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Original Paper |
University of Miami, School of Medicine (C.J.L., R.J.S.), Florida
Mayo Medical School (L.B.), Rochester, Minnesota
Address reprint requests to: Carlos J. Lavernia, MD, 1321 NW 14th Street, Suite 203, Miami, FL 33125.
| ABSTRACT |
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Methods: One hundred and nineteen patients were evaluated. Standard preoperative laboratory tests were performed on all patients. Medical severity of illness was assessed on all patients using the Charlson Comorbidity Index. Anesthesia and surgical time was recorded. Short term outcome was assessed utilizing hospital charges as a measure of resource consumption, length of stay (LOS), in-hospital consults and the presence and number of complications during hospitalization. Non-parametric Kruskall Wallis and chi-square statistical analyses were performed. A p value <.05 was considered significant.
Results: Mean age was 64.6 years±15.62. 52.9% had osteoarthritis (OA), 4.2% had rheumatoid arthritis (RA), 5.9% had osteonecrosis (ON), 9.2% had a hip fracture and 28% had a failed total knee arthroplasty (TKA) or total hip arthroplasty (THA). Mean albumin and total lymphocyte count (TLC) were 38.5 g/L±4.78 SD and 1884 cells/µL±762 SD, respectively. Patients with albumin levels less than 34 g/L had 32.7% higher charges ($50,108±8203 SE vs. $33,720±1128 SE, p < .006), higher medical severity of illness (p=.03) and longer LOS (8.6±1.7 SE vs. 5.2±.356 SE days, p<.001). Patients with TLC less than 1200 cells/µL had higher charges ($32,544±1050 SE vs. $42,098±3122 SE, p=.004), longer LOS (5.7±.531 vs. 5.4 days±.368, p=.004) and anesthesia (242.85±17.55 SE vs. 198.6 min.±6.06 SE, p=.02) and surgical times (177.14 min.±17.57 SE vs. 120.21 min.±6.22 SE, p=.002) when compared with patients with TLC higher than 1200 cells/µL. These findings were still significant when adjusted for medical severity of illness and age.
Conclusions: Our data demonstrate that preoperative nutritional status is an excellent predictor of short term outcome. Serum albumin and TLC correlate with resource consumption, length of stay and operative time in patients undergoing joint replacement surgery. These parameters may be improved with nutritional supplementation prior to surgery.
Key words: nutrition, arthroplasty, outcome, resource consumption, hip, knee
Abbreviations: BMI=body mass index LOS=length of stay MANOVA=multivariate analysis of variance SD=standard deviation SE=standard error TLC=total lymphocyte count
| INTRODUCTION |
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Nutrition significantly affects the healing process. Patients with burns, sepsis or surgery enter a catabolic phase with a significantly increased nutritional demand. Postoperative loss of appetite decreases the exogenous caloric supply necessary for energy and wound healing. Proteins are then mobilized from lean body mass, such as skeletal muscle, to aid in this process during the perioperative period. Protein demand can be increased up to 35% while intake is significantly reduced [5].
The role of nutrition and diet in orthopedics was first reported by Cuthbertson in 1936 [6,7]. A higher complication rate was reported in patients with low albumin recovering from hip fractures [8]. This has also been observed in cerebral palsy patients undergoing surgery for scoliosis correction [9]. Few studies have tried to assess the importance of nutrition in joint replacement surgery.
Studies have reported a high incidence of subclinical malnutrition in patients undergoing orthopaedic surgical procedures [10]. Total protein, albumin, total lymphocyte count (TLC), transferrin levels and delayed hypersensitivity have been used as nutritional markers. The joint replacement population consists mostly of elderly patients. Studies suggest that these patients are at an increased risk of protein-calorie malnutrition [11,12,13].
Our objective of was to assess the effect of preoperative nutritional parameters on the short term outcome and resource consumption in patients undergoing joint replacement surgery.
| METHODS |
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Standard preoperative laboratory tests were performed prior to surgery. Patients were grouped into normal and abnormal albumin and TLC levels. Albumin levels of 34 g/L or less and TLC less than 1200 cells/µL were considered the lower limit of normal. Preoperative medical questionnaires (CJL) and medical charts were reviewed for secondary medical diagnoses. Medical severity of illness was assessed utilizing the Charlson Comorbidity Index which takes into account the number as well as the severity of medical illness at the time of the surgical procedure [14]. Each disease was given a weight score, and the patients total score was obtained by adding each individual disease score.
Anesthesia and surgical times were documented from the operating room records. Short-term surgical outcome parameters included hospital charges as a measure of health resource consumption, length of stay (LOS), the presence of in-hospital complications and the number of in-hospital medical or surgical consults obtained. Charges and LOS were provided by the chief financial officer of our hospital. Complications were defined as events that occurred during surgery or the preoperative period that could increase resource consumption. Length of stay in days was divided into four categories: 03, 46, 79 and >10 days. Likewise, three categories were used for the number of in-hospital consults and for the comorbidity index: 0, 1 and 2 or more. The resulting data were analyzed as ordinal variables.
Non-parametric Kruskall-Wallis, chi-square and stepwise multiple regression analysis were utilized on the statistical analysis. A p-value less than .05 was considered statistically significant.
| RESULTS |
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The mean (±SD) body mass index (BMI) in our study group was 27.02 kg/m2±4.6. The average charge (±SD) for all patients was $36,750.58±20.118 (range $15,684$206,604; median $33,106), with an average LOS of 5.9±4.9 days, mean number of in-hospital consults of 0.93±1.29 and an average anesthesia and surgical times of 212.72 minutes±72.14 and 138.71 minutes±75.14, respectively. The average comorbidity index score for all patients was 0.66. Table 2 shows the number as well as the percentage of comorbid medical conditions present at the time of surgery. Among the 119 patients, the overall complication rate was 26.1% (number of complications/number of patients). Two of six patients who presented more than one complication had albumin levels of less than 34 g/L. Table 3 shows the number as well as the percentage of complications in all patients divided by albumin levels.
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| DISCUSSION |
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Unfavorable results in malnourished patients have also been reported in surgical populations [15,16,17]. Patients with low albumin levels have increased postoperative morbidity and mortality. In the postsurgical catabolic state, patients who are better nourished heal faster, thereby shortening their hospital stay. In our study, those patients with low albumin levels were hospitalized an average of three days more than those with normal albumin levels. As shown in Table 3, all complications in patients with albumin levels of 34 g/L or less were major complications. This could account for the increased number of in-hospital specialist consultations and longer hospital stays observed in our study.
Low albumin levels have also been associated with higher mortality rates in hospitalized and surgical patients [18,19]. Corti et al. [20] reported that men 71 years or older, with hypoalbuminemia (<35 g/L), had a 1.9 times greater risk of death from any cause than men with normal albumin levels. Herrmann et al. looked at 15,511 patients serum albumin level within the first 48 hours of admission as a predictor of death and readmission. The low-albumin group (<34 g/L) had a death rate of 14% and a mean readmission time of 97.2 days, while the normal albumin level group had a 4% death rate and a 109-day mean readmission time [4]. In our cohort, only one surgical procedure was complicated by death. This patient had a preoperative albumin level of 24 g/L.
Puskarich et al. [21] found TLC to have an 87.5% negative predictive value for patients developing infection after surgical fixation of long bone fracture. The positive predictive value was only 14.6%. Therefore, a low TLC value is not reliable in predicting possible infections, but patients with a higher TLC are unlikely to develop an infection. Delmi et al. [9] found that patients with fractured necks of the femur that were given nutritional supplementation for 32 days after admission had significantly better clinical outcomes. The complication and death rates were 44% for the supplemented group and 87% for the control groups. After six months these values were still lower for the supplemented group (40% vs. 74%).
The effects of preoperative nutritional status have been studied before in joint replacement. Gherini et al. [22] studied 103 hips in 92 patients and concluded that preoperative transferrin levels were predictors of delayed wound healing. Greene et al. [23] found a direct correlation of low TLC and albumin levels with wound complications in patients that underwent joint replacement. Del Salvio et al. reported that patients with albumin levels less than 39 g/L doubled their hospital stays, for the most part patients with preoperative diagnosis of osteonecrosis [24]. We did not find an increased risk of intrahospital infection or wound-healing problems in our group of patients; however, a longer follow-up might show an adverse effect in preoperative malnutrition on outcome.
Some authors have shown an inverse relationship between age and nutrition [10,11]. The average age in our two groups was very similar (64.54 vs. 65.18 years). Patients in our study with low albumin had a higher Charlson Comorbidity Index. Friedman et al. consider the presence of comorbid conditions as the most frequent cause of hypoalbuminemia [25]. Old age and comorbidities could therefore be confounding variables. In our study, there was no statistically significant correlation between age and albumin or TLC. We did not find age to be a confounding variable. Comorbid diseases were also analyzed as a confounding variable utilizing MANOVA, and our results continued to be statistically significant.
The senior author in this study routinely screened for preoperative nutritional parameters. In many cases, surgery was postponed until the patients were better nourished. This could explain the reduced number of patients with low albumin and TLC in our cohort. Out of all patients studied, 22 had albumin levels below 34 g/L. Stepwise multiple regression analysis showed that preoperative diagnosis was the most important predictor of hospital charges and surgical time. Patients with hip fractures had lower preoperative mean albumin levels than the rest of the cohort, but this was not statistically significant (3.3273±.573 vs. 3.9065±.435, p=.388). Our results demonstrate that low albumin levels are predictors of short-term outcome after arthroplasty for all patients, but especially for hip fracture patients.
In this study, we included primary, revision and hemiarthroplasty procedures. Multiple regression analysis was performed and surgical procedure was not found to be a confounding variable.
This study emphasizes the importance of assessing nutritional status preoperatively. The orthopedic surgeon should be aware of the increased surgical risk in the malnourished patient. Increased surgical and anesthesia times, longer LOS and more in-hospital consults signify greater health-resource consumption. With continuously increasing health care costs, it is important to identify factors that reliably predict short-term outcome.
| CONCLUSIONS |
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| ACKNOWLEDGMENTS |
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Received May 1, 1998. Accepted December 1, 1998.
| REFERENCES |
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