Search PubMed⌕ Search

Biomedical subjects

B J Barrett

Publications and source records attributed to B J Barrett.

35 records · Page 2Linked to original sources
PubMed1994

Advance prediction of early death in patients starting maintenance dialysis.

Accurate information on short-term prognosis is needed to help patients, their doctors, and society to make appropriate decisions concerning starting dialysis. We sought to develop a clinically applicable prognostic scoring system to aid in the prediction of death within 6 months of starting maintenance dialysis. Factors potentially predictive of early death were examined retrospectively in an inception cohort of all 325 patients starting dialysis for irreversible renal failure between 1980 and 1991 at a single tertiary care center. The overall mortality rate was 22% at 6 months. Age, cardiac failure, ischemic heart disease, dysrhythmia requiring therapy, severe peripheral vascular disease, advanced neoplasia, ventilator dependency, coma, systemic sepsis, and hepatic failure were independent, significant, prognostic indicators for early death. Multivariate models were used to suggest weights for these variables in a simplified scoring system. Patients with scores < or = 4 (N = 201) had a 6-month mortality rate of 4%, whereas those with a score higher than 9 (N = 21) had a 6-month mortality rate of 100%. Thus, when age and multiple comorbid illnesses were taken into account, it was possible to identify with 100% accuracy 29% of the patients who died within 6 months of starting maintenance dialysis therapy, accounting for 6.5% of the cohort studied. A larger prospective study is warranted to validate this scoring system.

Aged↗
PubMed1994

Differences in hormonal and renal vascular responses between normotensive patients with autosomal dominant polycystic kidney disease and unaffected family members.

We tested the hypothesis that overactivity of the renal and systemic renin-angiotensin system is important to the pathogenesis of hypertension in autosomal dominant polycystic kidney disease (ADPKD). Up to 21 normotensive subjects with ADPKD and creatinine clearance > 70 ml/min/1.73 m2 were compared to 12 unaffected controls from the same families. Blood pressure, serum chemistry, sodium excretion, plasma renin and serum aldosterone and atrial natriuretic peptide (ANP) levels were measured at baseline, after acute sodium depletion, and after chronic higher sodium intake with and without enalapril. Effective renal plasma flow was measured by paraaminohippurate clearance in the higher sodium state, before and during an intravenous infusion of angiotensin II at 3 ng/kg/min. This was to test whether, by analogy to non-modulating essential hypertension, renal blood flow would fall to a lesser extent in the ADPKD subjects. The groups were comparable at baseline apart from a higher supine mean arterial pressure in the ADPKD group (median 91 vs. 81 mm Hg, P = 0.002). There were no significant differences between ADPKD and control subjects in blood pressure or hormonal response to sodium depletion. During chronically higher sodium intake, serum ANP was significantly higher (median 130 vs. 81 ng/liter, P = 0.0006) and plasma renin tended to be higher (median 20.5 vs. 13.5, P = 0.08) in ADPKD than in control subjects. The ADPKD group had a higher renal vascular resistance (median 7420 vs. 5915 dyn.sec.cm-5, P = 0.009) before angiotensin, but tended to have a lower percentage rise in resistance during angiotensin (median 31.5 vs. 46, P = 0.14).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Contrast nephrotoxicity.

Iodinated contrast media have some nephrotoxic potential but rarely cause significant renal failure in patients with normally functioning kidneys. Patients with existing renal impairment, with or without diabetes, those with current congestive heart failure of Class III or IV, those with reduced effective arterial volume (e.g., nephrotic, cirrhotic), or those receiving drugs that may impair renal function or increase contrast nephrotoxicity are at higher risk. Contrast nephrotoxicity may be clinically important in patients with other factors simultaneously affecting the renal response to contrast or in whom acute renal failure would seriously affect prognosis. The pathogenesis of contrast nephrotoxicity probably involves a combination of direct tubular toxicity and renal ischemic injury. Knowledge of the pathogenetic pathways is accumulating and is leading to the discovery of rational specific prophylactic measures to reduce the burden of nephrotoxicity. After the efficacy of these measures has been established, they should be considered for use in patients at high risk. Existing data indicate a limited role for the newer low-osmolality media for the prevention of nephrotoxicity.

Acute Kidney Injury↗
PubMed1993

Metaanalysis of the relative nephrotoxicity of high- and low-osmolality iodinated contrast media.

To determine whether low-osmolality contrast media (LOCM) are less nephrotoxic than high-osmolality contrast media (HOCM), the authors searched MEDLINE and EMBASE databases and other sources to find randomized trials with data collected on changes in glomerular filtration rate or serum creatinine (SCr) level with LOCM and HOCM. Forty-five trials were found. Data were unavailable from 14 trials. When the P values from the other 31 trials were pooled, an overall P value of .02 was found. Among 24 trials with available data, the mean change in SCr was 0.2-6.2 mumol/L less with LOCM than HOCM. Among 25 trials with available data, the pooled odds of a rise in SCr level of more than 44 mumol/L with LOCM was 0.61 (95% confidence interval [CI], 0.48-0.77) times that after HOCM. For patients with existing renal failure, this odds ratio was 0.5 (CI, 0.36-0.68), while it was 0.75 (CI, 0.52-1.1) in patients without prior renal failure. Greater changes in SCr level occurred only in those with existing renal failure and were less common with LOCM (odds ratio, 0.44; CI, 0.26-0.73). Use of LOCM may be beneficial in patients with existing renal failure.

Contrast Media↗
PubMed1992

A comparison of nonionic, low-osmolality radiocontrast agents with ionic, high-osmolality agents during cardiac catheterization.

BACKGROUND: Nonionic, low-osmolality radiocontrast agents are used frequently because they are believed to be safer than ionic, high-osmolality agents, but they are also more expensive. We conducted a randomized trial to compare the incidence of adverse events after the administration of ionic, high-osmolality and of non-ionic, low-osmolality radiocontrast agents during cardiac angiography. METHODS: We compared the need to treat patients for adverse reactions and the frequency and severity of specific hemodynamic, systemic, and symptomatic side effects in two groups of patients randomly assigned to receive either ionic, high-osmolality or nonionic, low-osmolality radiocontrast material, and also in 366 patients who could not be randomized. RESULTS: Treatment for adverse events was required in 213 of 737 patients who received high-osmolality contrast agents (29 percent) but in only 69 of 753 patients who received nonionic agents (9 percent) (95 percent confidence interval for the percent difference, 15.9 to 23.6 percent). Hemodynamic deterioration and symptoms also occurred more often in the high-osmolality group, as did severe or prolonged reactions (2.9 percent, as compared with 0.8 percent in the nonionic group; P = 0.035). The severe reactions were largely confined to patients with severe cardiac disease. Multivariate analysis showed that the presence of severe coronary disease and unstable angina were predictors of clinically important adverse reactions. If all the patients in our randomized trial had been given nonionic contrast material, the incremental cost per procedure would have been $89. CONCLUSIONS: Nonionic, low-osmolality contrast material is better tolerated during cardiac angiography than ionic, high-osmolality contrast material. Since cost constraints may prevent the universal use of nonionic contrast material, its selective use in patients with severe cardiac disease could be considered.

Contrast Media↗
PubMed1992

Contrast nephropathy in patients with impaired renal function: high versus low osmolar media.

Prescription of low osmolar contrast to prevent nephrotoxicity in subjects with pre-existing renal impairment is costly and has not been clearly shown to be effective. We entered 249 subjects with a pre-contrast serum creatinine greater than 120 mumol/liter (1.35 mg/dl) having cardiac catheterization or intravenous contrast into a randomized controlled trial comparing high and low osmolar contrast. The outcome assessed was a rise in serum creatinine repeated 48 to 72 hours after contrast. A further 117 patients entered the non-randomized prospective arm of the study. In the randomized study the serum creatinine rose by at least 25% after contrast in 8 of 117 (6.8%) given high and in 5 of 132 (3.8%) given low osmolar contrast (P greater than 0.05, one-tailed 95% confidence interval for the difference 3 to 7.8%). More severe renal failure (greater than 50% increase in serum creatinine) after contrast was uncommon (3.4% with high and 1.5% with low osmolar contrast). A rise in serum creatinine after contrast was significantly associated with the severity of the pre-contrast renal impairment and the presence of diabetes mellitus, but not with type of contrast. Diabetics with a serum creatinine greater than 200 mumol/liter (2.25 mg/dl) pre-contrast had a highest risk of deterioration in renal function after contrast. We conclude that in patients with pre-existing renal impairment the incidence of contrast nephropathy was not significantly different comparing high osmolar and nonionic contrast. The potential benefit of nonionic contrast in moderate renal impairment is likely to be small, but trials in diabetics with severe renal impairment should be undertaken urgently.

Aged↗
PubMed1992

Nonionic low-osmolality versus ionic high-osmolality contrast material for intravenous use in patients perceived to be at high risk: randomized trial.

To determine the cost-effectiveness of selective use of nonionic low-osmolality contrast material, the authors randomly assigned 955 patients to receive high-osmolality and 1,158 to receive low-osmolality intravenous contrast material. All patients had one or more of the following perceived risk factors for adverse reactions: prior reaction to contrast material, allergies, asthma, diabetes, cardiac or renal disease, anxiety, severe illness, and age greater than 50 years. The occurrence of any adverse event, need for therapy, or subjective symptoms was assessed in a double-blind fashion. An adverse reaction necessitating the attention of a physician occurred in 3.9% (n = 37) of patients in the high-osmolality and 0.9% (n = 10) of patients in the low-osmolality groups (P less than .000005). Therapy was administered to 1.4% (n = 13) and 0.5% (n = 6), respectively (P = .035). The difference was due to a reduction in urticaria and other mild anaphylactoid reactions. In a multivariate analysis, only prior reactions and allergy were independent risk factors. Selective use of intravenous nonionic contrast material is best justified in those with prior reactions, allergy, or asthma; at least 67% of reactions would be prevented.

Contrast Media↗
PubMed1990

Clinical and psychological correlates of somatic symptoms in patients on dialysis.

Somatic symptoms are common in patients on dialysis. Their causes are largely unknown and their therapy is unsatisfactory. To examine the relationship of psychological and clinical factors to these symptoms, 191 interviews were done in patients on hemo- and peritoneal dialysis. The severity of 8 somatic symptoms (tiredness, sleep disturbance, cramps, pruritus, headache, nausea, dyspnea, joint pain) of importance in dialysis patients was measured using previously validated scales. Indices of affect and quality of life were obtained, as was demographic, clinical and laboratory information. The severity of each symptom was significantly related to the indices of affect and quality of life. Using multiple logistic regression, poor affect score was the strongest correlate of each of the following somatic symptoms, tiredness, pruritus, sleep disturbance and cramps. It was ahead of any clinical or demographic variable and was also significantly correlated with the severity of the other symptoms. Indices of hyperparathyroidism were significantly associated with headache, joint pain, dyspnea and nausea. We conclude that the strongest correlate of common somatic symptoms in dialysis patients is affect disturbance, and that therapy aimed at improving the affect may improve the symptoms.

Affect↗
PubMed1989

Contrast material-induced renal failure in patients with diabetes mellitus, renal insufficiency, or both. A prospective controlled study.

To determine the risk of nephrotoxicity induced by the infusion of radiographic contrast material, we undertook a prospective study of consecutive patients undergoing radiographic procedures with intravascular contrast material. There were three study groups: patients with diabetes mellitus and normal renal function (n = 85), patients with preexisting renal insufficiency (serum creatinine level, greater than or equal to 150 mumol per liter) without diabetes (n = 101), and patients with both diabetes and renal insufficiency (n = 34). The control group consisted of patients undergoing CT scanning or abdominal imaging procedures without the infusion of contrast material who had diabetes mellitus (n = 59), preexisting renal insufficiency (n = 145), or both (n = 64). Clinically important acute renal failure (defined as an increase of greater than 50 percent in the serum creatinine level) attributable to the contrast material did not occur in nondiabetic patients with preexisting renal insufficiency or in diabetics with normal renal function. The incidence of clinically important contrast-induced renal failure among the diabetic patients with preexisting renal insufficiency was 8.8 percent (95 percent confidence interval, 1.9 to 23.7 percent), as compared with 1.6 percent for the controls. The incidence of acute renal insufficiency, more broadly defined as an increase of greater than 25 percent in the serum creatinine level after the infusion of contrast material, was 11.8 percent among all patients with preexisting renal insufficiency. After the exclusion of patients whose acute renal insufficiency could be attributed to other causes, the incidence was 7.0 percent (95 percent confidence interval, 3.2 to 12.8 percent), as compared with 1.5 percent in the control group. The risk of acute renal insufficiency attributable to the contrast material was therefore 5.5 percent, and the relative risk associated with the infusion of contrast material was 4.7. These rates were similar whether the osmolarity of the contrast material was high or low. We conclude that there is little risk of clinically important nephrotoxicity attributable to contrast material for patients with diabetes and normal renal function or for nondiabetic patients with preexisting renal insufficiency. The risk for those with both diabetes and preexisting renal insufficiency is about 9 percent, which is lower than previously reported.

Clinical Trials as Topic↗
PubMedDate not supplied

Prevalence and correlates of elevated serum creatinine levels: the Framingham Heart Study.

BACKGROUND: Elevated serum creatinine (SCr) levels are a predictor of end-stage renal disease, but little is known about the prevalence of elevated SCr levels and their correlates in the community. METHODS: In this cross-sectional, community-based sample, SCr levels were measured in 6233 adults (mean age, 54 years; 54% women) who composed the "broad sample" of this investigation. A subset, consisting of 3241 individuals who were free of known renal disease, cardiovascular disease, hypertension, and diabetes, constituted the healthy reference sample. In this latter sample, sex-specific 95th percentiles for SCr levels (men, 136 micromol/L [1.5 mg/dL]; women, 120 micromol/L [1.4 mg/dL]) were labeled cutpoints. These cutpoints were applied to the broad sample in a logistic regression model to identify prevalence and correlates of elevated SCr levels. RESULTS: The prevalence of elevated SCr levels was 8.9% in men and 8.0% in women. Logistic regression in men identified age, treatment for hypertension (odds ratio [OR], 1.75; 95% confidence interval [CI], 1.27-2.42), and body mass index (OR, 1.08; 95% CI, 1.01-1.15) as correlates of elevated SCr levels. Additionally, men with diabetes who were receiving antihypertensive medication were more likely to have raised SCr values (OR, 2.94; 95% CI, 1.60-5.39). In women, age, use of cardiac medications (OR, 1.58; 95% CI, 1.10-2.96), and treatment for hypertension (OR, 1.42; 95% CI, 1.07-1.87) were associated with elevated SCr levels. CONCLUSIONS: Elevated SCr levels are common in the community and are strongly associated with older age, treatment for hypertension, and diabetes. Longitudinal studies are warranted to determine the clinical outcomes of individuals with elevated levels of SCr and to examine factors related to the progression of renal disease in the community.

Adult↗
PubMedDate not supplied

An economic analysis of strategies for the use of contrast media for diagnostic cardiac catheterization.

A decision tree model was used to estimate the incremental cost per quality-adjusted life year (QALY) of low- as opposed to high-osmolality contrast media for cardiac angiography. Analyses were done from the viewpoints of a third-party payer and society using data from a randomized trial and the literature. Assuming low-osmolality media reduce the risk of myocardial infarction and stroke, the incremental cost per QALY gained with these media is $17,264 in high-risk or $47,874 in low-risk patients for a third-party payer. From a societal viewpoint, the corresponding costs are $649 and $35,509. These estimates are sensitive to the cost and volume of the contrast medium employed and to the estimate of reduction in severe adverse events with low-osmolality media. The authors conclude that, in the context of restricted budgets, limiting the use of low-osmolality media to high-risk patients is justifiable, as the incremental cost per QALY in high-risk patients may be reasonable and it is not certain that low-osmolality media prevent severe or fatal events. A considerable reduction in the cost per QALY gained is possibly by minimizing the volume of contrast medium used.

Cardiac Catheterization↗