Biomedical subjects

M M Rovers

Publications and source records attributed to M M Rovers.

28 records · Page 2Linked to original sources

PubMed2000

Comparison of balanced and random allocation in clinical trials: a simulation study.

BACKGROUND: Before analysing the results of a randomised controlled clinical trial in which 200 children were balanced over five prognostic factors, we wanted to know the efficiency of balanced allocation compared to simple randomisation as well as the efficiency of adjusted as compared to unadjusted statistical analysis in small and large sample sizes. METHODS: A simulation study with 1000 replications of each assignment was performed for both relatively large trials (n = 100) and for small trials (n = 20). Four options for the design and analysis were studied: (1) simple randomisation with simple univariate analysis, (2) simple randomisation with multivariate modelling, (3) balanced allocation with simple univariate analysis and (4) balanced allocation with multivariate modelling. In addition, we also considered the effect of an unmeasured covariable, which was either uncorrelated or correlated with another covariate. RESULTS/CONCLUSION: The simulations show that a combination of balanced allocation and multivariate analysis as compared to simple randomisation and multivariate analysis leads to more valid and precise treatment effects as well as to smaller confidence intervals, especially in small trials (n = 20). Multivariate analysis with all known prognostic factors produces on average smaller Type I errors and Type II errors in balanced allocation compared to simple randomisation. If an unmeasured covariate is strongly correlated with another covariate the treatment effect is estimated more precisely as compared to an unmeasured covariate that is not correlate or less strongly correlated.

Confidence Intervals↗

PubMed2000

Seasonal variation in the prevalence of persistent otitis media with effusion in one-year-old infants.

The objective of this population-based cohort study was to evaluate the prevalence of persistent otitis media with effusion (OME) and its seasonal variation in 12-month-old infants. All 30099 infants born in the eastern part of The Netherlands between 1 January 1996 and 1 April 1997 were invited for hearing screening, comprising a protocol of three possible tests. Those who failed all three screening tests were referred to an ENT clinic for examination. Prevalences (i.e. the probability that a child would fail all the screening tests) were calculated by searching for the best logistic model for the first, second and third screening test as well as for the visit to an ENT department. By multiplying the prevalences found by the different models with each other, a prevalence was calculated that accounted for increasing age and the timing of the successive hearing tests. Furthermore, 95% confidence intervals were calculated for this age-season-corrected prevalence. When all the children attended the hearing tests at 9, 10, 11 and 12 months of age and when the number of births was the same in all months, the overall prevalence was 4.8% [95% CI 4.3, 5.2]. The highest prevalence (8.0%) was found in April, and the lowest (1.5%) in October. Rates of bilateral OME during the late winter months were twice as high as those during the late summer.

Cohort Studies↗

PubMed2000

The effect of ventilation tubes on language development in infants with otitis media with effusion: A randomized trial.

OBJECTIVE: To study the effectiveness of ventilation tubes on the language development in infants with persistent otitis media with effusion (OME). All existing studies addressed children 3 years of age or older. Currently, OME is detected and treated with ventilation tubes at a younger age. Because of the critical relationship between age, hearing, and language development, we conducted a study of the effects of ventilation tubes on language development in infants 1 to 2 years old with persistent OME. DESIGN: A multicenter, randomized, controlled trial (embedded in a cohort) with 2 treatment arms: 1) treatment with ventilation tubes (VT group; n = 93); or 2) with a period of watchful waiting (WW group; n = 94). Hearing loss and expressive and comprehensive language were assessed every 6 months, while tympanometry and otoscopy were performed every 3 months. Other factors with potential influence on language development were also included: adenoidectomy, hospital, attending day care, sex, age at randomization, educational level of the mother, upper respiratory infections, and the native country of the parents and older siblings. The trial was designed to allow for the detection of a mean difference in language development of 3 months or more between children allocated to the VT and WW groups. RESULTS: No relevant differences were found in expressive or comprehensive language between the 2 groups after adjustment for educational level of the mother, IQ of the child, and differences at baseline. A principal component analysis showed that in the VT group, the children with frequent complaints improved 1.6 months more in comprehensive language than those with no or some complaints. The children with favorable language stimulation, however, did not improve more than the children with less favorable stimulation. No differences were found for expressive language among the various clusters. The probability to improve >3 months in comprehensive language was.48 (95% confidence interval [CI]:.29-.68) for children with highly educated mothers versus.09 (95% CI:.02-.30) for children whose mothers had a low educational level. In the WW group, these changes were.30 (95% CI:.14-.53) and.14 (95% CI:.04-.35), respectively. The probability to improve >4 months in expressive language was.52 (95% CI:.32-.71) for children with highly educated mothers versus.06 (95% CI:.01-.31) for children whose mothers had a low educational level. In the WW group these changes were.42 (95% CI:.23-.64) and.11 (95% CI:.03-.35), respectively. In addition, there were delays in expressive language in both groups compared with their age expected values. The comprehensive language of the children who were effusion-free during the follow-up (n = 54) improved 1.5 months (95% CI: -.2-3.2) more than that of the children who had persistent effusion during the entire follow-up (n = 28). No differences were found for expressive language development. Disregarding the intervention contrast, improvements in hearing seemed to be related to improvements in language development, especially in verbal comprehension. DISCUSSION: In this study, we used the Reynell, Schlichting, and Lexi tests to study the relation between early persistent OME and language development. These tests are directly related to normal language, widely accepted, and validated. It cannot be ruled out that more specific measures such as auditory perception tests would have produced more differences between groups, but the focus was on general language development. A total of 10 children in the WW group received treatment with ventilation tubes during follow-up. A further 11 children dropped out during the trial. A sensitivity analysis with the 10 children who received ventilation tubes did not change the results, and baseline differences were not found between the 11 children who dropped out and those who completed the trial. CONCLUSIONS: In the total group of infants with persistent OME, ventilation tubes did not h

Child Language↗

PubMed1999

Prognostic factors for persistent otitis media with effusion in infants.

OBJECTIVE: To study prognostic factors for persistent otitis media with effusion (OME) in a birth cohort of 30,099 children born in the eastern part of The Netherlands between January 1, 1996, and April 1, 1997. DESIGN: Case-referent study. SUBJECTS: Children who failed a triple hearing test before their first birthday and were subsequently diagnosed with bilateral OME during 3 of the 4 bimonthly visits to an ear, nose, and throat (ENT) department (n = 372). The persistent cases were compared with 3 referent groups: (1) all the children who attended the first of 3 hearing tests; (2) all the children of the birth cohort who were referred to an ENT department after the third hearing test; and (3) all the children who were diagnosed with bilateral OME during the first visit to an ENT department. RESULTS: When all the children who participated in the first hearing test were taken as referents, persistent OME was associated with upper respiratory tract infections, attending a day-care center, having older siblings, and a family history of otitis media. When all the children who were referred to an ENT department were taken as referents, only attending a day-care center was associated with persistent OME. When the children diagnosed with bilateral OME during the first visit to an ENT department were taken as referents, no prognostic factors were found for OME persistence. CONCLUSION: When a child is referred early, an otolaryngologist can ask the parent about the presence of prognostic factors to decide which policy to follow.

Case-Control Studies↗

PubMed1999

Day-care and otitis media in young children: a critical overview.

UNLABELLED: To review the evidence concerning the association between (different forms of) day-care and otitis media in children aged 0-4 years, we performed a meta-analysis of studies identified by a systematic search with Medline from 1966 to July 1997 and by the reference lists. Seventeen articles were classified as useful because these articles studied children of 0-4 years of age and because odds ratios as well as confidence intervals were presented or could be calculated. All these studies found a association between attending a day-care centre and otitis media. The association between otitis media and family care was less clear. Differences in study design, age of the subjects, and controlled variables did not explain the association. CONCLUSION: Day-care is a risk factor for developing otitis media: the number of children seems to be important for this effect, probably due to increased exposure to otitis media pathogens.

Child Day Care Centers↗

PubMed1999

Comparison of the CAPAS and Ewing tests for screening of hearing in infants.

OBJECTIVE: To study the similarities and differences between the non-automated labour intensive Ewing hearing test and the less labour intensive automated CAPAS (Compact Amsterdam Paedo-Audiometrical Screening) hearing test. SETTING: A multicentre study in which all the children born in the eastern part of the Netherlands between 1 January 1996 and 1 April 1997 were routinely screened for hearing impairment at 9 months of age. METHODS: Differences and similarities between the two methods were described for the proportion of children who failed every test, the percentage of referred children, the yield of bilateral and unilateral otitis media with effusion (OME), the positive predictive value of the third test result, and the yield of persistent OME after 4-6 months' follow up at an ENT department. RESULTS: 12,603 infants were screened with the CAPAS test and 17,496 with the Ewing test. There were differences between the CAPAS and Ewing tests respectively in the proportions of children lost to follow up (10.1% v 15.2%), the proportions of children referred diagnosed with OME (59% v 81%), the yield of bilateral otitis media with effusion (2.4% v 3.0%), and the yield of persistent OME after 4-6 months' follow up (1.1% v 1.6%). CONCLUSIONS: The CAPAS test is more practical than the Ewing test, but the non-automated Ewing test seems to be more reliable and valid for detecting conductive hearing loss.

Follow-Up Studies↗

PubMed1998

Hearing deficits at school age; the predictive value of otitis media in infants.

AIM: To evaluate the long-term predictive value of persistent/recurrent otitis media with effusion (OME) in infants in relation with hearing levels at (early) school age. DESIGN: A case-cohort study among a population-based sample of school-age children screened for hearing deficits. POPULATION AND METHODS: Schoolchildren (second grade, 5-6 years of age) in the city of Utrecht, the Netherlands, who failed the hearing screening test and a sample of children invited for this screening. History of otitis media (serosa and acute) was assessed using three sources of information: a self-completion questionnaire mailed to the parents; medical records of otolaryngology visits; data from the (Ewing) hearing screening test at 9 months of age. RESULTS: Children who failed the primary Ewing test and children with recurrent and or persistent OME in the first 2 years of life showed an increased risk of failing school audiometry compared to children without such an OME history (OR=1.6 and 2.3, respectively). In a logistic model, the results of the primary Ewing test and the frequency of acute otitis media, proved to be moderately predictive for the screening test result at school age. CONCLUSION: OME in infants is a prognostic factor for hearing performance in the early school years.

Audiometry↗

PubMed1998

Prognostic factors for otitis media with effusion in infants.

To determine the prognostic factors for otitis media with effusion (OME) in 1-year-old infants, we studied 240 patients and 366 controls in a case-cohort study. On univariate analysis factors which were associated with OME were family history, older siblings, upper respiratory infections and acute otitis media (AOM). After multivariate analysis, however, only the occurrence of more than four upper respiratory infections and children with older siblings were associated with OME. Thus, upper respiratory infections and older siblings appear to be related to the development of OME.

Case-Control Studies↗

PubMed1997

Self-treatment by adults during slow-onset exacerbations of asthma.

Self-management plans are considered today an essential component of the management of asthma. The objective of the present study was (a) to explore patients' present practical knowledge of self-treatment of asthma, and (b) to provide an assessment of the effect of an educational program on this knowledge and self-treatment behaviour. Twenty four adults with asthma from the outpatient clinic of the Department of Pulmonary Medicine participated in a self-management program. They were provided with explanations on the symptoms and precipitating factors of their asthma, on its treatment with medication and their side-effects, and with personal written guidelines for self-adjustment of their medication. Prior to the program their practical knowledge of adequate self-treatment was investigated using a hypothetical scenario of a slow-onset asthma exacerbation. The effectiveness of the teaching and training program was evaluated by the change in knowledge prior to and 5 months after the program and self-reported behaviour of the participants at follow-up. (a) More than 60% of the patients lacked practical knowledge of self-treatment of a slow-onset exacerbation of asthma. (b) The educational program resulted in a significant increase (47%) of this knowledge. (c) Actual self-treatment behaviour, as recorded by the patients 5 months after completing the educational program, was adequate in only two of ten patients, who experienced an exacerbation during the study period. Many adults with asthma are deficient in practical knowledge of self-treatment of a slow-onset exacerbation. This knowledge was significantly augmented by an educational program. Nevertheless actual self-treatment behaviour at follow-up was inadequate in the majority of patients.

Acute Disease↗

PubMed1997

Compliance with inhaled medication and self-treatment guidelines following a self-management programme in adult asthmatics.

Two of the principal components of self-management are compliance with medication and adherence to self-treatment guidelines. The aim of this study was to evaluate compliance objectively. Twenty two adult asthmatics attended a self-management programme. During a 2 week run-in period, compliance with inhaled steroids and peak expiratory flow (PEF) were electronically-registered. For PEF this resulted in a personal best value (PBV). Subsequently, patients attended four educational group sessions. During the four weeks of follow-up, patients were instructed to measure their PEF on a fixed day of the week and when they experienced an increase in symptoms. If PEF fell below 80% of PBV, patients had to double their use of inhaled steroids; if PEF fell below 60%, they had to start a short course of oral steroids. During run-in, mean compliance was 83% and compliance per patient varied from 6 to 106%. During follow-up, on days without exacerbation, compliance with inhaled steroids increased by 12% (95% confidence interval (95% CI) 3-21%) compared to run-in, ranging 21-200%. On days when patients should have doubled their inhaled steroids, compliance decreased by 28% (95% CI -39 to -17), and compliance ranged 46-94%. Of the 10 patients who should have doubled their medication, only three did so, whilst four increased the use of inhaled steroids but only by one or two puffs; three patients did not alter their behaviour. In five patients (24%) PEF fell below 60% of their PBV, after which four started prednisolone (self-report). In conclusion, even after a formal self-management programme, patients with asthma comply only partially to self-treatment guidelines. Most are willing to increase, but not double, their inhaled steroids. This suggests that more emphasis is needed to reassure patients about the safety of inhaled steroids.

Administration, Inhalation↗