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Biomedical subjects

B J Barrett

Publications and source records attributed to B J Barrett.

At least 19 recordsLinked to original sources
PubMed1997

Prediction of early death in end-stage renal disease patients starting dialysis.

Demand for dialysis for patients with end-stage renal disease is growing, as is the comorbidity of dialysis patients. Accurate prediction of those destined to die quickly despite dialysis could be useful to patients, providers, and society in making decisions about starting dialysis. To determine whether age and comorbidity accurately predict death within 6 months of first dialysis for end-stage renal disease, a prospective cohort study of 822 patients starting dialysis at one of 11 Canadian centers was performed. Patient characteristics were recorded at first dialysis. Follow-up continued until death or study end (at least 6 months after enrollment). One hundred thirteen of 822 (13.7%) patients died within 6 months. Although an existing scoring system predicted prognosis, adverse scores greater than 9 were found in only 9.7% of those who died; only 52% of those who scored higher than 9 died within 6 months. No score cutoff point combined high true-positive and low false-positive rates for predicting early death. Age, severity of heart failure or peripheral vascular disease, arrhythmias, malnutrition, malignancy, or myeloma were independent prognostic factors identified in multivariate models. However, the best fit discriminant and logistic models were also unable to accurately predict death within 6 months. Clinicians were very accurate in assigning patients to prognostic groups up to a 50% risk of death by 6 months, above which they tended to overestimate risk. However, clinicians were only marginally better than the predictive models in determining whether a given high-risk patient would die. The inability of a scoring system or clinical intuition to accurately predict death soon after starting dialysis for end-stage renal disease suggests that limiting access to dialysis on the basis of likely short survival may be inappropriate in Canada.

Aged↗
PubMed1996

Acetaminophen and adverse chronic renal outcomes: an appraisal of the epidemiologic evidence.

This article critically reviews existing epidemiologic studies of the association between habitual acetaminophen use and chronic renal disease exclusive of neoplasia. Relevant primary studies were identified by searching the Medline database from 1966 to March 1995. There are several case reports of analgesic nephropathy following exposure to acetaminophen alone, but the accuracy with which other causes of this lesion were excluded is unclear. Three case control studies have found an increased risk (odds ratio range, 2 to 4) with habitual acetaminophen exposure for papillary necrosis, chronic renal failure, or end-stage renal disease. These studies have been open to confounding by indication. It is also difficult to determine the risk with acetaminophen alone given the prevalent use of analgesic mixtures in the populations studied. Two prospective cohort studies have suggested an increased risk of renal impairment or papillary calcification following regular analgesic exposure. One of these studies was of subjects taking phenacetin-containing analgesic mixtures and the study population of the other was too small to reach statistically significant conclusions. Recent study results have raised the possibility that habitual acetaminophen use could increase the likelihood or rate of progression of chronic renal disease in general. This review suggests that there is currently insufficient evidence to conclude that habitual use of acetaminophen as a sole analgesic is associated with an increased risk of chronic renal disease. Further research is required to examine this question. Prudence suggests that habitual use of acetaminophen should be discouraged in the absence of strong medical indications.

Acetaminophen↗
PubMed1996

Detection and classification of inappropriate hospital stay.

OBJECTIVE: To study the reliability and validity of concurrent review of hospital-bed utilization carried out by a trained nurse. DESIGN: Analysis of interrater reliability and validity of utilization review. SETTING: Tertiary care hospital associated with a university. PATIENTS: Eighty patients randomly selected from 203 patients admitted to the hospital. INTERVENTIONS: Appropriateness of days of stay in hospital was classified prospectively, on the basis of clinical judgement, by two nurses working independently, by a third nurse working with the Appropriateness Evaluation Protocol (AEP) and by a multidisciplinary review panel of nurses and physicians working retrospectively with the use of data gathered by the first nurse. MAIN OUTCOME MEASURES: Agreement between different rates on the number of and reason for inappropriate admission days, total number of inappropriate days and of inappropriate days due to delayed discharge, to diagnostic procedures or to inefficient medical management. RESULTS: Agreement between the two nurses who used clinical judgement was substantial (kappa or the intraclass correlation coefficient [RI] 0.77 to 0.98 on the number of and reason for inappropriate admission days, on the total number of inappropriate hospital days and on days due to delayed discharge, diagnostic procedures or inefficient medical management. Agreement was moderate (RI 0.47) on the number of inappropriate day's stay awaiting surgery. Agreement was substantial (kappa or RI 0.69 to 0.94) between the two nurses who used clinical judgement and the panel, except on the total number of inappropriate days; however, for this variable, exclusion of one case increased the RI from 0.35 to 0.80. Agreement was substantial between the two nurses who used clinical judgement and the nurse who used the AEP on appropriateness of admission days and the number of inappropriate days. Agreement between the panel and the nurse who used the AEP on the number of inappropriate days rose from 0.36 to 0.88 when the one outlying case was excluded. Some admissions were classified as premature when the AEP was used, whereas other raters considered the admissions unnecessary. There was poor agreement between the nurse who used the AEP and the other raters on the number of inappropriate days' stay awaiting surgery or diagnostic tests. CONCLUSIONS: Data collection and judgement of appropriateness of hospital stay by a trained nurse is feasible and reliable. A nurse working prospectively and a panel working retrospectively sometimes disagree. The AEP provides a similar estimate of the number of inappropriate days but may be insensitive to patient factors that influence the timing of admission.

Female↗
PubMed1996

Concurrent utilization review and inappropriate hospital stay: evaluation of a program.

Using a crossover design, we tested the hypothesis that concurrent utilization review by a utilization officer would reduce length of stay and inappropriate bed days in a tertiary care hospital. The intervention groups included 396 consecutive patients admitted to specified services during two 1-month study periods and followed for at least 1 month or until discharge. Controls were 410 patients admitted to the same services during a preceding or subsequent month, separated by a 1-month washout period. Intervention cases had daily review of their care plan and medical condition by the utilization officer to identify existing or likely inappropriate hospital stay. The officer used interdisciplinary and interdepartmental consultation in attempting to resolve identified problems. A separate research nurse identified the controls and gathered data on the medical condition and care plan for a random 50% sample of both intervention and control cases. These data were used by a multidisciplinary panel to count and classify the reasons for inappropriate hospital days. Overall, there were no significant differences between the corresponding intervention and control groups for length of stay or proportion of inappropriate days. There was evidence of a time-related reduction in both length of stay and inappropriate days only in the subgroup of patients with a length of stay of < 15 d. As further evidence of this period effect unrelated to the intervention, length of stay had been declining for 1 of the groups of services before this study began. We concluded that concurrent utilization review, as practiced in this study, was ineffective in the short term. However, utilization review and modification of hospital processes can reduce inefficiency, as evidenced by the time-related reduction in inefficiency illustrated in our study.

Admitting Department, Hospital↗
PubMed1995

Hypertension in autosomal dominant polycystic kidney disease.

Hypertension occurs frequently in autosomal dominant polycystic kidney disease. Increased activity of the renin-angiotensin system contributes to the development and maintenance of hypertension before the development of renal failure. Angiotensin-converting enzyme inhibitors are indicated for treatment of hypertension before the development of renal failure, but in severe renal failure these agents may cause further deterioration in renal function. Treatment of hypertension may not retard the progression of renal failure but is necessary for the prevention of cardiovascular disease.

Antihypertensive Agents↗
PubMed1995

Hypoglycemia following inadvertent and factitious sulfonylurea overdosages.

OBJECTIVE: To recognize unreported sulfonylurea overdosages in hypoglycemic patients. CASES: We describe three patients with hypoglycemia due to inadvertent (in two patients) and factitious (in one patient) sulfonylurea overdosages. We review the world literature and summarize 43 previously published cases of inadvertently administered and 23 previously published cases of factitiously self-administered sulfonylurea overdosages with hypoglycemia. RESULTS: An inadvertently administered fulsonylurea overdosage usually occurred when a sulfonylurea was accidentally substituted for an intended medication with a similar generic or trade name. Features of the patients with a factitiously self-administered sulfonylurea overdosage included: 1) a history of the patient or patient's spouse having a medical job or sulfonylurea-treated diabetes mellitus; 2) an unusual affect or psychiatric history; 3) an abrupt onset of severe symptoms without previous milder symptoms; and 4) an absent hypoglycemic or hyperinsulinemic response to provocative testing. These features are not typical for an insulinoma. CONCLUSIONS: When a hypoglycemic patient denies antidiabetic medication use, we recommend sequentially performing: 1) a thorough pill inspection; 2) an interview for recently altered pill appearances; 3) a measurement of serum insulin and C-peptide levels during hypoglycemia; and 4) a blood or urine sulfonylurea screen. Discovery of an unreported sulfonylurea overdosage can eliminate the need to search for an insulinoma and prevent further overdosages from occurring.

Adult↗
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↗