JORT Journal

Introduction

Clinicians and researchers have continued to investigate how patient demographics, such as age and sex, might inform treatment or expected patient outcomes. Studies of this nature have demonstrated that orthopaedic ailments and injuries are disproportionate among specific patient populations. For example, female patients exhibit a higher likelihood of experiencing intraoperative proximal femur fractures in cement less total hip arthroplasty (THA) [1] as well as an unequal incidence of autoimmune conditions affecting the musculoskeletal system, such as rheumatoid arthritis (RA) [2]. These findings have important implications for clinicians aiming to provide more personalized medicine to their patients.

Studies have demonstrated that social demographics, particularly marital status, correlate with patient outcomes; marital status affects smoking cessation success, and tranquil relationships increase medication adherence in RA patients [3-5]. Further, marital status affects surgical outcomes. Following outpatient and trauma-related orthopaedic surgeries, married patients discharge home (as opposed to rehab or a nursing facility) more frequently and report a superior postoperative quality of life compared to unwed patients [6,7]. In literature, single patients were associated with an increase in hospital readmissions following total knee arthroplasty (TKA) [8], while another study found that marital status was predictive of surgical site infection after various orthopedic surgeries [9].

Although these studies concluded that married patients fared better according to several postoperative clinical variables [6-9], few studies have assessed any correlation between marital status and joint functionality following total joint arthroplasty via patient-reported outcome measures (PROMs) [10-12]. Joint functionality PROMs include the Hip Disability and Osteoarthritis Outcome Score, Joint Replacement (HOOS JR) and Knee Disability and Osteoarthritis Outcome Score, Joint Replacement (KOOS JR) for hip and knee arthroplasties, respectively [13,14]. Previous studies investigating these metrics compared to marital status are mixed – one demonstrated non-significant improvement in some PROMs in married patients after TKA and THA [10]. Another study demonstrated worse PROMs for unmarried patients two years after THA [12]. Finally, a different study demonstrated better outcomes after TKA in married patients via one outcome measure but no difference in the other measured PROM when controlling for preoperative score [11]. Another study found no connection between marital status and joint functionality score, measured by the HOOS JR and KOOS JR for hip and knee arthroplasty, respectively [10].

Given the mixed prior literature on marital status's impact on PROMs, we sought to investigate any association. Although Singh et al found no KOOS JR or HOOS JR differences at one year between married and unmarried patients, we sought to build upon this by incorporating more scores, particularly within TKA, and additional PROM threshold analyses [10]. We hypothesized that our higher-powered study would demonstrate similar HOOS JR and KOOS JR scores between married and unmarried patients after TKA and THA. We also included comparison of PROMIS-10 (Patient-Reported Outcomes Measurement Information System) scores pre- and post-operatively between married and unmarried cohorts for further analysis and interpretation. With the results from this study, we aim to expand on current literature so that clinicians and patients can set realistic expectations regarding surgical outcomes and recovery.

Materials and Methods

After IRB approval, a retrospective review was conducted on all THA and TKA cases performed at a single site by seven orthopedic surgeons. Cases occurred from June 1st, 2023, to November 30^th, 2023, and were required to have been fully compliant with PROM collection: PROMIS-10 (quality of life) and HOOS JR or KOOS JR (joint-specific) scores preoperatively, as well as three, six, and twelve months postoperatively. Additional data collected from the electronic medical record (EMR) included self-reported marital status, age, sex, body mass index (BMI), length of stay, morphine milligram equivalents (MMEs), and readmissions within thirty and ninety days. Patients were classified as married if they reported a marital status of married or partnered, while patients were classified as unmarried if they reported a marital status of single, divorced, separated, widowed. Analysis was not conducted on the subsets of the unmarried cohort due to low representation. Calculations of MMEs were conducted only during the hospital stay.

Cohort Identification

A total of 278 primary THAs and 409 primary TKAs were initially identified. Within TKA, 25 patients were excluded for incomplete clinical records rendering them incongruent with the study’s goals and 2 patients were excluded for refusal to disclose marital status. This resulted in 382 TKAs being included. In THA, 17 patients were excluded for incomplete clinical records, and 1 for no marital status. This resulted in 260 THAs included.

Statistical Analysis

Data were analyzed using Python v3.11 (Python Software Foundation, Wilmington, DE). Continuous variables were analyzed using student’s t-tests, while categorical variables were assessed using χ². The Fisher’s exact test was utilized when there were ≤5 instances. Statistical significance was determined at p< 05. Achievement of the Patient Acceptable Symptom State (PASS) was calculated as a proportion of patients who recorded at least 63.7 on the KOOS JR and at least 76.7 on the HOOS JR., based on established thresholds [15]. The minimal clinically important difference (MCID) achievement was compared to the previously described anchor-based threshold of 14 and 18 for the KOOS JR and HOOS JR, respectively [16]. The overall score change (Δ) was calculated and analyzed for both the KOOS JR and HOOS JR.

Results

Total Knee Arthroplasty

Regarding demographics, married TKA patients were significantly younger than unmarried patients (66.5 ± 7.7 v 69.5 ± 9.5, P=.0011; Table 1). The proportion of married females was significantly lower than unmarried (51.2% v 73.8%, P=.0001). No significant differences in KOOS JR, PROMIS-10 Physical (PCS), or PROMIS-10 Mental (MCS) were observed for any timepoint between married and unmarried patients (Table 2). Both married and unmarried patients achieved PASS at nondifferent rates (82.8% v. 86.5%, respectively; P=.3539; Supplementary Table 1). The MCID achievement rate was also nonsignificant between married and unmarried patients (72.3 v 77.0%, respectively; P=.1623). The ΔKOOS JR scores between married and unmarried patients were insignificant (Supplementary Table 2). Married patients had a shorter length of stay than unmarried patients (0.9 ± 0.4 v 1.2 ± 0.8 days, respectively; P<.0001; Table 3). No other differences were observed for clinical variables.

Table 1: Patient Demographics by Marital Status and Joint Arthroplasty Procedure.

Table 2: PROMs of Patients Having Undergone TKA by Marital Status.

Supplementary Table 1: Achievement of Patient Acceptable Symptom State (PASS) [15] by Cohort.

Supplementary Table 2: Δ12 month HOOS and KOOS.

Table 3: Clinical Outcomes of Patients by Marital Status and Joint Arthroplasty.

Total Hip Arthroplasty

Regarding demographics, married THA patients were significantly younger than unmarried patients (64.2 ± 11.0 v 67.1 ± 10.3 years, respectively; P=.0470; Table 1). The proportion of females was significantly lower in married than unmarried (53.0% v 69.6%, respectively; P=.0127). Preoperatively, married patients reported a higher PCS score than unmarried (41.1 ± 6.3 v. 38.7 ± 7.7, respectively; P=.0101; Table 4), and after twelve months postoperatively, married patients reported higher PCS than unmarried patients (50.6 ± 8.8 v 48.0 ± 9.9, respectively; P= 0.0411). Married patients reported a higher MCS than unmarried patients at six months postoperatively (53.2 ± 7.8 v 50.3 ± 7.7, respectively; P= 0.0061). Married patients also reported a higher MCS than unmarried patients at twelve months postoperatively (53.5 ± 7.7 v 51.1 ± 8.7, respectively; P= 0.0282). No other significant differences were observed with respect to PROMs. Both married and unmarried patients achieved PASS at similar rates (72.4 v. 74.7, respectively; P=.6996; Supplementary Table 1). The MCID achievement rate was also nonsignificant between married and unmarried patients (74.6 v 81.0%, respectively; P= 0.1309). The ΔHOOS JR was not significant between groups (Supplementary Table 2). Married patients had a shorter length of stay than unmarried patients (0.9 ± 0.5 v 1.2 ± 0.8 days, respectively; P= 0.0034, Table 3). No other clinical differences were observed.

Table 4: PROMs of Patients Having Undergone THA by Marital Status.

Discussion

Demographic factors remain important considerations in surgical practice, and our study sought to investigate the effect of a particular demographic factor, marital status, on both clinical and patient-reported outcomes after total joint arthroplasty. Specifically, we focused on what differences might be found in PROMs and recovery threshold achievements between these two cohorts. To accomplish this, we evaluated the differences between pre-operative and post-operative scores in the KOOS JR, HOOS JR, and PROMIS-10 scores in cohorts of married and unmarried patients after TKA and THA.

Overall, our study demonstrates little significant difference in PROMs after these procedures. For TKA, no difference in any measured PROM was seen between married and unmarried cohorts at any time point. For THA, patients did demonstrate slightly higher MCS scores at six and twelve months post-operatively and also demonstrated slightly higher PCS scores pre- and post-operatively; these differences, however, are of questionable clinical relevance, particularly considering that the PCS difference is observed both before and after intervention. All other PROMs measured were not significantly different between the cohorts, including PASS and MCID achievement rates.

Our study sheds further light on an area where previous literature showed mixed results. One study of 512 THA patients demonstrated better PROMs at 2-year follow up in married patients compared to unmarried [12]. Another study of TKA and THA patients demonstrated findings quite like ours: KOOS JR and HOOS JR scores were not significantly different between married and unmarried cohorts after TKA and THA, whereas a statistically significant difference of questionable clinical significance was noted in other PROMs between the married and unmarried THA cohorts [10]. Another demonstrated no significant difference in TJA patients’ PROMs regarding marital status or other difference in living situation [17]. Overall, when viewed in combination with previous literature, our study demonstrates equivalent PROMs after knee and hip arthroplasty, despite few clinically insignificant differences in PROMs between married and unmarried cohorts after THA.

Surgeons may hesitate to recommend surgery to a patient who self-reports as single, divorced, or widowed; however, this study’s results suggest that such bias is misguided. Surgeons should instead thoroughly assess the patient’s mental and physical health in addition to their social support network. In cases of scarce social support, the medical care team can implement creative solutions to bridge this gap, such as recommending a support group or, in select cases, a nursing facility to promote optimal healing. Clinicians should recognize that simple classifications such as marital status fail to consider external factors that may influence patient outcomes and should strive toward a more holistic evaluation for post-surgical care.

Limitations

This study has several limitations. To begin, this research project was retrospective in nature, hindering proactive data collection. The study may also lack generalizability given data collection at one metropolitan site. Further, one limitation that may warrant further study is our lack of further assessment of patients’ living arrangements. For instance, we did not capture whether an unmarried patient lives with a non-spousal partner or other family member who may participate in this patient’s recovery. However, despite these limitations, the group remains confident in the accuracy and completeness of the results and study.

Conclusions

In total hip and knee arthroplasty, no differences in joint-specific PROMs were observed between married and unmarried patients. Some differences were observed both pre- and post-operatively between married and unmarried patients on the PROMIS-10 score. Unmarried patients do incur significantly more time in hospital following joint arthroplasty than married patients. Orthopedic surgeons should use the findings of this study to conduct holistic assessments of patients and their candidacy for arthroplasty irrespective of their marital status.

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