FP-00014

Section 1 - Basic information about you and your application:

Title of research project
Safety and efficacy of day case joint replacement in the NHS setting: a registry-based national cohort study

Grant Type
The ORUK Inspiration Fund

Research area
Treatment

Duration
12

Start date
February 7, 2024

Have you previously received funding from ORUK?
No.

Profession
Orthopaedic surgeon

Your current job title/position
Orthopaedic Registrar ST4, Academic Clinical Fellow

Are you an early-career researcher (ECR)? (definition of ECR)
no

Section 2 - Lay summary

Lay summary:

Osteoarthritis of joints causes severe pain and disability, and will affect over half of people in their lifetimes. End stage osteoarthritis of the hip and knee can be fully treated with a hip or knee replacement. However, there is no consensus over how long patients should stay in hospital for after joint replacement; patients can either stay for one or more nights in hospital (“inpatient”) or go home on the day of surgery (“day case”).

 

Day case joint replacement is becoming more popular internationally, particularly after the COVID-19 pandemic where hospital beds were limited. From the small studies so far, it appears to be safe and effective. However, in the UK, the amount of day case joint replacement surgery we are doing nationally is currently unclear; in 2018, less than 6% were done as day case, but more recent studies suggest that some hospitals are doing up to 60% in selected patients.

 

Increasing day case surgery is one way of enabling us to do more operations per year, reducing cancellations and waiting lists. If we were to increase our proportion of joint replacements done as day case to just 15%, this would save the hospital stay equivalent of 19,000 joint replacements a year.

 

However, although anecdotally we are doing more in this country, exactly how much we are doing, and the results, have not yet been studied on a national scale. We need to ensure that this change in practice is safe for patients, and that they do as well after surgery as those who stay in hospital. We will evaluate certain characteristics that might predict a worse outcome, to help guide who should and shouldn’t be considered for day case surgery.

 

We will investigate this by using data from the National Joint Registry (NJR), which is the largest joint replacement registry in the world and records data on all hip and knee replacements done in England. This data can be linked with the Hospital Episode Statistics (HES) database, which holds data on all NHS funded hospital admissions in England. From these databases we can identify all patients in the country who have had a day case joint replacement in the last decade, and their results after surgery.

 

Our ambition is to investigate to what extent day case joint replacement could be used to reduce waiting lists and enable working patients back into employment. If the results following day case surgery are worse, then the practice might need to be modified and investigated further. If the results are the same or better, then increasing how much day case surgery we are offering might be one of the ways we are able to reduce waiting times.

Section 3 - Purpose of research

Purpose of research:

Day case knee joint refers to the practice of discharging patients home on the day of surgery. Increasing day case surgery is one possible solution to meet the unprecedented and rising demand for joint replacement. Anecdotally the practice has been increasing in the UK, especially since the COVID-19 pandemic, which has acted as a catalyst for the rapid uptake of day case pathways internationally.

 

However, despite this change, we currently do not know the volume of day case joint replacements in an NHS setting, nor its safety and efficacy, outside a few published individual cohort studies.

 

The methodology will utilise linked NJR and HES data to define a national day case cohort of patients. The aim is to assess safety and efficacy of day case joint replacement.

 

Research questions

• What are the recent trends in day case joint replacement in England?
• What are the short and longer-term outcomes (readmissions, complications, reoperations, revisions, mortality, PROMs), and how do they compare with an inpatient stay?
• What are the risk factors for adverse outcomes?
• What are the unit-level effects of day case pathways?

 

Key deliverables

 

Papers on the following:

• Systematic review and meta-analysis on day case joint replacement
• Trends in day case joint replacement in England
• Day case joint replacement: short term outcomes and risk factors
• Day case joint replacement: long term outcomes and PROMs
• Day case joint replacement: the unit-level effects of day case pathways

 

This work is urgently needed on a change in practice that is already happening. Results will be of interest regardless of direction; if there are safety concerns then risk factors identified can be used to inform patient selection. If day case surgery is safe and effective then this would provide compelling evidence to expand the practice in order to meet the current unprecedented demand for surgery.

Section 4 - Background to investigation

Background to investigation:

Hip and knee replacements are highly successful and cost-effective treatments for end-stage arthritis. With an ageing and increasingly active population, continued rise in their demand is expected. However, the COVID-19 pandemic has had a profound and lasting effect on elective surgery, with no sign yet of recovery. The number of patients awaiting arthroplasty who described their quality of life as ‘worse than death’ nearly doubled in the first year of the pandemic. In the future, seasonal pressures will continue to compound the issue where acute medical patients are prioritised at the expense of elective patients when inpatient resources become stretched.

 

It is therefore in the interest of patients and the healthcare system as a whole to minimise the inpatient burden of elective orthopaedics, without compromising on outcomes. Day case principles follow those of enhanced recovery after surgery (ERAS) pathways, where use of standardised peri-operative protocols and early rehabilitation have both improved outcomes and reduced length of stay in the modern era.

 

The benefits of day case joint replacement can be seen to the healthcare system as a whole from reduced inpatient resource and cost, and to individual patients from shorter waiting list times and earlier mobilisation. The introduction of a day case pathway also has local effects in reducing overall inpatient length of stay (LOS) in the unit. The potential disadvantage however is that inappropriate premature discharge can lead to patient harm, poorer outcomes, and cost savings undone with failed same-day discharge (SDD) or readmission.

 

Day case joint replacement was first popularised in the US, with the UK relatively slower on the uptake. The generalisability of US studies to the universal healthcare system of the NHS is doubtful. Real-world data is lacking as to the safety of the practice in the UK.

 

Literature review

 

To form the background to this body of work which will be submitted for the award of a PhD, an updated systematic review and meta-analysis of the literature is in progress, with preliminary results as follows.

 

A systematic literature search was performed of MEDLINE and EMBASE databases from inception to April 2023 to include all studies comparing day case to inpatient hip and knee replacement. Meta-analysis was performed where appropriate using a random effects model. The study protocol was registered prospectively (PROSPERO CRD42023392811), and conducted in line with Cochrane and PRISMA recommendations.

 

Results

Thirty-eight studies were included, comprising 83,888 day case patients. Studies were predominantly from the US or Canada, retrospective in nature, and at serious risk of bias. Day case patients were on average younger (2 years), more likely to be male (OR 1.3), with a lower BMI and ASA grade compared to inpatients.

 

Overall, day case surgery was associated with significantly lower odds of readmission (OR 0.83, 95% CI 0.73 to 0.96, p = .009), ED attendance (OR 0.62, 95% CI 0.48 to 0.79, p < .001), and overall complications (OR 0.7, 95% CI 0.55 to 0.89, p = .004) than inpatients. There were no significant differences overall for reoperation or mortality. The overall successful same-day discharge (SDD) rate was 85% (95% CI 81 to 88%).

 

Conclusion

Within the limitations of the literature, the outcomes following day case hip and knee replacement appear non-inferior to those following an inpatient stay. The evidence is more robust for UKR than for TKR or THR. Day case discharge success is highest in UKR, followed by TKR, and comparatively lower in THR. PROMs, patient satisfaction, and cost effectiveness are either equal or favour day case surgery. There is a paucity of comparative UK studies. An adequately powered RCT is likely impractical. There is a need for a large observational NHS study.

 

Data access for this project has been granted by the NJR Research Committee with positive feedback from both the committee and patient representatives.

Section 5 - Plan of investigation

Plan of investigation:

Design

Retrospective analysis of prospectively collected observational data.

 

Setting

Population-based study using data from the National Joint Registry (NJR) which covers all hospitals that undertake joint replacement surgery in England, Wales, Northern Ireland, the Isle of Man and Guernsey. The NJR is the largest orthopaedic registry in the world. The Hospital Episode Statistics (HES) database records information on all NHS hospital admissions in England. Patient-level linkage can be performed to combine the two datasets.

 

Participants

Patients who underwent primary UKR or TKR in England between 1st April 2003 and 31^st December 2022.

 

Exclusion criteria

Revision procedures, same-day bilateral procedures, procedures in children (age < 18), records unable to be linked with HES, and records where patients have not explicitly given consent for their personal data to be stored in the NJR.

 

Equality and diversity statement

Limiting participants to England for this study is necessary as HES only covers England, and without HES data on admission and discharge dates it is not be possible to identify the day case patient cohort. Aside from this, the NJR collects data on all patients undergoing joint replacement regardless of age, disability, gender, ethnicity, religion, sexual orientation, and socioeconomic background.

 

Exposure

The exposure of interest is binary, namely whether the patient undergoing a knee replacement was a day case. Day case is defined here as date of operation being the same as the date of discharge. This definition is consistent with the British Associate of Day Surgery’s (BADS). This will be obtained from HES admission and discharge dates, patient classification, and postoperative duration data. The two groups will be termed day-case and inpatient.

 

Comparison group

The comparison inpatient group will be defined as those with a length of stay (LOS) of 1-2 days, based on the findings of the meta-analysis by Li et al. that these patients are a more valid control group than inpatients without a limit on the length of stay. A sensitivity analysis comparing to all inpatient stays will be performed to test this hypothesis.

 

Outcome measures

The first part of the project addresses key aim 1 to describe trends in day case practice in England. This will be assessed in context of the COVID-19 pandemic. Based on preliminary analysis of the data, a cut-off value will be set for proportion of day case above which a unit is considered a high proportion day case unit in the analysis.

 

All cause readmission is a commonly used primary outcome measure in the literature. It will be reliably captured in the HES database. Readmission soon after discharge can be considered a marker for failed or inappropriate discharge. It is a key factor in cost analysis. The reason for readmission is obtainable through HES ICD10 diagnosis codes.

 

Complication rate as an outcome measure adds further information by distinguishing between readmissions due to pain or failure to cope at home and readmissions due to complications, which may or may not be related to the exposure.

 

Reoperation is a measure for significant surgical complication and can be obtained from HES operation codes. Revision procedures are captured by the NJR but do not yet include reoperations that do not involve component exchange, such as manipulation under anaesthetic (MUA) for stiffness and fixation of periprosthetic fractures.

 

Mortality is required as an outcome measure to assess the safety of day case joint replacement.

 

PROMs are regularly recorded pre- and postoperatively, and ideally would form part of the assessment of day case surgery. However, redevelopment of the linkage process in 2021 has meant that these data are currently unavailable, with no current date set for resolution. An assessment of PROMs will be included if the data becomes accessible.

 

Covariates

The NJR and HES datasets include several covariates which will be adjusted for in the analysis. These will include patient factors: age, sex, ethnicity, socioeconomic status, American Society of Anesthesiologists (ASA) grade, detailed comorbidities from which a modified Charlson Comorbidity Index can be generated, and indication for surgery. Surgical factors include method of fixation, bearing, surgical approach, type of anaesthetic, and postoperative venous thromboembolism (VTE) prophylaxis.

 

Socioeconomic status will be classified at the time of primary procedure using the Index of Multiple Deprivation (IMD).

 

Statistical analysis

All statistical analysis will be done using the Stata software package (StataCorp; Texas). Simple descriptive statistics will be used to demonstrate the incidence of day-case surgery for each procedure, first overall and then over time. Proportion of surgeries occurring as day-case will then be calculated from total numbers including those who underwent inpatient stay, overall and then for each individual Trust. This will also be presented over time in order to illustrate trends.

 

The outcomes readmission, reoperation, revision, and death will all be modelled as time-to-event variables. Initially crude survival estimates will be generated using the Kaplan-Meier method. Basic stratification will be performed on potential confounders such as age group, gender, ASA grade, fixation, and bearing. More advanced analyses will then be performed by fitting flexible parametric survival models. Models will be adjusted by sequentially adding in the covariates of interest outlined above, with the most parsimonious models selected. This will identify risk factors for each outcome. Flexible parametric models have the advantage of being able to accommodate time-varying effects and providing an estimate for the baseline hazard. Results will be expressed as hazard ratios with 95% confidence intervals if hazards are proportional, or graphically if they are not. To facilitate comparisons with other studies in the literature, outcomes will also be analysed as binary with multivariable logistic regression used to generate odds ratios between day case and inpatient groups. Further sub-analyses will be conducted comparing outcomes between high and low proportion day case units.

Section 6 - Research environment and resources

Research environment and resources:

The team at ***** perform the analyses for the National Joint Registry (NJR) annual report as well as for other core outputs such as surgeon/unit and implant performance. They have substantial experience with the NJR, both solely and linked to other datasets such as HES.

This supervision team are part of the NJR Lot 2 contract team for statistical analysis and support and are hugely experienced in observational study techniques with a combined experience of two decades working on the NJR. I have been working with them during the ACF and will be continuing to do so for completion of the PhD and beyond.

This supervision team has extensive experience in doctorate supervision and has a proven track record of high-impact research outputs and success in obtaining research funding. Further materials are available for training in the form of the University’s Short Courses, which I have completed four of thus far, with materials of other courses available at no cost to me.

The data is therefore already routinely held and processed in the unit, meaning there are minimal additional costs necessary in terms of equipment.

The unit is based at *****, an outstanding centre for research in Population and Translational Health Sciences. ***** is a collaborative and multidisciplinary school. The Research Excellence Framework (REF 2021) confirms that ***** are a leading centre for health research, with 94% of BMS research impact case studies rated as world-leading. ***** currently hosts 255 research students and has a consistently excellent record in securing successful personal Fellowships. ***** will provide me with a nurturing and supportive environment. ***** holds a Silver Athena SWAN Award in recognition of the school’s ongoing commitment to promote equality, diversity and inclusion. They are fully signed up to the Research Concordat, and ***** is the Associate Pro Vice-Chancellor leading on Research Culture.

Section 7: Research impact

Who will benefit from this research?

There are over 700,000 patients in the UK currently awaiting an orthopaedic procedure. Versus Arthritis’ “Impossible to ignore” campaign was enacted in response to patient petitions regarding waiting times, which have not recovered since the pandemic.

Increasing day case joint replacement practice is one solution, and is one that centres around England are already practising. We do not have real-world data on this practice. A national cohort is therefore urgently needed to evaluate the safety of this significant change. If there are safety concerns then this could directly change practice, with risk factors evaluated to inform on patient selection. If day case joint replacement is safe and effective, the benefits are to the healthcare system as a whole from reduced inpatient resource and cost, and to individual patients as a result of shorter waiting list times.

Patients will therefore benefit regardless of the direction of results from this project.

How can your research be translated in real-life?

The results are anticipated to be of significant interest to the orthopaedic community and published in high impact-factor journals. They will be implemented directly by clinicians who practice evidence-based medicine, to inform on patient selection and during the consent process. I plan to present preliminary findings at BASK, BHS, and the BOA, as well as internationally at EFORT.

 

Engagement with key stakeholders such as BASK, BHS, Versus Arthritis, NJR, and patient groups is planned to aid dissemination. We have two PPI meetings planned in order to guide analysis and for the creation of patient-accessible materials based on our findings.

 

Further work will include a health economic analysis based on the clinical outcomes. Ultimately the aim is to influence, or pave the way for work that influences, NICE guidelines for day case surgery.

How will your research be beneficial for ORUK and its purpose?

The project fulfils the majority of the key ORUK funding aims. It assesses and informs on a change in practice that is already happening, and therefore expands knowledge and develops our understanding of peri-operative MSK protocols. Ensuring patient safety is paramount when assessing patient outcomes. If results of day case surgery are promising, the results have the potential to fundamentally change how we practice knee replacement in this country, and in doing so help to ease the burden on the NHS and support a health ageing society.

Section 8: Outreach and engagement

The aim is to use the results to produce a set of patient-accessible materials summarising the findings that can be provided to patients during the consent process. There is an active PPI group at our unit (the PEP-R group) with which we have two meetings planned, the first prior to analysis to validate what we are investigating, and the second to guide interpretation of the results and aid the production of materials. The plan is to engage stakeholders such as BHS, Versus Arthritis and the British Association of Day Case Surgery to aid in the dissemination of these materials.

Section 9: Research budget

Requested funding from ORUK

University fees (if any)
£10471

Salary
£99244

Consumables
£0

Publications
£0

Conference attendance
£0

Other items
£

Total 'requested fund'
£109715



Other items




Other secured funds

Internal funding
£0

Partner (University)
£0

Partner (Commercial)
£0

Partner (Charity)
£0

Other sources
£0

Total 'other funds)
£0

Section 10: Intellectual property and testing on animal

Is there an IP linked to this research?
No

Who owns and maintains this patent?


Does your research include procedures to be carried out on animals in the UK under the Animals (Scientific Procedures) Act?
No

If yes, have the following necessary approvals been given by:

The Home office(in relation to personal, project and establishment licences)?


Animal Welfare and Ethical Review Body?


Does your research involve the use of animals or animal tissue outside the UK?
No

Does the proposed research involve a protected species? (If yes, state which)



Does the proposed research involve genetically modified animals?


Include details of sample size calculations and statistical advice sought. Please use the ARRIVE guidelines when designing and describing your experiments.


There should be sufficient information to allow for a robust review of any applications involving animals. Further guidance is available from the National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs), including an online experimental design assistant to guide researchers through the design of animal experiments.

Please provide details of any moderate or severe procedures


Why is animal use necessary, are there any other possible approaches?


Why is the species/model to be used the most appropriate?