Augmenting external control arms using Bayesian borrowing: a case study in first-line non-small cell lung cancer

Aim: This study aimed to improve comparative effectiveness estimates and discuss challenges encountered through the application of Bayesian borrowing (BB) methods to augment an external control arm (ECA) constructed from real-world data (RWD) using historical clinical trial data in first-line non-small-cell lung cancer (NSCLC). Materials & methods: An ECA for a randomized controlled trial (RCT) in first-line NSCLC was constructed using ConcertAI Patient360™ to assess chemotherapy with or without cetuximab, in the bevacizumab-inappropriate subpopulation. Cardinality matching was used to match patient characteristics between the treatment arm (cetuximab + chemotherapy) and ECA. Overall survival (OS) was assessed as the primary outcome using Cox proportional hazards (PH). BB was conducted using a static power prior under a Weibull PH parameterization with borrowing weights from 0.0 to 1.0 and augmentation of the ECA from a historical control trial. Results: The constructed ECA yielded a higher overall survival (OS) hazard ratio (HR) (HR = 1.53; 95% CI: 1.21-1.93) than observed in the matched population of the RCT (HR = 0.91; 95% CI: 0.73-1.13). The OS HR decreased through the incorporation of BB (HR = 1.30; 95% CI: 1.08-1.54, borrowing weight = 1.0). BB was applied to augment the RCT control arm via a historical control which improved the precision of the observed HR estimate (1.03; 95% CI: 0.86-1.22, borrowing weight = 1.0), in comparison to the matched population of the RCT alone. Conclusion: In this study, the RWD ECA was unable to successfully replicate the OS estimates from the matched population of the selected RCT. The inability to replicate could be due to unmeasured confounding and variations in time-periods, follow-up and subsequent therapy. Despite these findings, we demonstrate how BB can improve precision of comparative effectiveness estimates, potentially aid as a bias assessment tool and mitigate challenges of traditional methods when appropriate external data sources are available.

The Inflation Reduction Act: An Opportunity to Accelerate Confidence in US Real-World Evidence

OBJECTIVES

The Inflation Reduction Act (IRA), enacted in 2022, brings substantial reforms to the US healthcare system, particularly regarding Medicare. A key aspect includes the introduction of Medicare price negotiation. The objective of this commentary is to explore the implications of the IRA for US pharmaceutical companies, with a specific focus on the role of real-world evidence (RWE) in the context of Medicare reforms.

METHODS

The commentary employs a qualitative analysis of the IRA's provisions related to healthcare and pharmaceutical regulation, focusing on how these reforms change the evidence requirements for pharmaceutical companies. It discusses the methodological aspects of generating and employing RWE, including techniques like target trial emulation and quantitative bias analysis methods to address biases inherent in RWE.

RESULTS

The commentary highlights that the IRA introduces a unique approach to value assessment in the US by evaluating drug value several years post-launch, as opposed to at launch, similar to health technology assessments in other regions. It underscores the central role of RWE in comparing drug effectiveness across diverse clinical scenarios to improve the accuracy of real-world data comparisons. Furthermore, the article identifies key methodologies for managing the inherent biases in RWE, which are crucial for generating credible evidence for IRA price negotiations.

CONCLUSIONS

This article underscores the importance of these methodologies in ensuring credible evidence for IRA price negotiations. It advocates for an integrated approach in evidence generation, positioning RWE as pivotal for informed pricing discussions in the US healthcare landscape.

Use of Advanced Flexible Modeling Approaches for Survival Extrapolation from Early Follow-up Data in two Nivolumab Trials in Advanced NSCLC with Extended Follow-up

OBJECTIVES

Immuno-oncology (IO) therapies are often associated with delayed responses that are deep and durable, manifesting as long-term survival benefits in patients with metastatic cancer. Complex hazard functions arising from IO treatments may limit the accuracy of extrapolations from standard parametric models (SPMs). We evaluated the ability of flexible parametric models (FPMs) to improve survival extrapolations using data from 2 trials involving patients with non-small-cell lung cancer (NSCLC).

METHODS

Our analyses used consecutive database locks (DBLs) at 2-, 3-, and 5-y minimum follow-up from trials evaluating nivolumab versus docetaxel in patients with pretreated metastatic squamous (CheckMate-017) and nonsquamous (CheckMate-057) NSCLC. For each DBL, SPMs, as well as 3 FPMs-landmark response models (LRMs), mixture cure models (MCMs), and Bayesian multiparameter evidence synthesis (B-MPES)-were estimated on nivolumab overall survival (OS). The performance of each parametric model was assessed by comparing milestone restricted mean survival times (RMSTs) and survival probabilities with results obtained from externally validated SPMs.

RESULTS

For the 2- and 3-y DBLs of both trials, all models tended to underestimate 5-y OS. Predictions from nonvalidated SPMs fitted to the 2-y DBLs were highly unreliable, whereas extrapolations from FPMs were much more consistent between models fitted to successive DBLs. For CheckMate-017, in which an apparent survival plateau emerges in the 3-y DBL, MCMs fitted to this DBL estimated 5-y OS most accurately (11.6% v. 12.3% observed), and long-term predictions were similar to those from the 5-y validated SPM (20-y RMST: 30.2 v. 30.5 mo). For CheckMate-057, where there is no clear evidence of a survival plateau in the early DBLs, only B-MPES was able to accurately predict 5-y OS (14.1% v. 14.0% observed [3-y DBL]).

CONCLUSIONS

We demonstrate that the use of FPMs for modeling OS in NSCLC patients from early follow-up data can yield accurate estimates for RMST observed with longer follow-up and provide similar long-term extrapolations to externally validated SPMs based on later data cuts. B-MPES generated reasonable predictions even when fitted to the 2-y DBLs of the studies, whereas MCMs were more reliant on longer-term data to estimate a plateau and therefore performed better from 3 y. Generally, LRM extrapolations were less reliable than those from alternative FPMs and validated SPMs but remained superior to nonvalidated SPMs. Our work demonstrates the potential benefits of using advanced parametric models that incorporate external data sources, such as B-MPES and MCMs, to allow for accurate evaluation of treatment clinical and cost-effectiveness from trial data with limited follow-up.

HIGHLIGHTS

Flexible advanced parametric modeling methods can provide improved survival extrapolations for immuno-oncology cost-effectiveness in health technology assessments from early clinical trial data that better anticipate extended follow-up.Advantages include leveraging additional observable trial data, the systematic integration of external data, and more detailed modeling of underlying processes.Bayesian multiparameter evidence synthesis performed particularly well, with well-matched external data.Mixture cure models also performed well but may require relatively longer follow-up to identify an emergent plateau, depending on the specific setting.Landmark response models offered marginal benefits in this scenario and may require greater numbers in each response group and/or increased follow-up to support improved extrapolation within each subgroup.

Migrant status and risk of compulsory admission at first diagnosis of psychotic disorder: a population-based cohort study in Sweden

BACKGROUND

Minority ethnic and migrant groups face an elevated risk of compulsory admission for mental illness. There are overlapping cultural, socio-demographic, and structural explanations for this risk that require further investigation.

METHODS

By linking Swedish national register data, we established a cohort of persons first diagnosed with a psychotic disorder between 2001 and 2016. We used multilevel mixed-effects logistic modelling to investigate variation in compulsory admission at first diagnosis of psychosis across migrant and Swedish-born groups with individual and neighbourhood-level covariates.

RESULTS

Our cohort included 12 000 individuals, with 1298 (10.8%) admitted compulsorily. In an unadjusted model, being a migrant [odds ratio (OR) 1.48; 95% confidence interval (CI) 1.26-1.73] or child of a migrant (OR 1.27; 95% CI 1.10-1.47) increased risk of compulsory admission. However after multivariable modelling, region-of-origin provided a better fit to the data than migrant status; excess risk of compulsory admission was elevated for individuals from sub-Saharan African (OR 1.94; 95% CI 1.51-2.49), Middle Eastern and North African (OR 1.46; 95% CI 1.17-1.81), non-Nordic European (OR 1.27; 95% CI 1.01-1.61), and mixed Swedish-Nordic backgrounds (OR 1.33; 95% CI 1.03-1.72). Risk of compulsory admission was greater in more densely populated neighbourhoods [OR per standard deviation (s.d.) increase in the exposure: 1.12, 95% CI 1.06-1.18], an effect that appeared to be driven by own-region migrant density (OR per s.d. increase in exposure: 1.12; 95% CI 1.02-1.24).

CONCLUSIONS

Inequalities in the risk of compulsory admission by migrant status, region-of-origin, urban living and own-region migrant density highlight discernible factors which raise barriers to equitable care and provide potential targets for intervention.

A cloud based tool for knowledge exchange on local scale flood risk

There is an emerging and urgent need for new approaches for the management of environmental challenges such as flood hazard in the broad context of sustainability. This requires a new way of working which bridges disciplines and organisations, and that breaks down science-culture boundaries. With this, there is growing recognition that the appropriate involvement of local communities in catchment management decisions can result in multiple benefits. However, new tools are required to connect organisations and communities. The growth of cloud based technologies offers a novel way to facilitate this process of exchange of information in environmental science and management; however, stakeholders need to be engaged with as part of the development process from the beginning rather than being presented with a final product at the end. Here we present the development of a pilot Local Environmental Virtual Observatory Flooding Tool. The aim was to develop a cloud based learning platform for stakeholders, bringing together fragmented data, models and visualisation tools that will enable these stakeholders to make scientifically informed environmental management decisions at the local scale. It has been developed by engaging with different stakeholder groups in three catchment case studies in the UK and a panel of national experts in relevant topic areas. However, these case study catchments are typical of many northern latitude catchments. The tool was designed to communicate flood risk in locally impacted communities whilst engaging with landowners/farmers about the risk of runoff from the farmed landscape. It has been developed iteratively to reflect the needs, interests and capabilities of a wide range of stakeholders. The pilot tool combines cloud based services, local catchment datasets, a hydrological model and bespoke visualisation tools to explore real time hydrometric data and the impact of flood risk caused by future land use changes. The novel aspects of the pilot tool are; the co-evolution of tools on a cloud based platform with stakeholders, policy and scientists; encouraging different science disciplines to work together; a wealth of information that is accessible and understandable to a range of stakeholders; and provides a framework for how to approach the development of such a cloud based tool in the future. Above all, stakeholders saw the tool and the potential of cloud technologies as an effective means to taking a whole systems approach to solving environmental issues. This sense of community ownership is essential in order to facilitate future appropriate and acceptable land use management decisions to be co-developed by local catchment communities. The development processes and the resulting pilot tool could be applied to local catchments globally to facilitate bottom up catchment management approaches.

A COMPARISON OF THE METHOD OF EXCRETION OF NEUTRAL RED AND PHENOL RED BY THE MAMMALIAN KIDNEY

A direct examination with the method of perfusion of the excretion by the frog's kidney of phenol red and neutral red has shown that the dyes are eliminated in different manners as a result of different mechanisms. The former is excreted in much the greater part by the glomeruli; the latter by the tubules. Urea is excreted in a manner similar to phenol red. The indirect examination of the function of the mammalian kidney by means of excretion ratios has shown a like contrast between the manner of elimination of the two dyes, and here again was found a similarity in the manner of excretion of phenol red and urea. This would seem to be as close an examination as can be made with our present methods of experimentation of the question of the mechanism of the excretion of these substances by mammals. As the facts stand they constitute strong presumptive evidence that in mammals and amphibia the like results have arisen from like causes, phenol red and urea being eliminated chiefly through the glomeruli in both instances while neutral red is excreted principally through the tubules.

Abbreviated method of determining vein volume in balloon-controlled vein ablation

Traditional surgical ligation and stripping for the treatment of saphenous vein incompetence has been replaced by minimally invasive alternative treatments during the last five years. Endovenous ablation with radiofrequency (RP) and laser (EVL) have proven to be safe, durable, and widely accepted by patients. Catheter-delivered sclerotherapy (CDS) with foam and liquid for ablation of the great saphenous vein is also under investigation. In this technique, vein volume must be measured accurately by ultrasound just prior to the procedure and can require up to 11 diameter measurements. The purpose of this study was to identify an abbreviated method of determining vein volume to expedite associated endovenous procedures. Seventy-five veins were treated in 55 subjects with catheter-directed sclerotherapy in a three-center clinical study using a standardized protocol. Vein volume was carefully calculated by determining vein diameter over the Treatment Length in 4 cm intervals. These measurements were compared to vein volume calculations where only three measurements were taken. Our results suggest that the abbreviated method is capable of significantly reducing the number of diameter measurements without sacrificing accuracy. We found the method produced a vein volume that fell within 1 mL or 15% of the actual vein volume in 80% of cases. The abbreviated method cannot be used with accuracy in veins that are Erratic.

Cost-effective analysis of conventional and nurse-led clinics for common otological procedures

The need to reduce costs while providing a first-class service has led to the expansion in the role of nurses in recent years. We present results of a comparison of the cost-effectiveness of conventional and nurse-led out-patient ear clinics. Our results indicate that cost-effective health care is a distinct competitive advantage for nurses taking up some roles conventionally performed by doctors. The difference in mean cost of out-patient visit per patient between the two groups is £75.28. This is equivalent to a reduction in cost to the hospital of more than £47000 for the 626 patients seen in a nurse-led ear clinic in a year. The nurse-led service is thus more cost-effective and presents an opportunity by freeing up otolaryngologists’ time to see more complex patients and has the potential for reducing out-patient access time in the NHS.

Home based neuromuscular electrical stimulation as a new rehabilitative strategy for severely disabled patients with chronic obstructive pulmonary disease (COPD)

BACKGROUND

Passive training of specific locomotor muscle groups by means of neuromuscular electrical stimulation (NMES) might be better tolerated than whole body exercise in patients with severe chronic obstructive pulmonary disease (COPD). It was hypothesised that this novel strategy would be particularly effective in improving functional impairment and the consequent disability which characterises patients with end stage COPD.

METHODS

Fifteen patients with advanced COPD (nine men) were randomly assigned to either a home based 6 week quadriceps femoris NMES training programme (group 1, n=9, FEV(1)=38.0 (9.6)% of predicted) or a 6 week control period before receiving NMES (group 2, n=6, FEV(1)=39.5 (13.3)% of predicted). Knee extensor strength and endurance, whole body exercise capacity, and health related quality of life (Chronic Respiratory Disease Questionnaire, CRDQ) were assessed.

RESULTS

All patients were able to complete the NMES training programme successfully, even in the presence of exacerbations (n=4). Training was associated with significant improvements in muscle function, maximal and endurance exercise tolerance, and the dyspnoea domain of the CRDQ (p<0.05). Improvements in muscle performance and exercise capacity after NMES correlated well with a reduction in perception of leg effort corrected for exercise intensity (p<0.01).

CONCLUSIONS

For severely disabled COPD patients with incapacitating dyspnoea, short term electrical stimulation of selected lower limb muscles involved in ambulation can improve muscle strength and endurance, whole body exercise tolerance, and breathlessness during activities of daily living.

Skeletal muscle strength and endurance in patients with mild COPD and the effects of weight training

This study poses two questions: 1) is there an abnormality in isokinetic skeletal muscle strength and endurance in mild chronic obstructive pulmonary disease (COPD)? and 2) what is the effect of a randomized, controlled, 12 week hospital outpatient weight training programme in terms of skeletal muscle function and exercise tolerance? Upper and lower limb isokinetic maximum and sustained muscle function were compared in 43 COPD patients (age 49+/-11 yrs), mean forced expiratory volume in one second (FEV1) 77+/-23% pred and 52 healthy, sedentary subjects (age 51 (10) yrs), mean FEV1 109+/-16% pred. The 43 COPD patients were randomly allocated into training (n=26) and control (n=17) groups. Isokinetic and isotonic muscle function, whole body endurance, maximal exercise capacity and lung function were measured. The COPD patients had reduced isokinetic muscle function (with the exception of sustained upper limb strength) as compared with healthy sedentary subjects. Muscle function improved after weight training in the COPD patients. Whole body endurance during treadmill walking also improved with no change in maximal oxygen consumption. A deficit in skeletal muscle function can be identified in patients with mild chronic obstructive pulmonary disease which cannot be explained by factors such as hypoxaemia and malnutrition. Intervention with weight training is effective in countering this deficit which the authors conclude is probably due to muscle deconditioning.

Development of an in vitro bioassay for Clostridium botulinum type B neurotoxin in foods that is more sensitive than the mouse bioassay

A novel, in vitro bioassay for detection of the botulinum type B neurotoxin in a range of media was developed. The assay is amplified by the enzymic activity of the neurotoxin's light chain and includes the following three stages: first, a small, monoclonal antibody-based immunoaffinity column captures the toxin; second, a peptide substrate is cleaved by using the endopeptidase activity of the type B neurotoxin; and finally, a modified enzyme-linked immunoassay system detects the peptide cleavage products. The assay is highly specific for type B neurotoxin and is capable of detecting type B toxin at a concentration of 5 pg ml(-1) (0.5 mouse 50% lethal dose ml(-1)) in approximately 5 h. The format of the test was found to be suitable for detecting botulinum type B toxin in a range of foodstuffs with a sensitivity that exceeds the sensitivity of the mouse assay. Using highly specific monoclonal antibodies as the capture phase, we found that the endopeptidase assay was capable of differentiating between the type B neurotoxins produced by proteolytic and nonproteolytic strains of Clostridium botulinum type B.

Preoperative esophageal transit studies are a useful predictor of dysphagia after fundoplication

Fundoplication performed for gastroesophageal reflux disease may be complicated by postoperative dysphagia despite successful reduction in reflux symptoms. This is more likely in those patients with reflux who have concurrent esophageal dysmotility. The aim of this study was to establish whether esophageal transit studies using a technetium-99m jello bolus (jello esophageal transit) could detect the presence of motility disorders preoperatively and hence predict surgical outcome. Transit studies in 33 healthy volunteers yielded a normal range of 2 to 24 seconds using ninety-fifth percentile distribution. In the second phase of the study, 26 patients accepted for laparoscopic fundoplication were enrolled: jello esophageal transit, manometry, and endoscopy were attempted preoperatively in all subjects. A clinical dysphagia score was assigned from a questionnaire. Six months after surgery, five patients had dysphagia and of these four were found to have abnormal preoperative jello esophageal transit, for a sensitivity of 80%. Of the 21 patients who had no dysphagia after surgery, 20 patients had normal preoperative jello esophageal transit, showing a specificity of 95%. This esophageal transit study is noninvasive, reliable, and sensitive. When performed prior to fundoplication, it appears to be of significant value in detecting a subtle functional motility disorder that predisposes to postoperative dysphagia. Jello esophageal transit may assist the surgeon in planning treatment of gastroesophageal reflux disease.

Low intensity peripheral muscle conditioning improves exercise tolerance and breathlessness in COPD

This randomized, controlled study investigated the physiological effects of a specially designed 12 week programme of isolated conditioning of peripheral skeletal muscle groups. The programme required minimal infrastructure in order to allow continued rehabilitation at home after familiarization within hospital. Forty eight patients, aged 40-72 yrs with chronic obstructive pulmonary disease (COPD) (mean (SD) forced expiratory volume in one second (FEV1) 61 (27)% of predicted normal) were randomly allocated into training (n = 32) and control (n = 16) groups. Physiological assessments were performed before and after the 12 week study period, and included peripheral muscle endurance and strength, whole body endurance, maximal exercise capacity (maximum oxygen consumption (V'O2,max)) and lung function. The training group showed significant improvement in a variety of measures of upper and lower peripheral muscle performance, with no additional breathlessness. Whole body endurance measured by free arm treadmill walking increased by 6,372 (3,932-8,812) 3 (p < 0.001). Symptom-limited maximal V'O2 was unchanged. However, the training group showed a reduction in ventilatory equivalents for oxygen and carbon dioxide, both at peak exercise and at equivalent work rate (Wmax). In summary, low intensity isolated peripheral muscle conditioning is well-tolerated, simple and easy to perform at home. The various physiological benefits should enable patients across the range of severity of chronic obstructive pulmonary disease to improve daily functioning.

Effects of dilevalol (R,R-labetalol) compared with nifedipine on heart rate, blood pressure and muscle blood flow at rest and on exercise in hypertensive patients

1. Dilevalol (R,R-labetalol) is a non-selective beta-adrenoceptor antagonist with beta 2-adrenoceptor agonist activity. Its effects after 1 month's administration on heart rate, blood pressure and muscle blood flow were studied in a double-blind crossover comparison with nifedipine in 16 hypertensive patients. 2. Dilevalol and nifedipine were similarly effective in lowering systolic and diastolic blood pressure at rest, but dilevalol limited the rise in systolic blood pressure induced by exercise more than nifedipine (rise of 27 vs 53 mm Hg respectively, P < 0.01). 3. Dilevalol decreased resting heart rate compared with nifedipine (73 vs 92 beats min-1 respectively, P < 0.01). Dilevalol limited the exercise induced rise in heart rate more than nifedipine (36 vs 48 beats min-1 respectively, P < 0.01). 4. Muscle blood flow (measured by strain gauge plethysmography) was not affected by either dilevalol or nifedipine at rest. After exercise, dilevalol caused an increase in excess blood flow compared with placebo (10.8 vs 5.1 ml min-1 dl-1 respectively, P < 0.01). The difference between dilevalol and nifedipine did not reach statistical significance (10.8 vs 6.5 ml min-1 dl-1 respectively, P > 0.05). 5. On blood pressure and heart rate, dilevalol demonstrated beta-adrenoceptor blocker activity at rest and on exercise. On muscle blood flow, dilevalol appeared to have no effect at rest, but may have acted as a beta-adrenoceptor blocker rather than as a beta 2-adrenoceptor agonist during exercise.

Class II HLA DNA polymorphisms in type 1 (insulin-dependent) diabetic patients of north Indian origin

Genetic associations with Type 1 (insulin-dependent) diabetes may be primary or secondary to linkage disequilibrium. Studies of different racial groups should allow these to be distinguished. We have reported that Type 1 diabetes is associated with HLA-DR3 and -DR4 in subjects of North Indian (Punjab) origin and now present the results of a study of HLA class II DNA polymorphisms in this group and in white caucasoid subjects. DR4 in North Indian Type 1 diabetic patients was associated with DQ beta and DX alpha DNA polymorphisms identical to those found in DR4-positive white caucasoid patients. This DQ beta/DX alpha pattern was increased in frequency in North Indian diabetic patients vs control subjects (33.3% vs 8.5%, p less than 0.001, relative risk = 5.12 (95% confidence limits: 1.96-13.4)). A DQ beta polymorphism with very low relative risk for Type 1 diabetes in white caucasoid subjects was also markedly reduced in North Indian diabetic patients vs control subjects (2.3% vs 24.7%, p less than 0.02, relative risk = 0.10 (95% confidence limits: 0.02-0.46)). This pattern was associated with DR2 in white caucasoid subjects, but with DRw6 in North Indians. A DR3-associated DR beta polymorphism was markedly increased in North Indian diabetic patients vs control subjects (90.2% vs 40.7%, p less than 10(-6), relative risk = 12.1 (95% confidence limits: 4.32-33.9)). The DQ subregion may be a primary site of genetic influence on susceptibility to Type 1 diabetes. Further studies in different racial groups will clarify the HLA associations of Type 1 diabetes.

HLA-DR and DQ DNA polymorphisms in subjects of Asian Indian and white Caucasian origin

There is a close correspondence between serologically defined DR types and DR beta chain restriction fragment length polymorphisms (RFLPs). There is also an association between DR types and DQ alpha and DQ beta RFLPs because of linkage disequilibrium. We present the results of an analysis of DR beta, DQ alpha and DQ beta RFLPs in Asian Indians and white Caucasian subjects. DR beta RFLPs were similar in the two groups. Clearly distinguishable DR beta patterns were observed for DR1, 2, 3, 4, 5, 7 and w10. The DR beta patterns associated with DR3 were, however, also found with w6. The DR7 DR beta patterns were also found with w9. For DR specificities 1, 3, 4, 5, 7 and w10, the associated DQ alpha and DQ beta RFLPs were similar in both racial groups, but for DR2, however, marked differences were found. The DR2-positive white Caucasian subjects all possessed a single DQ alpha/DQ beta combination whereas the DQ alpha/DQ beta patterns in DR2-positive Asian Indians showed considerable heterogeneity. The pattern seen in white subjects was present in only a minority of Asians. DR-DQ relationships clearly vary in different racial groups. RFLP analysis of HLA-linked diseases in different populations should prove to be an important technique in identifying the primary genetic factor(s) in these disorders.

The HLA-D associations of type 1 (insulin-dependent) diabetes in Punjabi Asians in the United Kingdom

Type 1 (insulin-dependent) diabetes is less common in Asian Indians than in white Caucasoids. Forty-five Punjabi Asians with Type 1 diabetes and 96 racially matched control subjects were HLA-DR typed. DR3 was increased in diabetic patients vs control subjects (82% vs 38%, p less than 10(-5)) with relative risk 7.7 and etiological fraction 0.72. DR4 was increased in diabetic patients vs control subjects (31% vs 7%, p less than 0.003) with relative risk 5.7 and etiological fraction 0.26. DR2 showed a negative association (relative risk 0.19, etiological fraction -0.28), as did DR7 (relative risk 0.21, etiological fraction -0.33). HLA-DQ beta-chain gene probing using restriction enzyme BamHI in 43 diabetic patients and 90 control subjects showed that the DR1-associated 6.2 and 3.2 kb fragments were less common in diabetic patients than in the control subjects (12% vs 36%, p less than 0.02). A 12 kb fragment was associated with DR4 in both diabetic patients and control subjects. DR3 is the major susceptibility factor for Type 1 diabetes in Punjabi Asians and DR4 is a second marker. Gene probing indicates that the same DR4 subset is associated with the condition as in white Caucasoids. DR1 and its associated DQ beta restriction fragments are reduced in Asian Type 1 diabetic patients making it unlikely that DR1 haplotypes carry a predisposing factor in this racial group. We conclude that the genetic component of Type 1 diabetes in Punjabis shows differences from that of the white Caucasoid population and that the lower frequency of DR4 in this population may contribute to the lower prevalence of Type 1 diabetes.

[Control of infection in a primarily surgical intensive care unit]

All of one year's 251 patients of a predominantly surgical intensive care unit (i.c.u.) were continuously followed up for infections according to a standard protocol. These protocols were evaluated for 174 patients who stayed at least 48 h at the unit. More than one third (36.7%) were already infected on admission (external origin), 35% contracted infections at the unit, primarily or additionally (internal origin) and 40% remained without an infection. Fifty eight percent of patients already infected on admission were surgical and required intensive care for complications. Among the patients who contracted their infection solely at the unit 61.5% suffered from trauma. Patients having contracted their infections at the i.c.u. stayed significantly longer than those without (additional) infections (13 and 6 days respectively). Mortality was highest (45%) in patients who were already infected on admission and who acquired additional infections during their stay at the i.c.u. Of patients with infections of exclusively external or internal origin 23.5 and 17.9% respectively died whereas among those who remained uninfected this proportion was only 7%. The 75 infections acquired before admission to the i.c.u. included infections of the respiratory tract in 14.4% of all patients, peritonitis with 10.3%, urinary tract in 8.0% and septicemia in 5.2%. Artificial ventilation was employed more often in infected patients (73.8-100%) than in non-infected ones (56.3%). They also carried more intravasal catheters (2.76-3.05 per patient) than the latter group (1.79). Of the 82 infections acquired in the i.c.u. the respiratory tract was affected in 19.5% of all patients and the urinary tract in 13.8%.(ABSTRACT TRUNCATED AT 250 WORDS)

Predictive value of serial carcinoembryonic antigen levels in long-term follow-up of ovarian cancer

The predictive value of serial levels of carcinoembryonic antigen (CEA) in tumor monitoring was examined in 213 patients with ovarian cancer; each patient had been followed-up at monthly intervals for at least 12 months. CEA was not detectable throughout the period of observation in 35% of the patients. In general. patterns showing a disappearance of CEA or persistently low levels were associated with a good prognosis, whereas those showing a reappearance or highly elevated and rising levels were associated with a poor prognosis. A transient reappearance of CEA was observed in 10 patients; this did not appear to be associated with tumor recurrence or progression. "False positive" results were obtained in 6 patients in whom no tumor has been clinically detectable to date. "False negative" results were obtained in 4 patients with obvious tumor progression. In terms of a good or poor prognosis, the use of CEA levels was highly accurate in patients with minimal or no residual disease (97% and 89%, respectively); the rate fell to 62% in patients with extensive disease. As the clinical significance and limitations become better known, serial CEA levels should contribute substantially to the monitoring of patients with ovarian cancer.

Carcinoembryonic antigen and beta 2-microglobulin as serum tumor markers in women with genital cancer

A comparative study of carcinoembryonic antigen (CEA) and beta 2-microglobulin (beta 2-MG) in serum was made by radioimmunoassay in 77 women with genital cancer. With a positive level defined as 5 ng of CEA/ml and 3.0 microgram of beta 2-MG/ml, CEA was positive in 31% of the women with cancer of the corpus, 36% of those with cancer of the cervix and 36% of those with cancer of the ovary the corresponding figures for beta 2-MG were 6%, 27% and 56%, respectively. The additional use of beta 2-MG provided an increase in positive results, especially in cases of cancer of the ovary. A direct relationship between the extent of tumor and serum marker level was more evident for beta 2-MG than CEA. There was no correlation between serial levels of CEA and beta 2-MG in most patients. CEA levels appeared to predict subsequent tumor behavior more accurately in patients with good prognoses (ie, complete or partial tumor response), whereas beta 2-MG levels gave the same prediction in those with bad prognoses (ie, nonresponsive or progressive tumor).

Susceptibilities of bacteria to different antibiotic regimens. Study in two nursery populations

Hospital nursery A has used chloramphenicol and nursery B has used the combination of penicillin G sodium and kanamycin sulfate routinely in the treatment of neonatal sepsis and other bacterial infections. A hypothesis was formulated that these different antibiotic pressures would select out a substantial number of populations of resistant bacteria in each of the two nurseries. This was tested by periodic sampling of the skin, mouth, and rectal flora of babies and the permanent personnel in these nurseries. These bacteria were studied for susceptibility to a number of antibiotics. The population of resistant strains selected out was correlated with the antibiotics used in each nursery. There is a need for continuing surveillance of hospital nursery strains of bacteria for in vitro susceptibilities to commonly prescribed antimicrobials.

Antibacterial activity of tobramycin against gram-negative bacteria and the combination of ampicillin/tobramycin against E. coli

The antibacterial activity of tobramycin, gentamicin, erythromycin, cloxacillin, kanamycin, cephalexin, penicillin, carbenicillin and polymyxin were compared against 303 clinical bacterial isolates from a pediatric hospital patient population. Standard disk diffusion and agar-dilution methods were employed. Significant activity was demonstrated for tobramycin against pseudomonas, Klebsiella, Escherichia coli and both Staphylococcus aureus and albus; Tobramycin was significantly more active against Pseudomonas than gentamicin or the other antibiotics testedmcomparable activity to gentamicin was present for the other types of bacteria; Cross-resistance was not encountered between tobramycin and gentamicin. 30 isolates of E. coli were tested against the combination of tobramycin and ampicillin by the growth-curve method. Synergism was demonstrated in 4 isolates, antagonism in 1 and an additive effect in 25. A bactericidal effect was present at 24h against 17 isolates with tobramycin alone and against 25 isolates when combined with ampicillin. These results provide in vitro rationale for the consideration of tobramycin for clinical use in patients with Psuedomonas infections for the combination of ampicillin and tobramycin for the treatment of selected E.coli infections.