Faculty Bibliography

Gout is a chronic disease in which excessively high levels of serum urate (hyperuricemia) result in tissue depositions of sodium urate crystals and intermittent inflammatory attacks. Patients who have gout frequently experience a range of comorbidities, which complicates management and affects long-term prognosis. We review some of the more important of these comorbidities and consider the extent to which gout or hyperuricemia may be either a consequence or a cause of these related conditions. In addition, we briefly consider several neurological conditions in which the presence of gout or a high serum urate level may be associated with less disease, rather than more

Chronic kidney disease (CKD) is a risk factor for poor outcomes in patients with coronary artery disease (CAD), but it is unknown whether CKD influences the efficacy of alternative CAD treatment strategies. Thus, we compared outcomes in stable CAD patients with and without CKD randomized to percutaneous coronary intervention (PCI) and optimal medical therapy (OMT) or OMT alone in a post hoc analysis of the 2,287 patient COURAGE study. At baseline, 320 patients (14%) had CKD defined as a glomerular filtration rate of <60 mL/min/1.73 m(2), as estimated by the abbreviated 4-variable Modification of Diet in Renal Disease equation. The patients with CKD were older (68 +/- 9 vs 61 +/- 10 years; p <0.001) and more often had diabetes mellitus (42% vs 33%; p = 0.002), hypertension (81% vs 65%; p <0.03), heart failure (13% vs 3.4%; p <001), and three-vessel CAD (37% vs 29%, p = 0.01). After adjustment for these differences, CKD remained an independent predictor of death or nonfatal myocardial infarction (hazard ratio 1.48, 95% confidence interval 1.15 to 1.90). PCI had no effect on these outcomes. Furthermore, at 36 months, a similar percentage of patients with CKD treated with OMT (70%) and PCI plus OMT (76%) were angina free compared to patients without CKD. In conclusion, CKD is an important determinant of clinical outcomes in patients with stable CAD, regardless of the treatment strategy. Although PCI did not reduce the risk of death or myocardial infarction when added to OMT for patients with CKD, it also was not associated with worse outcomes in this high-risk group

Pregabalin is prescribed for neuropathic pain. We report the first case of pregabalin toxicity in a hemodialysis patient and her successful treatment with hemodialysis. The patient was a 30-year-old woman on long-term hemodialysis therapy who experienced significant myoclonus of the arms and legs when her dose of pregabalin was mistakenly increased. The drug has 3 properties that contribute to making it amenable to removal by hemodialysis: relatively low molecular weight (159.23 Da), relatively low volume of distribution (0.5 L/kg), and not bound to plasma proteins. We achieved hemodialysis clearance of 88.8 mL/min, which was associated with resolution of symptoms immediately after hemodialysis

BACKGROUND: Individuals with advanced chronic kidney disease (CKD) and end-stage renal disease (ESRD) have high plasma total homocysteine (tHcy) levels, which may be a risk factor for cognitive impairment. Whether treatment with high-dose B vitamins to decrease high tHcy levels improves cognition in persons with kidney disease is unknown. STUDY DESIGN: Randomized controlled trial. SETTING & PARTICIPANTS: A substudy of 659 patients (mean age, 67.3 +/- 11.7 years) who participated in a randomized double-blind clinical trial 5 years in duration conducted in 36 US Department of Veterans Affairs medical centers of the effect on all-cause mortality of vitamin-induced lowering of plasma tHcy level. 236 (35.8%) were treated by using dialysis (ESRD) and 423 (64.2%) had a Cockcroft-Gault estimated creatinine clearance of 30 mL/min or less (advanced CKD). All had high tHcy levels (>/=15 mumol/L) at baseline. Cognitive assessments began during the follow-up period of the main trial 3 years after treatment began; participants subsequently were retested 1 year later to assess cognitive change. INTERVENTION: Daily high-dose B vitamin capsule (40 mg of folic acid, 100 mg of vitamin B(6), and 2 mg of vitamin B(12)) or placebo. OUTCOMES: Cognitive function at initial assessment and 1 year later. MEASUREMENTS: Telephone Interview of Cognitive Status-modified, supplemented with attention, working memory, and executive function tests. RESULTS: Initial cognitive function was impaired in approximately 19% of patients regardless of treatment assignment (vitamin or placebo) or kidney disease status (advanced CKD or ESRD). Treatment decreased tHcy levels by 26.7%. Unadjusted and adjusted analyses showed that treatment did not improve initial cognitive outcomes or affect subsequent cognitive status 1 year later. LIMITATIONS: Cognitive assessments began after treatment was initiated; cognitive assessment was limited. CONCLUSION: Treatment with high daily doses of B vitamins, which decreased tHcy levels, did not affect cognitive outcomes in patients with advanced CKD and ESRD

This issue provides a clinical overview of nephrolithiasis focusing on prevention, diagnosis, treatment, practice improvement, and patient information. Readers can complete the accompanying CME quiz for 1.5 credits. Only ACP members and individual subscribers can access the electronic features of In the Clinic. Non-subscribers who wish to access this issue of In the Clinic can elect 'Pay for View.' Subscribers can receive 1.5 category 1 CME credits by completing the CME quiz that accompanies this issue of In the Clinic. The content of In the Clinic is drawn from the clinical information and education resources of the American College of Physicians (ACP), including PIER (Physicians' Information and Education Resource) and MKSAP (Medical Knowledge and Self Assessment Program). Annals of Internal Medicine editors develop In the Clinic from these primary sources in collaboration with the ACP's Medical Education and Publishing division and with assistance of science writers and physician writers. Editorial consultants from PIER and MKSAP provide expert review of the content. Readers who are interested in these primary resources for more detail can consult www.acponline.org, http://pier.acponline.org, and other resources referenced within each issue of In the Clinic

BACKGROUND: Abnormalities in the gene regulating methylenetetrahydrofolate reductase (MTHFR) are associated with increased homocysteine levels and increased mortality in normal and chronic kidney disease (CKD) populations. STUDY DESIGN: Gene association study. SETTING & PARTICIPANTS: This was a substudy of 677 patients from 21 Veterans Affairs medical centers participating in a randomized clinical trial (Homocysteinemia in Kidney and End-Stage Renal Disease [HOST]) of the effect on all-cause mortality of vitamin-induced lowering of plasma homocysteine levels. Of 677 patients, 213 (31%) were treated by using dialysis (end-stage renal disease [ESRD]) and 464 (69%) had a Cockcroft-Gault estimated creatinine clearance less than 30 mL/min (advanced CKD). PREDICTOR: Polymorphisms C677T (rs1801133) and A1298C (rs1801131) of the MTHFR gene. OUTCOMES: Unadjusted and adjusted all-cause mortality. MEASUREMENTS: DNA was extracted from blood samples and amplified by means of polymerase chain reaction. RESULTS: The adjusted hazard ratio in a recessive model of the relationship between the C677T polymorphism and all-cause mortality in all patients was 1.47 (95% confidence interval, 1.00 to 2.16; P = 0.05). In patients with ESRD with the mutant TT genotype, the adjusted hazard ratio for mortality in all patients was 2.27 (95% confidence interval, 1.07 to 4.84; P = 0.03); patients with advanced CKD showed a similar, although not significant, trend. The risk of myocardial infarction (P = 0.05) and composite risk of myocardial infarction, stroke, lower-extremity amputation, and mortality (P = 0.02) were greater in patients with ESRD with the mutant T allele at nucleotide 677. The overall relationship between the A1298C polymorphism and mortality was not significant (P = 0.6). LIMITATIONS: Participants were 98% men; DNA samples were not obtained at enrollment in HOST; linkage disequilibrium with another causal polymorphism is a potential confounding factor; and power was reduced by the limited number of participants. CONCLUSIONS: These findings provide additional support for the hypothesis that the mutant TT genotype at nucleotide 677 of the gene regulating MTHFR activity may increase the mortality risk in patients with ESRD

BACKGROUND AND OBJECTIVES: Data from several countries suggest a recent world-wide increase in the prevalence of stone disease. However, these studies have not analyzed the effect that increases in utilization of imaging modalities have had on detection of asymptomatic stones. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: A retrospective chart review of all patients who had an abdominal or retroperitoneal ultrasound in 2005 at a Department of Veterans' Affairs Medical Center was conducted. The charts of patients who had ultrasounds demonstrating kidney stones were further reviewed. Patients were classified into symptomatic and asymptomatic groups on the basis of their clinical history. Age and sex for all patients were recorded. For those patients with stones, additional data were recorded. Of all patients in the study, the percentage of those with asymptomatic stones was calculated. Taking into account uncertainty about symptomaticity in some patients, a sensitivity analysis for the presence or absence of gross and microhematuria was performed to determine a range for the percent of asymptomatic stones. Appropriate statistical tests were used to determine significance. RESULTS: The prevalence of all kidney stones in the study group was 8.6 %. Using the sensitivity analysis, 29.8 to 45.7% of all stones were asymptomatic. Of stones found on abdominal ultrasounds, 71.4% were asymptomatic, whereas 36.8% of stones found on retroperitoneal ultrasound were asymptomatic. CONCLUSIONS: Asymptomatic stones have a relatively high prevalence on ultrasound. Epidemiologic estimates of prevalence of nephrolithiasis need to account for increases in utilization of imaging modalities and the resulting detection bias