Biomedical subjects
Publications and source records attributed to R J Scholten.
In the Netherlands, evidence-based medicine is advocated as a basis for the preparation of clinical guidelines. A systematic review should be the cornerstone of every aspect of a guideline for which a recommendation is required. To reduce the necessary effort, continuation of national and international collaboration is needed in the preparation and maintenance of high-quality systematic reviews.
Systematic reviews of the literature provide a summary of the current status of medical scientific research. They are important for the solution of medical questions by doctors active in clinical practice, may serve to support practice guidelines, and are used in health care to take policy decisions and to determine the research agenda. The Cochrane Library is the most important source of information on the efficacy of interventions in health care and comprises eight databases. The most relevant for doctors active in clinical practice are the Cochrane Database of Systematic Reviews, the Database of Abstracts of Reviews of Effects, and the Cochrane Central Register of Controlled Trials. At present, the first two databases contain over 5000 systematic reviews of the literature. The third database listed above is the largest database in the world with references to (randomised) controlled studies.
BACKGROUND: Carpal tunnel syndrome is a common disorder, which can be treated with surgery or conservative options. However, there is insufficient evidence and no consensus among physicians with regard to the preferred treatment for carpal tunnel syndrome. Therefore, a randomized controlled trial is conducted to compare the short- and long-term efficacy of surgery and splinting in patients with carpal tunnel syndrome. An attempt is also made to avoid the (methodological) limitations encountered in earlier trials on the efficacy of various treatment options for carpal tunnel syndrome. METHODS: Patients of 18 years and older, with clinically and electrophysiologically confirmed idiopathic carpal tunnel syndrome, are recruited by neurologists in 13 hospitals. Patients included in the study are randomly allocated to either open carpal tunnel release or wrist splinting during the night for at least 6 weeks. The primary outcomes are general improvement, waking up at night and severity of symptoms (main complaint, night and daytime pain, paraesthesia and hypoesthesia). Outcomes are assessed up to 18 months after randomization.
In a systematic review (SR) the information from the original studies is searched, selected, extracted, appraised and summarised in a transparent, valid and reproducible manner. SRs are therefore an efficient and reliable source of information for the clinician, health policy maker and researcher. SRs can be identified in various sources. The search strategy is determined by the desired comprehensiveness, the availability of various sources and the need for additional comments on the SR by a referee. In Medline a sensitive filter is available for searching SRs. An SR should be based on a carefully formulated clinical question that can be answered on the basis of data from the original studies. SRs should be thoroughly assessed as they can differ substantially in terms of quality. In such an appraisal the following aspects should be considered: question, search strategy, selection of studies, quality assessment, data extraction and data presentation, (statistical) summary of the data, statistical and clinical heterogeneity, results and conclusion. Various assessment lists are available. Differences in conclusions between SRs on the same subject can be analysed in a systematic manner and can often be resolved.
A randomised controlled trial, involving 112 adolescents with asthma, and a 2-year follow-up was conducted to assess the impact of an intervention programme aimed at enhancing adherence to asthma medication. This programme had a duration of 1 year and consisted of an experimental group which received usual care from a paediatrician, but additionally attended individual and group sessions with an asthma nurse, and a control group which received usual care only. The programme aimed at enhancing adherence by stimulating a positive attitude, increasing feelings of social support, and enhancing self-efficacy. At baseline, and after 12-month (T1) and 24-month (T2) follow-up, the participants filled in questionnaires which were based on the concepts of the ASE-model. Adherence was assessed by self-report (range: 1-10) at the same points in time. After 12 months, 97 adolescents (87%) were available for follow-up, decreasing to 86 adolescents (77%) after 24 months. No statistically significant differences were found between the control and the experimental group, except for one. At T2, self-reported adherence appeared to be statistically significantly higher in the experimental group. In conclusion, there seems to have been no substantial effect of the intervention programme.
OBJECTIVE: This paper presents the method we used in programming research on the efficacy of therapeutic interventions for nine chronic benign pain disorders. METHODS: We started with an inventory to identify commonly applied interventions. For these interventions we searched the literature to identify gaps in evidence. First, we searched for recent reviews, of which we assessed the methodologic quality. If only reviews of poor or moderate quality were found, a new systematic review was recommended. When we found no recent reviews, we searched for randomized controlled trials (RCTs). If there was insufficient or inconsistent evidence, the performance of a new RCT was advised. This structured procedure resulted in a list with topics for which new systematic reviews were recommended and topics for which new RCTs were needed. These lists were the starting points for priority setting by four Centers for Pain Management and Research. All members of the centers were asked to state the priority of each topic. The resulting hierarchy of topics for their own center was discussed in a meeting in each center, giving participants the opportunity to elucidate their views and considerations. RESULTS: The final result was a robust priority list for the need of research (systematic reviews and RCTs) on chronic benign pain syndromes. DISCUSSION: The strength and weaknesses of this approach are discussed. This method of priority setting is by no means restricted to treatments for chronic pain; it is also a useful approach for programming research to enable evidence-based medicine in other fields of interest.
BACKGROUND: Carpal tunnel syndrome (CTS) is a common disorder for which several surgical treatment options are available. However, there is no consensus on the most effective method of treatment. The object of this systematic review is to compare the efficacy of the various surgical techniques in relieving the symptoms of CTS and promoting return to work and/or activities of daily living. METHODS: Computer-aided searches of Medline, EMBASE and the Cochrane Controlled Trials Register were conducted, together with reference checking. A rating system, based on the number of studies and their methodological quality and findings, was used to determine the strength of the available evidence for the efficacy of the treatment. RESULTS: Fourteen studies were included in the review. None of the alternatives to standard open carpal tunnel release (OCTR) seems to offer better relief of symptoms. There is conflicting evidence about whether endoscopic carpal tunnel release results in earlier return to work and/or activities of daily living. CONCLUSION: Standard OCTR is still the preferred method of treatment for CTS. It is just as effective as the alternatives, but is technically less demanding, so incurs a lower risk of complications and of added costs.
OBJECTIVE: Our systematic review summarizes the evidence about the accuracy of those tests. SEARCH STRATEGY: We performed a literature search of MEDLINE (1966-1999) and EMBASE (1988-1999) with additional reference tracking. SELECTION CRITERIA: Articles written in English, French, German, or Dutch, that addressed the accuracy of at least one physical diagnostic test for meniscus injury with arthrotomy, arthroscopy, or magnetic resonance imaging as the gold standard were included. We excluded studies if no reference group or only test-positives had been included, if the study pertained to cadavers only, or if only physical examination under anesthesia was considered. DATA COLLECTION/ANALYSIS: Two reviewers independently selected studies, assessed the methodologic quality, and abstracted data using a standardized protocol. We calculated sensitivity, specificity, and likelihood ratios for each test, and summary estimates when appropriate and possible. MAIN RESULTS: Of 402 identified studies, 13 met the inclusion criteria. The results of the index and reference tests were assessed independently (blindly) of each other in only 2 studies, and in all studies verification bias seemed to be present. The study results were highly heterogeneous The summary receiver operating characteristic curves of the assessment of joint effusion, the McMurray test and joint line tenderness indicated little discriminative power for these tests. Only the predictive value of a positive McMurray test was favorable. CONCLUSIONS: The methodologic quality of studies addressing the diagnostic accuracy of meniscal tests was poor, and the results were highly heterogeneous. The poor characteristics indicate that these tests are of little value for clinical practice.
STUDY DESIGN: A systematic review of randomized and double-blind controlled trials was performed. SUMMARY OF BACKGROUND DATA: Nonsteroidal anti-inflammatory drugs are the most frequently prescribed medications worldwide and are widely used for patients with low back pain. OBJECTIVES: To assess the effects of nonsteroidal anti-inflammatory drugs in the treatment of nonspecific low back pain with or without radiation, and to assess which type of nonsteroidal anti-inflammatory drug is most effective. METHODS: For this study, the Cochrane Controlled Trials Register, Medline and Embase, and reference lists of articles were searched. Two reviewers blinded with respect to authors, institution, and journal independently extracted data and assessed the methodologic quality of the studies. If data were considered clinically homogeneous, a meta-analysis was performed. If data were considered clinically heterogeneous, a qualitative analysis was performed using a rating system with four levels of evidence: strong, moderate, limited, and no evidence. RESULTS: This review involved 51 trials and 6057 patients. Of these trials, 16 (31%) were of high quality. The pooled relative risk for global improvement after 1 week was 1.24 (95% confidence interval [CI] = 1.10-1.41), and for additional analgesic use was 1.29 (95% CI = 1.05-1.57), indicating a statistically significant but small effect in favor of nonsteroidal anti-inflammatory drugs as compared with a placebo. The results of the qualitative analysis showed that there is conflicting evidence (Level 3) that nonsteroidal anti-inflammatory drugs are more effective than paracetamol for acute low back pain, and that there is moderate evidence (Level 2) that nonsteroidal anti-inflammatory drugs are not more effective than other drugs for acute low back pain. There is strong evidence (Level 1) that various types of nonsteroidal anti-inflammatory drugs are equally effective for acute low back pain. CONCLUSIONS: The evidence from the 51 trials included in this review suggests that nonsteroidal anti-inflammatory drugs are effective for short-term symptomatic relief in patients with acute low back pain. Furthermore, there does not seem to be a specific type of nonsteroidal anti-inflammatory drug that is clearly more effective than others. Sufficient evidence on chronic low back pain still is lacking.
Knowledge concerning aetiologic hypotheses can be obtained through systematic reviews of observational studies. In observational studies, heterogeneity between studies is expected, because of differences in study design and analysis. Data from observational studies have to be made comparable before pooling of results from component studies is possible. In this, definition of exposure and disease and adjustment for confounding have to be taken into account. Three methods to deal with heterogeneity are presented: ignoring (fixed effects model), modelling (random effects model) and exploring (meta regression). Any combination of data in meta-analysis of observational studies has to be based on statistical, methodological and clinical considerations. The same considerations are applied for the choice which method is used.
Optimal search strategies for the identification of publications on aetiological research are currently not available. The definition of adequate selection criteria is necessary to limit the harvest to a relevant and homogeneous set of publications. Yet, the harvest should be high in order to prevent many relevant papers being missed. The methodological assessment of aetiological research should be aimed at the estimation of the presence of selection bias, information bias, and confounding. Important items of the methodological assessment are independent and standardised assessment of exposure and outcome, high response rate, no selective dropout, and adjustment for confounding in the analysis.
BACKGROUND: Non-steroidal anti-inflammatory drugs (NSAIDs) are the most frequently prescribed medications worldwide and are widely used for patients with low back pain. OBJECTIVES: The objective of this systematic review was to assess the effects of NSAIDs in the treatment of non-specific low back pain and to assess which type of NSAID is most effective. SEARCH STRATEGY: We searched the Medline and Embase databases and the Cochrane Controlled Trials Register (CCTR) up to and including September 1998 if reported in English, Dutch or German. We also screened references given in relevant reviews and identified trials. SELECTION CRITERIA: Randomised trials and double-blind controlled trials of NSAIDs in non-specific low back pain with or without radiation were included. DATA COLLECTION AND ANALYSIS: Two reviewers blinded with respect to authors, institution and journal independently extracted data and assessed methodological quality. A methodological quality score was applied, and studies meeting at least six of 11 specified criteria were considered high quality studies. If data were considered clinically homogeneous, a meta-analysis was performed using a fixed effects model for statistically homogeneous subgroups and a random effects model for statistically heterogeneous subgroups. If data were considered clinically heterogeneous, a qualitative analysis was performed using a rating system with four levels of evidence (strong, moderate, limited, no). MAIN RESULTS: A total of 51 trials (total number of patients = 6057) were included in this review, of which 46 were published in English and five in German. Sixteen trials (31%) were of high quality. The pooled Relative Risk for global improvement after one week was 1.24 (95% CI 1.10, 1.41) and for additional analgesic use 1.29 (95% CI 1.05, 1.57), indicating a statistically significant effect in favour of NSAIDs compared to placebo. The results of the qualitative analysis showed that there is conflicting evidence (level 3) that NSAIDs are more effective than paracetamol for acute low back pain, and that there is moderate evidence (level 2) that NSAIDs are not more effective than other drugs for acute low back pain. There is strong evidence (level 1) that various types of NSAIDs are equally effective for acute low back pain. REVIEWER'S CONCLUSIONS: In conclusion, the evidence from the 51 trials included in this review suggests that NSAIDs are effective for short-term symptomatic relief in patients with acute low back pain. Furthermore, there does not seem to be a specific type of NSAID which is clearly more effective than others. Sufficient evidence on chronic low back pain is still lacking.
Explore the source record for details and available documents.
UNLABELLED: Our aim was to provide a meta-analysis of the literature concerning the validation of thoracic impedance cardiography (TIC) and to explain variations in reported results from differences in the studies. One hundred fifty-four studies (164 Fisher's Z-transformed correlation coefficients) comparing measurements of cardiac output or related parameters from TIC and a reference method were analyzed. Papers were classified according to differences in TIC methodology, reference method, and subject characteristics. Pooling using the random-effects method yielded an overall correlation of r = 0.82 (95% confidence interval: 0.80-0.84). ANOVA revealed a significant influence of the reference method and the subject characteristics on the correlation coefficient. In cardiac patients, the correlation was significantly decreased. No influence of the applied TIC methodology was found. CONCLUSION: TIC might be useful for trend analysis of different groups of patients. However, since the reference method was of significant influence, differences between TIC and the reference method are incorrectly attributed to TIC alone.
Meta-analysis comprises the analysis of the data of similar studies gathered in a systematic review. If the results of the studies differ (strongly), this is called heterogeneity. Possible causes of heterogeneity are: a wrong choice of type of measure of treatment effect, differences of methodological quality between studies, or real differences between studies. Heterogeneity between studies can be assessed by thorough examination of the differences between study characteristics in combination with a visual inspection of the degree of overlap of the confidence intervals of the estimates of effect of the different studies. By applying the random effects model for pooling, (non-systematic) heterogeneity between studies can be addressed. In case of heterogeneity between studies, sources of heterogeneity should be explored by means of subgroup analysis according to strict, present criteria. Subgroup analysis should address subgroups of patients within studies.
Meta-analysis comprises the analysis of the data gathered in a systematic review. Meta-analysis can be defined as the combination of pooling results of similar studies into one overall estimate of the effect on the one hand and the exploration of sources of heterogeneity between studies on the other. A general statistical model is available for pooling the estimates of various types of effect parameters. Pooling enables the estimation of the effect of an intervention or exposure as precisely as possible (with narrow confidence intervals) which allows detection of minor effects. The Mantel-Haenszel method is also an excellent method for pooling effect parameters of dichotomous outcomes. Pooling provides an efficient means of summarizing the available knowledge.
The methodological quality of the primary studies included in a systematic review may influence its results and final conclusions. Methodological quality may be defined in various ways. Partially because of this there are many different assessment lists. The most important dimension of quality is internal validity, defined as the confidence that the design, performance and report of a trial prevent or reduce systematic errors (bias) in the outcomes. For only a limited number of internal validity items a relationship with bias has been proven in empirical studies: concealment of randomisation and blinding of patients and outcome assessors. Preferably, quality should be assessed by at least 2 assessors independently. There is no consensus whether assessment should be done blinded for authors, journal, results and conclusions. Internal validity can be incorporated into statistical pooling in various ways: as a selection criterion, to be used as weight or to hierarchically order studies in a presentation. Well-designed comparative studies are needed to provide clearer guidelines for methodological assessment in the future.
Structured searching and selection of studies is an important component of a systematic review. It is recommended to record the various steps in a protocol in advance. The thoroughness of the searching and selection will partially depend on the available resources, like manpower and funds. A search action should be based on an unequivocally formulated research or clinical question, that is operationalized into clear inclusion and exclusion criteria. The actual start of a search strategy is a search in preferably multiple databases like Medline and EMBASE-Excerpta Medica. Additional search actions can be performed in trial registers and printed indexes and by correspondence with experts and hand searching of journals. Storage of the search results in a bibliographic database is recommended. Various methodological problems may play a role in searching and selecting studies for a review: studies may selectively not be published, results are only partially presented in the publication, studies are selectively included in reference lists, and reviewers themselves may make systematic errors in the selection process.