change, Total Knee Arthroplasty, Unicompartmental Knee Arthroplasty
- Keywords
- Same-day discharge, Fast-track surgery, Hip arthroplasty, Knee arthroplasty, Unicompartmental knee arthroplasty, Cognitive function, SDMT, Stroop test
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 48 participants (estimated)
- Lead sponsor
- Odense University HospitalUniversity, hospital or other
- Study start
- 18 May 2026 (actual)
- Primary completion
- 31 Oct 2026 (estimated)
- Study completion
- 30 Nov 2026 (estimated)
- First posted
- 20 May 2026 (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 observational study is to explore early cognitive changes in patients aged 70 years or older undergoing same-day discharge after hip or knee replacement surgery. The main question it aims to answer is:
Does patients experience cognitive changes in cognitive test performance from before surgery to the first day after surgery?
Participants will:
- Complete a cognitive test battery virtually about 14 days before surgery, and on the first and seventh day after their operation.
- Record pain levels and pain medicine use during the first week after surgery
Detailed description
Introduction Background Postoperative cognitive dysfunction (POCD) is a prevalent complication in elderly patients and has significant clinical and socioeconomic consequences, delayed recovery, decreased quality of life, persistent neurocognitive disorders and increased morbidity and mortality within the first year of surgery . The pathogenesis remains poorly understood, partly due to varying diagnostic approaches and methodologies. Nevertheless, there is consensus that POCD is multifactorial influenced by factors such as advanced age, sleep disturbances, and inadequate perioperative pain management .
Sleep deprivation, in particular, can exacerbate hyperalgesia, impair cognition, and lead to increased respiratory and cardiac risks due to REM sleep rebound. Fast-track surgical protocols, which emphasize multimodal rehabilitation-including regional anesthesia, opioid-sparing analgesia, and early mobilization-have been shown to reduce postoperative pain, sleep disturbances, and the risk of delirium. These protocols have reduced the average length of hospital stays worldwide. In Denmark length of hospital stay after total hip arthroplasty (THA), total knee arthroplasty (TKA) and unicompartmental knee (UKA) is now only one day and an increasing number of patients are discharged on the day of surgery. Same-day discharge enable earlier return to a familiar environment and potentially enhanced pathophysiological recovery.
No studies have described early postoperative cognitive test performance in elderly patients undergoing same-day discharge hip and knee arthroplasty. This study therefore aims to address this knowledge gap by examining early cognitive changes in patients aged ≥70 years after same-day discharge hip and knee arthroplasty.
Aim The primary aim of this study is to report early cognitive changes measured with Symbol Digit Modality Test (SDMT) in patients over 70 years undergoing same-day discharge THA, TKA and UKA. Secondary, to report cognitive changes using the Stroop Color Test and verbal fluency test as well as patient's perceived cognitive function. As patients return home on the day of surgery in this contemporary same-day discharge arthroplasty setting, we hypothesize that early postoperative changes in cognitive performance will be limited compared with earlier fast-track studies with a longer median length of stay (LOS).
Methods
The cognitive tests:
The cognitive tests will be administered by research assistants with prior research experience.
Eligible participants will be recruited from the outpatient clinic. Testing will be performed virtually with the patients being at home. The patients will receive instructions to complete all sessions in the same quiet room and on the same device, to keep environmental stimuli (lighting, background noise, screen distance, seating, posture, and internet conditions) constant and thereby reduce within-subject variance and practice effects. The baseline test will be administered 14 days +- 3 days prior to surgery to avoid preoperative anxiety effects. Postoperatively, testing will be carried out on postoperative day 1 and day 7. More frequent testing is avoided to reduce practice effects.
Only patients receiving spinal anesthesia will be included to minimize confounding from general anesthesia and to reflect current fast-track practice. Spinal anesthesia is administered using a relatively short-acting blockade bupivacaine 5 mg/mL, 2.5 mL (12.5 mg) in THA, while for primary TKA and UKA, bupivacaine 5 mg/mL, 2 mL (10 mg) . Standard local infiltration analgesia (LIA) will be used with 150 mL ropivacaine 2 mg/mL in knee arthroplasties but not in hip arthroplasties . Peripheral nerve blocks are not used. Patients will also receive cloxacillin 2 gr, methylprednisolone 125 mg and 1 gr tranexamic acid intravenously immediately prior to skin incision.
Postoperative pain management and other medication Postoperative pain management will follow a standardized multimodal, opioid-sparing regimen. All patients will receive paracetamol (1 g × 4) in combination with ibuprofen 400 mg × 3 (7 days) for THA patients in and 400 mg × 4 (14 days) for TKA and UKA patients, unless contraindicated.
Opioids will be reserved as rescue medication, administered only on an "as needed" basis. Morphine 10 mg tablets will be used as first-line rescue analgesia, with oxycodone 5 mg as an alternative for patients who do not tolerate morphine.
Data Source:
A REDCap database has been established in collaboration with the Open Patient Data Explorative Network (OPEN) at Odense University Hospital (25). Patients scheduled for hip and knee arthroplasty at Svendborg hospital and included in the planned study will be enrolled in the database following informed consent. Patient's baseline database will be registered on comorbidities and medication use entered by trained research staff.
Statistics and sample size Although this is an exploratory study, the sample size was guided by considerations from both the literature and our pilot planning. Because the design is paired, each participant serves as their own control (baseline vs. postoperative assessment). For the SDMT we assumed a minimal clinically important difference (MCID) of 4 points , a within-subject correlation of 0.85 between baseline and postoperative scores, and a standard deviation of 7.5 . With a two-sided alpha of 0.05 and 80% power, this corresponds to approximately 14 participants with complete paired measurements per subgroup (THA, TKA, and UKA) if analyses are performed separately. To account for anticipated dropout/non-same-day discharge, we will aim to enroll 16 patients per subgroup to obtain 14 participants with complete paired measurements.
Continuous variables will be summarized as mean with standard deviation (SD) and range if approximately normally distributed; otherwise as median with interquartile range (IQR) and range. Categorical variables will be described using absolute and relative frequencies (n, %).
Patient involvement Patients who have previously undergone hip or knee arthroplasty were involved in the design process. Their feedback informed the research questions and outcome measures, ensuring relevance and patient-centeredness. During pilot testing, participating patients also provided input on the planned assessment procedures and overall feasibility, which further informed methodological adjustments.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Target follow-up
- 7 Days
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| Total Hip Arthroplasty | – | –Patients aged 70 years or older undergoing elective unilateral total hip arthroplasty with planned discharge on the day of surgery. |
| Total Knee Arthroplasty | – | –Patients aged 70 years or older undergoing elective unilateral total knee arthroplasty with planned discharge on the day of surgery. |
| Unicompartmental Knee Arthroplasty | – | –Patients aged 70 years or older undergoing elective unilateral unicompartmental knee arthroplasty with planned discharge on the day of surgery. |
Who may qualify
- Ages
- 70 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Older adult
- Study population
- Patients scheduled for hip or knee arthroplasty at Svendborg hospital, Denmark.
Key inclusion criteria (3 listed)
- Unilateral elective primary Total Hip Arthroplasty, Total Knee Arthroplasty, or Unicompartmental Knee
- Native Danish speaker
- Spinal anesthesia
Key exclusion criteria (7 listed)
- Inability or unwillingness to provide informed consent
- Inability to comply with virtual study procedures or follow-up sessions, including because of visual or hearing impairment
- Known dementia or other diagnosed cognitive disorders or Brief Assessment of Impaired Cognition (BASIC)≤20
- Parkinson's disease or other neurological conditions causing functional impairment
- History of alcohol abuse (≥35 units per week)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
Change in Symbol Digit Modalities Test (SDMT) score from baseline to postoperative day 1.
Time frame: From baseline, 14 days before surgery, and postoperative day 1.
The SDMT is a validated neuropsychological tool that measures processing speed, attention, and visual scanning. The SDMT will be administered virtually as an oral 90-second test. The primary metric will be the SDMT score, defined as the number of correct digit substitutions completed within 90 seconds
7 secondary outcomes
Change in Symbol Digit Modalities Test (SDMT) score from baseline to postoperative day 7.
Time frame: From baseline, 14 days before surgery, and postoperative day 7.
Change in Stroop Color-Word Test score from baseline to postoperative day 1.
Time frame: From baseline, 14 days before surgery, and postoperative day 1.
Change in Stroop Color-Word Test score from baseline to postoperative day 7.
Time frame: From baseline, 14 days before surgery, and postoperative day 7.
Change in Verbal fluency assessment score from baseline to postoperative day 1.
Time frame: From baseline, 14 days before surgery, and postoperative day 1.
Change in Verbal fluency assessment score from baseline to postoperative day 7.
Time frame: From baseline, 14 days before surgery, and postoperative day 7.
Reporting patient-reported cognitive function on postoperative day 1.
Time frame: Postoperative day 1.
Change in patient-reported cognitive function from postoperative day 1 to postoperative day 7.
Time frame: From postoperative day 1 and postoperative day 7.
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 22 Jun 2026.
- Background: PubMed 33143651Nissen SK, Fournaise A, Lauridsen JT, Ryg J, Nickel CH, Gudex C, Brabrand M, Andersen-Ranberg K. Cross-sectoral inter-rater reliability of the clinical frailty scale - a Danish translation and validation study. BMC Geriatr. 2020 Nov 3;20(1):443. doi: 10.1186/s12877-020-01850-y.
- Background: PubMed 34923428Strober LB, Bruce JM, Arnett PA, Alschuler KN, DeLuca J, Chiaravalloti N, Lebkuecher A, Di Benedetto M, Cozart J, Thelen J, Cadden M, Guty E, Roman CAF. A much needed metric: Defining reliable and statistically meaningful change of the oral version Symbol Digit Modalities Test (SDMT). Mult Scler Relat Disord. 2022 Jan;57:103405. doi: 10.1016/j.msard.2021.103405. Epub 2021 Nov 16.
- Background: PubMed 20830649Morrow SA, Drake A, Zivadinov R, Munschauer F, Weinstock-Guttman B, Benedict RH. Predicting loss of employment over three years in multiple sclerosis: clinically meaningful cognitive decline. Clin Neuropsychol. 2010 Oct;24(7):1131-45. doi: 10.1080/13854046.2010.511272. Epub 2010 Sep 8.
- Background: PubMed 18929686Harris PA, Taylor R, Thielke R, Payne J, Gonzalez N, Conde JG. Research electronic data capture (REDCap)--a metadata-driven methodology and workflow process for providing translational research informatics support. J Biomed Inform. 2009 Apr;42(2):377-81. doi: 10.1016/j.jbi.2008.08.010. Epub 2008 Sep 30.
- Background: PubMed 38839429Springborg AH, Jensen CB, Gromov K, Troelsen A, Kehlet H, Foss NB. Acute postoperative pain and catastrophizing in unicompartmental knee arthroplasty: a prospective, observational, single-center, cohort study. Reg Anesth Pain Med. 2025 Sep 4;50(9):706-711. doi: 10.1136/rapm-2024-105503.
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- Individual participant dataSharing planned: No. Individual participant data will not be publicly shared due to Danish data protection regulations and the nature of the clinical dataset. De-identified data may be made available from the investigators upon reasonable request and subject to applicable approvals.
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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.
Martin Lindberg-Larsen, Professor principal investigator
Head of Research / Consultant Orthopaedic Surgeon at Odense University Hospital. Department of Clinical Research, University of Southern Denmark (SDU)
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Postoperative Cognitive Dysfunction (POCD) and Cognitive Change, run by Odense University Hospital at 1 site in Denmark.
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 3 inclusion and 7 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 22 Jun 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 Denmark. 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 Abdullahi Abdirisak Hirsi, MD (+4553376575, abdullahi.abdirisak.hirsi2@rsyd.dk), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in Symbol Digit Modalities Test (SDMT) score from baseline to postoperative day 1. (time frame: From baseline, 14 days before surgery, and postoperative day 1.). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07598552, which also lists 23 linked publications.
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 22 Jun 2026.