The Role of the Cerebellum in Learning to Predict Reward: Evidence from Cerebellar Ataxia.

Recent findings in animals have challenged the traditional view of the cerebellum solely as the site of motor control, suggesting that the cerebellum may also be important for learning to predict reward from trial-and-error feedback. Yet, evidence for the role of the cerebellum in reward learning in humans is lacking. Moreover, open questions remain about which specific aspects of reward learning the cerebellum may contribute to. Here we address this gap through an investigation of multiple forms of reward learning in individuals with cerebellum dysfunction, represented by cerebellar ataxia cases. Nineteen participants with cerebellar ataxia and 57 age- and sex-matched healthy controls completed two separate tasks that required learning about reward contingencies from trial-and-error. To probe the selectivity of reward learning processes, the tasks differed in their underlying structure: while one task measured incremental reward learning ability alone, the other allowed participants to use an alternative learning strategy based on episodic memory alongside incremental reward learning. We found that individuals with cerebellar ataxia were profoundly impaired at reward learning from trial-and-error feedback on both tasks, but retained the ability to learn to predict reward based on episodic memory. These findings provide evidence from humans for a specific and necessary role for the cerebellum in incremental learning of reward associations based on reinforcement. More broadly, the findings suggest that alongside its role in motor learning, the cerebellum likely operates in concert with the basal ganglia to support reinforcement learning from reward.

Effect of anterior approach compared to posterolateral approach on readiness for discharge and thrombogenic markers in patients undergoing unilateral total hip arthroplasty: a prospective cohort study.

INTRODUCTION: The direct anterior approach (DAA) for total hip arthroplasty (THA) is considered less invasive than the posterolateral approach (PLA), possibly leading to earlier mobilization, faster recovery, and lower levels of thrombogenic markers. The purpose of the current study was to prospectively compare readiness for discharge, rehabilitation milestones, markers of thrombosis and inflammation at 6 weeks postoperatively between DAA and PLA. METHODS: A total of 40 patients (20 anterior and 20 posterolateral) were prospectively enrolled. Readiness for discharge, length of stay (LOS), and related outcomes were additionally documented. Blood was drawn at baseline, wound closure, 5-h post-closure, and 24-h post-closure for assays of interleukin-6 (IL-6), PAP (plasmin anti-plasmin), a marker of fibrinolysis, and PF1.2 (Prothrombin fragment 1.2), a marker of thrombin generation. RESULTS: Compared to the PLA group, the DAA group was ready for discharge a mean 13 h earlier (p = 0.03), while rehabilitation milestones were met a mean 10 h earlier (p = 0.04), and LOS was 13 h shorter (p = 0.02) on average. Pain scores at all study timepoints and patient satisfaction at 6 weeks were similar (p > 0.05). At 24 h postoperatively, PAP levels were 537.53 ± 94.1 µg/L vs. 464.39 ± 114.6 µg/L (p = 0.05), and Il-6 levels were 40.94 ± 26.1 pg/mL vs. 60.51 ± 33.0 pg/mL (p = 0.03), in DAA vs. PLA, respectively. CONCLUSIONS: In the immediate postoperative period, DAA patients were ready for discharge before PLA patients. DAA patients had shorter LOS, a lower inflammatory response, and higher systemic markers of fibrinolysis. However, these differences may not be clinically significant. Future studies with larger study populations are warranted to confirm the validity and significance of these findings. LEVEL OF EVIDENCE: Level II, Therapeutic Study.

Gambling associated risk-taking decision in cerebellar ataxia.

INTRODUCTION: People with cerebellar ataxia (CA) can develop impulsive and compulsive behaviors that significantly affect their and their family's quality of life. To further assess the decision-making process associated with these behaviors, we used the Iowa Gambling Task (IGT) to study people with CA. METHODS: Sixty individuals with CA and thirty age-matched controls were enrolled in the study to complete the IGT. No participants had a prior or comorbid neurologic or psychiatric disorder associated with impulsivity. IGT performance in each of the five 20-trial blocks was compared between groups and the progression of participants' performance was assessed with simple linear regression models. Subgroup analyses were performed with genetic and non-genetic CA cases. RESULTS: CA cases obtained significantly lower IGT total scores than controls (-5.30 ± 37.53 vs. 21.30 ± 37.37, p = 0.004). In addition, those with CA made riskier decisions throughout the task compared to controls. Although both CA and controls learned to make decisions with more favorable outcomes over the course of completing the IGT, CA participants never matched the controls' performance. IGT performance did not correlate with ataxia severity or depressive symptoms. CONCLUSION: The IGT may capture a unique behavioral symptom of CA. Future studies may help elucidate the mechanisms underlying impaired decision-making in CA and further the understanding of a broader spectrum of cerebellar cognitive affective syndrome.

Impulsivity Trait Profiles in Patients With Cerebellar Ataxia and Parkinson Disease.

BACKGROUND AND OBJECTIVES: Individuals with cerebellar ataxia (CA) can develop impulsive behavioral symptoms, often resulting in negative interpersonal consequences, detrimentally affecting their quality of life. Limited evidence exists concerning impulsivity in CA and its associated behavioral changes. We assessed impulsive traits in CA using the Barratt Impulsivity Scale (BIS-11) and compared them with those of Parkinson disease (PD) to investigate the differences in the impulsive trait profiles between CA and PD. METHODS: We conducted a dual-center cross-sectional study with individuals with CA and PD enrolled through consecutive sampling from movement disorders clinics at Columbia University Medical Center and Vanderbilt University Medical Center, respectively. Age-matched controls were recruited at the respective institutions. Participants were excluded if they had prior or comorbid neurologic and psychiatric diseases known to be associated with impulsivity. All participants completed the BIS-11 questionnaire as a measure of impulsive traits. We used a general linear model and a least absolute shrinkage and selection operation regression to compare the total, subscale, and individual items of the BIS-11 scores between groups. Subgroup analyses were performed to isolate cerebellar contributions to impulsivity from potential effects of extracerebellar pathology and dopaminergic dysfunction or medications. RESULTS: A total of 190 participants-90 age-matched controls, 50 participants with CA, and 50 with PD-completed the assessments. Persons with CA reported 9.7% higher BIS-11 scores than controls (p < 0.001), while persons with PD reported 24.9% higher scores than controls (p < 0.001). In CA, the most affected domain of impulsivity was nonplanning. In contrast, persons with PD noted greater impulsivity across the nonplanning, attentional, and motor domains. DISCUSSION: Impulsivity in CA is uniquely driven by the nonplanning trait, unlike in PD. This suggests that the cerebellum and basal ganglia may differentially govern impulsive behaviors with the cerebellum contributing to the brain circuitry of impulsivity in a domain-specific manner.

Recommended Musculoskeletal and Sports Medicine Model Curriculum for Emergency Medicine Residency Training.

ABSTRACT: Musculoskeletal and sports medicine conditions are common in the emergency department (ED). Emergency physicians may not be receiving adequate education to achieve clinical competency in musculoskeletal medicine during residency training. This article aims to provide a standardized musculoskeletal and sports medicine curriculum for emergency medicine training. Broad curriculum goals include proficiency in evaluating and managing patients presenting to the ED with acute and chronic musculoskeletal complaints and other medical conditions related to or affected by physical exertion, sports participation, or environmental exposure. Specific objectives focus on knowledge of these disorders, physical examination skills, procedural skills including musculoskeletal ultrasound, appropriate consultation and referral, and patient education for these conditions. Educational methods will consist of didactics; online self-directed learning modules; simulation; and supervised clinical experiences in the ED, primary care sports medicine clinics, and orthopedic clinics if available. Curriculum implementation is expected to vary across programs due to differences in residency program structure and resources.

The Impact of Compulsivity and Impulsivity in Cerebellar Ataxia: A Case Series.

Background: The cerebellum has recently been identified to have a key role in reward processing, and individuals with ataxia have been found to be more impulsive and compulsive as part of cerebellum-related cognitive and behavioral disturbances. Case Report: We reported five individuals with cerebellar ataxia who demonstrate impulsive and compulsive behaviors, including hobbyism, gambling, and compulsive medication use, to illustrate that these symptoms can be highly disabling. Discussion: These five cases provide examples of behavioral symptoms in cerebellar ataxia. Further investigations of the pathomechanism of these symptoms will advance our understanding of the cerebellum in cognition and behavior.

Factors Affecting Recovery Trajectories in Pediatric Female Concussion.

OBJECTIVE: Up to one-third of children with concussion have persistent postconcussion symptoms lasting beyond 4 weeks. Females have been shown to have prolonged concussion recovery compared with males. This study examined characteristics in pediatric athletes with concussion to investigate the underlying factors that may contribute to this difference and their relation to recovery trajectories in females compared with males. DESIGN: A retrospective cohort study of pediatric patients with sports-related concussion (SRC). SETTING: A subspecialty pediatric concussion program. SUBJECTS: One hundred ninety-two records were reviewed, 75 females and 117 males, ages 7 to 18 years old. ASSESSMENT OF RISK FACTORS: Sex of patient, time to presentation to specialty care after injury, presence of vision, and vestibular deficits on initial clinical examination. MAIN OUTCOME MEASURES: The main outcome of interest was time to clinical recovery, defined by resolution of symptoms, recovery of physical examination deficits, including vision and vestibular examination, recovery of neurocognitive function, and return to school, exercise, and sport. RESULTS: Pediatric females, on average, presented later to specialty care for evaluation after SRC than males. Females also took longer to recover on 5 markers of recovery: time to return to school without accommodations, time to return to noncontact exercise, time to return to full sport, time to recovery of neurocognitive function on computerized testing, and time to clinical recovery of vision and vestibular deficits on examination including smooth pursuits, saccades, gaze stability, near point of convergence, and balance. These sex-based differences in recovery disappeared when controlling for time to presentation to specialty care. CONCLUSIONS: In this cohort of pediatric patients, ages 7 to 18 years old with SRC, females took longer to recover than males. Our results indicate, however, that a modifiable extrinsic factor, time to presentation to specialty care, may contribute to this difference in recovery between the sexes.

Artistic Gymnastics Injuries; Epidemiology, Evaluation, and Treatment.

Artistic gymnastics is a physically demanding sport that requires flexibility, agility, and extreme upper and lower body strength. The specific biomechanics of the sport leads to a unique injury profile. Gymnastic skills require intense upper body weight-bearing, placing unusual forces across the upper extremity joints and predisposing them to injury. In addition, the required body control during air aerobatics (tumbling, twisting, flipping) necessitates precise landing techniques to avoid spine and lower extremity injury. Common gymnastic injuries include those of the spine and upper extremity such as spondylolysis, shoulder instability, ulnar collateral ligament injuries, capitellar osteochondritis dissecans, and several wrist pathologies. Understanding the injury etiology, prevention, and treatment protocols is important for a successful recovery and return to sport.

An Analysis of Sports Specialization in NCAA Division I Collegiate Athletics.

BACKGROUND: Youth sports specialization has become more prevalent despite consequences such as increased injury rates and burnout. Young athletes, coaches, and parents continue to have misconceptions about the necessity of sports specialization, giving athletes the encouragement to focus on a single sport at a younger age. PURPOSE: To characterize the motivations for specialization and determine when elite athletes in various individual and team sports made the decision to specialize. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A Likert-style survey was developed and distributed to athletes from two National Collegiate Athletic Association (NCAA) Division I institutions. The survey's Flesch-Kincaid grade level was 6.3. Statistical analysis was performed via the Student t test, where a P value less than .05 was considered significant. RESULTS: A total of 303 athletes with a mean ± SD age of 19.9 ± 1.52 years across 19 sports were surveyed; 94.7% of specialized athletes had previously played another organized sport prior to college, and 45% of athletes had played multiple sports up to age 16 years. The mean age of specialization was 14.9 years, with a significant difference between athletes competing in team (15.5 years) and individual (14.0 years) sports (P = .008). Males in individual sports specialized earlier than those in team sports (P ≤ .001). Nearly one-fifth (17.4%) of athletes reported specializing at age 12 years or earlier. Personal interest, skill level, time constraints, and potential scholarships were the most important reasons for specialization overall. For individual sports, the motivations for specialization were similar, but collegiate (P < .001) or professional (P < .001) ambitions were significantly larger contributing factors. CONCLUSION: Early sports specialization is uncommon among NCAA Division I athletes for most team sports, whereas individual sports tend to have athletes who specialize earlier and are more motivated by professional and collegiate goals. This study characterized the timing of specialization among elite athletes, providing a basis for understanding the motivations behind youth sports specialization. Physicians should be prepared to discuss the misconception that early sports specialization is necessary or common among most team-focused collegiate-level athletes. Knowing the motivations for sports specialization will guide clinicians in their discussions with youth athletes.

Ultrasound-Guided Hip Injections.

The diagnosis of hip pain can be difficult to isolate because the discomfort can originate from several locations and compensatory pain patterns. Pain generators can include the intra- and extra-articular hip structures, the lumbar spine, the pelvic floor, or a combination of these. It can also be referred as pain from the bowel, bladder, or reproductive organs. Injections into and around the hip have become an important part of both diagnostic and nonsurgical treatment algorithm for hip pain. The proximity of the hip to important neurovascular structures, lack of palpable anatomic landmarks, and deep location of targets can make use of ultrasonography-guided injections ideal. These injections have been growing in popularity in the orthopedic community because ultrasonography allows for a real-time visualization of dynamic anatomy without any radiation exposure to the patient and physician. The use of ultrasonography has allowed for in-office image guidance with improved accuracy for more targeted and advanced procedures. The patient's response to these injections can help guide patient selection for surgery and allow for better pain control of the soft-tissue pathology that often accompanies intra-articular pathology. This article highlights the diagnostic and therapeutic value of ultrasonography-guided hip injections for an orthopedic practice. The focus is on sonographic anatomy, introduction to technique, common indications, and pearls and pitfalls of these procedures.

High prevalence of greater trochanteric pain syndrome among patients presenting to spine clinic for evaluation of degenerative lumbar pathologies.

BACKGROUND: Greater trochanteric pain syndrome (GTPS) is a relatively common diagnosis among the general population. OBJECTIVE: We aim to determine the prevalence of GTPS among patients who presented to the spine clinic. METHODS: Medical records of patients who were evaluated in the spine clinic were reviewed over a 12-month period (4/1/2016 to 3/31/2017). Patient demographics, presenting symptomatology, physical examination findings, presence or absence of GTPS, medical imaging findings, and interventions were recorded analyzed. Statistical analysis was performed using SPSS Statistics 23.0 (Chicago, IL). Statistical significance is defined as p < 0.05. RESULTS: A total of 273 consecutive patients (145 women, 128 men) were evaluated for degenerative lumbar pathologies by a single spine surgeon over the study period. The average patient age was 61.9 years. Overall, there were 138/273 patients (50.5%) with GTPS (Group I), while 135/273 patients (49.5%) did not have GTPS (Group II). There were 73 patients in Group I received trochanteric injection for GTPS treatment and subsequently returned to clinic for follow-up, and there were 36/73 (49.3%) patients reporting improvement in their symptoms after trochanteric injection. There was a statistically significant predilection for presence of GTPS in the female gender (60% vs 32.8%, p = <0.01). There was no statistically significant difference in the prevalence of low back pain, buttock, thigh or groin pain between the two groups. CONCLUSION: GTPS is a very common but often unrecognized or misdiagnosed condition. Accurate diagnosis and differentiation of GTPS from lumbar spinal pathologies are essential in avoiding potential unnecessary spinal procedures.

Medical retirement from sport after concussions: A practical guide for a difficult discussion.

PURPOSE OF REVIEW: In patients with a considerable history of sports-related concussion, the decision of when to discontinue participation in sports due to medical concerns including neurologic disorders has potentially life-altering consequences, especially for young athletes, and merits a comprehensive evaluation involving nuanced discussion. Few resources exist to aid the sports medicine provider. RECENT FINDINGS: In this narrative review, we describe 10 prototypical vignettes based upon the authors' collective experience in concussion management and propose an algorithm to help clinicians navigate retirement discussions. Issues for consideration include absolute and relative contraindications to return to sport, ranging from clinical or radiographic evidence of lasting neurologic injury to prolonged concussion recovery periods or reduced injury threshold to patient-centered factors including personal identity through sport, financial motivations, and navigating uncertainty in the context of long-term risks. SUMMARY: The authors propose a novel treatment algorithm based on real patient cases to guide medical retirement decisions after concussion in sport.

Effects of Intravenous Cold Saline on Hyperthermic Athletes Representative of Large Football Players and Small Endurance Runners.

OBJECTIVE: To evaluate the cooling effects of intravenous (IV) cold normal (0.9%) saline on hyperthermic athletes. DESIGN: Randomized crossover study design. SETTING: Controlled research laboratory. PARTICIPANTS: Twelve male participants who were representative of a collegiate cross-country (6) and American football (6) population. INTERVENTIONS: Participants underwent body composition analysis using a BodPod. They were placed in an environmentally controlled chamber and brought to a Tc of 39.5°C with dynamic exercise. When temperatures were reached, they were treated with either 2 L of cold saline (CS) (4°C) or intravenous room temperature (22°C) saline (RS) over a ∼30-minute period. Tre was measured with a rectal temperature probe every minute during the treatment period. MAIN OUTCOME MEASURES: Total ΔTre (ending Tre - starting Tre) and cooling rate (total change in Tre/time) were measured for each condition, and body composition variables calculated included body surface area (BSA), BSA-to-mass ratio (BSA/mass), lean body mass, and body fat percentage (%BF) (P < 0.05). RESULTS: Statistically significant differences were found in the total ΔTre and cooling rate between the CS and RS trials. The cooling rate for the CS trials was significantly correlated to mass, BSA, BSA/mass, and %BF. CONCLUSIONS: In hyperthermic athletes, core temperature was reduced more effectively using chilled saline during IV infusion. Body composition had a significant impact on overall cooling revealing that the smaller and leaner participants cooled at a greater rate. When indicated, CS infusion could be considered for cooling hyperthermic individuals when other methods are not available.

Clinical Indicators of the Need for Telemetry Postoperative Monitoring in Patients With Suspected Obstructive Sleep Apnea Undergoing Total Knee Arthroplasty.

BACKGROUND AND OBJECTIVES: Obstructive sleep apnea is associated with increased complication rates postoperatively. Current literature does not provide adequate guidance on management of these patients. This study used the STOP-Bang questionnaire to diagnose patients with possible obstructive sleep apnea (score ≥3). We hypothesized that a STOP-Bang score of 3 or greater would significantly correlate with the number of oxygen desaturation episodes during the first 48 hours after total knee arthroscopy. METHODS: The STOP-Bang questionnaire was administered to 110 patients preoperatively. All patients underwent spinal-epidural anesthesia with a saphenous nerve block and sedation and were connected to the Nellcor OxiMax N-600x pulse oximeter for 48 hours postoperatively. RESULTS: Final analysis included 98 patients. There was no significant difference in the total number of desaturation events between STOP-Bang groups (score <3 vs ≥3 and score <5 vs ≥5). The total number of desaturation events on postoperative day 1 was greater than that on day 0 (32.8 ± 42.7 vs 4.1 ± 10.0, P < 0.0001). The total number of desaturation events correlated with length of hospital stay (r = 0.329, P = 0.0001). Patients with a preoperative serum CO2 of 30 mmol/L or greater had significantly longer episodes of desaturation on postoperative day 0 compared with CO2 of less than 30 mmol/L (233.7 ± 410.1 vs 82.0 ± 126.2 seconds, P = 0.044). CONCLUSIONS: A high preoperative value of CO2 should be a warning for possible prolonged episodes of desaturation postoperatively. An attempt to limit postoperative desaturation events should be made to minimize length of stay.

Diagnosis of Intraabdominal Fluid Extravasation After Hip Arthroscopy With Point-of-Care Ultrasonography Can Identify Patients at an Increased Risk for Postoperative Pain.

BACKGROUND: Intraabdominal fluid extravasation (IAFE) after hip arthroscopy has historically been diagnosed in catastrophic circumstances with abdominal compartment syndrome requiring diuresis or surgical decompression. A previous retrospective study found the prevalence of symptomatic IAFE requiring diuresis or decompression to be 0.16%, with risk factors including surgical procedure and high pump pressures. IAFE can be diagnosed rapidly by using point-of-care ultrasound (POCUS) via the Focused Assessment With Sonography for Trauma (FAST) examination, which is a well-established means to detect free fluid with high specificity and sensitivity. In this study, we used POCUS to determine the incidence of IAFE in patients undergoing hip arthroscopy. We predicted a higher incidence and that patients with IAFE would have symptoms of peritoneal irritation such as pain and nausea. METHODS: One hundred patients undergoing ambulatory hip arthroscopy were prospectively enrolled. A FAST examination was performed after induction by a trained anesthesiologist to exclude the preoperative presence of intraperitoneal fluid. Postoperatively, the same anesthesiologist repeated the FAST examination, and patients with new fluid in the abdominal or pelvic peritoneum were diagnosed with IAFE. Patients were followed up in the postanesthesia care unit (PACU) for 6 hours assessing pain, antiemetic and opioid use, and length of stay. RESULTS: Sixteen of 100 patients were found to have IAFE (16.0%; 99% confidence interval [CI], 8.4-28.1). These patients had, on average, a greater increase in pain score from their baseline assessment throughout their entire PACU stay (adjusted difference in means [99% CI]: 2.1 points [0.4-3.9]; P = .002). Patients with IAFE used more opioids, but this difference did not meet statistical significance (adjusted difference in means [99% CI]: 7.8 mg oral morphine equivalents [-2.8 to 18.3]; P = .053). There were no differences in postoperative nausea interventions or length of stay. CONCLUSIONS: Our incidence of IAFE was 16%, showing that IAFE occurs quite commonly in hip arthroscopy. Patients with IAFE had a greater increase in pain scores from baseline throughout the PACU stay. None of our patients required interventions. These findings suggest that even a small amount of new fluid in the peritoneum may be associated with a worse postoperative experience. This study brings awareness to a common yet potentially life-threatening complication of hip arthroscopy and highlights a unique and meaningful way that anesthesiologists in the perioperative setting can use POCUS to rapidly identify and guide management of these patients. Further studies with a larger sample size are needed to identify surgical and patient risk factors.

The Effect of Perioperative Corticosteroids in Total Hip Arthroplasty: A Prospective Double-Blind Placebo Controlled Pilot Study.

BACKGROUND: Surgery produces a rapid rise in interleukin 6 (IL-6) which may increase the risk of deep vein thrombosis and medical complications. Perioperative corticosteroids suppress IL-6 release in patients undergoing total knee arthroplasty. This study evaluates the effects of a perioperative corticosteroid regimen on IL-6 formation, thrombogenesis, fibrinolysis, and clinical outcomes in patients undergoing unilateral, uncemented, total hip arthroplasty. METHODS: Twenty-seven patients (14 placebo and 13 study) were enrolled in this randomized, double-blind, placebo-controlled trial. The study group received 20 mg of prednisone orally followed by 2 doses of intravenous hydrocortisone, each 8 hours apart. Blood was drawn at several time points for IL-6, prothrombin fragment 1.2, and plasmin-alpha-2-antiplasmin complex, a marker of fibrinolysis. In-hospital visual analog pain (visual analog scale) scores, patient-controlled analgesia use, and ability to climb stairs were recorded. RESULTS: Mean serum IL-6 levels at 6 and 24 hours postoperatively were significantly lower for the study group, whereas serum prothrombin fragment 1.2 and plasmin-alpha-2-antiplasmin were not statistically different at any study time point. Average pain scores were similar (P > .05), but study group experience less severe pain (P < .01) and less patient-controlled analgesia (P = .02). At 3 months, 4 patients in the placebo and 1 patient in the study group had difficulty going up and down staircases (P = .08). CONCLUSION: The use of corticosteroids was associated with a statistically significant decrease in IL-6 at 6 and 24 hours postoperatively but did not affect thrombogenic markers. The study group had improved postoperative analgesia and a trend toward improved functional outcome at 3 months postoperatively.

Sodium bicarbonate vs sodium chloride for the prevention of contrast medium-induced nephropathy in patients undergoing coronary angiography: a randomized trial.

CONTEXT: Sodium bicarbonate has been suggested as a possible strategy for prevention of contrast medium-induced nephropathy, a common cause of renal failure associated with prolonged hospitalization, increased health care costs, and substantial morbidity and mortality. OBJECTIVE: To determine if sodium bicarbonate is superior to sodium chloride for preventing contrast medium-induced nephropathy in patients with moderate to severe chronic kidney dysfunction who are undergoing coronary angiography. DESIGN, SETTING, AND PATIENTS: Randomized, controlled, single-blind study conducted between January 2, 2006, and January 31, 2007, and enrolling 353 patients with stable renal disease who were undergoing coronary angiography at a single US center. Included patients were 18 years or older and had an estimated glomerular filtration rate of 60 mL/min per 1.73 m(2) or less and 1 or more of diabetes mellitus, history of congestive heart failure, hypertension, or age older than 75 years. INTERVENTIONS: Patients were randomized to receive either sodium chloride (n = 178) or sodium bicarbonate (n = 175) administered at the same rate (3 mL/kg for 1 hour before coronary angiography, decreased to 1.5 mL/kg per hour during the procedure and for 4 hours after the completion of the procedure). MAIN OUTCOME MEASURE: The primary end point was a 25% or greater decrease in the estimated glomerular filtration rate on days 1 through 4 after contrast exposure. RESULTS: Median patient age was 71 (interquartile range, 65-76) years, and 45% had diabetes mellitus. The groups were well matched for baseline characteristics. The primary end point was met in 13.3% of the sodium bicarbonate group and 14.6% of the sodium chloride group (relative risk, 0.94; 95% confidence interval, 0.55-1.60; P = .82). In patients randomized to receive sodium bicarbonate vs sodium chloride, the rates of death, dialysis, myocardial infarction, and cerebrovascular events did not differ significantly at 30 days (1.7% vs 1.7%, 0.6% vs 1.1%, 0.6% vs 0%, and 0% vs 2.2%, respectively) or at 30 days to 6 months (0.6% vs 2.3%, 0.6% vs 1.1%, 0.6% vs 2.3%, and 0.6% vs 1.7%, respectively) (P > .10 for all). CONCLUSION: The results of this study do not suggest that hydration with sodium bicarbonate is superior to hydration with sodium chloride for the prevention of contrast medium-induced nephropathy in patients with moderate to severe chronic kidney disease who are undergoing coronary angiography. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00312117.