Impact of body mass on hospital resource use in total hip arthroplasty

Weighing the Impact: The Influence of Body Mass Index on Facility Costs in Total Joint Arthroplasty

BACKGROUND

Using time-driven activity-based costing (TDABC), a novel cost calculation method that more accurately reflects true resource utilization in health care, we sought to compare the total facility costs across different body mass index (BMI) groups following total joint arthroplasty (TJA).

METHODS

The study consisted of 13,806 TJAs (7,340 total knee arthroplasties [TKAs] and 6,466 total hip arthroplasties [THAs]) performed between 2019 and 2023. The TDABC data from an analytics platform was employed to depict total facility costs, comprising personnel and supply costs. For the analysis, patients were stratified into four BMI categories: <30, 30 to <35, 35 to <40, and ≥40. Multivariable regression was used to determine the independent effect of BMI on facility costs.

RESULTS

When indexed to patients who had BMI <30, elevated BMI categories (30 to <35, 35 to <40, and ≥40) were associated with higher total personnel costs (TKA 1.03x versus 1.07x versus 1.13x, P < .001; THA 1.00x versus 1.08x versus 1.08x, P < .001), and total supply costs (TKA 1.01x versus 1.04x versus 1.04x, P < .001; THA 1.01x versus 1.02x versus 1.03x, P = .007). Total facility costs in TJAs were significantly greater in higher BMI categories (TKA 1.02x versus 1.05x versus 1.08x, P < .001; THA 1.01x versus 1.05x versus 1.05x, P < .001). Notably, when incorporating adjustments for demographics and comorbidities, BMI values of 35, 40, and 45 relative to BMI of 25, exhibit a significant association with a 2, 3, and 5% increase in total facility cost for TKAs and a 3, 5, and 7% increase for THAs.

CONCLUSIONS

Using TDABC methodology, this study found that overall facility costs of TJAs increase with BMI. The present study provides patient-level cost insights, indicating the potential need for reassessment of physician compensation models in this population. Further studies may facilitate the development of risk-adjusted procedural codes and compensation models for public and private payors.

LEVEL OF EVIDENCE

Level IV, economic and decision analyses.

Risk Factors for Increased Hospital Costs for Primary Total Hip Arthroplasty

BACKGROUND

Patient medical complexity increases the cost of primary total hip arthroplasty (THA). The goal of this study was to quantify the impact of specific medical comorbidities on the real hospital cost of primary THA.

METHODS

This study consisted of a retrospective analysis of 1,222 patient encounters for Current Procedural Terminology code 27130 (primary THA) between January 2017 and March 2020 at a high-volume urban academic medical center. Patient demographics, comorbidities, and admission data were collected, and univariate and multivariate gamma regression analyses were performed to identify associations with increased costs incurred during THA admission.

RESULTS

The median total cost for THA was $30,580. Univariate analysis showed increased cost for body mass index (BMI) > 35 versus BMI < 35 ($31,739 versus 30,071; P < .05), American Society of Anesthesiologists (ASA) score 3 to 4 versus ASA 1 to 2 ($32,268 versus 30,045; P < .05), prevalence of diabetes ($31,523 versus 30,379; P < .05), congestive heart failure ($34,814 versus 30,584; P < .05), peripheral vascular disease (PVD) ($35,369 versus 30,573; P < .05), chronic pulmonary disease (CPD) ($34,625 versus 30,405; P < .05), renal disease ($31,973 versus 30,352; P < .05), and increased length of stay (r = 0.424; P < .05). Multivariate gamma regression showed that BMI > 35 (relative risk [RR] = 1.05), ASA 3 to 4 (RR = 1.07), PVD (RR = 1.29), CPD (RR = 1.13), and renal disease (RR = 1.09) were independently associated with increased THA hospital cost (P < .01). Increased costs seen in BMI > 35 versus BMI < 35 patients were largely due to hospital room and board ($6,345 versus 5,766; P = .01) and operating room costs ($5,744 versus 5,185; P < .05).

CONCLUSIONS

A BMI > 35, PVD, CPD, renal disease, and ASA 3 to 4 are associated with higher inpatient hospital costs for THA.

LEVEL OF EVIDENCE

Level III; Retrospective cohort study.

Obesity and perioperative outcomes in older surgical patients undergoing elective spine and major arthroplasty surgery

STUDY OBJECTIVE

To determine whether obesity status is associated with perioperative complications, discharge outcomes and hospital length of stay in older surgical patients.

DESIGN

Secondary analysis of five independent study cohorts (N = 1262).

SETTING

An academic medical center between 2001 and 2017 in the United States.

PATIENTS

Patients aged 65 years or older who were scheduled to undergo elective spine, knee, or hip surgery with an expected hospital stay of at least 2 days.

MEASUREMENTS

Body mass index (BMI) was stratified as nonobese (BMI ≤ 30 kg/m2), obesity class 1 (30 kg/m2 ≤ BMI < 35 kg/m2) or obesity class 2-3 (BMI ≥ 35 kg/m2). Primary outcomes included predefined intraoperative and postoperative complications, hospital length of stay (LOS), and discharge location. Univariate and multivariate logistic regression was performed.

MAIN RESULTS

Obesity status was not associated with intraoperative adverse events. However, obesity class 2-3 significantly increased the risk for postoperative complications (IRR 1.43, 95% CI 1.03-1.95, P = 0.03), hospital LOS (IRR 1.13, 95% CI 1.02-1.25, P = 0.02) and non-home discharge destination (OR 1.95, 95% CI 1.35-2.81, P < 0.001) after accounting for patient related factors and surgery type.

CONCLUSIONS

Obesity class 2-3 status has prognostic value in predicting an increased incidence of postoperative complications, increased hospital LOS, and non-home discharge location. These results have important clinical implications for preoperative informed consent and provide areas to target for care improvement for the older obese individual.

The Effect of Obesity on Operating Room Utilization in Breast Surgery

BACKGROUND

The current obesity epidemic is associated with increased health care costs associated with comorbidities such as diabetes and heart disease as well as postoperative complications. However, the effect of obesity on operating room (OR) utilization, especially in common breast procedures, has not been completely evaluated. Our study is the first to examine the effect of patient obesity on operative time (OPT) for common breast procedures.

METHODS

The American College of Surgeons National Surgical Quality Improvement Project databases for 2010-2018 were searched for this retrospective review. Patients undergoing common breast operations (lumpectomy, lumpectomy with sentinel lymph node biopsy (SLNB) (+/- injection), lumpectomy and axillary lymph node dissection (ALND), simple mastectomy, mastectomy with SLNB (+/- injection), and mastectomy with ALND) were filtered out by Current Procedural Terminology code and divided into three groups based on their body mass index (BMI) and weight. Using the two-sample t-test, OPT for the procedures was compared among the lowest and highest BMI and weight categories. We also used a linear regression t-test to demonstrate that for every unit increase in BMI, there was a corresponding increase in OPT for each procedure.

RESULTS

When the lowest and highest BMI and weight groups were compared, significant differences in OPT (P < 0.0001) were seen for each of the procedures. Numerous factors that could affect the complexity of surgery and thus OR time were identified. The correlation between BMI and weight and OPT remained significant after controlling for these variables. The differences between the highest and lowest BMI groups were most pronounced for higher complexity procedures, such as lumpectomy with ALND and mastectomy with ALND, with average operating times increasing by 18.2 min and 18.6 min, respectively, for patients with a higher BMI.

CONCLUSIONS

Patient BMI and weight significantly affect OPT for common breast procedures. Therefore, patient BMI should be taken into account to improve OR scheduling.

Total Hip Arthroplasty in the Obese Patient: Tips and Tricks and Review of the Literature

AIM

There is a lack of consensus on the optimal method of performing primary hip arthroplasty in obese patients and limited evidence. This article presents a series of considerations based on the authors' experiences as well as a review of the literature.

PREOPERATIVE CARE

In the preoperative phase, an informed consent process is recommended. Weight loss is recommended according to NHS England guidelines, and body habitus should be taken into account. When templating, steps are taken to avoid overestimating the implant size.

SURGICAL PROCEDURE

During the surgical procedure, specialist bariatric equipment is utilised: bariatric beds, extra supports, hover mattresses, longer scalpels, diathermy, cell saver and minimally invasive surgery equipment. Communication with the anaesthetist and surgical team to anticipate is vital. Intraoperative sizing and imaging, if required, should be considered. Pneumatic foot pumps are preferable for VTE prophylaxis. Regional anaesthesia is preferred due to technical difficulty. IV antibiotics and tranexamic acid are recommended. The anterior and posterior surgical approaches are most frequently used; we advocate posterior. Incisions are extensile and a higher offset is considered intraoperatively, as well as dual mobility and constrained liners to reduce dislocation risk. When closing the wound, Charnely button and sponge should be considered as well as negative pressure wound dressings (iNPWTd) and drains.

POST-OPERATIVE CONSIDERATIONS

Postoperatively, difficult extubation should be anticipated with ITU/HDU beds available. Epidural anaesthetics for postoperative pain management require higher nursing vigilance. Chemical prophylaxis is recommended.

CONCLUSION

Despite being technically more difficult with higher risks, functional outcomes are comparable with patients with a normal BMI.

Length of Hospital Stay for Osteoarthritic Primary Hip and Knee Replacement Surgeries in New Zealand

This study aims to explore the length of stay (LOS) of publicly funded osteoarthritic primary hip and knee replacement surgeries in New Zealand. Patients with osteoarthritis who underwent publicly funded primary hip and knee replacement surgery in 2005-2017 were included. We have identified 53,439 osteoarthritic primary hip replacements and 50,072 osteoarthritic primary knee replacements. LOS has been reduced by almost 40% over the last 13 years. Logistic regression showed that women, Māori, Pacific and Asian patients, older patients, people with more comorbidities and those having opiates on discharge and patients in earlier years were more likely to have extended LOS following hip replacements and knee replacements. Regional differences were noted in LOS between the Waitemata District Health Board (DHB) compared to Tairāwhiti DHB where patients were the most likely to have a LOS of more than 5 days after hip and knee replacements. LOS after hip and knee replacements has been reduced dramatically. Women, Māori, Pacific and Asian patients, older patients and people with more comorbidities are more likely to have extended LOS. Patients dispensed opiates on discharge had a longer LOS. There are great geographical variations in LOS for primary hip and knee surgeries in New Zealand.

Risk Factors Associated With Health Care Utilization and Costs of Patients Undergoing Lower Extremity Joint Replacement

BACKGROUND

The Comprehensive Care for Joint Replacement program implemented by the Centers for Medicare and Medicaid Services did not incorporate risk adjustment for lower extremity joint replacement (LEJR). Lack of adjustment places hospitals at financial risk and creates incentives for adverse patient selection.

OBJECTIVE

To identify patient-level risk factors associated with health care utilization and costs of patients undergoing LEJR.

METHODS

A comprehensive search of research databases from January 1, 1990, through January 31, 2016, was conducted. The databases included Ovid MEDLINE In-Process & Other Non-Indexed Citations, Ovid MEDLINE, Ovid EMBASE, Ovid Cochrane Central Register of Controlled Trials, Ovid Cochrane Database of Systematic Reviews, and SCOPUS and is reported according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. The search identified 2020 studies. Eligible studies focused on primary unilateral and bilateral LEJR. Independent reviewers determined study eligibility and extracted utilization and cost data.

RESULTS

Seventy-nine of 330 studies (24%) were included and were abstracted for analysis. Comorbidities, age, disease severity, and obesity were associated with increased costs. Increased number of comorbidities and age, presence of specific comorbidities, lower socioeconomic status, and female sex had evidence of increased length of stay. We found no significant association between indication for surgery and the likelihood of readmission.

CONCLUSION

Developing a risk adjustment model for LEJR that incorporates clinical variables may serve to reduce the likelihood of adverse patient selection and enhance appropriate reimbursement aligned with procedural complexity.

The Evaluation of Comorbidities Relative to Length of Stay for Total Joint Arthroplasty Patients

BACKGROUND

The ability to identify those at risk for longer inpatient stay helps providers with postoperative planning and patient expectations. Decreasing length of stay (LOS) in the future will be determined by appropriate patient selection, risk stratification, and preoperative patient optimization. The purpose of this study was to identify factors that place patients at risk for extended postoperative LOSs.

METHODS

The study cohort included 2009 primary total knee arthroplasty (TKA) patients and 905 total hip arthroplasty (THA) patients. Patient comorbidities were prospectively identified and the LOS for each patient was tracked after a primary arthroplasty. Statistical analysis was performed to correlate which comorbidities were associated with longer inpatient stays.

RESULTS

In the TKA population, gender, smoking status, venous thromboembolism history, body mass index, and diabetes status were not found to be a significant predictor for the LOS. Age was found to be a factor in univariate regression testing (P < .001). In the THA population, univariate testing showed female gender (P < .001), smoking status (P = .002), and age (P < .001) to be factors, but like the TKA population, venous thromboembolism history or diabetes status was not significant. In THA multivariate analysis, age (P < .001) and female gender (P = .018) continued to be factors, but smoking was determined to be a confounding variable.

CONCLUSION

Age and gender were associated with a longer LOS after THA, whereas only age was a significant factor after TKA. Development of age-adjusted LOS models may help aid patient expectations and risk management.

The Cost and Outcome Effectiveness of Total Hip Replacement: Technique Choice and Volume-Output Effects Matter

BACKGROUND

Total hip replacement (THR) must be managed in a more sustainable manner. More cost-effective surgical techniques and the centralization/regionalization of services are two solutions. The former requires an assessment of newer minimally invasive and muscle-sparing surgical techniques. The latter necessitates an effective volume-outcome (VO) relationship. Prior studies have failed to evaluate and control for the VO relation.

OBJECTIVE

The objective of this study was to evaluate the relative cost and outcome effectiveness of two minimally invasive and one muscle-sparing techniques while evaluating and controlling for a potentially endogenous VO relation.

METHODS

An all payer claims database for all THR performed in Maine in 2011 was used. The cost and outcome effectiveness of newer minimally invasive (modified Hardinge) and muscle-sparing (modified Watson-Jones) techniques were compared with the standard bearer posterior minimally invasive method. Using regression analysis, the outcomes analyzed were as follows: total costs, length of hospital stay, nursing care and home discharges, and use of physical therapy. Regression analysis was also used to evaluate and control for VO effects.

RESULTS

(1) Newer muscle-sparing and minimally invasive approaches are substantially more effective; (2) irrespective of technique, higher volume surgeons are more effective; (3) technique-specific VO effects for more complex techniques exist and show substantial savings when yearly volume exceeds 30-50; and (4) the anterolateral muscle-sparing technique is accessible to the average surgeon.

CONCLUSION

Reliance on newer surgical techniques and centralization/regionalization of THR services can reduce costs.

Predictors of Hospital Length of Stay in an Enhanced Recovery After Surgery Program for Primary Total Hip Arthroplasty

BACKGROUND

Shorter length of stay (LOS) for total hip arthroplasty (THA) is becoming standard, yet variables identifying candidates for a 1-day discharge in an enhanced recovery after surgery program are not well defined. With growing emphasis on cost-efficiency and bundled care for THA, this study looked to identify variables that correlated with LOS.

METHODS

A retrospective chart review was performed for 273 primary THAs, from April 2014 to January 2015. Clinical measures differentiating a 1-day LOS cohort from that of a LOS longer than 1 day were identified. Direct medical costs were calculated for services billed during hospitalization.

RESULTS

Logistic regression identified the following preoperative patient characteristics to correlate with an LOS >1 day: older age (odds ratio [OR]: 1.06, P < .001), increased body mass index (OR: 1.06, P = .005), female gender (OR: 1.76, P = .031), American Society of Anesthesiologists score 3 or 4 (OR: 1.84, P = .029), and coronary artery disease (OR: 3.90, P = .013). After adjusting for age, body mass index, and gender, the following perioperative variables led to an LOS ≥2 days: general anesthesia (OR: 2.24, P = .007), longer operative time (OR: 1.04, P < .001), and increased blood loss (OR: 1.01, P = .001). Postoperatively, not ambulating on the day of surgery strongly correlated with an LOS ≥2 days (OR: 3.9, P < .001). Hospital costs were approximately $2900 higher for a 2-day LOS.

CONCLUSION

With growing emphasis on cost-efficiency, studying the association of clinical factors with LOS is necessary to develop a preoperative and perioperative predictive risk stratification model that may be used to help optimize discharge protocols for patients in an enhanced recovery after surgery program.

Addressing obesity in the management of knee and hip osteoarthritis - weighing in from an economic perspective

Background

Obesity is one of the only modifiable risk factors for both incidence and progression of Osteoarthritis (OA). So there is increasing interest from a public health perspective in addressing obesity in the management of OA. While evidence of the efficacy of intereventions designed to address obesity in OA populations continues to grow, little is known about their economic credentials.

The aim of this study is to conduct a scoping review of: (i) the published economic evidence assessing the economic impact of obesity in OA populations; (ii) economic evaluations of interventions designed to explicitly address obesity in the prevention and management of OA in order to determine which represent value for money. Besides describing the current state of the literature, the study highlights research gaps and identifies future research priorities.

Methods

In July 2014, a search of the peer reviewed literature, published in English, was undertaken for the period January 1975 – July 2014 using Medline Complete (Ebscohost), Embase, Econlit, Global Health, Health Economics Evaluation Database (HEED), all Cochrane Library databases as well as the grey literature using Google and reference lists of relevant studies. A combination of key search terms was used to identify papers assessing the economic impact of obesity in OA or economic evaluations conducted to assess the efficiency of obesity interventions for the prevention or management of OA.

Results

14 studes were identified; 13 were cost burden studies assessing the impact of obesity as a predictor for higher costs in Total Joint Arthroplasty (TJA) patients and one a cost-effectiveness study of an intervention designed to address obesity in the managment of mild to moderate OA patients.

Conclusion

The majority of the economic studies conducted are cost burden studies. While there is some evidence of the association between severe obesity and excess hospital costs for TJA patients, heterogeneity in studies precludes definitive statements about the strength of the association. With only one economic evaluation to inform policy and practice, there is a need for future research into the cost-effectiveness of obesity interventions designed both for prevention or management of OA along the disease spectrum and over the life course.

Changes in Payment Regulation and Acute Care Use for Total Hip Replacement: Trends in Length of Stay, Costs, and Discharge, 1997-2012

PURPOSE

To describe trends in the length of stay (LOS), costs, mortality, and discharge destination among a national sample of total hip replacement (THR) patients between 1997 and 2012.

DESIGN

Longitudinal retrospective design

METHODS

Descriptive analysis of the Healthcare Cost and Utilization Project (HCUP) National Inpatient Sample data.

FINDINGS

A total of 3,516,636 procedures were performed over the study period. Most THR patients were women, and the proportion aged 44-65 years increased. LOS decreased from 5 to 3 days. Charges more than doubled, from $22,184 to $53,901. Deaths decreased from 43 to 12 deaths per 10,000 patients. THR patients discharged to an institutional setting declined, while those discharged to the community increased.

CONCLUSION

We found an increase in THR patients, who were younger, women, had private insurance, and among those discharged to community-based settings.

CLINICAL RELEVANCE

Findings have implications for patient profiles, workplace environments, quality improvement, and educational preparation of nurses in acute and postacute settings.

The Relationship of Obesity to Increasing Health-Care Burden in the Setting of Orthopaedic Polytrauma

BACKGROUND

With the rise of obesity in the American population, there has been a proportionate increase of obesity in the trauma population. The purpose of this study was to use a computed tomography-based measurement of adiposity to determine if obesity is associated with an increased burden to the health-care system in patients with orthopaedic polytrauma.

METHODS

A prospective comprehensive trauma database at a level-I trauma center was utilized to identify 301 patients with polytrauma who had orthopaedic injuries and intensive care unit admission from 2006 to 2011. Routine thoracoabdominal computed tomographic scans allowed for measurement of the truncal adiposity volume. The truncal three-dimensional reconstruction body mass index was calculated from the computed tomography-based volumes based on a previously validated algorithm. A truncal three-dimensional reconstruction body mass index of <30 kg/m(2) denoted non-obese patients and ≥ 30 kg/m(2) denoted obese patients. The need for orthopaedic surgical procedure, in-hospital mortality, length of stay, hospital charges, and discharge disposition were compared between the two groups.

RESULTS

Of the 301 patients, 21.6% were classified as obese (truncal three-dimensional reconstruction body mass index of ≥ 30 kg/m(2)). Higher truncal three-dimensional reconstruction body mass index was associated with longer hospital length of stay (p = 0.02), more days spent in the intensive care unit (p = 0.03), more frequent discharge to a long-term care facility (p < 0.0002), higher rate of orthopaedic surgical intervention (p < 0.01), and increased total hospital charges (p < 0.001).

CONCLUSIONS

Computed tomographic scans, routinely obtained at the time of admission, can be utilized to calculate truncal adiposity and to investigate the impact of obesity on patients with polytrauma. Obese patients were found to have higher total hospital charges, longer hospital stays, discharge to a continuing-care facility, and a higher rate of orthopaedic surgical intervention.

Total hip replacement and surface replacement for the treatment of pain and disability resulting from end-stage arthritis of the hip (review of technology appraisal guidance 2 and 44): systematic review and economic evaluation

BACKGROUND

Total hip replacement (THR) involves the replacement of a damaged hip joint with an artificial hip prosthesis. Resurfacing arthroplasty (RS) involves replacement of the joint surface of the femoral head with a metal surface covering.

OBJECTIVES

To undertake clinical effectiveness and cost-effectiveness analysis of different types of THR and RS for the treatment of pain and disability in people with end-stage arthritis of the hip, in particular to compare the clinical effectiveness and cost-effectiveness of (1) different types of primary THR and RS for people in whom both procedures are suitable and (2) different types of primary THR for people who are not suitable for hip RS.

DATA SOURCES

Electronic databases including MEDLINE, EMBASE, The Cochrane Library, Current Controlled Trials and UK Clinical Research Network (UKCRN) Portfolio Database were searched in December 2012, with searches limited to publications from 2008 and sample sizes of ≥ 100 participants. Reference lists and websites of manufacturers and professional organisations were also screened.

REVIEW METHODS

Systematic reviews of the literature were undertaken to appraise the clinical effectiveness and cost-effectiveness of different types of THR and RS for people with end-stage arthritis of the hip. Included randomised controlled trials (RCTs) and systematic reviews were data extracted and risk of bias and methodological quality were independently assessed by two reviewers using the Cochrane Collaboration risk of bias tool and the Assessment of Multiple Systematic Reviews (AMSTAR) tool. A Markov multistate model was developed for the economic evaluation of the technologies. Sensitivity analyses stratified by sex and controlled for age were carried out to assess the robustness of the results.

RESULTS

A total of 2469 records were screened of which 37 were included, representing 16 RCTs and eight systematic reviews. The mean post-THR Harris Hip Score measured at different follow-up times (from 6 months to 10 years) did not differ between THR groups, including between cross-linked polyethylene and traditional polyethylene cup liners (pooled mean difference 2.29, 95% confidence interval -0.88 to 5.45). Five systematic reviews reported evidence on different types of THR (cemented vs. cementless cup fixation and implant articulation materials) but these reviews were inconclusive. Eleven cost-effectiveness studies were included; four provided relevant cost and utility data for the model. Thirty registry studies were included, with no studies reporting better implant survival for RS than for all types of THR. For all analyses, mean costs for RS were higher than those for THR and mean quality-adjusted life-years (QALYs) were lower. The incremental cost-effectiveness ratio for RS was dominated by THR, that is, THR was cheaper and more effective than RS (for a lifetime horizon in the base-case analysis, the incremental cost of RS was £11,284 and the incremental QALYs were -0.0879). For all age and sex groups RS remained clearly dominated by THR. Cost-effectiveness acceptability curves showed that, for all patients, THR was almost 100% cost-effective at any willingness-to-pay level. There were age and sex differences in the populations with different types of THR and variations in revision rates (from 1.6% to 3.5% at 9 years). For the base-case analysis, for all age and sex groups and a lifetime horizon, mean costs for category E (cemented components with a polyethylene-on-ceramic articulation) were slightly lower and mean QALYs for category E were slightly higher than those for all other THR categories in both deterministic and probabilistic analyses. Hence, category E dominated the other four categories. Sensitivity analysis using an age- and sex-adjusted log-normal model demonstrated that, over a lifetime horizon and at a willingness-to-pay threshold of £20,000 per QALY, categories A and E were equally likely (50%) to be cost-effective.

LIMITATIONS

A large proportion of the included studies were inconclusive because of poor reporting, missing data, inconsistent results and/or great uncertainty in the treatment effect estimates. This warrants cautious interpretation of the findings. The evidence on complications was scarce, which may be because of the absence or rarity of these events or because of under-reporting. The poor reporting meant that it was not possible to explore contextual factors that might have influenced study results and also reduced the applicability of the findings to routine clinical practice in the UK. The scope of the review was limited to evidence published in English in 2008 or later, which could be interpreted as a weakness; however, systematic reviews would provide summary evidence for studies published before 2008.

CONCLUSIONS

Compared with THR, revision rates for RS were higher, mean costs for RS were higher and mean QALYs gained were lower; RS was dominated by THR. Similar results were obtained in the deterministic and probabilistic analyses and for all age and sex groups THR was almost 100% cost-effective at any willingness-to-pay level. Revision rates for all types of THR were low. Category A THR (cemented components with a polyethylene-on-metal articulation) was more cost-effective for older age groups. However, across all age-sex groups combined, the mean cost for category E THR (cemented components with a polyethylene-on-ceramic articulation) was slightly lower and the mean QALYs gained were slightly higher. Category E therefore dominated the other four categories. Certain types of THR appeared to confer some benefit, including larger femoral head sizes, use of a cemented cup, use of a cross-linked polyethylene cup liner and a ceramic-on-ceramic as opposed to a metal-on-polyethylene articulation. Further RCTs with long-term follow-up are needed.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013003924.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Complications of Morbid Obesity in Total Joint Arthroplasty: Risk Stratification Based on BMI

This study stratifies complication risk in primary total joint arthroplasty (TJA) based on body mass index (BMI). Demographics, co-morbidities, perioperative variables, and complications were reviewed for 22,808 patients. Chi-squared, one-way ANOVA, univariate and multivariable regression analysis were performed. Increasing BMI led to an increase (P<0.05) in combined complications, acute kidney injury (AKI), cardiac arrest (CA), reintubation, reoperation, and superficial infection (SI). Univariate analysis for BMI>40 revealed an increase in combined complications (15.21-vs-17.40%), AKI (1.93-vs-3.87%), CA (0.22-vs-0.57%), reintubation (0.47-vs-0.95%), reoperation (2.36-vs-3.37%), and SI (0.82-vs-1.65%). Multivariable regression showed BMI>40 as an independent predictor for combined complications (OR=1.18), AKI (OR=1.79), CA (OR=3.94), reintubation (OR=2.56), reoperation (OR=1.44), and SI (OR=2.11). Morbid obesity confers increased risk for complications in TJA.

Which patient characteristics influence length of hospital stay after primary total hip arthroplasty in a ‘fast-track’ setting?

After implementation of a ‘fast-track’ rehabilitation protocol in our hospital, mean length of hospital stay for primary total hip arthroplasty decreased from 4.6 to 2.9 nights for unselected patients. However, despite this reduction there was still a wide range across the patients’ hospital duration. The purpose of this study was to identify which specific patient characteristics influence length of stay after successful implementation of a ‘fast-track’ rehabilitation protocol. A total of 477 patients (317 female and 160 male, mean age 71.0 years; 39.3 to 92.6, mean BMI 27.0 kg/m2;18.8 to 45.2) who underwent primary total hip arthroplasty between 1 February 2011 and 31 January 2013, were included in this retrospective cohort study. A length of stay greater than the median was considered as an increased duration. Logistic regression analyses were performed to identify potential factors associated with increased durations. Median length of stay was two nights (interquartile range 1), and the mean length of stay 2.9 nights (1 to 75). In all, 266 patients had a length of stay ≤ two nights. Age (odds ratio (OR) 2.46; 95% confidence intervals (CI) 1.72 to 3.51; p <  0.001), living situation (alone vs living together with cohabitants, OR 2.09; 95% CI 1.33 to 3.30; p = 0.002) and approach (anterior approach vs lateral, OR 0.29; 95% CI 0.19 to 0.46; p <  0.001) (posterolateral approach vs lateral, OR 0.24; 95% CI 0.10 to 0.55; p < 0.001) were factors that were significantly associated with increased length of stay in the multivariable logistic regression model.

Cite this article: Bone Joint J 2015;97-B:19–23.

Obesity, orthopaedics, and outcomes

Obesity, one of the most common health conditions, affects an ever-increasing percentage of orthopaedic patients. Obesity is also associated with other medical conditions, including diabetes, cardiovascular disease, pulmonary disease, metabolic syndrome, and obstructive sleep apnea. These comorbidities require specific preoperative and postoperative measures to improve outcomes in this patient population. Patients who are obese are at risk for increased perioperative complications; however, orthopaedic procedures may still offer notable pain relief and improved quality of life.

The effect of obesity and increasing age on operative time and length of stay in primary hip and knee arthroplasty

We retrospectively reviewed 589 patients undergoing lower-limb arthroplasty, recording age, body mass index (BMI) and co-morbidities. The effect of these on operative duration and length of stay (LOS) was analysed. For a 1 point increase in BMI we expect LOS to increase by a factor of 2.9% and mean theatre time to increase by 1.46minutes. For a 1-year increase in age, we expect LOS to increase by a factor of 1.2%. We have calculated the extra financial costs associated. The current reimbursement system underestimates the financial impact of BMI and age. The results have been used to produce a chart that allows prediction of LOS following lower limb arthroplasty based on BMI and age. These data are of use in planning operating lists.

Obesity increases operating room times in patients undergoing primary hip arthroplasty: a retrospective cohort analysis

Background. Obesity impacts utilization of healthcare resources. The goal of this study was to measure the relationship between increasing body mass index (BMI) in patients undergoing total hip arthroplasty (THA) with different components of operating room (OR) time.

Methods. The Stanford Translational Research Integrated Database Environment (STRIDE) was utilized to identify all ASA PS 2 or 3 patients who underwent primary THA at Stanford Medical Center from February 1, 2008 through January 1, 2013. Patients were divided into five groups based on the BMI weight classification. Regression analysis was used to quantify relationships between BMI and the different components of total OR time.

Results. 1,332 patients were included in the study. There were no statistically significant differences in age, gender, height, and ASA PS classification between the BMI groups. Normal-weight patients had a total OR time of 138.9 min compared 167.9 min (P < 0.001) for morbidly obese patients. At a BMI > 35 kg/m² each incremental BMI unit increase was associated with greater incremental total OR time increases.

Conclusion. Morbidly obese patients required significantly more total OR time than normal-weight patients undergoing a THA procedure. This increase in time is relevant when scheduling obese patients for surgery and has an important impact on health resource utilization.

Obesity increases length of stay and direct medical costs in total hip arthroplasty

BACKGROUND

The number of obese patients undergoing THA is increasing. Previous studies have shown that obesity is associated with an increased likelihood of complications after THA, but there is little information regarding the impact of obesity on medical resource use and direct medical costs in THA.

QUESTIONS/PURPOSES

We sought to examine the relationship between obesity, length of stay, and direct medical costs in a large cohort of patients undergoing THAs.

METHODS

The study included 8973 patients who had undergone 6410 primary and 2563 revision THAs at a large US medical center between January 1, 2000, and September 31, 2008. Patients with bilateral procedures within 90 days after index admission and patients with acute trauma were excluded. Data regarding clinical, surgical characteristics, and complications were obtained from the original medical records and the institutional joint registry. Patients were classified into eight groups based on their BMI at the time of surgery. Direct medical costs were calculated by using standardized, inflation-adjusted costs for services and procedures billed during hospitalization and the 90-day window. Study end points were hospital length of stay, direct medical costs during hospitalization, and the 90-day window. End points were compared across the eight BMI categories in multivariable risk-adjusted linear regression models.

RESULTS

Mean length of stay and the direct medical costs were lowest for patients with a BMI of 25 to 35 kg/m(2). Increasing BMI was associated with longer hospital stays and costs. Every five-unit increase in BMI beyond 30 kg/m(2) was associated with approximately USD $500 higher hospital costs and USD $900 higher 90-day costs in primary THA (p = 0.0001), which corresponded to 5% higher costs. The cost increase associated with BMI was greater in the revision THA cohort where every five-unit increase in BMI beyond 30 kg/m(2) was associated with approximately USD $800 higher hospital costs and USD $1500 higher 90-day costs. These estimates remained unchanged after adjusting for comorbidities or complications.

CONCLUSIONS

Obesity is associated with longer hospital stays and higher costs in THA. The significant effect of obesity on costs persists even among patients without comorbidities but the increased costs associated with obesity may be balanced by the potential benefits of THA in the obese. Increasing prevalence of obesity likely contributes to the increasing financial burden of THA worldwide.

LEVEL OF EVIDENCE

Level IV, economic and decision analyses. See the Instructions for Authors for a complete description of levels of evidence.

The increased utilization of operating room time in patients with increased BMI during primary total hip arthroplasty

While obesity is associated with increased need for total hip arthroplasty (THA), the relationship between body mass index (BMI) and operative duration is unknown. We reviewed a series of 425 primary THAs implanted by one surgeon from 2004 to 2010. Patients were grouped by BMI based on the World Health Organization's categorization. Intraoperative time measurements (Total Room Time, Anesthesia Induction Time, Surgery Time) were compared across groups. Mean times were analyzed using a one-way ANOVA with post-hoc least squares difference test. Operating time increased progressively with increasing BMI category. Significant differences were found between normal weight patients and all 3 obesity groups in total room and surgery times. Obese patients spend more time in the OR during THA, reflecting the burden obesity poses to surgeons and hospitals.

Impact of obesity on the cost of major colorectal surgery

BACKGROUND

The incidence of obesity is increasing in New Zealand. The aim of the study was to determine whether obesity impacts on the cost of treating patients undergoing major colorectal surgery.

METHODS

Between 1 February 2008 and 31 July 2009, consecutive patients undergoing major colorectal surgery at Christchurch Hospital, New Zealand, were enrolled in the study. Body mass index (BMI) and waist-to-hip ratios were assessed using standardized techniques. Patients with a high surgical risk were identified using established criteria and all patients were assessed using the Portsmouth modification of the Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (P-POSSUM). Cost analysis was performed using a structured query language database. Patients were analysed using accepted groupings for BMI, waist circumference and waist-to-hip ratio.

RESULTS

A total of 372 patients were enrolled in the study, of whom 345 were included in the analysis. The incidence of diabetes was significantly higher with increased BMI (P = 0·002), whereas all other co-morbidities, and P-POSSUM values, did not differ between BMI groups. The groups were similar in terms of case mix. Treatment of obese patients (BMI at least 30 kg/m(2)) was significantly more expensive than that of normal weight patients (BMI 20-24·9 kg/m(2)): €10,036 versus €7390 (P = 0·005). Treatment costs for patients with a BMI of 25-29·9 kg/m(2) were next highest (€9048) followed by those for patients whose BMI was less than 20 kg/m(2) (€8884). Patients with a waist circumference above recognized standards for men and women also cost significantly more to treat (€10,063 versus €7836; P = 0·014).

CONCLUSION

Excess body fat was associated with higher costs of major colorectal surgery.

Predictors of length of hospital stay after total hip replacement

PURPOSE

To identify variables affecting length of hospital stay after total hip replacement (THR) while controlling for potential confounders.

METHODS

Records of 199 consecutive elective unilateral THRs were reviewed. Clinical and demographic data including age, gender, body mass index, comorbidities, surgical factors (surgical approach, type of prosthesis, use of cement, operating time), anaesthetic factors (type of anaesthesia, ASA physical status), and length of hospital stay were recorded.

RESULTS

64% of patients left hospital within 12 days, 28% within 3 weeks, and 8% after 3 weeks. The median length of hospital stay was longer in women than men (11.5 vs. 9 days, p=0.009), in patients aged >65 years than those younger (13 vs. 9 days, p<0.0001), and in those with American Society of Anesthesiologists (ASA) grades 3 and 4 than grades 1 or 2 (14 vs. 9 days, p<0.0001). A greater proportion of women than men (45% vs. 27%, p=0.007), patients aged >65 years than those younger (61% vs. 37% or 24%, p<0.0001), and those with ASA grades 3 and 4 than grades 1 and 2 (68% vs. 25%, p<0.0001) stayed 12 days or longer. In the multiple regression analysis, the predictors for prolonged hospital stay (12 days or more) were patient age >65 years (p<0.003), female gender (p<0.05), and ASA grades 3 and 4 (p<0.0001). Of the 72 patients with prolonged stay, 7% had no, 26% had one, 42% had 2, and 25% had all 3 predictors.

CONCLUSION

Prolonged hospital stay after THR is largely predetermined by case mix. Our study helps to identify individuals who need longer rehabilitation and more care.

Ninety day mortality and its predictors after primary shoulder arthroplasty: an analysis of 4,019 patients from 1976-2008

BACKGROUND

Examine 90-day postoperative mortality and its predictors following shoulder arthroplasty

METHODS

We identified vital status of all adults who underwent primary shoulder arthroplasty (Total shoulder arthroplasty (TSA) or humeral head replacement (HHR)) at the Mayo Clinic from 1976-2008, using the prospectively collected information from Total Joint Registry. We used univariate logistic regression models to assess the association of gender, age, body mass index, American Society of Anesthesiologist (ASA) class, Deyo-Charlson comorbidity index, an underlying diagnosis and implant fixation with odds of 90-day mortality after TSA or HHR. Multivariable models additionally adjusted for the type of surgery (TSA versus HHR). Adjusted Odds ratio (OR) with 95% confidence interval (CI) were calculated.

RESULTS

Twenty-eight of the 3, 480 patient operated died within 90-days of shoulder arthroplasty (0.8%). In multivariable-adjusted analyses, the following factors were associated with significantly higher odds of 90-day mortality: higher Deyo-Charlson index (OR, 1.54; 95% CI:1.39, 1.70; p < 0.001); a diagnosis of tumor (OR, 16.2; 95%CI:7.1, 36.7); and ASA class III (OR, 3.57; 95% CI:1.29, 9.91; p = 0.01) or class IV (OR, 13.4; 95% CI:2.44, 73.86; p = 0.003). BMI ≥ 30 was associated with lower risk of 90-day mortality (OR, 0.25; 95% CI:0.08, 0.78). In univariate analyses, patients undergoing TSA had significantly lower 90-day mortality of 0.4% (8/2, 580) compared to 1% in HHR (20/1, 411) (odds ratio, 0.22 (95% CI: 0.10, 0.50); p = 0.0003).

CONCLUSIONS

90-day mortality following shoulder arthroplasty was low. An underlying diagnosis of tumor, higher comorbidity and higher ASA class were risk factors for higher 90-day mortality, while higher BMI was protective. Pre-operative comorbidity management may impact 90-day mortality following shoulder arthroplasty. A higher unadjusted mortality in patients undergoing TSA versus HHR may indicate the underlying differences in patients undergoing these procedures.

Does morbid obesity negatively affect the hospital course of patients undergoing treatment of closed, lower-extremity diaphyseal long-bone fractures?

Obesity is prevalent in the developed world and is associated with significant costs to the health care system. The effect of morbid obesity in patients operatively treated for long-bone fractures of the lower extremity is largely unknown. The National Trauma Data Bank was accessed to determine if morbidly obese patients (body mass index >40) with lower extremity fractures have longer length of hospital stay, higher cost, greater rehabilitation admission rates, and more complications than nonobese patients. We identified patients with operatively treated diaphyseal femur (6920) and tibia (5190) fractures. Polytrauma patients and patients younger than 16 years were excluded. Morbidly obese patients were identified by ICD-9 and database comorbidity designation (femur, 131 morbidly obese; tibia, 75 morbidly obese). Patients meeting these criteria who were not morbidly obese were used as controls. Sensitivity analyses were performed to analyze patients with isolated trauma to the tibia or femur. Morbidly obese patients were more likely to be admitted to a subacute facility. Length of stay trended higher in morbidly obese patients. There was no significant relationship between obesity and inpatient mortality or inpatient complications. These trends held true when considering patients with multiple injuries and patients who had isolated long-bone injuries. Our study showed that morbidly obese patients may have greater rehabilitation needs following long-bone fractures in the lower extremity. Our study showed no difference in mortality or complications, although further studies are needed to confirm these findings.

Does obesity affect early outcome of rotator cuff repair?

BACKGROUND

Obesity is linked to major health conditions and poor surgical outcomes. The impact of obesity on self-perceived outcome after rotator cuff repair (RCR) is unclear.

MATERIALS AND METHODS

We studied 154 patients who underwent RCR. Obesity was considered a body mass index (BMI) greater than 30. Preoperative and postoperative evaluations included the Disabilities of the Arm, Shoulder and Hand (DASH), Simple Shoulder Test, and visual analog scales for pain, function, and quality of life. Obese and control patients were compared for baseline demographics, surgical findings, and postoperative outcomes.

RESULTS

Our overall population had a mean BMI of 28.4 (95% confidence interval, 27.7-29.1). There were 57 obese patients (BMI >30) and 97 nonobese patients with 1- or 2-tendon rotator cuff tears. Mean follow-up was 54.8 weeks (range, 52.0-88.7 weeks). Preoperative DASH score was 45.2 for obese patients and 43.4 for control patients (P = .524). The mean improvement in DASH score was 30.7 for obese patients and 26.1 for nonobese patients (P = .152). There were no significant differences in the Simple Shoulder Test and visual analog scale scores. Worse follow-up DASH scores in both groups were associated with worker's compensation status (P = .003) and total comorbidities (P < .001). Multiple linear regression analysis showed that BMI (continuous) and obesity (dichotomous) were not significantly related to outcome after we controlled for confounding variables.

CONCLUSIONS

Although obesity is considered a risk factor for poor postoperative outcomes after some surgical procedures, in our experience, obesity does not have an independent, significant effect on self-reported early outcomes after RCR.