This study adheres to the Standard Protocol Items for Randomized Trials (SPIRIT) guidelines [30] and follows the recommendations of the Standards for Universal Reporting of Decision Aids Evaluation (SUNDAE) [31]. It is reported according to the Consolidated Standards of Reporting Trials (CONSORT) extended guidelines for cluster-randomised controlled trials (C-RCTs) [32].
Study design
This study was a two-armed, multicentre (two centres), pragmatic superiority [33], C-RCT. Each cluster consisted of one single hip or knee surgeon randomised (allocated 1:1) to either continue standard consultation or perform SDM with an in-consult PtDA developed explicitly for patients with hip or knee OA before this study. Nineteen clusters across two university hospitals in Denmark were randomised and stratified by centre. The scheduled consultation duration remained consistent, regardless of the intervention or control group. The primary and secondary outcomes based on patient-reported data are collected one week post-consultation (timepoint 1 [T1]), and a project nurse registered the patients’ received or scheduled treatment six months post-consultation. The tertiary outcomes are assessed three months (timepoint 2 [T2]) and 12 months after treatment begins (timepoint 3 [T3]) and will be reported in follow-up studies.
Specific objectives and hypotheses
Objective 1: To investigate whether using an in-consult PtDA enhances the decisional quality for patients with severe OA of the hip or knee referred for treatment.
Hypothesis 1
Patients receiving consultations using an in-consult PtDA will achieve higher decisional quality than those receiving standard consultations.
Objective 2: To investigate whether an in-consult PtDA increases patient-experienced involvement in SDM.
Hypothesis 2
Patients receiving consultations using an in-consult PtDA will report greater involvement in SDM than those who receive standard consultations.
Objective 3: To compare durations between consultations using SDM with an in-consult PtDA and standard consultations and explore the learning curve in using the in-consult PtDA, expressed as the consultation duration.
Hypothesis 3.1
The duration will not differ between consultations using the in-consult PtDA and standard consultations.
Hypothesis 3.2
The duration of consultations using the in-consult PtDA will decrease over time, indicating a learning curve associated with PtDA integration.
Objective 4: To determine whether consultations using the in-consult PtDA are superior to standard consultations regarding the level of changes in the patient-reported outcomes of pain, physical function and QoL at 3 and 12 months following surgery.
Hypothesis 4
Consultations using a PtDA are superior to standard consultations regarding the level of changes in the patient-reported outcomes of pain, physical function and QoL at 3 and 12 months after surgery.
Objective 5: To determine the association between informed patient-centred (IPC) decisions and the level of changes in the patient-reported outcomes of pain, physical function and QoL at 3 and 12 months after surgery.
Hypothesis 5
IPC decisions are positively associated with the level of changes in patient-reported outcomes related to pain, physical function and QoL at 3 and 12 months after surgery.
Objective 6: To evaluate whether consultations using a PtDA are superior to standard consultations regarding patient satisfaction at 3 and 12 months after surgery.
Hypothesis 6
Consultations using a PtDA are superior to standard consultations regarding patient satisfaction at 3 and 12 months after surgery.
Participants, interventions and outcomes
Participants
Patients with OA in their hip or knee referred from general practice and scheduled for consultations with orthopaedic surgeons across the two study centres are screened for eligibility by the surgeons during the consultations regardless of the intervention arm. The surgeons inform the patients about the trial concept using a standardised protocol and obtain verbal informed consent.
The inclusion criteria for patients are:
-
Diagnosed with severe primary OA eligible for primary THR, TKR or UKR
-
Aged ≥ 18 years
-
Able to understand and read Danish
-
Provide informed consent
-
Able to receive mail in the electronic digital mailbox (E-Boks)
Patients with the following will be excluded:
-
Previous THR, TKR or UKR
-
Cognitive impairment
-
Non-OA-related diagnoses
Interventions
Two new in-consult PtDAs for patients with severe OA in the hip or knee were developed from a generic PtDA template adhering to the criteria set by the International Patient Decision Aid Standards [34, 35] to be tested in the intervention group. Both PtDAs, entitled ‘Which Treatment Is Right for Me?’ (Fig. 1), are presented in booklet form and represent the first editions of such aids for hip and knee OA in Denmark. Structured into five sections following the framework outlined by Steffensen et al. [36], these PtDAs feature option cards illustrating the pros and cons of each treatment, simplified statistics and patient stories.
Surgeons in the intervention group received a three-hour introduction and training course on the SDM concept and using an in-consult PtDA the day before the trial commenced at each of the two centres. This introduction also provided information about screening, recruitment, intervention and survey delivery at specific time points. Surgeons in the control group participated in a mandatory introductory course covering trial design with detailed task discussions. The sequence of activities within the orthopaedic clinic flow is illustrated in Fig. 2.
Outcomes
-
Demographics (T1) include participants’ age, sex, education level, income status, PtDA handout (yes or no) and a single-item self-reported pain score on a five-point Likert scale. At the cluster level, the information includes surgical experience (years), surgeon’s age, sex and surgical joint speciality (hip or knee; Table 1).
Table 1
Data collection, consent and timing of the questionnaires.
Outcome
Domain
|
Measurement
instruments
|
Objectives
|
Consultation
|
(T1)
|
(T2)
|
Six months post-consultation
|
(T3)
|
Score range
|
Items: N
(range)
|
Patient informed consent
|
Informed consent
|
|
x
|
x
|
|
|
|
|
|
Demographics
|
Demographic questionnaire
|
|
|
X
|
|
|
|
-
|
|
IPC decision
|
Concordance and Knowledge scores (HK-DQI) [37]
|
1, 6
|
|
X
|
|
|
|
Cat (yes [0]/no [1])
|
Concordance score
Knowledge sum score
(0–1)
|
Knowledge score
|
Knowledge score (HK-DQI) [37]
|
1
|
|
X
|
|
|
|
Con (0–100)
|
Five items
(0–5)
|
Treatment received
|
Patient journal
|
1
|
|
|
|
X
|
|
Cat (non-surgical [0]/surgical [1])
|
One item
(0–1)
|
Patient involvement
|
Decisional process score (HK-DQI) [37]
|
2
|
|
X
|
|
|
|
Con (0–100)
|
Five items
(0–4)
|
Patient-reported engagement
|
CollaboRATE [47]
|
2
|
|
X
|
|
|
|
Con (0–100)
|
Three items (0–9)
|
Time duration
|
Self-documented
|
3
|
X
|
|
|
|
|
Con (minutes)
|
-
|
Quality of life
|
EQ-5D-5L [41]
|
4, 6
|
|
X
|
X
|
|
X
|
Con (− 0.757–1.000)
|
Five items
(1–5)
|
Physical function
|
OHS [43]
|
4, 6
|
|
X
|
X
|
|
X
|
Con (0–48)
|
12 items
(0–4)
|
Physical function
|
OKS [42]
|
4, 6
|
|
X
|
X
|
|
X
|
Con (0–48)
|
12 items
(0–4)
|
Physical function
|
FJS [48]
|
4, 6
|
|
X
|
X
|
|
X
|
Con (0–100)
|
12 items
(1–5)
|
Patient satisfaction
|
One question on satisfaction with received treatment
|
5
|
|
|
X
|
|
X
|
Cat (yes/no)
|
One item
(0–1)
|
Decision regret
|
Decision regret scale [45]
|
5
|
|
|
X
|
|
X
|
Con (0–100)
|
Five items
(0–4)
|
Timepoints of data collection, send out through REDCap. Data types include Cat (categorical) and Con (continuous) variables, collected at T1 (one week post-visit), T2 (three months post-treatment), and T3 (12 months post-treatment). |
Primary outcome:
-
The primary outcome is the Hip/Knee OA Decision Quality Instrument (HK-DQI; T1), a patient-centred questionnaire designed to evaluate the quality of decision-making for joint replacement decisions. The HK-DQI is based on the Decision Quality Instrument (DQI), a disease-specific tool developed in the US in 2010 [37] that has separate versions tailored for hip (DQI-Hip) and knee (DQI-Knee) OA. These versions share identical content but differ in joint-specific terminology, collectively forming the HK-DQI [38]. The HK-DQI consists of three sections that assess decision-specific goals and concerns, decision-specific knowledge and the decision-making process [37]. It has demonstrated strong psychometric properties, including test-retest reliability, validity, sensitivity, acceptability and feasibility [37, 39]. Recently, both HK-DQI versions have been translated into Danish, and their psychometric properties have been rigorously evaluated.
-
The IPC decision (T1) is calculated as the percentage of patients who are well-informed (answering at least three out of five knowledge questions correctly) and concordance between preferred and received treatment (surgical or non-surgical).
Secondary outcomes:
-
CollaboRATE (T1) is a three-item patient-reported outcome measure assessing the level of SDM in the clinical encounter, evaluating healthcare quality and provider performance on a scale from 0 (no effort) to 9 (maximum effort) [40].
-
The surgeon learning curve (T1) is measured by surgeons after each consultation throughout the trial period, documenting their duration.
Tertiary outcomes:
-
EuroQol five-dimension five-level questionnaire (EQ-5D-5L; T1, T2 and T3) is a generic, concise, five-item preference-based health status measurement. It generates a single index value for health status ranging from − 0.757 to 1.000, with 1 indicating full health, 0 indicating death and a value below 0 indicating a health state worse than death [41].
-
Oxford Hip Score (OHS) and Oxford Knee Score (OKS; T1, T2 and T3) are both 12-item questionnaires with a score from 0 (worst) to 48 (best) points. They assess joint-specific outcomes and are widely used in research related to THR and TKR/UKR. Recognised for their reproducibility, validity and sensitivity to clinically meaningful changes, the OHS and OKS are tools for evaluating hip and knee function [42, 43].
-
Forgotten Joint Score (FJS; T1, T2 and T3) is a 12-item questionnaire assessing participants’ awareness of their artificial joints during activities of daily living (ADL) with a score ranging on a scale from 0 to 100 with higher values indicating that the patients successfully ‘forgetting’ the joint replacement during ADL. The FJS is used to assess the level of patient satisfaction after joint replacements, particularly in the hip and knee [44].
-
The decision regret scale (T2 and T3) is a five-item questionnaire used to assess the extent of regret or dissatisfaction individuals may experience regarding a specific decision, such as a healthcare choice or treatment option. The sum scores are scaled from 0 to 100, where 0 signifies no regret [45, 46].
-
Satisfaction (T2 and T3) comprises one question with response possibilities on a seven-point Likert scale assessing the patient’s overall satisfaction with health-related outcomes after treatment. The sum scores are scaled from 0 to 100, where 0 indicates high satisfaction.
Delivery of interventions and assessments
Patients with severe OA of the hip or knee referred from general practice and scheduled for appointments with orthopaedic surgeons at the two centres were screened for eligibility by the surgeon at the end of their consultation, irrespective of the intervention arm.
-
Intervention consultation: Patients in the intervention group consulting a surgeon actively participate in the decision-making process through SDM facilitated by an in-consult PtDA in addition to standard preliminary examinations.
-
Standard consultation: Patients in the control group undergo standard preliminary examinations with a surgeon and receive information following the usual practices at each centre.
-
Enrolment: Surgeons in both groups screen, recruit, obtain informed consent and provide written information to eligible patients at the end of the consultation. Eligible patients are enrolled regardless of the chosen treatment option. For patients undergoing non-surgical treatment, the treatment begins on the enrolment date, while for surgical patients, it begins on the date of surgery. Local project nurses ensure the recording of all screened patients in the electronic Research Electronic Data Capture (REDCap) database.
-
First survey at T1: One week after visiting the orthopaedic outpatient clinic, enrolled patients receive the (T1) survey in their electronic digital mailbox.
-
Second survey at T2: Follow-up assessments (T2) are collected through the patient’s electronic digital mailbox three months after receiving surgical or non-surgical treatment.
-
Treatment received or scheduled is registered by project nurses six months after consultation through a review of the patients’ electronic medical files.
-
Third survey at T3: The final follow-up assessments (T4) are sent via the patient’s electronic digital mailbox 12 months after their treatment began.
Enrolment and trial dates
Setting and enrolment strategies
The study recruited patients and surgeons from the orthopaedic departments specialising in fast-track hip and knee replacement at two university hospitals in the Region of Southern Denmark. These departments collectively perform almost 2,700 out of the approximately 26,000 THR, TKR and UKR surgeries performed annually in Denmark. An inclusion period of 12 months was expected, with an inclusion rate of 23% involving weekly enrolment of 11 patients and an anticipated dropout rate of 20%. The inclusion flow is illustrated as a CONSORT flow diagram (Fig. 3) [32].
Trial dates
Patient enrolment began in October 2023 at the first centre and in November 2023 at the second centre. The 12-month follow-up period commenced after patients received surgical or non-surgical treatment. Due to current waiting lists, the data collection period was estimated to last approximately two years, with an anticipated completion during the summer of 2026.
Randomisation and blinding
In October 2022, orthopaedic surgeons specialised in hip or knee replacements from both centres were randomised for the PATI study. Before the start of the trial, surgeons in the intervention group participated in the development phase of two new in-consult PtDAs (Fig. 2) that will be used in the intervention arm. A 1:1 randomisation was implemented using a computer-generated randomisation schedule, stratified by the surgeons’ employment centres and using permuted blocks of size 10. Additional blocks, each with a size of two, were introduced to accommodate potential changes, such as surgeons leaving or newly hired to the departments during the trial period.
An independent data manager created the computer-generated list of random numbers using the randomisation tool in REDCap [49]. The administrator responsible for the PATI study and the randomisation procedure will remain blinded to the sequence of random numbers within the blocks throughout the trial period. The randomisation of the clusters was disclosed to the two centres before the start of the trial. Patients will not be blinded to the interventions but will not be provided with explicit information about the intervention or control assignments. Similarly, the surgeons, project managers, and project nurses involved in the trial will not be blinded.
Data collection, sample size and analyses
Data collection
Upon their enrolment, patients’ assessments will be sent through REDCap. They will directly enter all data related to patient-reported outcomes into REDCap, with the ‘required fields’ option activated to ensure no missing items from completed questionnaires. Patients who fail to respond will receive reminders after three and six days. In case of continued non-response, the local project nurse will be notified and initiate up to two phone calls. If no response is obtained, the patients will be marked as ‘lost to follow-up’ in the database for the specific time point.
Sample size
The required sample size was estimated considering the possibility of some surgeons leaving the two centres during the trial period. Therefore, the sample size was calculated based on 15 clusters (surgeons) with an assumed intraclass correlation coefficient of 0.02, which represents how strongly individuals within clusters are related [50]. We also assumed a superiority difference between groups of 15% based on data from a comparable US setting, indicating that 40% of patients in the intervention group have high decisional quality compared to 25% in the control group [37, 38]. A total sample size of 615 patients will be enrolled to achieve a statistical power of 80% at a two-sided significance level of 0.05, which corresponds to approximately 41 patients in each cluster, accounting for an expected 20% loss to follow-up.
Statistical analysis plan
The statistics will be reported according to the guidelines outlined by the Enhancing the Quality and Transparency of Health Research (EQUATOR) network [51] and CONSORT [32] statements. A detailed statistical analysis plan was developed with the study protocol to ensure transparent and reproducible statistical methods.
The primary and secondary outcomes will be statistically analysed using mixed-effect models based on linear or binomial regression according to the data type of interest [52]. Due to the hierarchical structure of the data, surgeons will be incorporated as random effects. The analysis will be performed using the intention-to-treat approach, and in case of a cross-over, a per-protocol analysis will be conducted as sensitivity analysis [52]. Given the common presence of ceiling effects in several SDM assessment scores [53, 54], a sensitivity analysis will be conducted using a mixed-effect Tobit regression model [55] to explore their potential influences.
Consultation time will be analysed using a t-test if normally distributed and a Wilcoxon rank sum test otherwise. Histograms will be visually inspected to assess the normality assumption. The learning curve will be explored through descriptive analysis.
The proportion of missing data will be explored. If less than 5% of the data is missing, a complete case analysis will be performed. If more than 5% of the data is missing, the missing data structures will be investigated, considering potential imputation methods [52, 56].
Data monitoring and auditing
Given this study’s minimal risk, an external Data and Safety Monitoring Board was not established. Instead, the study manager and local project nurses are conducting meticulous internal data monitoring. The study manager and project nurses hold weekly meetings, either in person or by phone, to ensure adherence to the protocol and the smooth progression of the project.
All aspects of participant enrolment, including recruitment and survey response rates across the two centres, are being systematically tracked. No interim analyses are planned for this study.
Ethics and dissemination
Protocol amendments
Any substantial adjustments to the protocol will be appropriately registered at www.ClinicalTrials.gov, reported to The Regional Committees on Health Research Ethics for Southern Denmark and addressed in the primary C-RCT publication.
Patient and public involvement
Before initiating the PATI study, a qualitative study contributed to developing two distinct in-consult PtDAs tailored to patients with hip and knee OA entitled “Which Treatment Is Right for Me?” Surgeons randomised to the intervention group and fifteen patients actively participated in focus group discussions and remained engaged throughout the development and testing processes.
Study participant consent
Before the C-RCT began, a comprehensive kickoff meeting was conducted to engage all study staff from each centre. In this meeting, participants were briefed about its objectives, their respective roles and the anticipated timeline for enrolment. This meeting was held to foster an open communication environment, encouraging study staff and surgeons to contribute with suggestions or raise any concerns related to the trial material and setup.
Patient consent
Eligible patients are presented with verbal and written information about the study, including the privacy protection concept according to ethical standards outlined in the Declaration of Helsinki [57]. Then, the patients express their voluntary agreement to participate by signing an informed consent form within the REDCap platform at T1.