Patient Optimization

Mitchell R. Klement, MD

Andrew K. Battenberg, MD

Neither of the following authors nor any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this chapter: Dr. Klement and Dr. Battenberg.

ABSTRACT

The goal of all orthopedic surgery is to give the patient the best possible outcome. To achieve this goal, one must be technically proficient and minimize complications. Patient optimization involves the recognition of patient-specific risk factors for postoperative complications by the surgeon, and taking proactive measures to modify or reduce these risks before surgery. In general, these patient-specific risk factors are broken down into categories and those discussed herein are obesity, diabetes, malnutrition, smoking, alcohol and drug use, psychiatric disease, and rheumatologic conditions. Within each category this chapter will address the current literature, methods to identify those at increased risk, and steps to reduce these risks. Patient optimization involves a collaboration between family physicians, internal medicine specialists, infection disease specialists, anesthesiology, psychiatrists, and the ancillary staff. As a team, surgeons can ensure their patients are optimized before surgery and minimize complications.

Keywords: comorbidities; complications; patient optimization; perioperative management; risk factors

Introduction

In the era of value-based care, maximizing surgical outcomes, patient satisfaction, and minimizing perioperative complications are paramount. However, the key to surgical success starts not in the operating room but at the preoperative consultation. Optimization involves the recognition of patient-specific risk factors for complications and taking the appropriate steps to decrease, or modify, these risk factors. Postoperative complications directly affect patient outcomes, surgeon and hospital reimbursement, and increase costs to society. As orthopedic surgery becomes more common, and patients continue to live longer with more medical comorbidities, complications should be avoided whenever possible. Thus, a multidisciplinary, team-based approach to patient optimization should be used in the pre-and perioperative periods to provide the highest level of patient care.

Obesity

Obesity is defined as excessive fat accumulation and is commonly measured by the body mass index (BMI, weight in kg divided by meters squared, kg/m²). By this measure, a person with a BMI above 25 kg/m² is considered overweight and a BMI above 30 kg/m² is considered obese (Table 1). The prevalence of obesity is increasing at alarming proportions. From 1998 to 2011, obesity prevalence has increased from 39% to 52% of patients undergoing total hip arthroplasty (THA) and from 57% to 70% of patients undergoing total knee arthroplasty (TKA).¹ Furthermore, obesity has been associated with an increased risk of complications and adverse events, including increased superficial and deep infection, greater revision surgery rate, and worse patient-reported outcomes.²^,³^,⁴ In addition to higher rates of diabetes and vascular disease, worsening obesity has also been associated with greater rates of malnutrition, which may be a significant contributing factor to increased complications.⁵

Conventionally, body mass index has been studied as a categorical variable according to standard BMI classifications by the World Health Organization (WHO, Table 1). However, when treated as a continuous variable, increasing BMI remains associated with increased complication rates—most concerning is an 8% increased risk of infection for every unit of BMI greater than 25 kg/m^2.4 In 2013, a workgroup was convened by the American Association of Hip and Knee Surgeons (AAHKS) to review the evidence on complications and obesity.⁶ The authors concluded that in patients with a
BMI >40 kg/m² the functional improvements become less and the complication profile increases. The authors argue that arthroplasty should be delayed above this threshold.⁶

Table 1 World Health Organization Classification of Underweight, Normal Weight, and Obesity

Description		Body Mass Index (BMI, Kg/m²)
Underweight		<18.5
Normal Weight		18.5-24.9
Overweight		25.0-29.9
Obese
	Class I	30.0-34.9
	Class II	35.0-39.9
	Class III (ie, morbidly obese)	≥40.0
Kg = kilograms; m = meters

Methods to lose weight preoperatively include dietary assistance, exercise, and surgical methods such as bariatric surgery. Although obesity is considered a modifiable risk factor for complications and adverse events, data regarding benefits of weight loss before orthopedic surgery are limited. Preoperative weight loss >5% was not associated with a decreased risk of SSI or readmission.⁷ Additionally, the data regarding bariatric surgery is conflicting. Some studies demonstrate reduced complications⁸ whereas others show no difference or even worse outcomes compared with morbidly obese nonbariatric surgical patients.⁹^,¹⁰ Dramatic weight loss or bariatric surgery without proper nutritional guidance may lead to malnutrition and a persistent catabolic state, which could explain the possibility of higher complications in the preoperative weight loss populations. Although further studies are needed demonstrating reduced weight reduces surgical complications, any loss of weight may make surgery technically easier and improve patient well-being.

Diabetes

In the United States, 29.1 million Americans (9.3%) are estimated to have diabetes, with projections to 48.3 million by 2050—nearly double the current number.¹¹ Diabetes has been associated with poor outcomes following orthopedic surgery, including more in-hospital complications,¹² greater readmission rates,¹³ higher infection rates,²^,¹⁴ and worse patient-reported outcomes.¹⁵ Patients who are insulin-dependent are at even greater risk of adverse events than those who are not insulin-dependent.¹⁶ Alarmingly, when a recent study routinely screened arthroplasty patients for diabetes, 58.9% were found to be dysglycemic (prediabetic or diabetic),¹⁷ and 20.6% were found to be diabetic, of which 40.9% were previously undiagnosed.¹⁷ The rate is further elevated in patients older than 65 years.¹⁷ Therefore, consideration should be made for routine preoperative screening for diabetes before elective orthopedic surgery, especially for patients older than 65 years, patients with medical comorbidities, patients with a family history of diabetes, and patients undergoing procedures with a higher risk of complications.

Hemoglobin A1c (HgbA1c) is most widely used and is the most widely studied measure of glycemic control. Preoperative recommendations for the prevention of surgical site infection (SSI) include HgbA1c less than 7% and glucose level less than 200 mg/dL from the 2013 International Consensus Meeting (ICM) on Periprosthetic Joint Infection, a glucose level less than 200 mg/dL from the Center for Disease Control, and a HgbA1c less than 7% from Society for Healthcare Epidemiology of America.¹⁸ Preoperative glycemic control measured by HgbA1c correlates with postoperative blood glucose control, with HgbA1c greater than 7.45% associated with a significant risk of postoperative glucose levels greater than 200 mg/dL.¹⁹ Regarding clinical outcomes, using a threshold of 7.7% appears to be more indicative of infection and may be a better cutoff than 7%.²⁰ However, there is controversy around its ability to predict surgical outcomes. Because HgbA1c depends on the life cycle of red blood cells, it may take up to 3 months to observe changes in perceived glycemic control. This can confound interpretation of varying HgbA1c values pre-and perioperatively and may lead to unnecessary delays in surgery.

Serum fructosamine levels measure glycated serum proteins and reflect mean glucose over shorter time periods, 14 to 21 days.²¹ Patients with fructosamine levels greater than 292 µmol/L have a significantly higher risk for deep infection, readmission, and revision surgery.²¹ This simple and inexpensive test can be an alternative to HgbA1c and give more information on recent glycemic control; however, further study is needed of whether correcting fructosamine preoperatively reduces adverse events.²¹ Patients above this threshold should have further consultation with their internist or endocrinologist to improve their blood glucose control before elective surgery.

Malnutrition

Malnutrition is common in orthopedic patients and ranges from 4% to 45.9%.²²^,²³ Risk appears to increase with increasing age, particularly above 55 years.²⁴ Malnutrition is associated with greater risk of SSI, postoperative complication, readmission, and mortality.²²^,²³^,²⁴ Proposed mechanisms include lack of protein and other macronutrients needed for cellular proliferation, synthesis, and wound healing, as well as decreased immune function necessary to prevent and fight infection.²⁵

Currently, there is no agreed upon definition of malnutrition and no single test is used to conclusively define it. Commonly used tests and their thresholds include serum albumin less than 3.5 mg/dL, serum prealbumin less than 15 mg/dL, and serum transferrin less than 200 mg/dL, with any one of these deficiencies indicating a possible malnourished state. Albumin is easy to measure, is inexpensive, and has the longest half-life (14 to 20 days). It is, therefore, most useful as an indicator of chronic malnutrition and is less sensitive to acute changes in nutritional status.²⁵ Transferrin has a 10-day half-life, but is less reliable in assessing mild malnutrition, and is more susceptible to derangement with liver disease or various forms of anemia. Prealbumin has the shortest half-life (2 to 3 days) and varies more widely in response to acute events or changes in protein intake. Further laboratory evidence of malnutrition is a total lymphocyte count <1,500 cells/mm. Additional methods to assess malnutrition include standardized scoring tools, such as the subjective global assessment, which combines patient responses on current weight, recent changes to weight, food intake, eating habits, and activity level with objective measures on physical examination.²⁵

The efficacy of oral nutritional supplementation or correction of malnutrition in the nutritionally deficient patient has not been well studied, particularly in the orthopedic literature. Meta-analyses of nonsurgical patients have found significant reductions in complications, readmissions, and mortality with use of oral nutritional supplements, and further study in orthopedic surgical patients is needed.²⁶ Patients identified as malnourished should be counseled regarding their diet, and consultation with a nutritionist should be strongly considered. Supplementation with a high protein oral nutritional supplement may be beneficial, especially during the perioperative period.

Underweight Patients

Underweight patients are defined as having a BMI of less than 18.5 kg/m² (Table 1). These individuals have been shown to have a higher risk of infection, transfusion, readmission, and mortality.²⁷^,²⁸ There is contradictory evidence, however, with regard to wound complication and infection rates with some studies indicating lower rates for underweight patients.²⁹^,³⁰ Underweight patients have greater resource utilization as measured by length of stay, hospital charge, and need for skilled nursing.²⁹ The increases in length of stay and hospital charge postarthroplasty are likely related to greater rates of postoperative anemia and increased need for transfusion. Thus, identification, workup, and treatment of preoperative anemia should be performed in underweight patients for any procedure with a significant expected blood loss.

No studies have been performed that evaluate potential risk reduction with interventions that increase BMI of underweight patients. It is important to note that underweight status can have multiple causes and can be multifactorial, including genetic predisposition, age, eating disorders, or existence of a chronic disease state. Because of the heterogeneity of such patients, attempting to “optimize” underweight status can prove to be difficult. Most importantly, any nutritional deficiencies should be identified and treated, and underlying medical problems contributing to underweight status should be further evaluated and managed as part of multidisciplinary team with primary care, nutritionist, and the surgeon.

Vitamin D Deficiency

Vitamin D deficiency (VDD) is common, with rates reported to be up to 40% in orthopedic surgical patients.³¹ VDD can be screened for by measuring serum 25-hydroxyvitamin D (25[OH]D) levels. VDD can be defined as normal (≥32 ng/mL), insufficient (<32 ng/mL), and deficient (<20 ng/mL) based on the serum measurement.³¹ Vitamin D is well known for its role in calcium homeostasis, which impacts bone mineral density, fracture healing, and muscle function, but Vitamin D also plays an important role in immune function. Previous work has demonstrated vitamin-D’s regulation and activation of the innate and adaptive immune responses.³² Recent studies have shown a higher rate of VDD in periprosthetic joint infections and a higher rate of postoperative complications and infection in arthroplasty patients with VDD.³³^,³⁴ In a mouse model of periprosthetic infection, VDD mice were shown to have an increased bacterial burden when compared with VDD mice that received rescue vitamin D supplementation.³⁵ Bacterial burden was equivalent between normal mice and the VDD mice that received rescue supplementation, demonstrating vitamin D’s importance in immune function and its potential as a modifiable risk factor.

Males, patients aged 51 to 75 years, patients with darker skin tones, and patients undergoing sports or trauma orthopedic surgery are most at risk of VDD.³¹ Patients identified as having VDD should be treated perioperatively with a goal 25-hydroxyvitamin D level greater than 30 ng/mL. The recommended dietary allowance of vitamin D is between 200 and 2,000 international units (IU) per day for healthy adults,³⁶ but high-dose rapid-correction regimens have been described and can be implemented under the guidance of an internist or endocrinologist, particularly in cases of severe deficiency.

Smoking

Cigarette smoking remains the leading cause of preventable death in the United States and currently 15% of US adults still smoke.³⁷ Unlike the optimization of chronic medical conditions discussed herein, smoking is a preoperative habit that can be quit altogether. Cigarette smoke contains nearly 4,000 chemicals that result in vasoconstriction, displacement of oxygen on red blood cells, and deleterious effects on bone and soft tissues.³⁸ Smoking in orthopedic patients undergoing surgery ranges from 9% to 60%.³⁹^,⁴⁰ In addition to the known risks to general health and malignancy, smoking has been associated with increased nonsurgical and surgical readmissions,³⁹ increased bony nonunion (fractures, osteotomies, fusions),⁴¹ and wound healing complications.⁴⁰ Screening can be performed by urine tobacco metabolites. For active smokers, a positive test is urine nicotine of greater than 200 ng/mL and urine anabasine greater than 10 ng/mL. For nonsmokers or former smokers using nicotine replacement, a negative test is urine nicotine of greater than 200 ng/mL and urine anabasine less than 2 ng/mL. Finally, for nonsmokers and those not using nicotine replacement, a negative test would be a urine nicotine of less than 17 ng/mL and urine anabasine less than 2 ng/mL.

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