Validation of the GetReal Trial Tool - Facilitating discussion and understanding more pragmatic design choices and their implications

BACKGROUND

The GetReal Trial Tool is a decision support tool to assess the impact of design choices on generalizability of clinical trials to routine clinical practice, while taking into account the risk of bias, precision, acceptability and operational feasibility. This study describes the validation of the GetReal Trial Tool.

METHODS

Twelve experts took part in the GetReal Trial tool validation using the protocols of 6 trials conducted with pragmatic elements. The tool entails 7 domains with a total of 43 questions. A pooled Kappa statistic (95% CI) using random effects model was estimated using Open Meta (analyst) software. The possible operational challenges were collated and discussed with the trialists that conducted the trials.

RESULTS

Agreement in the design choices made for the trial protocols was >50% for all the trials and all teams reached consensus during discussion. The pooled Kappa statistic (95% CI) was 0.236 (0.154-0.318). The GetReal Trial tool highlighted several operational challenges, of which almost half had been experienced previously by the trialists. Out of 25 additional operational challenges mentioned by the trialists, 76% were already highlighted by the tool. The tool was considered helpful to optimize trials right from the design stage.

CONCLUSION

The GetReal Trial Tool helps to scrutinize the choice of study design in the light of Real World Evidence generation. The tool identifies most of the operational challenges experienced by trialists to date. The tool serves the intended purpose of facilitating discussion and understanding more pragmatic design choices and their implications.

Development of a claims-based flare algorithm for systemic lupus erythematosus

OBJECTIVE

To develop a claims-based algorithm identifying systemic lupus erythematosus (SLE) flares using a linked claims-electronic medical record (EMR) dataset.

METHODS

This study was a retrospective analysis of linked administrative claims and EMR data spanning 1 January 2003 to 31 March 2019. Included were adult SLE patients with at least 12 months of continuous enrollment in claims data, 12 months of clinical activity in EMR, and an absence of malignancies excluding basal and squamous cell carcinoma. Patient follow-up was divided into 30-day windows, and a proxy SLEDAI-2K score based on the EMR data was calculated for each 30-day period. A flare was defined as an increase of at least 4 from the baseline score. A series of potential flare predictor variables identified in claims were based on a combination of established variables from a previous algorithm, with the addition of other SLE-related indicators based on clinical input. Logistic regression models were built to predict monthly SLE flares.

RESULTS

Inclusion criteria identified 2427 patients. Results from a logistic model with forward selection capping the number of variables at 10 performed well with a c-statistic of 0.76 and a Brier score of 0.07. The top five predictors were any inpatient admission (OR = 4.76), outpatient office visit (OR = 3.04), MRI (OR = 2.26), ER visit (OR = 2.25), and number of rheumatology visits (OR = 1.75); p < .01 for all.

CONCLUSIONS

The final algorithm shows promise in providing an alternative and more streamlined way for identifying likely flares in administrative claims data that will advance the study of SLE within the context of flares.

The GetReal Trial Tool: Design, Assess and Discuss Clinical Drug Trials in Light of RWE Generation

Methodologies incorporating Real World Elements into clinical trial design (also called pragmatic trials) offer an attractive opportunity to assess the effect of a treatment strategy in routine care and as such guide decision making in practice. Uptake of these methods is slow for several reasons, including uncertainty about acceptability of trial results, lack of experience with the methodology and operational challenges. We developed the 'Get Real Trial Tool', an easy-to-use interface, which allows users to assess the impact of design choices on generalisability to routine clinical practice, while taking into account risk of bias, precision, acceptability and operational feasibility. The tool is grounded in the scientific literature on pragmatic trials combined with knowledge of experts from academia, pharmaceutical companies, HTA bodies, patient organisations, and regulators. The aim is to help researchers optimise trial design and facilitate translation of evidence from pragmatic trials to clinical practice. In this paper we describe the development, structure and application of the GetReal Trial Tool.

Validation of claims-based indicators used to identify flare-ups in inflammatory bowel disease

BACKGROUND & AIMS

There are currently no validated claims-based indicators for identifying a worsening of disease in patients with inflammatory bowel disease (IBD). Therefore, we aimed to develop and validate indicators that identify flare-ups of IBD using data from Danish nationwide registries.

METHODS

Using Danish nationwide administrative data, we identified all patients with Crohn's disease (CD) or ulcerative colitis (UC) who had at least one measurement of faecal calprotectin between 1 January 2015 and 31 June 2017. We tested several different claims-based indicators of disease flare-ups against levels of faecal (F-)calprotectin (no flare-up: <250 mg/kg; mild flare-up: 250-1000 mg/kg; severe flare-up: ⩾1000 mg/kg). A generalised estimating equation was used to evaluate whether the proposed indicators could predict disease activity.

RESULTS

A total of 890 children and 4719 adults with CD, and 592 children and 5467 adults with UC were included in the study. During the observation period, 48-61% and 48-55% of the CD and UC patients, respectively, had no flare-up, 26-29% (CD) and 24-26% (UC) experienced a mild flare-up, and 12-23% (CD) and 21-27% (UC) experienced a severe flare-up. Combinations of indicators that could predict a flare-up in CD and UC adults included hospitalisation, surgery, initiation or switch of biological therapy, treatment with systemic steroids, locally acting steroids or topical 5-aminosalicylates, colonoscopy/sigmoidoscopy, and magnetic resonance imaging/computed tomography. In children, only the number of gastroenterology visits was significant as an indicator among UC patients, and none were seen in children with CD. Overall, the indicator combinations resulted in a predictive ability of 0.62-0.67.

CONCLUSION

Administrative claims data can be useful for identifying patients exhibiting (F-calprotectin defined) flare-ups of their IBD. Clinically relevant events captured in the Danish national patient registry are associated with increased levels of calprotectin and hence increased disease activity, and can be used as valid outcomes in future studies.

Series: Pragmatic trials and real world evidence: Paper 6. Outcome measures in the real world

Results from pragmatic trials should reflect the comparative treatment effects encountered in patients in real-life clinical practice to guide treatment decisions. Therefore, pragmatic trials should focus on outcomes that are relevant to patients, clinical practice, and treatment choices. This sixth article in the series (see Box) discusses different types of outcomes and their suitability for pragmatic trials, design choices for measuring these outcomes, and their implications and challenges. Measuring outcomes in pragmatic trials should not interfere with real-world clinical practice to ensure generalizability of trial results, and routinely collected outcomes should be prioritized. Typical outcomes include mortality, morbidity, functional status, well-being, and resource use. Surrogate endpoints are typically avoided as primary outcome. It is important to measure outcomes over a relevant time horizon and obtain valid and precise results. As pragmatic trials are often open label, a less subjective outcome can reduce bias. Methods that decrease bias or enhance precision of the results, such as standardization and blinding of outcome assessment, should be considered when a high risk of bias or high variability is expected. The selection of outcomes in pragmatic trials should be relevant for decision making and feasible in terms of executing the trial in the context of interest. Therefore, this should be discussed with all stakeholders as early as feasible to ensure the relevance of study results for decision making in clinical practice and the ability to perform the study.

The Social Value of Pragmatic Trials

Pragmatic trials aim to directly inform health care decision-making through the collection of so-called 'real world data' from observations of comparative treatment effects in clinical practice. In order to ensure the applicability and feasibility of a pragmatic trial, design features may be necessary that deviate from standard research ethics requirements. Examples are traditional requirements to seek written informed consent and to perform extensive data and safety monitoring. Proposals for deviations from standard research ethics practice have resulted in controversy about their ethical acceptability. One of the justifications for altered procedures is the allegedly high social value of pragmatic trials. In order to properly operationalize the concept in the ethical assessment of pragmatic trial designs, specification is warranted. We identified three determinants from common claims about a pragmatic trial's social value: (1) the extent to which the research question has real world relevance, (2) the trial design's ability to generate a real world answer and (3) the probability of direct uptake of the results by decision-makers in practice. Subsequently, we discuss how these determinants should be applied to the practice of pragmatic trials, and to what extent they might be applicable to explanatory trials.

Comprehensive review of factors implicated in the heterogeneity of response in depression

BACKGROUND

Heterogeneity in overall response and outcomes to pharmacological treatment has been reported in several depression studies but with few sources that integrate these results. The goal of this study was to review the literature and attempt to identify nongenetic factors potentially predictive of overall response to depression treatments.

METHODS

A comprehensive review of the literature from the last 10 years was performed using three key databases (PubMed, EMBASE, and Cochrane). All relevant studies that met the inclusion criteria were selected and scored for their levels of evidence using the NICE scoring method. A subjective assessment of the strength of evidence for each factor was performed using predefined criteria.

RESULTS

Our broad search yielded 76 articles relevant to treatment heterogeneity. Sociodemographic factors, disease characteristics, and comorbidities were the most heavily researched areas. Some of the factors associated with more favorable overall response include being married, other social support, and low levels of baseline depressive symptoms. Evidence relating to baseline disease severity as a factor predictive of antidepressant response was particularly convincing among the factors reviewed. The presence of comorbid anxiety and pain contributed to worse antidepressant treatment outcomes.

CONCLUSIONS

Several factors either predictive of or associated with overall response to antidepressant treatment have been identified. Inclusion of factors predictive of response in the design of future trials may help tailor treatments to depression patients presenting to the average clinical practice, resulting in improved outcomes.

A comprehensive review of predictive and prognostic composite factors implicated in the heterogeneity of treatment response and outcome across disease areas

AIM

To assess and present the current body of evidence regarding composite measures associated with differential treatment response or outcome as a result of patient heterogeneity and to evaluate their consistency across disease areas.

METHODS

A comprehensive review of the literature from the last 10 years was performed using three databases (PubMed, Embase and Cochrane). All articles that met the inclusion/exclusion criteria were selected, abstracted and assessed using the NICE level-of-evidence criteria.

RESULTS

Forty-nine studies were identified in the data abstraction. Approximately one-third focused on existing composite measures, and the rest investigated emerging composite factors. The majority of studies targeted patients with cancer, cardiovascular disease or psychological disorders. As a whole, the composite measures were found to be disease-specific, but some composite elements, including age, gender, comorbidities and health status, showed consistency across disease areas. To complement these findings, common individual factors found in five previous independent disease-specific literature assessments were also summarised, including age, gender, treatment adherence and satisfaction, healthcare resource utilisation and health status.

CONCLUSIONS

Composite measures can play an important role in characterising heterogeneity of treatment response and outcome in patients suffering from various medical conditions. These measures can help clinicians to better distinguish between patients with high likelihood to respond well to treatment and patients with minimal chances of positive therapeutic outcomes. Herein, the individual factors identified can be used to develop novel predictive or prognostic composite measures that can be applicable across disease areas. Reflecting these cross-disease measures in clinical and public health decisions has the distinctive appeal to enable targeted treatment for patients suffering from multiple medical conditions, which may ultimately yield significant gains in individual outcomes, population health and cost-effective resource allocation.

Review of treatment response in rheumatoid arthritis: assessment of heterogeneity

OBJECTIVE

Rheumatoid arthritis (RA) is a chronic, systemic, progressive, inflammatory disorder. The primary goals of treatment in RA are to reduce the signs and symptoms of disease, prevent progression of joint damage and improve patients' physical function. Patients with different sociodemographic characteristics, varying degrees of severity of illness, and comorbidities tend to exhibit differential response to treatment. The purpose of this review was to identify a broad set of factors that are associated with and/or predictive of RA treatment response and determine those that warrant further research.

RESEARCH DESIGN AND METHODS

A comprehensive review of the literature from the last 10 years was performed using three key databases (PubMed, EMBASE, and Cochrane). All relevant articles that met the inclusion/exclusion criteria were selected and scored for their levels of evidence using the National Institute of Clinical Excellence (NICE) scoring method. Data on study design, interventions and treatment outcomes were abstracted using a structured abstraction table.

RESULTS

A total of 30 articles were included in the review and data abstraction. Besides gender, baseline clinical variables such as C-reactive protein level, erythrocyte sedimentation rate, measures of disease activity, and Health Assessment Questionnaire scores (based on five patient-centered dimensions) were consistently associated with treatment response over time.

CONCLUSIONS

This comprehensive literature review identified several factors associated with treatment response which might be valuable to include as relevant measures in future studies of RA treatment. Inclusion of these factors, particularly those in the clinical and sociodemographic domains, in the design of future trials will further the understanding that ultimately may help clinicians deliver targeted treatment to community practice RA patients, thus resulting in improved patient outcomes.

A review of treatment response in type 2 diabetes: assessing the role of patient heterogeneity

The response to treatment for type 2 diabetes typically varies among individuals within a study population. This variation is known as heterogeneity of treatment response. We conducted a comprehensive literature review to identify factors that account for heterogeneity of treatment response in patients treated for type 2 diabetes. Three databases (PubMed, EMBASE and Cochrane Library) were searched for articles published in the last 10 years describing investigations of factors associated with treatment response and outcomes among people with type 2 diabetes receiving pharmacological treatment. Of the 43 articles extracted and summarized, 35 (81%) discussed clinical factors, 31 (72%) described sociodemographic factors and 17 (40%) reported on comorbidity or behavioural factors. Clinical factors identified included baseline glycated hemoglobin A1c or fasting plasma glucose (FPG) levels, insulin response or sensitivity, C-peptide, body composition, adipose tissue proteins, lipid profile, plasma albumin levels and duration of disease or insulin treatment. Other factors identified included age, sex, race, socioeconomic status and comorbidities. This review identified the following research gaps: use of multiple definitions for response, few patient-reported measures and lack of evidence regarding whether factors were associated with treatment response for only specific medications or across pharmacological therapies. Furthermore, identification of factors associated with type 2 diabetes treatment response was generally a secondary objective in the research reviewed. Understanding which patient subgroups are more likely to respond to treatment and identifying factors associated with response may result in targeted treatment decisions and alter the interpretation of efficacy or effectiveness of results. In conclusion, accounting for these factors in clinical trials and when making clinical treatment decisions may improve therapy selection and individual patient outcomes.

Stability and treatment outcome of distinct classes of mania

BACKGROUND

Psychopathological heterogeneity in manic syndromes may in part reflect underlying latent classes with characteristic outcome patterns. Differential treatment course and outcome after 12 weeks of treatment were examined for three distinct classes of patients with acute mania in bipolar disorder.

SUBJECTS AND METHODS

Three thousand four hundred and twenty-five patients with acute mania were divided into three distinct mania classes: 'Typical', 'Psychotic' and 'Dual' (i.e. comorbid substance use) mania. Persistence of class differences and social outcomes were examined, using multilevel regression analyses and odds ratios.

RESULTS

The three classes showed substantial stability post-baseline in the pattern of associations with class-characteristic variables. Psychotic and Dual mania predicted poorer outcome in terms of psychosis comorbidity and overall bipolar and mania severity, while Dual mania additionally predicted poorer outcome of alcohol and substance abuse. Worse social outcomes were observed for both Dual and Psychotic mania.

CONCLUSION

The identified distinct classes are stable and associated with differential treatment outcome. Overall, Dual and Psychotic mania show less favourable outcomes compared to Typical mania. These findings additionally give rise to concern on the generalisability of randomized clinical trials RCTs.

Olanzapine monotherapy and olanzapine combination therapy in the treatment of mania: 12-week results from the European Mania in Bipolar Longitudinal Evaluation of Medication (EMBLEM) observational study

BACKGROUND

To evaluate the 12-week outcomes (effectiveness, tolerability, and patterns of medication use) of olanzapine (either in antimanic monotherapy or in combination with other antipsychotics, anticonvulsants, and/or lithium) in patients with bipolar mania or mixed mania.

METHOD

EMBLEM (European Mania in Bipolar Longitudinal Evaluation of Medication) is a 24-month prospective observational study of in- and outpatients with acute mania/mixed mania conducted in 14 European countries. Primary outcome measures included Clinical Global Impressions-Bipolar Disorder scale (overall, mania, and depression); 5-item Hamilton Depression Rating Scale; and Young Mania Rating Scale. Tolerability measures included a questionnaire to assess patients' symptomatic complaints.

RESULTS

Overall, 2004 patients received olanzapine (olanzapine monotherapy, n=673; olanzapine combination, n=1331). Concomitant therapy with antidepressants and/or anxiolytics was possible in both groups. The countries significantly differed in the use of olanzapine monotherapy versus olanzapine combination (p<.0001). Baseline-to-endpoint changes on the CGI-BP subscales, YMRS, and HAMD-5 were significant within both treatment groups (p<.0001). Olanzapine monotherapy was generally better tolerated than olanzapine combination, particularly with regard to sedation (12% vs 17%; p<.001), tremor (2% vs 5%; p<.001), and akathisia (3% vs 6%; p<.001).

DISCUSSION

The acute-phase EMBLEM results suggest that in naturalistic settings, olanzapine (both as monotherapy and combination) may be effective in treating patients with bipolar mania. The use of olanzapine monotherapy or combination varies significantly across countries, but combination is generally the rule, rather than the exception.

The social, psychopathological and consumer context of rate of symptom improvement in acute mania

BACKGROUND

Knowledge of moderators of symptom improvement over time in acute mania improves predictability of individual patient outcomes. This study attempted to identify such moderators of the rate of symptom improvement.

METHODS

In 3459 patients with high levels of mania in whom a change in psychotropic treatment was initiated and who were assessed six times over three months, clinical and social moderators of the rate of response were examined. Additionally, moderators of symptom improvement in individuals with high baseline levels of comorbid depression (n = 815) and psychosis (n = 1849) were identified.

RESULTS

Within three months, mania symptoms were reduced by 52%, psychotic symptoms by 56% and depressive symptoms by 36%. High levels of baseline depression, greater illness severity in the past year, lower age of onset and rapid cycling reduced the rate of mania symptom improvement by 5-15%. Social variables indicating disadvantage similarly had negative contributions (5%-14%). Several reasons for change of medication involving patient choice, patient compliance, side effects and lack of effectiveness impacted negatively (reductions of 10%, 6%, 14% and 9% respectively). For the psychosis dimension, both low mania scores (22% reduction) and high depression scores (14% reduction) at baseline impacted negatively, whereas rate of reduction in depression was not conditional on baseline psychopathology.

CONCLUSIONS

The rate of symptom improvement in acute mania is to a large extent conditional on the context as provided by the social, psychopathological and consumer environment. Understanding the context of treatment response offers valuable insights into treatment approaches aimed at moderation of traditional pharmacological interventions.

The management of bipolar mania: a national survey of baseline data from the EMBLEM study in Italy

BACKGROUND

Although a number of studies have assessed the management of mania in routine clinical practice, no studies have so far evaluated the short- and long-term management and outcome of patients affected by bipolar mania in different European countries. The objective of the study is to present, in the context of a large multicenter survey (EMBLEM study), an overview of the baseline data on the acute management of a representative sample of manic bipolar patients treated in the Italian psychiatric hospital and community settings. EMBLEM is a 2-year observational longitudinal study that evaluates across 14 European countries the patterns of the drug prescribed in patients with bipolar mania, their socio-demographic and clinical features and the outcomes of the treatment.

METHODS

The study consists of a 12-week acute phase and a < or = 24-month maintenance phase. Bipolar patients were included into the study as in- or out-patients, if they initiated or changed, according to the decision of their psychiatrist, oral antipsychotics, anticonvulsants and/or lithium for the treatment of an episode of mania. Data concerning socio-demographic characteristics, psychiatric and medical history, severity of mania, prescribed medications, functional status and quality of life were collected at baseline and during the follow-up period.

RESULTS

In Italy, 563 patients were recruited in 56 sites: 376 were outpatients and 187 inpatients. The mean age was 45.8 years. The mean CGI-BP was 4.4 (+/- 0.9) for overall score and mania, 1.9 (+/- 1.2) for depression and 2.6 (+/- 1.6) for hallucinations/delusions. The YMRS showed that 14.4% had a total score < 12, 25.1% > or = 12 and < 20, and 60.5% > or = 20. At entry, 75 patients (13.7%) were treatment-naïve, 186 (34.1%) were receiving a monotherapy (of which haloperidol [24.2%], valproate [16.7%] and lithium [14.5%] were the most frequently prescribed) while 285 (52.2%) a combined therapy (of which 8.0% were represented by haloperidol/lithium combinations). After a switch to an oral medication, 137 patients (24.8%) were prescribed a monotherapy while the rest (415, 75.2%) received a combination of drugs.

CONCLUSION

Data collected at baseline in the Italian cohort of the EMBLEM study represent a relevant source of information to start addressing the short and long-term therapeutic strategies for improving the clinical as well as the socio-economic outcomes of patients affected by bipolar mania. Although it's not an epidemiological investigation and has some limitations, the results show several interesting findings as a relatively late age of onset of bipolar disorder, a low rate of past suicide attempts, a low lifetime rate of alcohol abuse and drug addiction.

Functional impairment in patients with mania: baseline results of the EMBLEM study

OBJECTIVES

The European Mania in Bipolar Longitudinal Evaluation of Medication (EMBLEM) is a large-scale prospective observational multicentre study to evaluate the longitudinal course of bipolar disorder and its associations with pharmacological treatment following an acute manic or mixed episode. We present an overview of the study design and patient characteristics at baseline while focusing on factors influencing work performance in the year prior to enrollment.

METHODS

A total of 530 investigators across 14 European countries enrolled 3,681 patients with acute mania between December 2002 and June 2004. Longitudinal observations are ongoing until July 2006. Socio-demographic variables, psychiatric history, clinical status and information on pharmacological treatment for bipolar disorder were recorded. Items from the SLICE of LIFE were applied, including a measure of work impairment during the previous year. The distribution of the baseline characteristics was analysed with descriptive statistics. Eighteen variables were investigated as hypothesized risk factors for work impairment applying logistic regression models.

RESULTS

In the previous year, 28 and 68% of patients were classified as having 'low' and 'high' work impairment, respectively. Clinical Global Impression - Bipolar Disorder (CGI-BP) overall, CGI-BP depression at baseline, rapid cycling during the previous 12 months, age between 35 and 64 years, substance abuse other than alcohol and cannabis and living without a partner or as dependent household member were significantly associated with work impairment during the previous year.

CONCLUSIONS

EMBLEM is to our knowledge the largest prospective observational study assessing patients during and after an acute episode of mania. Work impairment is significant in the year prior to an acute episode of mania.

Evidence for three distinct classes of 'typical', 'psychotic' and 'dual' mania: results from the EMBLEM study

OBJECTIVE

To describe patients included in the European Mania in Bipolar Longitudinal Evaluation of Medication (EMBLEM) study and to assess and clinically validate the presence of clinical subtypes of patients with acute mania.

METHOD

The EMBLEM study is a 2-year prospective, observational study on the treatment and outcome of patients who are treated for a manic or mixed episode. Latent Class Analysis was used to define discrete groups of patients at baseline.

RESULTS

Three groups were identified: 'typical mania' (59% of patients); 'psychotic mania' (27%) with more severe mania and presence of psychotic symptoms; and 'dual mania' (13%) with a high proportion of substance abuse. Patient groups differed in age of onset, social functioning and service needs.

CONCLUSION

Dual mania represents a distinct and not infrequent subgroup of patients with mania. The exclusion of patients with comorbid substance problems from clinical trials creates a gap in our knowledge on treatment effectiveness.

Voluntary vs. involuntary hospital admission in acute mania of bipolar disorder: results from the Swiss sample of the EMBLEM study

BACKGROUND

Patients with acute mania in bipolar disorder require pharmacological treatment to reduce symptoms. In addition, it is recognised that admission status is a clinically relevant aspect of bipolar disorder. There is, however, a lack of published data assessing the association of admission status with clinical or functional outcomes. The European-Mania-in-Bipolar-Longitudinal-Evaluation-of-Medication (EMBLEM) study has been designed to describe outcomes associated with medication therapies. Baseline data from this study are now available and we used these data to examine the characteristics of patients with acute mania in the Swiss EMBLEM cohort who were admitted involuntary and voluntary, respectively, and their functional and clinical status.

METHODS

Ninety-five patients with an acutely manic or mixed episode of bipolar disorder were included in the Swiss cohort of the study. Patients' history, psychosocial functioning, clinical measures of mania and depression, pharmacological and compliance variables were assessed. Statistical methods comprised univariate analyses of variance and logistic regression analyses to elucidate associations between variables of interest.

RESULTS

Patients with involuntary hospital admission (n = 55) were more aggressive and had less insight. They had a more frequent history of substance abuse and were less likely to take anticonvulsants or lithium. Furthermore, these patients showed lower compliance, which also guided physicians' decision on pharmacotherapy.

LIMITATION

The EMBLEM study had an observational and non-interventional design; therefore it was not possible to compare treatment groups by means of stringent between-group analyses. However, a main target of this study was to gather clinically relevant information on outcomes of acute mania associated with currently available medication therapies.

CONCLUSIONS

Involuntary admission status was significantly associated with clinical status, especially aggression and also compliance. Admission status in bipolar patients plays a clinically important role.

Assessment of tidal breathing parameters in infants with cystic fibrosis

Simple methods are needed to assess lung function in infants with cystic fibrosis (CF). This study determined the relationship between simple measurements obtained from tidal breathing with those from more complicated forced expiratory manoeuvres. Healthy infants and infants with CF were recruited from two maternity units and five specialist CF hospitals, respectively. Respiratory rate, tidal volume, minute ventilation and the tidal breathing ratio (TPTEF:TE) were measured in sedated infants and compared with forced expiratory volume in 0.4 seconds (FEV0.4) measured by the raised volume technique. Altogether, 95 healthy infants and 47 infants with CF of similar age, sex, ethnicity and proportion exposed to maternal smoking were recruited. There was no difference in TPTEF:TE and tidal volume between healthy infants and those with CF. Minute ventilation was significantly greater in infants with CF due to a mean (95% confidence interval) increase in respiratory rate of 5.8 (3.2-8.4) min(-1). Thirteen (28%) infants with CF had a respiratory rate elevated by >2 SD. However, no association between respiratory rate and FEV0.4 could be identified. Tidal breathing ratio was not useful in identifying diminished airway function in infants with cystic fibrosis. An elevated respiratory rate may be due in part to ventilation heterogeneity but is poorly predictive of diminished airway function measured by forced expiration.

Exploring the relationship between forced maximal flow at functional residual capacity and parameters of forced expiration from raised lung volume in healthy infants

The raised volume rapid thoraco-abdominal compression technique (RVRTC) is being increasingly used to assess airway function in infants, but as yet no consensus exists regarding the equipment, methods, or analysis of recorded data. The aim of this study was to explore the relationship between maximal flow at functional residual capacity (V'(maxFRC)) and parameters derived from raised lung volumes, and to address analytical aspects of the latter technique in an attempt to assist with future standardization initiatives. Forced vital capacity (FVC) from lung volume raised to 3 kPa, timed forced expiratory volumes (FEV(t)), and forced expiratory flow parameters at different percentages of expired FVC (FEF(%)) were measured in 98 healthy infants (1-69 weeks of age). V'(maxFRC) using the tidal rapid thoraco-abdominal compression (RTC) technique was also measured. The within-subject relationships and within-subject variability of the various parameters were assessed. Duration of forced expiration was < 0.5 sec in 5 infants, meaning that FEV(0.3) and FEV(0.4) were the only timed volume parameters that could be calculated in all infants during the first months of life, and even when it could be calculated, FEV(0.5) approached FVC in many of these infants. It is recommended that FEV(0.4) be routinely reported in infants less than 3 months of age. Contrary to previous reports, within subject variability of V'(maxFRC) was less than that of FEF(75) (mean CV = 6.3% and 8.9%, respectively).A more standardized protocol when analyzing data from the RVRTC would facilitate comparisons of results between centers in the future.

The association between birthweight, sex, and airway function in infants of nonsmoking mothers

The risk of respiratory illness and death is increased in infants of low birthweight for gestational age, but the underlying physiologic mechanisms remain unclear. We examined the hypothesis that airway function is diminished in infants of low birthweight for gestational age, independent of exposure to maternal smoking. Respiratory function was measured using partial and raised volume forced expiratory maneuvers in 103 infants (> 35 wk gestation; 56 boys) not exposed pre- or postnatally to maternal smoking who, according to birthweight, were either small (SGA; n = 38) or appropriate (AGA; n = 65) for gestational age. At testing, SGA infants were of similar postnatal age (mean [SD]: SGA 6.8 [2.4] wk, AGA 5.9 [2.3] wk), but remained shorter and lighter than AGA infants. In univariate analyses, FVC, forced expired volume in 0.4 s (FEV(0.4)), and FEF(75) were significantly diminished in SGA compared with AGA infants (mean [95% CI of difference]: FVC: 127 versus 143 ml [-29, -2]; FEV(0.4): 112 versus 125 ml [-24, -2]; and FEF(75): 173 versus 203 ml s(-1) [-57, -3], respectively), but these differences were no longer significant after allowing for sex and body size. Furthermore, FEF(75) was on average 35 ml s(-1) lower in boys than girls (95% CI: -61, -8). We conclude that diminished airway function in SGA infants shortly after birth appears to be primarily mediated through impaired somatic growth.

Assessment of passive respiratory mechanics in infants: double versus single occlusion?

The single breath or occlusion technique (SOT) is widely used to assess passive respiratory mechanics in infants, but depends on various underlying assumptions. Recently, it has been proposed that such measurements could be internally validated by performing two brief airway occlusions during the same expiration. The aim of this study was to evaluate the use of the double occlusion technique (DOT) using a new commercially available program (Jaeger MasterScreen BabyBody Erich Jaeger GmbH, Würzburg, Germany). Paired measurements of respiratory system compliance (Crs) and resistance (Rrs) using both SOT and DOT were obtained in 18 healthy sedated infants (age range 4-41 weeks, weight 2.7-9.9 kg). There was close agreement between both methods of assessing Crs in all infants, the mean within-subject difference (95% confidence interval (CI)) for DOT-SOT being -0.06 (-0.55- +0.42) mL x kPa(-1) x kg(-1). By contrast, estimates of Rrs,DO were on average 20% lower than those for Rrs,SO, (mean within-subject difference (95% CI) being -0.67 (-1.04- -0.31) kPa x L(-1) x s; p<0.01). The relatively lower values obtained for Rrs,DO may reflect the higher mean lung volume at which it was calculated. Further work is required to investigate the clinical and epidemiological relevance of this new approach, and whether there are any advantages of using both techniques when assessing passive mechanics in infants.

Influence of jacket placement on respiratory compliance during raised lung volume measurements in infants

SUMMARY. Recent introduction of the raised lung volume rapid thoraco-abdominal compression (RVRTC) technique for measuring forced expiratory maneuvers in infants provides the potential opportunity to assess respiratory mechanics simultaneously by using multiple linear regression (MLR) of the relaxed breaths preceding jacket inflation to force expiration. This study was undertaken to investigate whether data obtained from raised lung volume are influenced by placement of the rapid thoraco-abdominal compression (RTC) squeeze jacket. Paired measurements of tidal volume (V(T)) and respiratory rate (RR) during tidal breathing, and of inflation volume (V(inf)), respiratory system compliance (C(rs)), and resistance (R(rs)) during passive lung inflations were made in 60 (30 male) healthy term infants with and without a fastened, but uninflated RTC jacket in place. Jacket placement was associated with a significant reduction (P < 0.0001) in weight-corrected V(inf) [-1.86 (95% confidence interval, -2.46, -1.27) mL.kg(-1)] and C(rs) [-0.77 (-1.04, -0.49) mL.kPa(-1).kg(-1)]. This represented a reduction in weight-corrected C(rs) from 9.00 to 8.24 mL.kPa(-1).kg(-1), with the fall being >10% in 42% of infants studied. There was no significant change in R(rs) or weight-corrected V(T). If passive respiratory mechanics are to be measured during raised lung volume maneuvers, they should be performed prior to the jacket being fastened, unless considerable care is taken with each infant to ensure that the jacket does not restrict chest wall movement during maximum inflation.

Passive respiratory mechanics: the occlusion techniques

The aim of this position paper is to define quality control and acceptance criteria for measuring passive respiratory mechanics in infants using the occlusion techniques to ensure that valid results are obtained. These guidelines cover numerous aspects including: 1) terminology and definitions; 2) equipment; 3) data acquisition; 4) data handling and analysis; 5) reporting of results. Adherence to these guidelines should ensure that measurement of passive respiratory mechanics in infants in different lung function laboratories could be performed with an acceptable degree of safety, precision, and reproducibility. This will facilitate multi-centre collection of data and performance of clinical investigations.

Triethanolamine, tris, hepes, and cytosine arabinoside show neuritogenic activity in cultured chick embryo ganglia

Neuritogenesis, which occurs to a slight extent in chick embryo ganglia maintained under standard conditions and which is maximally stimulated by nerve growth factor, also was enhanced by presence in the medium of buffers (triethanolamine, Tris, and Hepes) and cytosine arabinoside and by the passage of direct electric current. The major effect of the buffers probably was to remove protons from cell membranes, that of the current to produce accelerated movement of ions through membranes of the ganglionic cells, and that of cytosine arabinoside to decrease the numbers of nonneural cells by inhibiting DNA synthesis. The buffers were neuritogenically ineffective on nerve growth factor-sensitive PC12 pheochromocytoma cells in culture. Media from ganglia in which triethanolamine or passage of electric current had elicited outgrowth of neurites produced no observable effect on PC12 cells under our experimental conditions. Current data fit the hypothesis that, whereas nerve growth factor exerts direct neuritogenic effects on neurons, the other treatments affect neural-nonneural interactions, possibly by way of gap junctions or changes in direct physical contact, so as to disinhibit inherent neural neuritogenic potential and/or to stimulate it.

Sex and age alter plasma membranes of cultured fibroblasts

Human skin fibroblasts were taken from age-matched male and female subjects. The cells were then cultured under identical conditions and passage-number matched. Plasma membranes were isolated and membrane enzyme activities, lipid composition, and structure of isolated plasma membranes were measured in order to determine the presence of significant sex differences in human fibroblast membrane properties. The results indicated that plasma membranes from normal female subjects had a 1.6-fold and 3.6-fold higher cholesterol/phospholipid ratio and oleic acid (18:2) content than normal male subjects. The limiting anisotropy and the rotational relaxation time of fluorescence probe molecules such as trans-parinaric acid and 1,6-diphenyl-1,3,5-hexatriene in the plasma membranes was not significantly different from fibroblasts of male versus female normal subjects. The total activity of plasma membrane (Na+, K+)-ATPase was significantly higher in female than male normal subjects. A potential 'membrane structural disorder', Huntington's disease, was confirmed in fibroblast membranes from male but not from female Huntington's disease subjects. The possibility that Huntington's disease was a 'premature membrane aging' phenomenon was considered. A comparison of plasma membrane enzymes, lipids, and structure from old and young Huntington's disease subjects did not show differences consistent with accelerated membrane aging as explaining the molecular basis for the disease. The age-dependent differences noted in aged Huntington's disease subjects: increased phosphatidylcholine/phosphatidylethanolamine ratio and sphingomyelin + lysophosphatidylcholine content of fibroblast plasma membranes were not significantly altered when compared to normal age-matched controls. However, (Na+, K+)-ATPase activity was significantly enhanced in fibroblast plasma membranes of older Huntington's disease subjects unlike those of control subjects. In conclusion, sex and age differences in membrane properties of cultured cells represent important potential variables in the elucidation of human genetic disorders that may be membrane-related.

Age-related alterations in cultured human fibroblast membrane structure and function

Membrane enzyme activities, lipid composition, and fluorescence probe characteristics in isolated plasma membranes, microsomes and mitochondria of cultured human fibroblasts were used to determine if structural alterations occurred as a function of donor age. The cells were sex matched and allowed to undergo approximately 8 population doublings under identical culture conditions. Plasma membrane (Na+, K+)-ATPase, microsomal NADPH cytochrome c reductase, and mitochondrial succinate cytochrome c activities showed variation as a function of increasing donor age but these changes were not statistically significant. At the same time the cholesterol/phospholipid molar ratio was unaltered in plasma membranes, decreased 50% in microsomes, and unchanged in mitochondria with increasing donor age. The phosphatidylcholine/phosphatidylethanolamine ratio increased in all three membrane fractions with increasing age of the fibroblast donor. The ratio of unsaturated/saturated fatty acids decreased in the phospholipids of microsomes but not of plasma membranes or mitochondria. The structural properties of the membranes were determined with two different fluorescence probe molecules, trans-parinaric acid and 1,6-diphenyl-1,3,5-hexatriene. These probe molecules indicated that the fluorescence lifetime and/or fluorescence polarization of the trans-parinaric acid probe decreased in microsomes, mitochondria, and in the plasma membrane, such that the limiting anisotropy, indicative of restrictions to probe motions, was significantly lower (high fluidity) with increasing subject age in plasma membranes, microsomes and mitochondria. The trans-parinaric acid fluorescence lifetime displayed two components in plasma membranes, microsomes, and mitochondria, a finding consistent with the coexistence of fluid and solid membrane lipid areas in the cultured human fibroblast subcellular membranes. The trans-parinaric acid partitioned preferentially into solid membrane areas. The limiting anisotropy of 1,6-diphenyl-1,3,5-hexatriene, a fluorescent probe that partitioned almost equally into different lipid domains, was also decreased in microsomes and mitochondria with increasing donor age. In contrast, 1,6-diphenyl-1,3,5-hexatriene indicated a small increase in limiting anisotropy (0.219 vs 0.195) in plasma membranes. Arrhenius plots of trans-parinaric acid and 1,6-diphenyl-1,3,5-hexatriene absorbance-corrected fluorescence in plasma membranes, microsomes and mitochondria demonstrated characteristic breakpoints near 20 degrees C and 30 degrees C. These breakpoints were not altered as a function of age.(ABSTRACT TRUNCATED AT 400 WORDS)

Actin filaments in human skin fibroblasts are similar in normal persons and patients with Huntington's disease

Actin filaments in skin fibroblasts from patients with Huntington's disease (HD) were examined using immunofluorescent methods. Actin filaments were seen along the axis of cell elongation (stress or sheath filaments) as well as in areas of membrane ruffling (lattice filaments). In some cases, filaments appeared to radiate from foci within the cell. Bundles of these filaments radiated in various directions at different depths within a cell. These structures are similar, in cells from both normal individuals and HD patients, to actin filaments observed in other cell types. The higher-than-normal confluent densities achieved in culture by fibroblasts from patients with Huntington's chorea do not involve alterations in the ultrastructure of actin filaments.

Fibroblasts in Huntington's disease

We investigated the growth of skin fibroblasts in tissue culture from 10 patients with Huntington's disease and eight healthy, unrelated controls. The patients' ages ranged from 34 to 56 years (mean 48.5), and the mean duration of their clinical illness was 12.4 years. The controls' ages ranged from 32 to 64 years (mean, 42.3). No statistically significant differences were observed between the two groups in out-growth of cells from the biopsies nor during subsequent routine culturing of fibroblasts. This contradicts the finding of earlier investigators that skin fibroblasts from patients with Huntington's disease grow poorly in tissue culture. Matched pairs of Huntington's disease and control cultures grew at the same rate, but Huntington's disease cells grew to a significantly higher maximal density (P less than 0.02). This may indicate a genetically determined change in the cell surface or metabolic difference in Huntington's disease.