Bias in meta-analysis detected by a simple, graphical test

OBJECTIVE

Funnel plots (plots of effect estimates against sample size) may be useful to detect bias in meta-analyses that were later contradicted by large trials. We examined whether a simple test of asymmetry of funnel plots predicts discordance of results when meta-analyses are compared to large trials, and we assessed the prevalence of bias in published meta-analyses.

DESIGN

Medline search to identify pairs consisting of a meta-analysis and a single large trial (concordance of results was assumed if effects were in the same direction and the meta-analytic estimate was within 30% of the trial); analysis of funnel plots from 37 meta-analyses identified from a hand search of four leading general medicine journals 1993-6 and 38 meta-analyses from the second 1996 issue of the Cochrane Database of Systematic Reviews.

MAIN OUTCOME MEASURE

Degree of funnel plot asymmetry as measured by the intercept from regression of standard normal deviates against precision.

RESULTS

In the eight pairs of meta-analysis and large trial that were identified (five from cardiovascular medicine, one from diabetic medicine, one from geriatric medicine, one from perinatal medicine) there were four concordant and four discordant pairs. In all cases discordance was due to meta-analyses showing larger effects. Funnel plot asymmetry was present in three out of four discordant pairs but in none of concordant pairs. In 14 (38%) journal meta-analyses and 5 (13%) Cochrane reviews, funnel plot asymmetry indicated that there was bias.

CONCLUSIONS

A simple analysis of funnel plots provides a useful test for the likely presence of bias in meta-analyses, but as the capacity to detect bias will be limited when meta-analyses are based on a limited number of small trials the results from such analyses should be treated with considerable caution.

Treatment of active ankylosing spondylitis with infliximab: a randomised controlled multicentre trial

BACKGROUND Treatment options for patients with ankylosing spondylitis are few. We aimed to assess the effectiveness of infliximab, an antibody to tumour necrosis factor (TNF)-alpha, in treatment of such patients.

METHODS

In this 12-week placebo-controlled multicentre study, we randomly assigned 35 patients with active ankylosing spondylitis to intravenous infliximab (5 mg/kg) and 35 to placebo at weeks 0, 2, and 6. One patient in the infliximab group was withdrawn from the study. Our primary outcome was regression of disease activity of at least 50%. To assess response, we used validated clinical criteria from the ankylosing spondylitis assessment working group, including disease activity (BASDAI), functional indices (BASFI), metrology (BASMI), and quality of life (short form 36). Analyses were done by intention to treat.

FINDINGS

18 (53%) of 34 patients on infliximab had a regression of disease activity at week 12 of at least 50% compared with three (9%) of 35 on placebo (difference 44% [95% CI 23-61], p<0.0001). Function and quality of life also improved significantly on infliximab but not on placebo (p<0.0001 and p<0.0001, respectively). Treatment with infliximab was generally well tolerated, but three patients had to stop treatment because of systemic tuberculosis, allergic granulomatosis of the lung, or mild leucopenia.

INTERPRETATION

Our results show that treatment with infliximab is effective in patients with active ankylosing spondylitis. Since there are some potentially serious adverse effects, we recommend that this treatment mainly be used in co-operation with rheumatological centres.

Language bias in randomised controlled trials published in English and German

BACKGROUND

Some randomised controlled trials (RCTs) done in German-speaking Europe are published in international English-language journals and others in national German-language journals. We assessed whether authors are more likely to report trials with statistically significant results in English than in German.

METHODS

We studied pairs of RCT reports, matched for first author and time of publication, with one report published in German and the other in English. Pairs were identified from reports round in a manual search of five leading German-language journals and from reports published by the same authors in English found on Medline. Quality of methods and reporting were assessed with two different scales by two investigators who were unaware of authors' identities, affiliations, and other characteristics of trial reports. Main study endpoints were selected by two investigators who were unaware of trial results. Our main outcome was the number of pairs of studies in which the levels of significance (shown by p values) were discordant.

FINDINGS

62 eligible pairs of reports were identified but 19 (31%) were excluded because they were duplicate publications. A further three pairs (5%) were excluded because no p values were given. The remaining 40 pairs were analysed. Design characteristics and quality features were similar for reports in both languages. Only 35% of German-language articles, compared with 62% of English-language articles, reported significant (p < 0.05) differences in the main endpoint between study and control groups (p = 0.002 by McNemar's test). Logistic regression showed that the only characteristic that predicted publication in an English-language journal was a significant result. The odds ratio for publication of trials with significant results in English was 3.75 (95% CI 1.25-11.3).

INTERPRETATION

Authors were more likely to publish RCTs in an English-language journal if the results were statistically significant. English language bias may, therefore, be introduced in reviews and meta-analyses if they include only trials reported in English. The effort of the Cochrane Collaboration to identify as many controlled trials as possible, through the manual search of many medical journals published in different languages will help to reduce such bias.

New Syntheses with Oils and Fats as Renewable Raw Materials for the Chemical Industry

Oils and fats are the most important renewable raw materials for the chemical industry. Hitherto, industrial oleochemistry has concentrated predominantly on the carboxy functionality of fatty acids but, more recently, modern synthetic methods have been applied extensively to fatty compounds for the selective functionalization of the alkyl chain. Radical, electrophilic, nucleophilic, and pericyclic as well as transition metal catalyzed additions to the C-C double bond of, for example, oleic acid as the prototype of a readily accessible, unsaturated fatty acid have led to a large number of novel fatty compounds from which interesting properties are expected. Functionalization of C-H bonds in the alkyl chain is also feasible with remarkable selectivity. Effective and highly versatile catalysts for the metathesis of esters of unsaturated fatty acids have been developed, which lead to new and interesting omega-unsaturated fatty acids. The epoxidation of unsaturated fatty acids has been developed extensively. Enzymatic reactions allow syntheses with high selectivity and yield of mono- and diglycerides and esters of carbohydrates with a variety of surfactant properties. Regio- and enantioselective microbial hydrations and hydroxylations widen the spectrum of selective reactions. Of considerable significance is that, with the use of gene technology, natural oils and fats have been improved significantly and will be improved still further, insofar as they show a more uniform and often unusual fatty acid spectrum. Numerous fatty acids are now available in a purity which makes them attractive for synthesis and as raw materials for the chemical industry.

EULAR recommendations for women's health and the management of family planning, assisted reproduction, pregnancy and menopause in patients with systemic lupus erythematosus and/or antiphospholipid syndrome

OBJECTIVES

Develop recommendations for women's health issues and family planning in systemic lupus erythematosus (SLE) and/or antiphospholipid syndrome (APS).

METHODS

Systematic review of evidence followed by modified Delphi method to compile questions, elicit expert opinions and reach consensus.

RESULTS

Family planning should be discussed as early as possible after diagnosis. Most women can have successful pregnancies and measures can be taken to reduce the risks of adverse maternal or fetal outcomes. Risk stratification includes disease activity, autoantibody profile, previous vascular and pregnancy morbidity, hypertension and the use of drugs (emphasis on benefits from hydroxychloroquine and antiplatelets/anticoagulants). Hormonal contraception and menopause replacement therapy can be used in patients with stable/inactive disease and low risk of thrombosis. Fertility preservation with gonadotropin-releasing hormone analogues should be considered prior to the use of alkylating agents. Assisted reproduction techniques can be safely used in patients with stable/inactive disease; patients with positive antiphospholipid antibodies/APS should receive anticoagulation and/or low-dose aspirin. Assessment of disease activity, renal function and serological markers is important for diagnosing disease flares and monitoring for obstetrical adverse outcomes. Fetal monitoring includes Doppler ultrasonography and fetal biometry, particularly in the third trimester, to screen for placental insufficiency and small for gestational age fetuses. Screening for gynaecological malignancies is similar to the general population, with increased vigilance for cervical premalignant lesions if exposed to immunosuppressive drugs. Human papillomavirus immunisation can be used in women with stable/inactive disease.

CONCLUSIONS

Recommendations for women's health issues in SLE and/or APS were developed using an evidence-based approach followed by expert consensus.

A meta-analysis of the effects of treatment on left ventricular mass in essential hypertension

PURPOSE

Antihypertensive medications have different effects on left ventricular mass. We conducted a meta-analysis of double-blind trials that measured the effects of antihypertensive therapy on left ventricular mass.

METHODS

Medical databases and review articles were screened for double-blind, randomized controlled trials (through September 2002) that reported the effects of diuretics, beta-blockers, calcium antagonists, angiotensin-converting enzyme (ACE) inhibitors, or angiotensin II receptor antagonists on echocardiographic left ventricular mass in essential hypertension. Treatment arms of the same drug class, weighted for the number of patients, were combined. Analysis of covariance was performed to detect differences among drug classes in effects on left ventricular structure.

RESULTS

Eighty trials with 146 active treatment arms (n = 3767 patients) and 17 placebo arms (n = 346 patients) were identified. Adjusted for treatment duration and change in diastolic blood pressure, there was a significant difference (P = 0.004) among medication classes: left ventricular mass index decreased by 13% with angiotensin II receptor antagonists (95% confidence interval [CI]: 8% to 18%), by 11% with calcium antagonists (95% CI: 9% to 13%), by 10% with ACE inhibitors (95% CI: 8% to 12%), by 8% with diuretics (95% CI: 5% to 10%), and by 6% with beta-blockers (95% CI: 3% to 8%). In pairwise comparisons, angiotensin II receptor antagonists, calcium antagonists, and ACE inhibitors were more effective at reducing left ventricular mass than were beta-blockers (all P <0.05 with Bonferroni correction).

CONCLUSIONS

Antihypertensive drug classes have different effects on left ventricular mass reduction. Whether a greater reduction of left ventricular mass results in better clinical outcomes remains to be determined.

Trends in the postmortem epidemiology of invasive fungal infections at a university hospital

BACKGROUND

Due to the lack of reliable diagnostic tools, clinical data on the significance of most invasive fungal infections are difficult to assess and information on frequency, disease pattern and prognostic impact still largely relies on autopsy data.

METHODS AND RESULTS

To determine temporal trends in invasive fungal infections, we analyzed data from 8124 autopsies performed between 1978 and 1992 on patients who died at the University Hospital of Frankfurt/Main. During that period, a total of 278 invasive fungal infections were found. The prevalence rose from 2.2% (1978-82) and 3.2% (1983-87) to 5.1% in the most recent years (P < 0.001). Besides the emergence of mixed and unclassified infections, this was mainly due to a significant increase in Aspergillus infections (P < 0.001), whereas the prevalence of Candida infections was stable and even showed a declining trend within the last years. The highest infection rates were found in aplastic syndromes (68%), followed by AML (25%) and AIDS (19%). In the majority of cases (76%), invasive fungal infection was related to the immediate cause of death. However, the proportion of patients with endstage underlying conditions increased significantly over time from 53% to 80% (P < 0.001). Accordingly, the number of patients who were not considered terminally ill but had died from fungal infection dropped from 35% to 17% within the last years (P < 0.01).

CONCLUSIONS

These observations document significant changes in frequency, aetiology and underlying disease processes in invasive fungal infections at autopsy and underscore the continuing need for more effective prevention, diagnosis, and treatment.

EULAR recommendations for the management of systemic lupus erythematosus. Report of a Task Force of the EULAR Standing Committee for International Clinical Studies Including Therapeutics

OBJECTIVE

Systemic lupus erythematosus (SLE) is a complex disease with variable presentations, course and prognosis. We sought to develop evidence-based recommendations addressing the major issues in the management of SLE.

METHODS

The EULAR Task Force on SLE comprised 19 specialists and a clinical epidemiologist. Key questions for the management of SLE were compiled using the Delphi technique. A systematic search of PubMed and Cochrane Library Reports was performed using McMaster/Hedges clinical queries' strategies for questions related to the diagnosis, prognosis, monitoring and treatment of SLE. For neuropsychiatric, pregnancy and antiphospholipid syndrome questions, the search was conducted using an array of relevant terms. Evidence was categorised based on sample size and type of design, and the categories of available evidence were identified for each recommendation. The strength of recommendation was assessed based on the category of available evidence, and agreement on the statements was measured across the 19 specialists.

RESULTS

Twelve questions were generated regarding the prognosis, diagnosis, monitoring and treatment of SLE, including neuropsychiatric SLE, pregnancy, the antiphospholipid syndrome and lupus nephritis. The evidence to support each proposition was evaluated and scored. After discussion and votes, the final recommendations were presented using brief statements. The average agreement among experts was 8.8 out of 10.

CONCLUSION

Recommendations for the management of SLE were developed using an evidence-based approach followed by expert consensus with high level of agreement among the experts.

EULAR recommendations for the management of systemic lupus erythematosus with neuropsychiatric manifestations: report of a task force of the EULAR standing committee for clinical affairs

OBJECTIVES

To develop recommendations for the diagnosis, prevention and treatment of neuropsychiatric systemic lupus erythematosus (NPSLE) manifestations.

METHODS

The authors compiled questions on prevalence and risk factors, diagnosis and monitoring, therapy and prognosis of NPSLE. A systematic literature search was performed and evidence was categorised based on sample size and study design.

RESULTS

Systemic lupus erythematosus (SLE) patients are at increased risk of several neuropsychiatric manifestations. Common (cumulative incidence > 5%) manifestations include cerebrovascular disease (CVD) and seizures; relatively uncommon (1-5%) are severe cognitive dysfunction, major depression, acute confusional state (ACS), peripheral nervous disorders psychosis. Strong risk factors (at least fivefold increased risk) are previous or concurrent severe NPSLE (for cognitive dysfunction, seizures) and antiphospholipid antibodies (for CVD, seizures, chorea). The diagnostic work-up of suspected NPSLE is comparable to that in patients without SLE who present with the same manifestations, and aims to exclude causes unrelated to SLE. Investigations include cerebrospinal fluid analysis (to exclude central nervous system infection), EEG (to diagnose seizure disorder), neuropsychological tests (to assess cognitive dysfunction), nerve conduction studies (for peripheral neuropathy) and MRI (T1/T2, fluid-attenuating inversion recovery, diffusion-weighted imaging, enhanced T1 sequence). Glucocorticoids and immunosuppressive therapy are indicated when NPSLE is thought to reflect an inflammatory process (optic neuritis, transverse myelitis, peripheral neuropathy, refractory seizures, psychosis, ACS) and in the presence of generalised lupus activity. Antiplatelet/anticoagulation therapy is indicated when manifestations are related to antiphospholipid antibodies, particularly thrombotic CVD.

CONCLUSIONS

Neuropsychiatric manifestations in SLE patients should be first evaluated and treated as in patients without SLE, and secondarily attributed to SLE and treated accordingly.

Bias in meta-analysis detected by a simple, graphical test

OBJECTIVE

Funnel plots (plots of effect estimates against sample size) may be useful to detect bias in meta-analyses that were later contradicted by large trials. We examined whether a simple test of asymmetry of funnel plots predicts discordance of results when meta-analyses are compared to large trials, and we assessed the prevalence of bias in published meta-analyses.

DESIGN

Medline search to identify pairs consisting of a meta-analysis and a single large trial (concordance of results was assumed if effects were in the same direction and the meta-analytic estimate was within 30% of the trial); analysis of funnel plots from 37 meta-analyses identified from a hand search of four leading general medicine journals 1993-6 and 38 meta-analyses from the second 1996 issue of the Cochrane Database of Systematic Reviews.

MAIN OUTCOME MEASURE

Degree of funnel plot asymmetry as measured by the intercept from regression of standard normal deviates against precision.

RESULTS

In the eight pairs of meta-analysis and large trial that were identified (five from cardiovascular medicine, one from diabetic medicine, one from geriatric medicine, one from perinatal medicine) there were four concordant and four discordant pairs. In all cases discordance was due to meta-analyses showing larger effects. Funnel plot asymmetry was present in three out of four discordant pairs but in none of concordant pairs. In 14 (38%) journal meta-analyses and 5 (13%) Cochrane reviews, funnel plot asymmetry indicated that there was bias.

CONCLUSIONS

A simple analysis of funnel plots provides a useful test for the likely presence of bias in meta-analyses, but as the capacity to detect bias will be limited when meta-analyses are based on a limited number of small trials the results from such analyses should be treated with considerable caution.

The International Classification of Functioning, Disability and Health: a new tool for understanding disability and health

Reliable and timely information about the health of populations is part of the World Health Organization's mandate in the development of international public health policy. To capture data concerning functioning and disability, or non-fatal health outcomes, WHO has recently published the revised International Classification of Functioning, Disability and Health (ICF). In this article, the authors briefly outline the revision process and discuss the rationale for the ICF and the needs that it serves in rehabilitation. The ICF is shown to be an essential tool for identifying and measuring efficacy and effectiveness of rehabilitation services, both through functional profiling and intervention targeting. Existing applications of the ICF in rehabilitation are then surveyed. The ICF, in short, offers an international, scientific tool for understanding human functioning and disability for clinical, research, policy development and a range of other public health uses.

Crystal structure of the xanthine oxidase-related aldehyde oxido-reductase from D. gigas

The crystal structure of the aldehyde oxido-reductase (Mop) from the sulfate reducing anaerobic Gram-negative bacterium Desulfovibrio gigas has been determined at 2.25 A resolution by multiple isomorphous replacement and refined. The protein, a homodimer of 907 amino acid residues subunits, is a member of the xanthine oxidase family. The protein contains a molybdopterin cofactor (Mo-co) and two different [2Fe-2S] centers. It is folded into four domains of which the first two bind the iron sulfur centers and the last two are involved in Mo-co binding. Mo-co is a molybdenum molybdopterin cytosine dinucleotide. Molybdopterin forms a tricyclic system with the pterin bicycle annealed to a pyran ring. The molybdopterin dinucleotide is deeply buried in the protein. The cis-dithiolene group of the pyran ring binds the molybdenum, which is coordinated by three more (oxygen) ligands.

Population study of dihydropyrimidine dehydrogenase in cancer patients

PURPOSE

We conducted a prospective study on a large set of cancer patients in an attempt to evaluate the incidence of complete or partial dihydropyrimidine dehydrogenase (DPD) deficiency as found in peripheral mononuclear cells (PMNC).

PATIENTS AND METHODS

One hundred eighty-five unselected consecutive cancer patients were included. The population consisted of 152 men (mean age, 62.1 years; range, 35 to 90) and 33 women (mean age, 59.2 years; range, 36 to 77). Sixty-eight were head and neck patients treated by a 5-day continuous infusion of fluorouracil (FU; starting dose, 1 g/m2/d, with dose adaptation based on pharmacokinetics) for which DPD activity was measured 2 to 3 days before FU administration (94 cycles analyzed). PMNC-DPD activity was measured by a radio-enzymatic assay using carbon-14-FU.

RESULTS

DPD activity in the entire population showed a unimodal distribution, which globally fits a gaussian distribution. Mean and median DPD activity values were 0.222 and 0.211 nmol/min/mg protein, respectively (range, 0.065 to 0.559). No total DPD deficiency was found. Multifactor analysis of variance showed that liver function (biologic evaluation) and age did not influence DPD activity, but that DPD activity was, on average, 15% lower in women (0.194 nmol/min/mg protein) than in men (0.228 nmol/min/mg protein) (P = .03). No difference was demonstrated between premenopausal and postmenopausal women. In patients treated with FU, the risk of developing side effects was not linked to pretreatment DPD activity. FU-related toxicity was linked to FU systemic exposure. The correlation between pretreatment DPD activity and FU systemic clearance (CI) was weak (n = 90, linear regression r = .31, P = .002). Pretreatment DPD activity in patients who required a dose reduction was not significantly different from DPD activity in patients who did not require dose modification.

CONCLUSION

From the present study, it appears that total DPD deficiency is a rare event. Although pretreatment DPD activity cannot be a useful indicator for improving FU dose adaptation strategy, the identification of severe DPD deficiency (< 0.100 nmol/min/mg protein) could lead to starting the treatment with a markedly reduced FU dose or even to using an alternative chemotherapy regimen.

Prevention of atrial fibrillation by Renin-Angiotensin system inhibition a meta-analysis

OBJECTIVES

The authors reviewed published clinical trial data on the effects of renin-angiotensin system (RAS) inhibition for the prevention of atrial fibrillation (AF), aiming to define when RAS inhibition is most effective.

BACKGROUND

Individual studies examining the effects of RAS inhibition on AF prevention have reported controversial results.

METHODS

All published randomized controlled trials reporting the effects of treatment with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers in the primary or secondary prevention of AF were included.

RESULTS

A total of 23 randomized controlled trials with 87,048 patients were analyzed. In primary prevention, 6 trials in hypertension, 2 trials in myocardial infarction, and 3 trials in heart failure were included (some being post-hoc analyses of randomized controlled trials). In secondary prevention, 8 trials after cardioversion and 4 trials assessing the medical prevention of recurrence were included. Overall, RAS inhibition reduced the odds ratio for AF by 33% (p < 0.00001), but there was substantial heterogeneity among trials. In primary prevention, RAS inhibition was effective in patients with heart failure and those with hypertension and left ventricular hypertrophy but not in post-myocardial infarction patients overall. In secondary prevention, RAS inhibition was often administered in addition to antiarrhythmic drugs, including amiodarone, further reducing the odds for AF recurrence after cardioversion by 45% (p = 0.01) and in patients on medical therapy by 63% (p < 0.00001).

CONCLUSIONS

This analysis supports the concept of RAS inhibition as an emerging treatment for the primary and secondary prevention of AF but acknowledges the fact that some of the primary prevention trials were post-hoc analyses. Further areas of uncertainty include potential differences among specific RAS inhibitors and possible interactions or synergistic effects with antiarrhythmic drugs.

Expression of epidermal growth factor receptor and survival in upper aerodigestive tract cancer

PURPOSE

To determine the expression of epidermal growth factor receptor (EGFR) in head and neck squamous cell carcinoma and to evaluate its prognostic value.

MATERIALS AND METHODS

EGFR was determined in tumor biopsies obtained from 109 consecutive patients with head and neck cancer (100 men, nine women). Control biopsies were obtained from 94 patients in a symetric nontumoral area of the same anatomic site. EGFR was measured by a binding assay using human recombinant iodine 125-EGF.

RESULTS

The presence of detectable EGFR levels was found in all explored tumors with highly marked differences between patients (median, 71 fmol/mg protein; range, 2 to 2,302). In 93 of 94 cases, EGFR levels were higher in tumor samples as compared with healthy control zones. There was no significant difference in EGFR expression according to the various anatomic sites explored or tumoral differentiation status. There was a significant difference of distribution for EGFR levels between stages I and II tumors and stages III and IV tumors. The tumor EGFR levels were not linked to the response to first-line chemotherapy by cisplatin (CDDP) and fluorouracil (5FU). Survival was assessable for 103 patients for overall survival and for 81 patients for recurrence. EGFR overexpression was associated with shorter relapse-free (P = .0125) and overall survival (P = .028) rates. By multivariate analysis, the only significant variable was EGFR for relapse-free survival and tumor staging for overall survival. The association of EGFR to tumor staging markedly improves the significance for overall survival predictability (P = .002).

CONCLUSION

EGFR determination deserves particular attention in head and neck cancer, since it independently carries a strong prognostic value.

Infection- and malignancy-associated hemophagocytic syndromes. Secondary hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis represents a spectrum of pathogenetically different diseases in which a T-cell induced, uncontrolled activation of phagocytosing macrophages may lead to fever, organomegaly, and pancytopenia. The underlying immunologic disturbance can either be genetically transmitted, like in FHL, or acquired, as in IAHS or MAHS. Triggering infections can be found in all these diseases and do not allow a reliable differentiation. An international treatment protocol has been developed for FHL. IAHS and MAHS also have a high fatality rate, justifying immunomodulatory treatment if the disease is progressive.

Influence of bubble size distribution on the echogenicity of ultrasound contrast agents: a study of SonoVue

RATIONALE AND OBJECTIVES

To study the relative contributions of different bubble size classes to SonoVue's echogenicity in fundamental acoustic imaging modes. SonoVue is a contrast agent, previously known as BR1, with a bubble size distribution extending from approximately 0.7 to 10 microm.

METHODS

A model for the acoustic response of SonoVue was determined and validated for a set of experimental data. This model was used to simulate the acoustic response of a standard batch of SonoVue as the sum of responses of non-overlapping bubble size classes.

RESULTS

The simulation was first validated for a standard SonoVue bubble size distribution. When this distribution was considered as five size classes with equal numbers of bubbles, it was found that bubbles smaller than 2 microm accounted for 60% of the total number but contained only 5% of the total gas volume. The simulation results indicated marked differences in the acoustic contributions from these classes, with 80% of the acoustic efficacy provided by bubbles 3 to 9 microm in diameter. The study also compared bubble distributions in number, surface, and volume, with the distribution computed in terms of acoustic efficacy.

CONCLUSIONS

This study shows why bubble volume is a much better indicator of SonoVue's efficacy than is bubble count. A low threshold in diameter was found for SonoVue microbubbles at approximately 2 microm, under which size bubbles do not contribute appreciably to the echogenicity at medical ultrasound frequencies.

European League Against Rheumatism recommendations for monitoring patients with systemic lupus erythematosus in clinical practice and in observational studies

OBJECTIVES

To develop recommendations for monitoring patients with systemic lupus erythematosus (SLE) in clinical practice and observational studies and to develop a standardised core set of variables to monitor SLE.

METHODS

We followed the European League Against Rheumatism (EULAR) standardised procedures for guideline development. The following techniques were applied: nominal groups, Delphi surveys for prioritisation, small group discussion, systematic literature review and two Delphi rounds to obtain agreement. The panel included rheumatologists, internists, dermatologists, a nephrologist and an expert related to national research agencies. The level of evidence and grading of recommendations were determined according to the Levels of Evidence and Grades of Recommendations of the Oxford Centre for Evidence-Based Medicine.

RESULTS

A total of 10 recommendations have been developed, covering the following aspects: patient assessment, cardiovascular risk factors, other risk factors (osteoporosis, cancer), infection risk (screening, vaccination, monitoring), frequency of assessments, laboratory tests, mucocutaneous involvement, kidney monitoring, neuropsychological manifestations and ophthalmology assessment. A 'core set' of minimal variables for the assessment and monitoring of patients with SLE in clinical practice was developed that included some of the recommendations. In addition to the recommendations, indications for specific organ assessments that were viewed as part of good clinical practice were discussed and included in the flow chart.

CONCLUSIONS

A set of recommendations for monitoring patients with SLE in routine clinical practice has been developed. The use of a standardised core set to monitor patients with SLE should facilitate clinical practice, as well as the quality control of care for patients with SLE, and the collection and comparison of data in observational studies.

Treatment benefit or survival of the fittest: what drives the time-dependent decrease in serious infection rates under TNF inhibition and what does this imply for the individual patient?

OBJECTIVE

To examine the risk of serious infection conveyed by tumour necrosis factor α (TNFα) inhibitors in the treatment of rheumatoid arthritis (RA).

METHODS

Data from patients with RA enrolled in the German biologics register RABBIT were used for analysis. Baseline patient characteristics, time-varying risk factors (treatment changes, functional capacity) and selection processes caused by dropout, death or switching to non-anti-TNF treatment were taken into account to estimate the adjusted incidence rate ratios (IRR(adj)) of serious infection during treatment with TNF inhibitors compared with non-biological disease-modifying antirheumatic drug treatment.

RESULTS

Data were available on 5044 patients, in whom 392 serious infections occurred. The crude rates of serious infections in patients treated with TNF inhibitors declined over the first 3 years of observation (from 4.8 to 2.2/100 patient-years). This decline was driven by (1) treatment termination or loss to follow-up in patients at increased risk and (2) a risk reduction through decreasing glucocorticoid doses and improvement in function. Adjusted for selection processes and time-varying risk factors, the following parameters assessed at baseline (age, chronic diseases) or at follow-up prior to the infection were significantly associated with an increased risk: age >60 years, chronic lung or renal disease, low functional capacity, history of serious infections, treatment with glucocorticoids (7.5-14 mg/day, IRR(adj) 2.1 (95% CI 1.4 to 3.2); ≥ 15 mg/day, IRR(adj) 4.7 (95% CI 2.4 to 9.4)) and treatment with TNFα inhibitors (IRR(adj) 1.8 (95% CI 1.2 to 2.7)).

CONCLUSION

Reasons for the decline in infection rates observed at the group level were identified. The results enable expected infection rates to be calculated in individual patients based on their risk profiles.

BR1: a new ultrasonographic contrast agent based on sulfur hexafluoride-filled microbubbles

RATIONALE AND OBJECTIVES

The basic characteristics of BR1, a novel echo contrast agent based on stabilized sulfur hexafluoride (SF6) microbubbles have been evaluated.

METHODS

The authors determined the physicochemical properties (bubble concentration, bubble size distribution, resistance to pressure, and stability) and the acoustic properties (backscatter and attenuation coefficients) of BR1. The diagnostic value of BR1 was evaluated further in minipigs. Left heart images were recorded before and after injection of different doses of BR1.

RESULTS

BR1 is formulated as a lyophilized product, which after addition of saline, provides a suspension containing 2 x 10(8) SF6 microbubbles/mL with a number mean diameter of 2.5 microns. More than 90% of the bubbles are below 8 microns. The use of SF6 rather than air provides an improved resistance to pressure increases such as the ones occuring in the left heart during systole. After reconstitution, the echogenicity and the bubble characteristics are unchanged for more than 8 hours. The high echogenicity remains almost constant over the entire medical frequency range (1-10 MHz). BR1 injections in animals resulted in a homogenous, dose-dependent opacification of the left heart.

CONCLUSIONS

Considering its high echogenicity, outstanding stability, and resistance to pressure changes, BR1 is a very promising ultrasound contrast agent.

The importance of ammonia in mammalian cell culture

Ammonia has been reported to be toxic and inhibitory for mammalian cell cultures for many years. Reduction of growth rates and maximal cell densities in batch cultures, changes in metabolic rates, perturbation of protein processing and virus replication have been reported. However, cellular mechanisms of ammonia toxicity are still the subject of controversy and are presented here. The physical and chemical characteristics of ammonia and ammonium are important, with the former capable of readily diffusing across cellular membranes and the latter competing with other cations for active transport by means of carrier proteins. The main source of the ammonia which accumulates in cell cultures is glutamine, which plays an important role in the metabolism of rapidly growing cells. Strategies to overcome toxic ammonia accumulation include substitution of glutamine by glutamate or other amino acids, nutrient control, i.e., controlled addition of glutamine at low concentrations, or removal of ammonia or ammonium from the culture medium by means of ion-exchange resins, ion-exchange membranes, gas-permeable membranes or electrodialysis.