The search for stable prognostic models in multiple imputed data sets

Background  

In prognostic studies model instability and missing data can be troubling factors. Proposed methods for handling these situations are bootstrapping (B) and Multiple imputation (MI). The authors examined the influence of these methods on model composition.     

The COSMIN checklist for evaluating the methodological quality of studies on measurement properties: A clarification of its content

Background  

The COSMIN checklist (COnsensus-based Standards for the selection of health status Measurement INstruments) was developed in an international Delphi study to evaluate the methodological quality of studies on measurement properties of health-related patient reported outcomes (HR-PROs). In this paper, we explain our choices for the design requirements and preferred statistical methods for which no evidence is available in the literature or on which the Delphi panel members had substantial discussion.     

Latent sensitisation to respiratory syncytial virus during acute bronchiolitis and lung function after recovery.

To determine whether latent sensitivity to respiratory syncytial virus antigen(s) occurs after infection, 27 infants with acute bronchiolitis were studied and compared with 15 hospital controls. Blood was collected for whole blood challenge, and histamine release was measured by a high performance liquid chromatography technique with fluorometric detection. There was a significantly greater histamine release to respiratory syncytial virus antigen(s) in those with bronchiolitis than in controls, expressed either in amount (median 154 nmol/l compared with 104 nmol/l) or percentage release (median 20% compared with 3%). There was a significant difference between index and control groups in terms of individual histamine responses. These findings strongly suggest that infants develop latent sensitivity to respiratory syncytial virus antigen(s) during the course of acute bronchiolitis. Serial lung function tests were performed in 15 infants. All infants had abnormalities of lung function at some stage, but the small numbers of subjects precluded comparison between ''sensitised'' and ''non-sensitised'' infants. Further study is indicated to define the relation of latent sensitisation and subsequent bronchial hyper-responsiveness after respiratory syncytial virus infection in infants.     

Cushing's syndrome secondary to inhaled corticosteroids mimicking HIV-associated lipodystrophy

We report the case of an asthmatic man with HIV infection who was initially diagnosed with HIV treatment-associated lipodystrophy. Further investigations showed he had Cushing's syndrome secondary to 1600 μg of budesonide dry powder inhaler. Cushing's syndrome has not been reported previously on this normal dose of inhaled budesonide.     

Real-time digital angiocardiography using a temporal high-pass filter

A temporal high-pass filtration technique for digital subtraction angiocardiography was studied, using real-time digital studies performed simultaneously with routine cineangiocardiography (cine) for qualitative image comparison. The digital studies showed increased contrast and suppression of background anatomy and also enhanced detection of wall motion abnormalities when compared with cine. This digital technique is compatible with panning the image intensifier during an injection. The digital images are comparable with, and in some cases better than, cine images. Clinical efficacy of this digital technique is currently being evaluated. Real-time display, as well as potential reductions in radiation and contrast material doses, may make digital angiocardiography an attractive technique.     

Pulmonary function in infants with cystic fibrosis: the effect of antibiotic treatment.

Since 1982 all infants born within the East Anglian Regional Health Authority have been screened for cystic fibrosis. Between April 1985 and April 1992 infants identified in this way have been entered into a randomised prospective controlled trial of antibiotic prophylaxis. Approximately half the infants received continuous oral flucloxacillin and the remainder received antibiotics when clinically indicated. Infants underwent tests of respiratory function at 3-4 months and at 1 year of age. Measurements of thoracic gas volume and airway conductance were made with an infant whole body plethysmograph, and maximum expiratory flow by the 'squeeze' technique. A total of 73 tests was performed of 42 infants. To facilitate comparisons, measurements were expressed as scores. The mean values of the scores for the two groups of infants fell within normal limits. There was no difference between the treatment groups at either age. A reduction in airways conductance was observed between the two tests.     

Pulmonary sequelae of neonatal respiratory distress in very low birthweight infants: a clinical and physiological study.

Twenty infants, mechanically ventilated in the neonatal period for respiratory distress syndrome, were compared with 15 healthy controls, matched for birthweight(less than 1501 g) but greater in mean gestational age. Clinical features and lung mechanics (by whole body plethysmography) were recorded at 6-monthly intervals until about one year. THe neonatal course of the mechanically ventilated infants was commonly complicated by tracheobronchial hypersecretion and the later course by a fairly high incidence of lower respiratory tract illness. In this group, thoracic gas volume, dynamic compliance, pulmonary and airways conductance were all abnormal during the middle 4 months of the first year and reverted towards normal towards the end of the first year. The control group had normal lung mechanics. Early lung function tests were of limited value in predicting later lower respiratory tract illness, which was more common in boys, after neonatal mechanical ventilation for longer than 24 hours or raised ambient oxygen for longer than 5 days. There were few predictive physical signs. In this group of very low birthweight infants, respiratory distress syndrome of sufficient severity to require mechanical ventilation led to significant physiological and clinical disturbances of lung function which lasted into the second 6 months of life and which were particularly severe in those who had recurrent lower respiratory tract illness.     

Double blind placebo controlled trial of nebulised budesonide for croup

AIMS: To determine whether nebulised budesonide improves the symptoms or shortens the duration of stay of children admitted to hospital with a clinical diagnosis of croup. METHODS: A prospective, randomised, double blind placebo controlled trial. Patients received either nebulised budesonide or placebo every 12 hours. The main outcome measures were duration of inpatient stay and croup scores at 30 minutes, one, two, four, 12, and 24 hours. RESULTS: 87 patients (89 admissions) aged 7-116 months entered the trial. Nebulised budesonide was associated with a significant improvement in symptoms at 12 hours (95% confidence interval (CI) 1 to 3) and 24 hours (95% CI 0 to 3). Patients with an initial croup score above 3 demonstrated a significant improvement in symptoms at two hours (95% CI 1 to 3). Nebulised budesonide was also associated with a 33% reduction in the length of stay (95% CI 2% to 63%) when the confounding variables of age, initial croup score, and coryzal symptoms were taken into consideration. CONCLUSIONS: Nebulised budesonide is an effective treatment for children admitted to hospital with a clinical diagnosis of croup.     

Invasive Haemophilus influenzae type b infections in children hospitalized in Hong Kong, 1986–1990

A 5-year territory-wide retrospective survey of invasive Haemophilus influenzae type b diseases was conducted in Hong Kong. Between 1986 and 1990, 57 cases (28 male) were recorded in children less than 12 years old (37 cases of meningitis, 9 of septicaemia and 11 of bacteraemic pneumonia). The annual incidence for children less than 5 years old was 2.7 per 10⁵ (95% confidence interval (CI) 2.0–3.5). Of the 57 cases, 39 were Chinese and 18 non-Chinese (7 Vietnamese refugees, 6 Caucasians, 5 others). The annual incidence in Vietnamese refugees less than 5 years old was 42.7 per 10⁵ (95% CI 17.2–87.9), giving a relative risk of 18.5 (95% CI 8.3–41.0). Chinese patients (68%) were under-represented as Chinese accounted for at least 94% of the population. Moreover, 14 of the 39 Chinese patients had pre-existing medical problems, compared with only 1 of the 18 non-Chinese patients (p = 0.022).