Presenting artificial intelligence, deep learning, and machine learning studies to clinicians and healthcare stakeholders: an introductory reference with a guideline and a Clinical AI Research (CAIR) checklist proposal

Background and purpose - Artificial intelligence (AI), deep learning (DL), and machine learning (ML) have become common research fields in orthopedics and medicine in general. Engineers perform much of the work. While they gear the results towards healthcare professionals, the difference in competencies and goals creates challenges for collaboration and knowledge exchange. We aim to provide clinicians with a context and understanding of AI research by facilitating communication between creators, researchers, clinicians, and readers of medical AI and ML research.Methods and results - We present the common tasks, considerations, and pitfalls (both methodological and ethical) that clinicians will encounter in AI research. We discuss the following topics: labeling, missing data, training, testing, and overfitting. Common performance and outcome measures for various AI and ML tasks are presented, including accuracy, precision, recall, F1 score, Dice score, the area under the curve, and ROC curves. We also discuss ethical considerations in terms of privacy, fairness, autonomy, safety, responsibility, and liability regarding data collecting or sharing.Interpretation - We have developed guidelines for reporting medical AI research to clinicians in the run-up to a broader consensus process. The proposed guidelines consist of a Clinical Artificial Intelligence Research (CAIR) checklist and specific performance metrics guidelines to present and evaluate research using AI components. Researchers, engineers, clinicians, and other stakeholders can use these proposal guidelines and the CAIR checklist to read, present, and evaluate AI research geared towards a healthcare setting.

The changing epidemiology of community-acquired pneumonia: nationwide register-based study in Sweden

BACKGROUND

There is limited evidence on the impact of pneumococcal conjugate vaccine childhood immunization programmes (PCV-CIP) on community-acquired pneumonia (CAP) in individuals with underlying diseases.

METHODS

A nationwide cohort study using Swedish health registers to assess the incidence of hospitalization with all-cause (AC-CAP) and pneumococcal or lobar (PL-CAP) CAP between 2005 and 2015, in relation to PCV-CIP introduction in 2007-09.

RESULTS

In total, 303 691 episodes of AC-CAP occurred, of which 14 225 were PL-CAP. Comparing before (2005-06) with after (2014-15) PCV-CIP, relative incidence reductions were 36% (95% Confidence Interval 32-40), 20% (14-25) and 16% (11-22) of AC-CAP for age groups < 2, 2-4 and 5-17 years, respectively, with similar reductions in young children with and without comorbidities. The reductions were more pronounced for PL-CAP. In the age groups 40-64, 65-74, 75-84 and ≥85 years there were relative increases of 11% (8-14), 18% (15-22), 15% (12-17) and 30% (27-34) of AC-CAP, respectively, but these increases were attenuated after adjustment for admittance practices using four control conditions. In adults with comorbidities, there was an increase in incidence of AC-CAP, and PL-CAP, in contrast to adults without reported underlying diseases where the incidence was stable or diminished for some age groups. Over the study period, there was an increased proportion of pneumonia patients with underlying diseases in all ages.

CONCLUSION

This emphasizes that direct preventive interventions should be targeted towards individuals with underlying diseases. Future studies should investigate reasons for the observed increased risk in adults with comorbidities, for example due to pneumococcal nonvaccine serotypes, or other pathogens, preferentially affecting subjects with underlying diseases.

A study of CO2/CO separation by sub-micron b-oriented MFI membranes

CO₂/CO separation is challenging. Here we report high-flux MFI membranes for effective CO₂removal from CO by selective CO₂adsorption in the MFI. On top, diffusional coupling at high CO₂loadings reduce the CO transport favouring CO₂/CO selectivity.

Soluble CD27 induces IgG production through activation of antigen-primed B cells

OBJECTIVES

High levels of soluble CD27 (sCD27), a marker of immune activation, are found in several infectious [including human immunodeficiency virus type-I (HIV-1)] and autoimmune diseases; however, a direct biological effect of sCD27 on B cells has not been established. The aim of this study was to investigate whether sCD27, by binding to CD70, can induce immunoglobulin G (IgG) production from B cells.

METHODS

B cells from healthy and HIV-1-infected individuals were cultured with recombinant human sCD27 (rhsCD27), and IgG production was measured. The role of rhsCD27 in inducing the expression of transcription factors involved in plasma cell differentiation was evaluated. Furthermore, we investigated the impact of different cytokines on the modulation of CD70 expression on B cells and the relationship between levels of IgG and sCD27 in serum from healthy and HIV-1-infected individuals.

RESULTS

We demonstrated that rhsCD27 induced IgG production from antigen-primed (CD27+) B cells. This effect was mediated by rhsCD27 binding to CD70 on B cells leading to activation of Blimp-1 and XBP-1, transcription factors associated with plasma cell differentiation. We found a significant correlation between levels of serum sCD27 and IgG in HIV-1-infected individuals and healthy controls.

CONCLUSIONS

sCD27 may act to enhance immunoglobulin production and differentiation of activated memory or recently antigen-experienced B cells, thus providing an activation signal to antigen-experienced B cells. This mechanism may operate during autoimmune and chronic infectious diseases, situations in which continuous immune activation leads to upregulation of CD70 expression and increased sCD27 cleavage.

BRICHOS - a superfamily of multidomain proteins with diverse functions

Background

The BRICHOS domain has been found in 8 protein families with a wide range of functions and a variety of disease associations, such as respiratory distress syndrome, dementia and cancer. The domain itself is thought to have a chaperone function, and indeed three of the families are associated with amyloid formation, but its structure and many of its functional properties are still unknown.

Findings

The proteins in the BRICHOS superfamily have four regions with distinct properties. We have analysed the BRICHOS proteins focusing on sequence conservation, amino acid residue properties, native disorder and secondary structure predictions. Residue conservation shows large variations between the regions, and the spread of residue conservation between different families can vary greatly within the regions. The secondary structure predictions for the BRICHOS proteins show remarkable coherence even where sequence conservation is low, and there seems to be little native disorder.

Conclusions

The greatly variant rates of conservation indicates different functional constraints among the regions and among the families. We present three previously unknown BRICHOS families; group A, which may be ancestral to the ITM2 families; group B, which is a close relative to the gastrokine families, and group C, which appears to be a truly novel, disjoint BRICHOS family. The C-terminal region of group C has nearly identical sequences in all species ranging from fish to man and is seemingly unique to this family, indicating critical functional or structural properties.

Efficacy of partner notification for Chlamydia trachomatis among young adults in youth health centres in Uppsala County, Sweden

BACKGROUND

The study was conducted to define the contact-tracing success rate of the partner notification services routinely provided by the community-based youth health centres and the county medical officer for communicable disease control (CMO) in Uppsala County, Sweden.

OBJECTIVE

The study had three goals, (i) to register the number of sexual partners routinely reported by each diagnosed index case with CT and the success rate in tracing and testing these partners for CT infection. (ii) To analyse the current notification practices in reporting the number of cases of unsuccessful contact tracing to the CMO. (iii) To determine the contact tracing success rate of the partner notification services provided by the CMO.

METHODS

Each diagnosed case of CT is obliged by law to participate in the contact-tracing procedure performed by the physician managing the patient or by a specialised sexually transmitted infection (STI) adviser. Successful contact-tracing is defined as the confirmed attendance of a sexual contact within 12 months of the contact with the index case.

RESULTS

The number of CT cases diagnosed by the youth health centres during the study period was 463 (299 females and 164 males). The females reported 660 male sexual contacts and the males reported 386 female contacts. Successful partner notification was achieved for 73% of all sexual contacts. 284 (190 females and 94 males) unsuccessful partner notifications were reported to the CMO of whom 98 (52%) of the female contacts and 20 (21%) of the male contacts were successfully notified by the CMO. However, for 134 (71 females and 63 males) partners, personal details given by the index case were insufficient for identification of the partner.

CONCLUSIONS

When asymptomatic, genital CT infection spreads among sexually active young adults with multiple, unidentified sexual partners, appropriate methods of partner notification are not sufficient to achieve its aims at the population level.

Medium- and short-chain dehydrogenase/reductase gene and protein families : the MDR superfamily

The MDR superfamily with ~350-residue subunits contains the classical liver alcohol dehydrogenase (ADH), quinone reductase, leukotriene B4 dehydrogenase and many more forms. ADH is a dimeric zinc metalloprotein and occurs as five different classes in humans, resulting from gene duplications during vertebrate evolution, the first one traced to ~500 MYA (million years ago) from an ancestral formaldehyde dehydrogenase line. Like many duplications at that time, it correlates with enzymogenesis of new activities, contributing to conditions for emergence of vertebrate land life from osseous fish. The speed of changes correlates with function, as do differential evolutionary patterns in separate segments. Subsequent recognitions now define at least 40 human MDR members in the Uniprot database (corresponding to 25 genes when excluding close homologues), and in all species at least 10888 entries. Overall, variability is large, but like for many dehydrogenases, subdivided into constant and variable forms, corresponding to household and emerging enzyme activities, respectively. This review covers basic facts and describes eight large MDR families and nine smaller families. Combined, they have specific substrates in metabolic pathways, some with wide substrate specificity, and several with little known functions.

Quantitative membrane proteomics applying narrow range peptide isoelectric focusing for studies of small cell lung cancer resistance mechanisms

Drug resistance is often associated with upregulation of membrane-associated drug-efflux systems, and thus global membrane proteomics methods are valuable tools in the search for novel components of drug resistance phenotypes. Herein we have compared the microsomal proteome from the lung cancer cell line H69 and its isogenic Doxorubicin-resistant subcell line H69AR. The method used includes microsome preparation, iTRAQ labeling followed by narrow range peptide IEF in an immobilized pH-gradient (IPG-IEF) and LC-MS/MS analysis. We demonstrate that the microsomal preparation and iTRAQ labeling is reproducible regarding protein content and composition. The rationale using narrow range peptide IPG-IEF separation is demonstrated by its ability to: (i) lowering the complexity of the sample by two-thirds while keeping high proteome coverage (96%), (ii) providing high separation efficiency, and (iii) allowing for peptide validation and possibly identifications of post-transcriptional modifications. After analyzing one-fifth of the IEF fractions (effective pH range of 4.0-4.5), a total of 3704 proteins were identified, among which 527 were predicted to be membrane proteins. One of the proteins found to be differentially expressed was Serca 2, a calcium pump located in the ER membrane that potentially could result in changes of apoptotic response toward Doxorubicin.

Influenza vaccination and mortality: prospective cohort study of the elderly in a large geographical area

The 50% reduced overall mortality previously associated with influenza vaccination among the elderly was based on studies neither fully taking into account systematic differences between individuals who accept or decline vaccination nor encompassing the entire general population. A population-based prospective cohort study was performed in Stockholm County (Sweden), including all persons aged > or =65 yrs (n = approximately 260,000), over three influenza seasons: 1998/1999, 1999/2000 and 2000/2001. The relative risks of mortality among vaccinated versus unvaccinated individuals were estimated using Cox's proportional hazards regression adjusted for, and stratified by, demographic factors and comorbid conditions during the three seasons and the respective following off-seasons. Influenza vaccination was associated with an unadjusted reduction in all-cause mortality during the three seasons of 50, 46 and 42%, respectively, which decreased to 14, 19 and 1%, respectively, following adjustment for confounders and differences in mortality between vaccinated and unvaccinated individuals following the influenza season. The numbers needed to treat to prevent one death, during the three seasons, were 297, 158 and 743, respectively. Vaccination remains the most important measure for prevention of influenza complications in elderly people, although the effectiveness in reducing all-cause mortality in elderly persons is lower than previously thought.

Organelle transport in melanophores analyzed by white light image correlation spectroscopy

Intracellular transport of organelles, vesicles and proteins is crucial in all eukaryotic cells, and is accomplished by motor proteins that move along cytoskeletal filaments. A widely used model of intracellular transport is Xenopus laevis melanophores. These cells help the frog to change color by redistributing melanin-containing organelles in the cytoplasm. The high contrast of the pigment organelles permits changes in distribution to be observed by ordinary light microscopy; other intracellular transport systems often require fluorescence labeling. Here we have developed white light Image Correlation Spectroscopy (ICS) to monitor aggregation and dispersion of pigment. Hitherto in ICS, images of fluorescent particles from Confocal Laser Scanning Microscopy (CLSM) have been used to calculate autocorrelation functions from which the density can be obtained. In the present study we show that ICS can be modified to enable analysis of light-microscopy images; it can be used to monitor pigment aggregation and dispersion, and distinguish between different stimuli. This new approach makes ICS applicable not only to fluorescent but also to black-and-white images from light or electron microscopy, and is thus very versatile in different studies of movement of particles on the membrane or in the cytoplasm of cells without potentially harmful fluorescence labeling and activation.

Molecular mobility of polymeric implants and acute inflammatory response: an experimental study in mice

An overlooked factor in biomaterial research is the surface molecular flexibility for polymer based implants. The mobility of the polymer chains provides a way for the surface to adapt itself to the environment. This is relevant when the implant comes in contact with a biological fluid and its constituents. By changing the length of the alkyl side chain of poly(alkyl methacrylates) (PAMAs) an interesting opportunity is provided where it is possible to study the surface molecular mobility without changing the surface hydrophobicity, nor does it introduce any additives or any changes in the degree of polymer cross-linking. Four variants of PAMAs were implanted in the peritoneum of Balb/c mice using a well described setup. End points were taken after 18 h and estimations of inflammatory cell recruitment and implant-associated cells were studied. Relationship between surface molecular mobility and inflammatory cell recruitment as well as surface-associated cells was noted.

Analysis of ancient sequence motifs in the H-PPase family

The unique family of membrane-bound proton-pumping inorganic pyrophosphatases, involving pyrophosphate as the alternative to ATP, was investigated by characterizing 166 members of the UniProtKB/Swiss-Prot + UniProtKB/TrEMBL databases and available completed genomes, using sequence comparisons and a hidden Markov model based upon a conserved 57-residue region in the loop between transmembrane segments 5 and 6. The hidden Markov model was also used to search the approximately one million sequences recently reported from a large-scale sequencing project of organisms in the Sargasso Sea, resulting in additional 164 partial pyrophosphatase sequences. The strongly conserved 57-residue region was found to contain two nonapeptidyl sequences, mainly consisting of the four 'very early' proteinaceous amino acid residues Gly, Ala, Val and Asp, compatible with an ancient origin of the inorganic pyrophosphatases. The nonapeptide patterns have charged amino acid residues at positions 1, 5 and 9, are apparent binding sites for the substrate and parts of the active site, and were shown to be so specific for these enzymes that they can be used for functional assignments of unannotated genomes.

Non-response to specific serotypes likely cause for failure to 23-valent pneumococcal polysaccharide vaccine in the elderly

During a randomised controlled trial with the 23-valent pneumococcal vaccine in older persons, antibody concentrations and opsonophagocytic activity (OPA) were compared between eight patients who developed culture-verified pneumococcal pneumonia and 38 controls, matched for age, sex and vaccination status. Patients who developed pneumococcal pneumonia did not respond with a significant increase of antibody concentration (>1microg/ml) post-vaccination to the infecting serotype, but responded equally well as controls to most other serotypes. Neither was there any significant difference in the OPA post-vaccination between patients and controls. In conclusion, the 23-valent pneumococcal vaccine should be regarded as 23 different vaccines, rather than one. Older persons who fail to respond to one serotype may well be protected against infection by the other 22 serotypes.

Additive preventive effect of influenza and pneumococcal vaccines in elderly persons

In 1999, all individuals > or = 65 yrs of age (n=258,754) in Stockholm County, Sweden, were offered influenza and pneumococcal vaccination in a prospective study on the effectiveness of these vaccines in reducing the need for hospital treatment and death due to influenza, pneumonia and invasive pneumococcal disease (IPD). Data on hospitalisation and mortality during 1 yr were obtained from the administrative database in Stockholm County Council. Vaccination was performed in 124,702 (48%) subjects; 72,107 had both vaccines, 29,346 only had the influenza vaccine and 23,249 only had the pneumococcal vaccine. Compared with the unvaccinated cohort, a lower incidence of hospitalisation for all endpoint diagnoses was seen in vaccinated persons. An additive effectiveness of vaccination was seen when both vaccines were given, with a reduction of hospital admissions for influenza (37%), pneumonia (29%) and IPD (44%). In-hospital mortality for pneumonia was significantly lower in those who received both vaccines, than in unvaccinated persons. To conclude, vaccination with influenza and pneumococcal vaccines together was effective in reducing the need for hospital admission for influenza and pneumonia. There was a strong indication that pneumococcal vaccination alone, was effective not only in the prevention of invasive pneumococcal disease, but also of pneumonia overall, although to a low degree.

Effects of a large-scale intervention with influenza and 23-valent pneumococcal vaccines in elderly people: a 1-year follow-up

To assess the effectiveness of influenza and pneumococcal vaccination in reducing hospitalisation and deaths in elderly people, the population aged > or =65 years in Stockholm County, Sweden (n = 259627) were invited to take part in a vaccination campaign with influenza and 23-valent pneumococcal vaccine (PV). A no. of persons (100,242) (vaccinated cohort) were vaccinated with one or both vaccines during the campaign. The incidence of hospital admissions during 1 year after the vaccination campaign, adjusted for sex and age, was significantly lower in the vaccinated than in the unvaccinated cohort for influenza (relative risk [RR] 0.68), pneumonia (RR 0.78), and invasive pneumococcal disease (RR 0.46). In the vaccinated cohort, the in-hospital mortality was lower for pneumonia (RR 0.55), COPD (RR 0.53) and cardiac failure (RR 0.72).

Changes in serotype distribution may hamper efficacy of pneumococcal conjugate vaccines in children

During the last 10 y we have observed an increased incidence of pneumococcal bacteremia in Sweden. In order to study the serotype distribution over time we collected 1136 invasive pneumococcal isolates from 1987, 1992 and 1997 from Swedish microbiological laboratories. Currently, new pneumococcal conjugate vaccines are being considered for introduction in the general childhood vaccination program in several countries, including Sweden. We studied the potential vaccine coverage rate for the new conjugate vaccines among our Swedish invasive isolates. We found that the serotype distribution fluctuated with time and observed a surprisingly low potential coverage rate for the 7-valent vaccine in Sweden, in contrast to other countries. Therefore we argue that pneumococcal conjugate vaccines have to be tailored to suit current, local serotype patterns and most likely will need to be changed over time.

Negligible adjuvant effect for antibody responses and frequent adverse events associated with IL-12 treatment in humans vaccinated with pneumococcal polysaccharide

To assess whether co-administration of recombinant human IL-12 (rhIL-12) and 23-valent pneumococcal polysaccharide vaccine (PPV) enhances the antibody response to this T cell-independent antigen, healthy immunocompetent volunteers (n=34, 55-65 years old) were vaccinated intramusculary with PPV and concurrently-treated subcutaneously with either rhIL-12 (1 or 4 microg) or placebo. The increases of total anti-pneumococcal IgG antibodies were numerically higher among the rhIL-12 recipients compared with placebo recipients, but the difference was not significant. The rhIL-12 recipients had a high incidence of local and systemic side effects. Given the lack of convincing evidence that rhIL-12 enhances the antibody response to PPV, the frequency and severity of the side effects was unacceptable.

Dynamics of penicillin-susceptible clones in invasive pneumococcal disease

In a 10-year period, 1987-1997, there was a >4-fold increase in the rate of pneumococcal bacteremia in Sweden. Invasive pneumococcal isolates (n=1136), which were obtained from 18 Swedish clinical microbiology laboratories from 1987 through 1997, and other national and international isolates were serotyped, and their clonal relationships were determined by molecular typing. The increase in invasive pneumococcal disease in Sweden during this period was associated particularly with an increase in isolates of serotypes 1 and 14. A 3-fold increase of type 14 was seen from 1987 through 1992, and a 10-fold increase of type 1 occurred from 1992 through 1997. One dominating penicillin-susceptible clone of type 14 was responsible for the increase of type 14 during the first 5 years. This clone also was found in Canada and the United States and was shown by multilocus sequence typing to correspond to a previously identified hyper-virulent clone. A novel penicillin-susceptible clone of type 1, which was not found among invasive isolates from 1987 or 1992, was responsible for the increase of serotype 1 during the last 5 years. These results illustrate the ability of virulent penicillin-susceptible pneumococcal clones to emerge and spread rapidly within a country.

Effects of a large-scale intervention with influenza and 23-valent pneumococcal vaccines in adults aged 65 years or older: a prospective study

BACKGROUND

The effectiveness of influenza and pneumococcal vaccination in the prevention of hospital admissions and death has not been assessed prospectively. We have therefore examined the effects of influenza and pneumococcal vaccination in individuals aged 65 years and older in a 3-year prospective study, between Dec 1, 1998 and May 31, 1999.

METHODS

All individuals in Stockholm County aged 65 years or older (259,627) were invited to take part in a vaccination campaign against influenza and pneumococcal infection. We recorded for all vaccine recipients (100,242) name, and date of birth, and whether they had been given both or one of the vaccines. All individuals (> or = 65 years) admitted to hospital in Stockholm County with influenza and pneumonia related diagnoses were identified between Dec 1, 1998, and May 31, 1999.

FINDINGS

The incidence (per 100,000 inhabitants per year) of hospital treatment was lower in the vaccinated than in the unvaccinated cohort for all diagnoses: 263 versus 484 (-46% [95% CI 34-56]) for influenza; 2199 versus 3097 (-29% [24-34)) for pneumonia; 64 versus 100 (-36% [3-58]) for pneumococcal pneumonia; and 20 versus 40 (-52% [1-77]) for invasive pneumococcal disease. The total mortality was 57% (55-60) lower in vaccinated than in unvaccinated individuals (15.1 vs 34.7 deaths per 1000 inhabitants).

INTERPRETATION

These findings show that general vaccination leads to substantial health benefits and to a reduction of mortality from all causes in this age group.

Recurrence of pneumonia in relation to the antibody response after pneumococcal vaccination in middle-aged and elderly adults

We have recently studied the efficacy of pneumococcal vaccine in preventing pneumonia recurrences after hospital treatment for community-acquired pneumonia in non-immunocompromised patients aged 50-85 y. Among these patients, we have now compared the antibody response to the pneumococcal vaccine between patients who developed pneumonia (n = 50) and patients without pneumonia recurrences (n = 100), during a mean follow-up period of 32 months after vaccination. The antibody levels of 5 pneumococcal serotypes were measured before, and 4 weeks, 1 y and 3 y after vaccination. A lower risk of pneumonia recurrences was seen in patients with antibody fold increases (FIs) > 4 from pre-vaccination to post-vaccination compared with patients with lower FIs (p = 0.02). The results suggest that in this patient category, the antibody response to pneumococcal vaccination is of importance for the risk of pneumonia recurrence.

Procalcitonin and C-reactive protein levels in community-acquired pneumonia: correlation with etiology and prognosis

BACKGROUND

The diagnostic value of admission serum levels of procalcitonin (PCT) and C-reactive protein (CRP) as indicators of the etiology and prognosis was prospectively investigated.

PATIENTS

96 patients, 50-85 years of age, treated in the hospital for community-acquired pneumonia (CAP).

RESULTS

On admission, all patients had elevated CRP levels (> 10 mg/l), but only 60 patients (54%) had elevated PCT levels (> 0.1 microgram/l). The severity of disease measured by APACHE II score was strongly associated with admission levels of PCT (p = 0.006), but not with CRP. Eight of nine patients with pneumonia caused by atypical agents had PCT levels < 0.5 microgram/l compared with 6/27 patients with pneumonia caused by classic bacterial pathogens, mainly Streptococcus pneumoniae (p = 0.03). No such correlation between CRP levels and etiology was found.

CONCLUSION

Our data indicate that in patients admitted to the hospital with CAP, measurement of PCT gives information about the severity of the disease, and may aid the physician to differentiate typical bacterial etiology from atypical etiology, and thereby to choose appropriate initial antibiotic treatment.

[The elderly should be vaccinated against pneumococci]

Invasive pneumococcal diseases are associated with substantial mortality in the elderly. The incidence of such diseases, particularly that of bacteraemic pneumococcal pneumonia, has increased in Sweden during the past decade. At the same time, there is a growing problem with beta-lactam-resistant and multiresistant pneumococci in many nearlying countries. Although pneumococcal vaccine probably provides only limited protection against pneumococcal pneumonia in the elderly, it yields approximately 70 per cent protection against invasive pneumococcal disease. Pneumococcal vaccination should therefore be recommended to all those 65 years old and above, and a nationwide strategy developed to implement good coverage in the age group.

Decision Accuracy in Computer-Mediated versus Face-to-Face Decision-Making Teams

Changes in the way organizations are structured and advances in communication technologies are two factors that have altered the conditions under which group decisions are made. Decisions are increasingly made by teams that have a hierarchical structure and whose members have different areas of expertise. In addition, many decisions are no longer made via strictly face-to-face interaction. The present study examines the effects of two modes of communication (face-to-face or computer-mediated) on the accuracy of teams' decisions. The teams are characterized by a hierarchical structure and their members differ in expertise consistent with the framework outlined in the Multilevel Theory of team decision making presented by Hollenbeck, Ilgen, Sego, Hedlund, Major, and Phillips (1995). Sixty-four four-person teams worked for 3 h on a computer simulation interacting either face-to-face (FtF) or over a computer network. The communication mode had mixed effects on team processes in that members of FtF teams were better informed and made recommendations that were more predictive of the correct team decision, but leaders of CM teams were better able to differentiate staff members on the quality of their decisions. Controlling for the negative impact of FtF communication on staff member differentiation increased the beneficial effect of the FtF mode on overall decision making accuracy. Copyright 1998 Academic Press.

Randomised trial of 23-valent pneumococcal capsular polysaccharide vaccine in prevention of pneumonia in middle-aged and elderly people. Swedish Pneumococcal Vaccination Study Group

BACKGROUND

We assessed the effectiveness of a 23-valent pneumococcal vaccine in the prevention of pneumococcal pneumonia and of pneumonia overall in non-immunocompromised middle-aged and elderly people.

METHODS

The prospective, multicentre, double-blind, randomised, placebo-controlled trial was carried out across departments of infectious diseases at six tertiary-care or university hospitals in Sweden. 691 non-immunocompromised patients aged 50-85 years who had been treated as inpatients for community-acquired pneumonia (CAP) were randomly assigned either 23-valent pneumococcal capsular polysaccharide vaccine or placebo (sodium chloride). We used Cox regression models to estimate the relative risks of pneumonia overall and pneumococcal pneumonia for the placebo group compared with the vaccine group.

FINDINGS

63 (19%) of 339 patients in the vaccine group and 57 (16%) of 352 patients in the placebo group developed a new pneumonia, corresponding to a relative risk over time for the placebo group compared with the vaccine group of 0.83 (95% CI 0.58-1.12, p=0.31). Pneumococcal pneumonia was diagnosed in 16 (4.5%) patients in the placebo group and in 19 (5.6%) in the vaccine group, corresponding to a relative risk for the placebo group of 0.78 (95% CI 0.40-1.51, p=0.45). We found no difference in the death rate between the two study groups.

INTERPRETATION

The 23-valent pneumococcal polysaccharide vaccine did not prevent pneumonia overall or pneumococcal pneumonia in middle-aged and elderly individuals.

[A handling program for resistant pneumococci. Physicians sometimes neglect mandatory notification]

Streptococcus pneumoniae infections belong to the leading worldwide causes of illness and death among young children, people with underlying debilitating medical conditions, and the elderly. Following early documentation of infections due to pneumococcal strains with reduced penicillin susceptibility in Australia in 1967, and of infections due to penicillin-resistant strains in South Africa in 1978, pneumococcal resistance to penicillin and other antibiotics has progressed rapidly and is now a global problem. In Sweden, notification of the occurrence of pneumococci with a minimum inhibitory concentration (MIC) > or = 0.5 mg/L for penicillin G (PcG) has been mandatory for general practitioners (GPs) and clinical microbiological laboratories since 1 January 1996. In 1996, 1,057 cases of infection by such pneumococci were reported by microbiological laboratories, but only 262 cases by GPs. With a view to minimising the impact of pneumococci with reduced penicillin susceptibility in Sweden, the National Board of Health and Welfare set up a working group of experts in November 1994. To reduce the transmission of such bacteria in the community, the working group introduced a control programme which includes the isolation of day-care children under six years of age carrying pneumococci with PcG-MICs > or = 0.5 mg/L. An enquiry among the 25 regional centres for infectious disease control in the country to ascertain compliance in the different counties of Sweden showed the programme to have been adhered to in a majority of counties, although many had chosen alternative measures to deal with the problem.

Recurrence of pneumonia in middle-aged and elderly adults after hospital-treated pneumonia: aetiology and predisposing conditions

In order to investigate the predisposing conditions and aetiologic agents in patients with recurrent pneumonia, we prospectively studied 653 immunocompetent patients, 50-85 years of age, who had been treated in hospital for community-acquired pneumonia. After an average patient follow-up period of 32 months, 11 variables were examined for association with the following end points: death, recurrence of pneumonia and recurrence of pneumococcal pneumonia. During the follow-up period there were 171 episodes of pneumonia in 115 of the 653 patients, and 52 deaths (all causes). Multivariate analysis showed that age, male sex, congestive heart failure and presence of other chronic diseases were significantly associated with higher mortality. Age and chronic pulmonary disease were associated with recurrence of pneumonia. The major aetiologic agents were Streptococcus pneumoniae (26%), Haemophilus influenzae (11%) and Moraxella catarrhalis (6%). We conclude that pneumonia recurrences are common in middle-aged and elderly patients after treatment in hospital for community-acquired pneumonia. The recurrence risk is higher in elderly patients, and in those with chronic pulmonary diseases. Given the prominence of H. influenzae and M. catarrhalis found in the present study, these organisms should always be considered when choosing the initial antibiotic in patients with recurrent pneumonia.

Activity of trovafloxacin against blood isolates of Streptococcus pneumoniae in Sweden

The in vitro activity of the fluoroquinolone trovafloxacin (CP-99,219) against 257 blood isolates of Streptococcus pneumoniae obtained from Swedish hospitals was compared with those of commonly prescribed oral antibiotics and also with those of ciprofloxacin and ofloxacin against a collection of strains resistant (n = 6) or intermediately resistant (n = 22) to penicillin (Pc-R). The MICs of trovafloxacin for Pc-R strains of pneumococci ranged from 0.032 to 0.25 mg/l. No difference was seen between the clinical isolates and the Pc-R strains (MIC50 = 0.064 mg/l and MIC90 = 0.125 mg/l for both collections). For the Pc-R strains, the MIC50 and MIC90 values of ciprofloxacin were 0.5 and 1 mg/l, and those of ofloxacin 2 and 4 mg/l. The incidence of resistance in the two collections (clinical isolates/Pc-R strains) was 3%/39% for tetracycline, 1%/18% for macrolides, and 3%/57% for trimethoprim/sulfamethoxazole. The results of the current study suggest that the clinical efficacy of trovafloxacin in the treatment of pneumococcal infections should be investigated.

Incidence, capsular types, and antibiotic susceptibility of invasive Streptococcus pneumoniae in Sweden

The number of reported cases of invasive pneumococcal infections in Sweden increased more than threefold from 1988 through 1992. We studied the capsular types and the antibiotic susceptibility of 619 pneumococcal strains isolated from blood or CSF at 18 Swedish microbiological laboratories in 1987 and in 1992. These strains belonged to 35 of the 84 recognized capsular types. We noted a remarkable increase in the prevalence of invasive infections with type 14 from 1987 (8.2%) to 1992 (18%) (P = .001), which correspond to a sevenfold increase in absolute numbers. The most prominent increase in infections was seen among elderly people; in 1992, type 14 accounted for 22.5% of the isolates from infected persons who were >64 years of age. The majority of the strains were susceptible to all antibiotics tested. However, there was a significant increase in trimethoprim-sulfamethoxazole resistance from 1.4% in 1987 to 7.1% in 1992. Nine multiresistant isolates (1.5%) were found.

Diagnostic and prognostic value of interleukin-6 and C-reactive protein in community-acquired pneumonia

The diagnostic and prognostic value of admission serum levels of interleukin-6 (IL-6) and C-reactive protein (CRP) was investigated in 203 hospital-treated patients with community-acquired pneumonia (CAP). In serum samples obtained during the first 24 h after admission, IL-6 was detectable in 198 patients (98%), with a median value of 50 ng/l. Ten % of the patients had IL-6 values of 1000 ng/l. A clear positive correlation between IL-6 and CRP was found (r = 0.29, p < 0.0001). Patients with high IL-6 or CRP levels had longer duration of fever, longer hospital stay, and had less often recovered clinically or radiographically on follow-up weeks after discharge. A high IL-6, but not a high CRP, also seemed to be associated with a higher mortality. Bacteremic pneumococcal pneumonia had the highest levels of IL-6 (mean 2852 and median 420 ng/l) and CRP (mean 292 and median 285 mg/l). High IL-6 values were also seen in patients with non-bacteremic pneumococcal pneumonia, while all patients with pneumonia due to other bacterial, or viral, aetiology had IL-6 levels of < or = 300 ng/l. In conclusion, IL-6 and CRP are promising diagnostic and prognostic tools in the management of CAP. Further studies are needed to establish the usefulness of repeated measurements early in the hospital course of the disease.

Short- and long-term prognosis for middle-aged and elderly patients hospitalized with community-acquired pneumonia: impact of nutritional and inflammatory factors

To investigate the impact of nutritional and inflammatory factors on short- and long-term prognosis for patients hospitalized for community-acquired pneumonia (CAP), 97 patients, 50-85 years old, admitted to the Department of Infectious Diseases at Danderyd Hospital were enrolled in a prospective study. 13 enrolment variables were examined for association with 6 outcome variables. Serum orosomucoid concentration, acute physiology and chronic health evaluation (APACHE) II score, body mass index (BMI) and triceps skinfold (TSF) were each associated with duration of hospital stay. A low TSF and BMI, and a high APACHE II score were all associated with death. A high APACHE II score and a high TSF were both associated with readmission within 6 months of discharge. The alfa-1-antitrypsin concentration was the most closely correlated with duration of fever. We conclude that the admission concentrations of alfa-1-antitrypsin and orosomucoid are better predictors of hospital morbidity than the more commonly used albumin and C-reactive protein (CRP) levels. Measurement of APACHE II and TSF on admission may give additional prognostic information on the interval from admission to 6 months after discharge.

Aetiology, outcome and prognostic factors in community-acquired pneumonia requiring hospitalization

Outcome and prognostic factors were prospectively studied in 277 adult patients (average age 62 yrs) with community-acquired pneumonia requiring hospitalization. The aetiology was established in 68%, with S. pneumoniae as the predominating agent. Mortality was 4% (12 of 277), and all but one who died were greater than or equal to 60 yrs of age. Features associated with high mortality included greater age, absence of chills and chest pain, high respiratory rate (greater than 30 breaths.min-1) and low serum albumin on admission, and the occurrence of airway colonization and secondary infection during hospital stay. Multivariate analysis showed that low serum albumin and the occurrence of secondary infection, but also absence of chills and airway colonization, were correlated to a higher mortality. In patients who survived, the median length of hospital stay was seven days, and at follow-up, about eight weeks after admission, 81% had recovered and chest X-ray was normal in 84%. In conclusion, we believe that the outcome of community-acquired pneumonia can be influenced by prophylactic measures against pneumococcal infection, and an increased surveillance of risk patients.