Lucas E. Nikkel

Impact of Comorbidities on Hospitalization Costs Following Hip Fracture

BACKGROUND Hip fractures are common in the elderly, and patients with hip fractures frequently have comorbid illnesses. Little is known about the relationship between comorbid illness and hospital costs or length of stay following the treatment of hip fracture in the United States. We hypothesized that specific individual comorbid illnesses and multiple comorbid illnesses would be directly related to the hospitalization costs and the length of stay for older patients following hip fracture. METHODS With use of discharge data from the 2007 Nationwide Inpatient Sample, 32,440 patients who were fifty-five years or older with an isolated, closed hip fracture were identified. Using generalized linear models, we estimated the impact of comorbidities on hospitalization costs and length of stay, controlling for patient, hospital, and procedure characteristics. RESULTS Hypertension, deficiency anemias, and fluid and electrolyte disorders were the most common comorbidities. The patients had a mean of three comorbidities. Only 4.9% of patients presented without comorbidities. The average estimated cost in our reference patient was

Discriminants of Prevalent Fractures in Chronic Kidney Disease

13,805. The comorbidity with the largest increased hospitalization cost was weight loss or malnutrition, followed by pulmonary circulation disorders. Most other comorbidities significantly increased the cost of hospitalization. Compared with internal fixation of the hip fracture, hip arthroplasty increased hospitalization costs significantly. CONCLUSIONS Comorbidities significantly affect the cost of hospitalization and length of stay following hip fracture in older Americans, even while controlling for other variables.

Risk of fractures after renal transplantation in the United States.

Patients with chronic kidney disease (CKD) have higher rates of fracture than the general population. Increased bone remodeling, leading to microarchitectural deterioration and increased fragility, may accompany declining kidney function, but there are no reliable methods to identify patients at increased risk for fracture. In this cross-sectional study of 82 patients with predialysis CKD, high-resolution imaging revealed that the 23 patients with current fractures had significantly lower areal density at the femoral neck; total, cortical, and trabecular volumetric bone density; cortical area and thickness; and trabecular thickness. Compared with levels in the lowest tertile, higher levels of osteocalcin, procollagen type-1 N-terminal propeptide, and tartrate-resistant acid phosphatase 5b were associated with higher odds of fracture, even after adjustment for femoral neck T-score. Discrimination of fracture prevalence was best with a femoral neck T-score of -2.0 or less and a value in the upper two tertiles for osteocalcin, procollagen type-1 N-terminal propeptide, or tartrate-resistant acid phosphatase 5b; these values corresponded to the upper half of the normal premenopausal reference range. In summary, these cross-sectional data suggest that measurement of bone turnover markers may increase the diagnostic accuracy of densitometry to identify patients with CKD at high risk for fracture.

Reduced fracture risk with early corticosteroid withdrawal after kidney transplant

Background. Although it is known that the incidence of fracture events is increased in renal transplantation recipients, the timing and the factors associated with risk of fractures are less well understood. The objective of this study was to estimate the time to fracture in renal transplantation recipients and to determine whether risk was associated with patient and transplantation characteristics. Methods. Using the U. S. Renal Data System, we retrospectively studied 68,814 patients, who underwent renal transplantation between 1988 and 1998. Fractures were identified from International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis codes in billing data. Time to first fracture was modeled during the first 5 years posttransplant using the Kaplan-Meier method and Cox proportional hazards models. Results. Of the patients who underwent transplantation, 22.5% developed a fracture within 5 years. Woman (hazard ratio [HR] 1.36, P<0.0001), patients older than 45 years of age (HR 1.14, P<0.0001) especially older than 65 years (HR 1.69, P<0.0001), and whites (HR 1.28, P<0.0001) were at increased risk of a fracture. Additionally, receipt of a deceased donor kidney (HR 1.30, P<0.0001), increased human leukocyte antigen mismatches (HR 1.09, P<0.014), diabetes (HR 1.88, P<0.0001), pretransplant dialysis (HR 1.08, P<0.0001), and an aggressive induction immunosuppression regimen (HR 1.14, P<0.0001) all significantly increased risk of fracture events during the first 5 years. Conclusions. In addition to patient demographic features, donor factors, including suboptimal organ quality and the need for more intense immunosuppression, were associated with an increased risk of fractures during the first 5 years after a renal transplant.

Kidney Transplantation with Early Corticosteroid Withdrawal: Paradoxical Effects at the Central and Peripheral Skeleton

Corticosteroid use after kidney transplantation results in severe bone loss and high fracture risk. Although corticosteroid withdrawal in the early posttransplant period has been associated with bone mass preservation, there are no published data regarding corticosteroid withdrawal and risk of fracture. We hypothesized lower fracture incidence in patients discharged from the hospital without than with corticosteroids after transplantation. From the United States Renal Data System (USRDS), 77 430 patients were identified who received their first kidney transplant from 2000 to 2006. Fracture incidence leading to hospitalization was determined from 2000 to 2007; discharge immunosuppression was determined from United Networks for Organ Sharing forms. Time‐to‐event analyses were used to evaluate fracture risk. Median (interquartile range) follow‐up was 1448 (808–2061) days. There were 2395 fractures during follow‐up; fracture incidence rates were 0.008 and 0.0058 per patient‐year for recipients discharged with and without corticosteroid, respectively. Corticosteroid withdrawal was associated with a 31% fracture risk reduction (HR 0.69; 95% CI 0.59–0.81). Fractures associated with hospitalization are significantly lower with regimens that withdraw corticosteroid. As this study likely underestimates overall fracture incidence, prospective studies are needed to determine differences in overall fracture risk in patients managed with and without corticosteroids after kidney transplantation.

Residual Fragments Following Ureteroscopic Lithotripsy: Incidence and Predictors on Postoperative Computerized Tomography

The use of early corticosteroid withdrawal (ECSW) protocols after kidney transplantation has become common, but the effects on fracture risk and bone quality are unclear. We enrolled 47 first-time adult transplant recipients managed with ECSW into a 1-year study to evaluate changes in bone mass, microarchitecture, biomechanical competence, and remodeling with dual energy x-ray absorptiometry (DXA), high-resolution peripheral quantitative computed tomography (HRpQCT), parathyroid hormone (PTH) levels, and bone turnover markers obtained at baseline and 3, 6, and 12 months post-transplantation. Compared with baseline, 12-month areal bone mineral density by DXA did not change significantly at the spine and hip, but it declined significantly at the 1/3 and ultradistal radii (2.2% and 2.9%, respectively; both P<0.001). HRpQCT of the distal radius revealed declines in cortical area, density, and thickness (3.9%, 2.1%, and 3.1%, respectively; all P<0.001), trabecular density (4.4%; P<0.001), and stiffness and failure load (3.1% and 3.5%, respectively; both P<0.05). Findings were similar at the tibia. Increasing severity of hyperparathyroidism was associated with increased cortical losses. However, loss of trabecular bone and bone strength were most severe at the lowest and highest PTH levels. In summary, ECSW was associated with preservation of bone mineral density at the central skeleton; however, it was also associated with progressive declines in cortical and trabecular bone density at the peripheral skeleton. Cortical decreases related directly to PTH levels, whereas the relationship between PTH and trabecular bone decreases was bimodal. Studies are needed to determine whether pharmacologic agents that suppress PTH will prevent cortical and trabecular losses and post-transplant fractures.

Electronic measures of surgical site infection: implications for estimating risks and costs.

PURPOSE Residual fragments following ureteroscopy for calculi may contribute to stone growth, symptoms or additional interventions. We reviewed our experience with ureteroscopy for calculus disease to define the incidence and establish factors predictive of residual fragments. MATERIALS AND METHODS Records associated with 667 consecutive ureteroscopic lithotripsy procedures for upper urinary calculi were reviewed. In 265 procedures (40%) computerized tomography was done between 30 and 90 days postoperatively. They comprised the study group. Residual fragments were defined as any residual ipsilateral stone greater than 2 mm. RESULTS Included in the study were 121 men and 127 women with a mean age of 47 years. Mean target stone diameter was 7.6 mm. The stone location was the kidney in 30% of cases, ureter in 50%, and kidney and ureter in 20%. Residual fragments were detected on computerized tomography after 101 of 265 procedures (38%). Pretreatment stone size was associated with residual fragments at a rate of 24%, 40% and 58% for stones 5 or less, 6 to 10 and greater than 10 mm, respectively (p <0.001). Additionally, stone location in the kidney (p <0.001) or the kidney and ureter (p = 0.044), multiple calculi (p = 0.003), longer operative time (p = 0.008) and exclusive use of flexible ureteroscopy (p = 0.029) were associated with residual fragments. In a multivariate model only pretreatment stone diameter greater than 5 mm was independently associated with residual fragments after ureteroscopy (diameter 6 to 10 and greater than 10 mm OR 2.03, p = 0.03 and OR 3.74, p = 0.003, respectively). CONCLUSIONS Of patients who underwent ureteroscopic lithotripsy for calculi 38% had residual fragments by computerized tomography criteria, including more than 50% with stones 1 cm or greater. Such data may guide expectations regarding the success of ureteroscopy in attaining stone-free status.

Pancreas–kidney transplantation is associated with reduced fracture risk compared with kidney-alone transplantation in men with type 1 diabetes

OBJECTIVE Electronic measures of surgical site infections (SSIs) are being used more frequently in place of labor-intensive measures. This study compares performance characteristics of 2 electronic measures of SSIs with a clinical measure and studies the implications of using electronic measures to estimate risk factors and costs of SSIs among surgery patients. METHODS Data included 1,066 general and vascular surgery patients at a single academic center between 2007 and 2008. Clinical data were from the National Surgical Quality Improvement Program (NSQIP) database, which includes a nurse-derived measure of SSI. We compared the NSQIP SSI measure with 2 electronic measures of SSI: MedMined Nosocomial Infection Marker (NIM) and International Classification of Diseases, Ninth Revision (ICD-9) coding for SSIs. We compared infection rates for each measure, estimated sensitivity and specificity of electronic measures, compared effects of SSI measures on risk factors for mortality using logistic regression, and compared estimated costs of SSIs for measures using linear regression. RESULTS SSIs were observed in 8.8% of patients according to the NSQIP definition, 2.6% of patients according to the NIM definition, and 5.8% according to the ICD-9 definition. Logistic regression for each SSI measure revealed large differences in estimated risk factors. NIM and ICD-9 measures overestimated the cost of SSIs by 134% and 33%, respectively. CONCLUSIONS Caution should be taken when relying on electronic measures for SSI surveillance and when estimating risk and costs attributable to SSIs. Electronic measures are convenient, but in this data set they did not correlate well with a clinical measure of infection.

Determinants of Medicare All-Cause Costs Among Elderly Patients with Renal Cell Carcinoma

Both type 1 diabetes mellitus and end stage renal disease are associated with increased fracture risk, likely due to metabolic abnormalities that reduce bone strength. Simultaneous pancreas-kidney transplantation is a treatment of choice for patients with both disorders, yet the effects of simultaneous pancreas-kidney versus kidney transplantation alone on post-transplantation fracture risk are unknown. From the United States Renal Data System we identified 11, 145 adults with type 1 diabetes undergoing transplantation of whom 4,933 had a simultaneous pancreas-kidney while 6, 212 had a kidney alone transplant between 2000 and 2006. Post-transplantation fractures resulting in hospitalization were identified from discharge codes. Time to first fracture was modeled and propensity score adjustment was used to balance covariates between groups. Fractures occurred in significantly fewer (4.7%) of pancreas-kidney compared to kidney-alone transplant (5.9%) cohorts. After gender stratification and adjustment for fracture covariates, pancreas-kidney transplantation was associated with a significant 31% reduction in fracture risk in men (hazard risk 0.69). Older age, white race, prior dialysis and pre transplantation fracture were also associated with increased fracture risk. Prospective studies are needed to determine the gender-specific mechanisms by which pancreas-kidney transplantation reduces fracture risk in men.