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Biomedical subjects

M Boers

Publications and source records attributed to M Boers.

At least 73 records · Page 4Linked to original sources
PubMed2000

Impact of quality items on study outcome. Treatments in acute lateral ankle sprains.

OBJECTIVE: This study investigates the influence of different aspects of methodologic quality on the conclusions of a systematic review concerning treatments of acute lateral ankle sprain. METHOD: A data set of a systematic review of 44 trials was used, of which 22 trials could be included in this study. Quality assessment of the individual studies was performed using the Delphi list. We calculated effect sizes of the main outcome measure in each study in order to evaluate the relationship between overall quality scores and outcome. Next, we investigated the impact of design attributes on pooled effect sizes by subgroup analysis. RESULTS: The quality of most studies (82%) was low; only 4 of 22 trials were of high quality. Studies with proper randomization and blinding procedure produce a slightly higher (not statistically significant) effect estimate compared to the other studies. CONCLUSION: Previous research has suggested that methodologically poorly designed studies tend to over-estimate the effect estimate. Our study does not confirm these conclusions.

Ankle Injuries↗
PubMed2000

Update on outcome assessment in rheumatic disorders.

Outcome assessment in rheumatic disorders is getting more and more attention. A series of Outcome Measures in Rheumatology (OMERACT) conferences has provided a good impulse for further research in the field. In this chapter we will review the results of the last OMERACT 4 conference in detail. This conference was focused on longitudinal/observational studies, rheumatoid arthritis (response criteria and imaging), and core sets for ankylosing spondylitis and systemic lupus erythematosus. Moreover, an overview of recent literature on measures of disease activity, quality of life measures, and imaging is presented. For the various rheumatic disorders, several new instruments and/or further validation steps are described.

Consensus Statements as Topic↗
PubMed2000

Systematic review of the cost effectiveness of prophylactic treatments in the prevention of gastropathy in patients with rheumatoid arthritis or osteoarthritis taking non-steroidal anti-inflammatory drugs.

A systematic review on the cost effectiveness of prophylactic treatments of non-steroidal anti-inflammatory drug (NSAID) induced gastropathy in patients with osteoarthritis or rheumatoid arthritis was conducted. Two reviewers conducted the literature search and the review. Both full and partial economic evaluations published in English, Dutch, or German were included. The criteria list published in the textbook of Drummond was used to determine the quality of the economic evaluations. The methodological quality of three randomised controlled trials (RCTs) in which the economic evaluations obtained probability estimates of NSAID induced gastropathy and adverse events was assessed by a list of internal validity criteria. The conclusions were based on a rating system consisting of four levels of evidence. Ten economic evaluations were included; three were based on RCTs. All evaluations studied misoprostol as prophylactic treatment: in one evaluation misoprostol was studied as a fixed component in a combination with diclofenac (Arthrotec). All economic evaluations comprised analytical studies containing a decision tree. The three trials were of high methodological quality. Nine economic evaluations were considered high quality and one economic evaluation was considered of low methodological quality. There is strong evidence (level "A") that the use of misoprostol for the prevention of NSAID induced gastropathy is cost effective, and limited evidence (level "C") that the use of Arthrotec is cost effective. Although the levels of evidence used in this review are arbitrary, it is believed that a qualitative analysis is useful: quantitative analyses in this field are hampered by the heterogeneity of economic evaluations. Existing criteria to evaluate the methodological quality of economic evaluations may need refinement for use in systematic reviews.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2000

Responsiveness of the core set, response criteria, and utilities in early rheumatoid arthritis.

OBJECTIVE: Validation of responsiveness and discriminative power of the World Health Organisation/International League of Associations for Rheumatology (WHO/ILAR) core set, the American College of Rheumatology (ACR), and European League for Rheumatology (EULAR) criteria for improvement/response, and other single and combined measures (indices) in a trial in patients with early rheumatoid arthritis (RA). METHODS: Ranking of measures by response (standardised response means and effect sizes) and between-group discrimination (unpaired t test and chi(2) values) at two time points in the COBRA study. This study included 155 patients with early RA randomly allocated to two treatment groups with distinct levels of expected response: combined treatment, high response; sulfasalazine treatment, moderate response. RESULTS: At week 16, standardised response means of core set measures ranged between 0.8 and 3.5 for combined treatment and between 0.4 and 1.2 for sulfasalazine treatment (95% confidence interval +/-0.25). Performance of patient oriented measures (for example, pain, global assessment) was best when the questions were focused on the disease. The most responsive single measure was the patient's assessment of change in disease activity, at 3.5. Patient utility, a generic health status measure, was moderately (rating scale) to poorly (standard gamble) responsive. Response means of most indices (combined measures) exceeded 2.0, the simple count of core set measures improved by 20% was most responsive at 4.1. Discrimination performance yielded similar but not identical results: best discrimination between treatment groups was achieved by the EULAR response and ACR improvement criteria (at 20% and other percentage levels), the pooled index, and the disease activity score (DAS), but also by the Health Assessment Questionnaire (HAQ) and grip strength. CONCLUSIONS: Responsiveness and discrimination between levels of response are not identical concepts, and need separate study. The WHO/ILAR core set comprises responsive measures that discriminate well between different levels of response in early RA. However, the performance of patient oriented measures is highly dependent on their format. The excellent performance of indices such as the ACR improvement and EULAR response criteria confirms that they are the preferred primary end point in RA clinical trials.

Adult↗
PubMed2000

At what age could screening for familial retinoblastoma be stopped? A register based study 1945-98.

AIM: To evaluate until what age children in families with retinoblastoma should be screened. METHODS: A register based cohort (n= 685) study of Dutch retinoblastoma patients (1945-1998). The records of all familial hereditary retinoblastoma patients from 1945 were reviewed and the age at diagnosis and either they were screened from birth determined. RESULTS: 75 patients had the familial hereditary form of retinoblastoma. The mean age at diagnosis in patients with fundus screening (n=50) from birth on was 4.9 months (median 1.9 months; range 1 day to 48 months). Thus, 4 years was the latest onset of familial retinoblastoma properly evaluated from birth. This mean age was significantly different (p<0.0001) from the mean age at diagnosis in patients without fundus screening (n=25) from birth (mean 17.2 months; median 10.0 months; range 1.5-63.0 months). CONCLUSIONS: Ophthalmological screening of children and sibs at risk for familial hereditary retinoblastoma is recommended until the age of 4 years in order to detect retinoblastoma as early as possible.

Age Factors↗
PubMed2000

Validity of the MACTAR questionnaire as a functional index in a rheumatoid arthritis clinical trial. The McMaster Toronto Arthritis.

OBJECTIVES: The McMaster Toronto Arthritis patient preference questionnaire (MACTAR) is a functional index that measures change in impaired activities selected by each patient in a baseline interview, and change in rheumatoid arthritis (RA) disease activity. In addition, it contains questions on the state of physical, social and emotional function and overall health, and their relation to RA. We evaluated MACTAR's feasibility and validity (content validity, construct validity, and responsiveness). METHODS: A randomized trial of combined treatment in 155 patients with early RA; patients' mean age at baseline was 50 years and median disease duration since diagnosis was 4 months. RESULTS: Feasibility: MACTAR requires trained interviewers. In the trial, interviews took about 15 min. In longer term followup, activities selected at baseline may become less relevant as the pattern of disability changes. Followup from 153 patients (99%) was available. At least 5 impaired activities were identified and ranked by 147 patients (95%); interviewers could follow 99% of these. The scoring system proved complex and required amendments. Content validity: Although its main focus is physical function, the MACTAR also contains generic questions; 75% of the patients named at least one impaired activity from the category "mobility." Only 48% were covered by Health Assessment Questionnaire (HAQ) items. Construct validity: MACTAR scores correlate highly with other functional indices and with measures of disease activity. Responsiveness: At 16 weeks the standardized response mean for the total MACTAR score in the combined-treatment group was excellent, at 2.2. Items that directly address change were even more responsive. CONCLUSION: The MACTAR interview is a valid and highly responsive instrument to assess change in functional ability of patients with early RA with active disease. It provides insight into problems--mainly of physical function--that really matter to patients. For standard clinical trials and clinical care, feasibility of the MACTAR is limited and the simpler HAQ remains the instrument of choice.

Arthritis, Rheumatoid↗
PubMed1999

Reliability and sensitivity to change of a simplification of the Sharp/van der Heijde radiological assessment in rheumatoid arthritis.

OBJECTIVE: To determine the reliability and sensitivity to change of a simplified radiological scoring method [simple erosion narrowing score (SENS)] for rheumatoid arthritis (RA). SENS was compared to the Sharp/van der Heijde score (SHS) as a gold standard. METHODS: Sets of seven radiographs of hands and feet were taken of 20 RA patients with a wide spectrum of radiological damage. For 14 patients, these seven radiographs were taken during a follow-up period of 5 yr, and for six patients during a follow-up of 10 yr. Each set of radiographs was scored twice by the same observer (DvdH). Erosions and joint space narrowing were scored with SHS (range 0-448) in 32 and 30 joints in the hands, respectively, and both in 12 joints in the feet. SENS gives a score of 1 if there is any erosion in a joint and also 1 if there is any narrowing in the joint (range 0-86). In each case, SENS was derived from SHS. To analyse data, generalizability theory and repeated measurements ANOVA were used. RESULTS: The overall reliability coefficient was 0.81 for SHS and 0.80 for SENS. Intra-observer reliability [intraclass correlation coefficient (ICC)] was 0.99 and 0.98 for SHS and SENS, respectively. The ICC for the sensitivity to change was 0.84 for SHS and 0.88 for SENS. The smallest detectable difference (SDD) could be determined for both methods. The presence of progression based on this SDD was very comparable between the two methods. CONCLUSION: The measurement properties of SENS are good and comparable to SHS. This makes SENS suitable for use in clinical practice and in large (epidemiological) studies, especially in the first years of disease.

Adult↗
PubMed1999

Reading radiographs in chronological order, in pairs or as single films has important implications for the discriminative power of rheumatoid arthritis clinical trials.

OBJECTIVE: To determine the influence of reading series of films in chronological order, in pairs with unknown time sequence, or as single films, on precision and sensitivity to change. METHODS: Two studies were performed with 10 and 12 patients fulfilling the American College of Rheumatology criteria. In Study 1, two sets of films with a 1 yr interval were scored in chronological order, in pairs, and as single films. In Study 2, four sets of films, with a 1 yr interval each, were scored in chronological order, as single films and as single-pair (right and left together). All films were scored with the Sharp/van der Heijde method by two independent observers. Data were analysed with a repeated measures ANOVA using a full mixed effects model. Two generalizability (G) coefficients were constructed for reliability and for change. RESULTS: Study 1: the interobserver reliability was similar for the three methods (G(reliability) chronological 0.94, paired 0.88, single 0.93); progression was a mean increase (averaged over patients, observers and methods) from 26 to 37 (P=0.046). The sensitivity for change was greater for the chronological than for the paired and single scoring (G(change) 0.39, 0.22 and 0.24, respectively). Study 2: the interobserver reliability was 0.86 for chronological, 0.76 for single-pair and 0.91 for single readings. Significantly more progression was measured with the chronological compared with the single-paired and single methods (15.9 vs 8.5 and 8.3; P=0.0001). A constant progression was suggested by chronological reading, in contrast to a stabilization in the other two methods after 1 yr. CONCLUSION: Reading films in chronological order is most sensitive to change in a time period up to 3 yr follow-up; this was already present after 1 yr, but even more pronounced with longer follow-up.

Analysis of Variance↗
PubMed1999

ACR and EULAR improvement criteria have comparable validity in rheumatoid arthritis trials. American College of Rheumatology European League of Associations for Rheumatology.

We compared the validity of the American College of Rheumatology (ACR) and the European League of Associations for Rheumatology (EULAR) definitions of response in rheumatoid arthritis (RA) clinical trials. US: ACR and EULAR improvement criteria were calculated in 7 large randomized RA clinical trials. The discriminant validity of the response criteria between treatment groups was studied using the Mantel-Haenszel chi-squared value. To compare both sets of criteria the chi-squared ratio was determined for each trial. Europe: In 2 large randomized RA clinical trials, ACR and EULAR criteria were calculated, once with extensive and once with 28 joint counts. The classification of patients with these 4 criteria were compared with each other using cross tables. We further studied the difference in response between treatment groups per trial, the association of response with patient and investigator assessment of improvement, and the association of response with radiological progression. US: The chi-squared ratio for most trials was close to 1. There was no clear pattern suggesting that the discriminant validity of the ACR criteria was stronger than the discriminant validity of the EULAR definition of response or vice versa. Europe: Conflicting results between ACR and EULAR were present in only 3% of patients in both trials. The discriminant validity of all 4 criteria (ACR and EULAR with reduced and extensive joint counts) was comparable. All criteria were related with the overall assessment of improvement by both investigator and patient. The association with radiographic progression was comparable for EULAR and ACR improvement criteria. There is a high level of agreement between ACR and EULAR improvement classification, and their validity is equivalent. The discriminating potential of the criteria between treatment groups is comparable, as is the association with patient's and investigator's overall assessment and with radiographic progression.

Antirheumatic Agents↗
PubMed1999

Validity of area-under-the-curve analysis to summarize effect in rheumatoid arthritis clinical trials.

There is a continuing interest in increasing the statistical efficiency of the analysis of clinically meaningful endpoints in rheumatology. One issue that is attracting increasing attention is whether the conventional practice of only reporting the outcome at the end of the study (EOS) might be replaced or complemented by a longitudinal summary that better reflects the clinical course of the disease. The area under the curve (AUC) is a summary measure that integrates serial assessments of a patient's endpoint over the duration of the study. We evaluated the utility of AUC as a summary measure for the analysis and reporting of two RA trials: (i) methotrexate combined with cyclosporine versus methotrexate and placebo in partial methotrexate responders in relatively late disease, and (ii) prednisone plus methotrexate plus sulfasalazine versus sulfasalazine alone in relatively early disease. We replicated the published results of each trial first using the conventional EOS and then AUC summaries. For each patient, the changes from baseline over time were transformed into a summary measure by calculating AUC using the trapezium rule and then standardizing it by the study duration. Using an approach similar to the index of responsiveness to change, we scaled treatment differences derived from EOS and AUC summary measures by their standard deviation of the control group. This signal-versus-noise ratio captures the treatment discrimination ability of each summary measure. Compared to EOS and within each treatment group, the AUC summary reported smaller effects (i.e., change from baseline) with reduced errors in the estimates. AUC measures preserved discriminant validity in treatment comparisons and reported smaller but more precise treatment effect estimates. In the COBRA trial with rapidly-acting medications, AUC seemed to be more sensitive than EOS to detect treatment difference. With slow acting medications and in relatively late disease patients as in the cyclosporine trial, EOS was more sensitive to detect treatment difference than was AUC. In this setting, AUC, however, still seemed to be more sensitive than EOS for the two responsive-to-change endpoints: tender joint counts and pain by visual analog scale. AUC integrates repeated assessments during the trial duration into summary measures. Compared to EOS, the report of RA trial results using AUC summary provides smaller estimates of treatment effects but with better precision. AUC summary is likely to preserve treatment group discrimination taking into account the appropriate onset and offset of the drug action. Trial reports using AUC summary have smaller effect sizes. For trials with long acting medications and short duration similar to the cyclosporine trial, AUC still preserves treatment discrimination but may not be as sensitive as EOS. The calculations of AUC require some additional work in the analysis of each endpoint.

Antirheumatic Agents↗
PubMed1999

Methodological issues in radiographic scoring methods in rheumatoid arthritis.

Radiographs are important endpoints in clinical trials in rheumatoid arthritis (RA). Several scoring methods exist. However, many methodological issues are unsolved and require more attention. The following issues will be addressed: the abnormalities that should be scored; joints that should be included in a scoring method; whether both right and left hands and feet should be scored; views that should be used; the order in which radiographs should be scored; how data should be evaluated; how intra/interobserver variation and sensitivity to change should be assessed; the optimum number of readers to assess radiographs; the score to be used if there are multiple readers; quality assurance, international training, a validation set of radiographs, and automated scoring of radiographs.

Arthritis, Rheumatoid↗
PubMed1999

Smallest detectable difference in radiological progression.

Omeract IV started a discussion on the development of radiological response criteria in rheumatoid arthritis (RA). Such criteria depend on the definition of what constitutes the minimum clinically important progression of damage. Because such a definition is currently not available, as a first step we have used the concept of random measurement error to determine what is the smallest detectable difference (SDD) in radiological progression between 2 radiographs of a particular patient. Baseline and 12 month radiographs (hands, wrists, feet) of 52 patients representative of the spectrum of radiological progression were selected from a randomized controlled trial of early rheumatoid arthritis (COBRA study) and were read paired and chronologically by 2 observers using the van der Heijde modified Sharp method (0-448 scale) and another 2 observers using the Scott modified Larsen method (0-200). The measurement error of progression was determined using the metric 95% limits of agreement method of Bland and Altman. In the setting of early RA the SDD is 11 modified Sharp score units and 8 modified Larsen score units if there is an equal distribution of baseline damage and progression in the sample and the mean score of the same trained observers is always used. The SDD is 15.5 modified Sharp score units and 11 modified Larsen score units if there is an equal distribution of baseline damage and progression in the sample and the mean score of any 2 trained observers is used. Other SDD were determined depending on the context of measurement. Although this exercise needs repetition in other settings, the SDD is a useful starting point in the development of radiological response criteria.

Adolescent↗
PubMed1999

A practical exercise in reading RA radiographs by the larsen and sharp methods.

A plenary radiograph reading session was conducted prior to the rheumatoid arthritis imaging group sessions to familiarize participants with radiograph scoring methods and their problems, and to introduce the concept of measurement error. After brief reviews on how to score radiographs using the Larsen and Sharp method, photographic slides of metacarpophalangeal joints of 2 patients were shown. Participants were asked to register their absolute scores on paper, and their progression scores on an interactive voting keypad, allowing immediate visualization of the results. The objectives of the session were clearly met, as evidenced by lively discussions in the groups. Participant mean scores agreed well with the expert scores. Sharp scores showed wider scatter between participants than Larsen scores. This was only partially explained by the greater score range inherent in the method. In addition, participants needed more time to score according to Sharp than Larsen. Participants were sensitized to the challenges of radiographic measurement of damage.

Arthritis, Rheumatoid↗
PubMed1999

Imaging in rheumatoid arthritis: results of group discussions.

None of the current scoring methods for radiological damage in rheumatoid arthritis (RA) is ideal. The objective for RA imaging at OMERACT IV was to start discussion about the problems and applicability of the current scoring methods for radiological damage and to start discussion on the challenge of new imaging techniques. The RA imaging module comprised preconference reading material, plenary sessions, small group discussions, and a plenary report of the group sessions, combined with interactive voting. The OMERACT filter guided the discussions. Priorities for further research in imaging studies were: (1) pathologies versus features on radiographs; (2) relation with longterm outcome; and (3) definition of minimum clinically important difference.

Arthritis, Rheumatoid↗