Showing papers on "Publication bias published in 2001"

Systematic reviews in health care: Investigating and dealing with publication and other biases in meta-analysis.

Abstract: This is the second in a series of four articles Studies that show a significant effect of treatment are more likely to be published, be published in English, be cited by other authors, and produce multiple publications than other studies.1–8 Such studies are therefore also more likely to be identified and included in systematic reviews, which may introduce bias.9 Low methodological quality of studies included in a systematic review is another important source of bias.10 All these biases are more likely to affect small studies than large ones. The smaller a study the larger the treatment effect necessary for the results to be significant. The greater investment of time and money in larger studies means that they are more likely to be of high methodological quality and published even if their results are negative. Bias in a systematic review may therefore become evident through an association between the size of the treatment effect and study size—such associations may be examined both graphically and statistically. #### Summary points Asymmetrical funnel plots may indicate publication bias or be due to exaggeration of treatment effects in small studies of low quality Bias is not the only explanation for funnel plot asymmetry; funnel plots should be seen as a means of examining “small study effects” (the tendency for the smaller studies in a meta-analysis to show larger treatment effects) rather than a tool for diagnosing specific types of bias Statistical methods may be used to examine the evidence for bias and to examine the robustness of the conclusions of the meta-analysis in sensitivity analyses “Correction” of treatment effect estimates for bias should be avoided as such corrections may depend heavily on the assumptions made Multivariable models may be used, with caution, to examine the relative importance of different types of bias ### Funnel plots Funnel …

A comparison of methods to detect publication bias in meta-analysis.

Abstract: Meta-analyses are subject to bias for many of reasons, including publication bias. Asymmetry in a funnel plot of study size against treatment effect is often used to identify such bias. We compare the performance of three simple methods of testing for bias: the rank correlation method; a simple linear regression of the standardized estimate of treatment effect on the precision of the estimate; and a regression of the treatment effect on sample size. The tests are applied to simulated meta-analyses in the presence and absence of publication bias. Both one-sided and two-sided censoring of studies based on statistical significance was used. The results indicate that none of the tests performs consistently well. Test performance varied with the magnitude of the true treatment effect, distribution of study size and whether a one- or two-tailed significance test was employed. Overall, the power of the tests was low when the number of studies per meta-analysis was close to that often observed in practice. Tests that showed the highest power also had type I error rates higher than the nominal level. Based on the empirical type I error rates, a regression of treatment effect on sample size, weighted by the inverse of the variance of the logit of the pooled proportion (using the marginal total) is the preferred method.

Multinational Companies and Productivity Spillovers: A Meta‐Analysis

Abstract: This paper presents a meta-analysis of the literature on multinational companies and productivity spillovers. By collecting information from a sample of published and unpublished papers on the impact of multinational presence on domestic productivity, we investigate whether certain aspects of the study design affect the results, and whether there is publication bias in the literature. Our findings show that some aspects of the empirical methods used, namely, how the presence of multinationals is defined, and whether cross-section or panel analysis is employed, may have an effect on the results. We also discover some evidence that there may be publication bias.

Meta-analysis of the association between the 7-repeat allele of the dopamine D (4) receptor gene and attention deficit hyperactivity disorder

Abstract: OBJECTIVE: Family, twin, and adoption studies show attention deficit hyperactivity disorder (ADHD) to have a substantial genetic component. Although several studies have shown an association between ADHD and the 7-repeat allele of the dopamine D4 receptor gene (DRD4), several studies have not. Thus, the status of the ADHD-DRD4 association is uncertain. METHOD: Meta-analysis was applied to case-control and family-based studies of the association between ADHD and DRD4 to assess the joint evidence for the association, the influence of individual studies, and evidence for publication bias. RESULTS: For both the case-control and family-based studies, the authors found 1) support for the association between ADHD and DRD4, 2) no evidence that this association was accounted for by any one study, and 3) no evidence for publication bias. CONCLUSIONS: Although the association between ADHD and DRD4 is small, these results suggest that it is real. Further studies are needed to clarify what variant of DRD4 (or some nea...

How efficacious and safe is short-acting methylphenidate for the treatment of attention-deficit disorder in children and adolescents? A meta-analysis

Abstract: Background: Numerous small clinical trials have been carried out to study the behaviourally defined efficacy and safety of short-acting methylphenidate compared with placebo for attention-deficit disorder (ADD) in individuals aged 18 years and less. However, no meta-analyses that carefully examined these questions have been done. We reviewed the behavioural evidence from all the randomized controlled trials that compared methylphenidate and placebo, and completed a meta-analysis. Methods: We searched several electronic sources for articles published between 1981 and 1999: MEDLINE, EMBASE, PsychINFO, ERIC, CINAHL, HEALTHSTAR, Biological Abstracts, Current Contents and Dissertation Abstracts. The Cochrane Library Trials Registry and Current Controlled Trials were also consulted. A study was considered eligible for inclusion if it entailed the following: a placebo- controlled randomized trial that involved short-acting methylphenidate and participants aged 18 years or less at the start of the trial who had received any primary diagnosis of ADD that was made in a systematic and reproducible way. Results: We included 62 randomized trials that involved a total of 2897 participants with a primary diagnosis of ADD (e.g., with or without hyperactivity). The median age of trial participants was 8.7 years, and the median “percent male” composition of trials was 88.1%. Most studies used a crossover design. Using the scores from 2 separate indices, this collection of trials exhibited low quality. Interventions lasted, on average, 3 weeks, with no trial lasting longer than 28 weeks. Each primary outcome (hyperactivity index) demonstrated a significant effect of methylphenidate (effect size reported by teacher 0.78, 95% confidence interval [CI] 0.64–0.91; effect size reported by parent 0.54, 95% CI 0.40–0.67). However, these apparent beneficial effects are tempered by a strong indication of publication bias and the lack of robustness of the findings, especially those involving core ADD features. Methylphenidate also has an adverse event profile that requires consideration. For example, clinicians only need to treat 4 children to identify an episode of decreased appetite. Interpretation: Short-acting methylphenidate has a statistically significant clinical effect in the short-term treatment of individuals with a diagnosis of ADD aged 18 years and less. However, the extension of this placebo-controlled effect beyond 4 weeks of treatment has not been demonstrated. Exact knowledge of the extent and definition of the short-term behavioural usefulness of methylphenidate is questioned.

Testing and adjusting for publication bias

Abstract: How can the scientific literature provide unbiased conclusions if it represents a biased sample of available studies? Publication bias refers to phenomena arising from bias in submitting, reviewing, accepting and publishing scientific results. Direct and indirect methods for investigating publication bias are now readily available, but indirect methods are generally open to alternative interpretations. Publication bias distorts attempts to review a scientific field quantitatively if the likelihood of locating completed studies depends on the strength or direction of the findings of quantitative studies. It is the responsibility of researchers, reviewers and editors to address issues of bias to ensure the existence of an unbiased literature.

Levels of Evidence

Abstract: Level 1 Evidence Level 1 evidence can come in one of 2 forms: a randomized clinical trial, which is associated with low study errors (low P value, confidence interval which excludes 1, or a ‘‘negative’’ result associated with a power of over 80%), or a meta-analysis. A meta-analysis refers to a study that statistically synthesizes the results of numerous ‘‘underpowered’’ randomized clinical trials and increases the confidence in an overall summary result. Unfortunately, limitations of meta-analyses include heterogeneity and publication bias. The Optic Neuritis Treatment Trial is an example of a randomized clinical trial which contains level 1 evidence.

Uses and abuses of meta-analysis.

Abstract: Meta-analysis, the statistical combi- nation of results from several studies to produce a single estimate of the effect of a treatment, continues to attract controversy. We illustrate the potentials and pitfalls of meta-analysis of controlled clinical trials. Cumulative meta-analysis demonstrates that this technique could prevent delays in the introduction of effective treatments. Meta-analyses are, however, liable to numerous biases both at the level of the individual trial (' garbage in, garbage out') and the dissemination of trial results (publication bias). We argue that meta-analysis should be performed only within the framework of systematic reviews - that is, reviews prepared using a systematic approach to minimise bias and address the combinability of studies.

A sensitivity analysis for publication bias in systematic reviews.

Abstract: There is no simple method of correcting for publication bias in systematic reviews. We suggest a sensitivity analysis in which different patterns of selection bias can be tested against the fit to the funnel plot. Publication bias leads to lower values, and greater uncertainty, in treatment effect estimates. Two examples are discussed. An appendix lists the S-plus code needed for carrying out the analysis.

The association between funding by commercial interests and study outcome in randomized controlled drug trials

Abstract: Methods. Randomized controlled drug trials (n = 314) published in five general interest medical journals over a 2-year period were reviewed. Study outcome was classified as positive or negative. Support was classified as pharmaceutical industry or non-industry. Association between source of support and outcome was tested with the chi-squared statistic. Results. Positive findings were found in 77% of studies, negative findings in 20% and an uncertain outcome in 3%. Support from commercial sources was found in 68% of trials. Negative findings were found in 13% of industry-supported studies and in 35% of non-industry-supported studies (chi-squared = 18.36, P , 0.0001, odds ratio = 3.54, 95% confidence interval 1.90‐6.62). Conclusions. An association was found between the source of study support and the published outcome. Though the reason for this association cannot be determined from the data collected, future studies may clarify the importance of this finding for readers concerned with the relationship of funding bodies to the publication of research outcomes.

Meta-analysis of HIV risk-reduction interventions within drug abuse treatment programs.

Abstract: A meta-analysis was conducted on studies using a treatment-comparison group design to evaluate HIV/AIDS risk-reduction interventions for clients enrolled in drug abuse treatment programs. Overall the interventions studied were found to have a reliable positive (weighted) effect size (d = 0.31) and this was unlikely to be due to publication bias. Effect sizes for specific categories of outcome variables were 0.31 for knowledge attitudes and beliefs; 0.26 for sexual behavior; 0.62 for risk-reduction skills; and 0.04 for injection practices. A number of potential moderators were examined. Effect sizes were negatively correlated with the presence of predominantly ethnic minority samples and positively correlated with the number of intervention techniques used the intensity of the intervention intervention delivery at a later stage of drug treatment or within methadone treatment and the presence of a number of specific intervention techniques. (authors)

Physiotherapy for patients with Parkinson's Disease: a comparison of techniques.

Abstract: BACKGROUND: Despite optimal medical and surgical therapies for Parkinson's disease, patients develop progressive disability. The role of the physiotherapist is to maximise functional ability and minimise secondary complications through movement rehabilitation within a context of education and support for the whole person. OBJECTIVES: To compare the efficacy and effectiveness of physiotherapy with placebo or no interventions in patients with Parkinson's disease. SEARCH STRATEGY: Relevant trials were identified by electronic searches of MEDLINE, EMBASE, CINAHL, ISI-SCI, AMED, MANTIS, REHABDATA, REHADAT, GEROLIT, Pascal, LILACS, MedCarib, JICST-EPlus, AIM, IMEMR, SIGLE, ISI-ISTP, DISSABS, Conference Papers Index, Aslib Index to Theses, the Cochrane Controlled Trials Register, the CentreWatch Clinical Trials listing service, the metaRegister of Controlled Trials, ClinicalTrials.gov, CRISP, PEDro, NIDRR and NRR; and examination of the reference lists of identified studies and other reviews. SELECTION CRITERIA: Only randomised controlled trials (RCT) were included, however those trials that allowed quasi-random methods of allocation were allowed. DATA COLLECTION AND ANALYSIS: Data was abstracted independently by KD and DJ and differences settled by discussion. MAIN RESULTS: Eleven trials were identified with 280 patients. Eight trials did not have adequate placebo treatments, all used small numbers of patients and the method of randomisation and concealment of allocation was good in only four trials. These methodological problems could potentially lead to bias from a number of sources. Although ten of the trials claimed a positive effect from physiotherapy, few outcomes measured were statistically significant. Walking velocity was measured in four trials and increased significantly in two of them. Stride length was the only other outcome measured in more than one trial, it was significantly improved in two trials. Five other outcomes improved significantly in individual studies, but eight other outcomes did not improve significantly. REVIEWER'S CONCLUSIONS: Considering the methodological flaws in many of the studies, the small number of patients examined, and the possibility of publication bias, there is insufficient evidence to support or refute the efficacy of physiotherapy in Parkinson's disease. The studies illustrate that a wide range of approaches are being employed by physiotherapists to treat Parkinson's disease. This was confirmed by the UK survey of physiotherapists. There is a need to develop a consensus as to 'best-practice'. Large well designed placebo-controlled RCTs are then needed to demonstrate the efficacy and effectiveness of 'best practice' physiotherapy in Parkinson's disease. The stage of the disease at which the physiotherapy is given should be specified at the outset. Outcome measures with particular relevance to patients, carers, physiotherapists and physicians should be chosen and the patients monitored for at least six months to determine the duration of any beneficial effects. The trials should be reported according to CONSORT guidelines.

Testing for Publication Bias in Political Science

Abstract: If the publication decisions of journals are a function of the statistical significance of research findings, the published literature may suffer from “publication bias.” This paper describes a method for detecting publication bias. We point out that to achieve statistical significance, the effect size must be larger in small samples. If publications tend to be biased against statistically insignificant results, we should observe that the effect size diminishes as sample sizes increase. This proposition is tested and confirmed using the experimental literature on voter mobilization.

Meta‐analyses in systematic reviews of randomized controlled trials in perinatal medicine: comparison of fixed and random effects models

Abstract: There is a need for empirical work comparing the random effects model with the fixed effects model in the calculation of a pooled relative risk in the meta-analysis in systematic reviews of randomized controlled trials. Such comparisons are particularly important when trial results are heterogeneous. We considered 84 independent meta-analyses in which each trial included a set of different women/newborns. These meta-analyses were included in systematic reviews published in the Cochrane Library's pregnancy and childbirth module. Twenty-one of these 84 meta-analyses demonstrated statistical heterogeneity at p<0.10. The random effects model estimates showed wider confidence intervals, particularly in those meta-analyses showing heterogeneity in the trial results. The summary relative risk for the random effects model tended to show a larger protective treatment effect than the fixed effects model in the heterogeneous meta-analyses. In this set of meta-analyses, statistical evaluation of publication bias cannot be shown to account for heterogeneity. Our empirical conclusion is that there may be opposing effects if the random effects model is used in the meta-analysis of clinical trials showing heterogeneity in the results: stronger treatment effects reflected in the summary relative risk, but wider confidence intervals about this summary measure.

Are antidepressants overrated? A review of methodological problems in antidepressant trials.

Abstract: There are no signs that the rapidly escalating use of antidepressants is reducing the burden of depressive disorders. This may be due to the fact that the evidence base for antidepressants is weaker than is commonly assumed. There are a number of methodological problems that may bias the results of clinical trials. Unblinding may inflate the response of people taking an active drug when compared with those taking an inert placebo. Modern measurement techniques may exaggerate the benefit of drug treatment. Excluding some randomized subjects from analysis may inflate the apparent effect of antidepressant drugs and publication bias means that published studies may not represent an accurate picture of the effects of treatment. In trials of long-term treatment discontinuation-related effects may masquerade as clinical efficacy. A brief survey of evidence from controlled trials does not present a consistently positive picture. Two of the largest and most reputable trials found only negligible differences between tricyclic antidepressants and placebo. The evidence on whether antidepressants are specific treatments is also inconclusive. Many other drugs not classed as antidepressants have shown positive effects in depression in controlled clinical trials. It is suggested that the interests of the pharmaceutical industry and the psychiatric profession have helped to establish the notion of the efficacy and specificity of antidepressant drugs.

Is there a "best" way to detect and minimize publication bias? An empirical evaluation.

Abstract: Using 14 meta-analyses that included both published (n = 199) and unpublished (n = 50) randomized trials, we evaluated the utility of different analytical approaches to detect, assess robustness, a

Residential EMF exposure and childhood leukemia: meta-analysis and population attributable risk.

Abstract: The controversy over the possible association between magnetic field exposure and childhood leukemia has led several researchers to summarize the literature using meta-analysis. This paper reviews these previous meta-analyses and extends them by adding results from four studies published since the most recent analysis. The analyses include odds ratio calculations based on both dichotomous and continuous exposure models, heterogeneity analysis including subgroup summaries and meta-regression, "leave one out" influence analyses, and publication bias assessments. In addition, there is a review of some of the considerations of the exposure assessments used in the studies and their implications for cross-study comparisons. Finally, the results of the analyses using dichotomous and continuous exposure model are combined with national exposure data to estimate the population attributable risk of childhood leukemia among children in the US. If an association exists, as many as 175-240 cases of childhood leukemia in the US may be due to magnetic field exposure.

Is body mass index the prognostic factor in breast cancer?: a meta-analysis.

Abstract: This study was performed to integrate the results of previous studies that investigated the relationship between body mass index (BMI) and prognosis in breast cancer. We reviewed the English literatures using the MEDLINE database from 1966 to 1999. The materials included 12 published articles with a total of 8,029 cases of breast cancer. The effect size was obtained from hazard ratio in each study. Homogeneity test was conducted before the integration of each effect size and the result demonstrated that the studies were heterogeneous. A random effect model was used to integrate the overall effect size. The integrated effect size was 1.56 (95% confidence interval, 1.22-2.00). In addition, publication bias should be accounted for because each published study was asymmetric in shape revealed by funnel plot. These results suggest that BMI have a prognostic significance in breast cancer. We believe that well-designed longitudinal studies, involving a large number of samples are required to resolve these issues.

Hepatitis A in workers exposed to sewage: a systematic review

Abstract: OBJECTIVES—To assess whether the scientific literature supports the hypothesis that workers exposed to sewage are at higher risk of hepatitis A (HA). METHODS—All original papers reporting epidemiological studies published in English, French, or German which reported on the risk of HA infection in workers exposed to sewage were eligible. They were identified by several methods and each original paper was assessed independently with a checklist by two people. Studies were classified according to the strength of their design. Non-eligible studies were also examined to assess the impact of publication bias. If the risk estimates diverged widely, causes for heterogeneity were assessed. A distinction was made between seroprevalence studies based on subclinical HA (defined only by the presence of anti-HA antibodies) and clinical HA. RESULTS—17 eligible studies were identified. No indication of an increased risk of clinical HA could be found. For seroprevalence the studies with the strongest design suggested a slightly increased risk of subclinical HA with an odds ratio (OR) <2.5. Heterogeneity was considerable and precluded a meta-analysis. Considering non-eligible studies would still decrease the OR. CONCLUSIONS—The systematic review does not confirm an increased risk of clinical HA in workers exposed to sewage. An increased risk of subclinical HA cannot be excluded but the association between seropositivity and exposure to sewage was not strong and became still weaker if publication bias was taken into account. Keywords: hepatitis A; sewage; systematic review

Multinational companies and productivity

Abstract: This paper presents a meta-analysis of the literature on multinational companies and productivity spillovers. By collecting information from a sample of published and unpublished papers on the impact of multinational presence on domestic productivity, we investigate whether certain aspects of the study design affect the results, and whether there is publication bias in the literature. Our findings show that some aspects of the empirical methods used, namely, how the presence of multinationals is defined, and whether cross-section or panel analysis is employed, may have an effect on the results. We also discover some evidence that there may be publication bias. The increasing importance of multinational companies (MNCs) and asso

Publication bias in presentations to the Annual Scientific Congress.

Abstract: Background: Free papers presented to the Annual Scientific Congress (ASC) of the Royal Australasian College of Surgeons (RACS) were reviewed for the years 1994, 1995 and 1996. Reports were examined for evidence of publication bias. Methods: Suitable free papers were identified from the proceedings of the meetings and authors were contacted to obtain information about the research reported and any publications resulting from it. Results: Responses were obtained from 302 of 576 presentations considered suitable. A total of 55% of responding authors reported publication of their paper. Basic science papers were most likely to be published. There was a significant bias in favour of publication of positive results (98 of 139 positive vs 76 of 159 inconclusive or negative reports; P < 0.01). Retrospective data were as likely to be published as prospective (51% and 57%, respectively). Reports describing studies of high-level evidence were more likely to be published in journals with a high impact factor. Conclusion: The ASC is a comprehensive meeting that attracts a wide range of free papers from most sections of the RACS. There appears to be no evidence of bias in selection of papers for inclusion in the meeting but there is bias in the subsequent publication, which favours positive reports.

Control of bias in randomized controlled trials published in prosthodontic journals

Abstract: Statement of Problem. Randomized controlled trials (RCTs) have become the gold standard for evaluating the effectiveness of treatment interventions. If not properly controlled, bias in the design of trial methodology can affect the validity of the study results. Purpose. The purpose of this investigation was to assess the methodological quality of RCTs published in 3 prosthodontic journals over a 10-year period. Material and Methods. Issues of The International Journal of Prosthodontics, The Journal of Prosthetic Dentistry, and The Journal of Prosthodontics published between 1988 and 1997 were searched manually to identify RCTs. Specific inclusion and exclusion criteria were established to identify articles about studies that qualified as RCTs. Two independent reviewers evaluated all qualified RCTs on the basis of how potential sources of bias in the trial methodology were controlled. Three areas—control of bias at entry, control of bias in assessment of outcome, and control of bias after entry—were evaluated with a scheme developed through the Cochrane Collaboration. A score of 1 or 0 was assigned for each of the 3 potential sources of bias, with the maximum quality score for an RCT being 3 (good bias control) and the minimum 0 (poor control). Frequencies were calculated for each dimension of trial methodology and overall quality scores of the RCTs. Results. Sixty-two RCTs were identified from 3631 articles screened. The method of randomization was explicit in only 47% of the RCTs. Forty percent of RCTs incorporated blinding in the assessment of outcome, and 76% accounted for all subjects at the end of the study. Overall quality scores revealed that only 16% of RCTs attempted to control bias in all 3 areas examined. Forty percent were deficient in 1 area, 34% were deficient in 2 areas, and 10% were deficient in all areas examined. Conclusion. The quality of RCTs published in prosthodontic journals may be improved by minimizing potential sources of bias and adequately reporting trial methodology. (J Prosthet Dent 2001;86:592-6.)

The powerful placebo: doubting the doubters

Abstract: Amanzio M, Pollo A, Maggi G, Benedetti F 2001 Response variability to analgesics: A role for nonspecific activation of endogenous opioids. Pain 90:205–215 De Craen AJ, Roos PJ, de Vries AL, Kleijnen J 1996 Effect of color of drugs: Systematic review of perceived effect of drugs and of their effectiveness. British Medical Journal 313:1624–1626 Hróbjartsson A, Gøtzsche PC 2001 Is the placebo powerless? An analysis of clinical trials comparing placebo with no treatment. New England Journal of Medicine 344:1595–1602 Kleijnen J, de Craen AJ, van Everdingen J, Krol L 1994 Placebo effect in double–blind clinical trial: A review of interactions with medications. The Lancet 344: 1347–1349

Bias in alternative medicine is still rife but is diminishing.

Abstract: EDITOR—In 1995, journals of alternative medicine published virtually no studies with negative results, which suggests that the literature was far from objective.1 To determine whether the situation has changed we analysed last year's volumes of three journals originally evaluated and compared our results with those …

Occupational therapy for Parkinson's disease

Abstract: Background Despite drug and surgical therapies for Parkinson's disease, patients develop progressive disability. The role of the occupational therapist is to support the patient and help them maintain their usual level of self-care, work and leisure activities for as long as possible. When it is no longer possible to maintain their usual activities, occupational therapists support individuals in changing and adapting their relationship with their physical and social environment to develop new valued activities and roles. Objectives To compare the efficacy and effectiveness of occupational therapy with placebo or no interventions (control group) in patients with Parkinson's disease. Search strategy Relevant trials were identified by electronic searches of MEDLINE, EMBASE, CINAHL, ISI-SCI, AMED, MANTIS, REHABDATA, REHADAT, GEROLIT, Pascal, LILACS, MedCarib, JICST-EPlus, AIM, IMEMR, SIGLE, ISI-ISTP, DISSABS, Conference Papers Index, Aslib Index to Theses, the Cochrane Controlled Trials Register, the CentreWatch Clinical Trials listing service, the metaRegister of Controlled Trials, ClinicalTrials.gov, CRISP, PEDro, NIDRR and NRR; and the reference lists of identified studies and other reviews were examined. Selection criteria Only randomised controlled trials (RCT) were included, however those trials that allowed quasi-random methods of allocation were allowed. Data collection and analysis Data was abstracted independently by two authors and differences were settled by discussion. Main results Two trials were identified with 84 patients in total. Although both trials reported a positive effect from occupational therapy, all of the improvements were small. The trials did not have adequate placebo treatments, used small numbers of patients and the method of randomisation and concealment of allocation was not specified in one trial. These methodological problems could potentially lead to bias from a number of sources reducing the strength of the studies further. Authors' conclusions Considering the significant methodological flaws in the studies, the small number of patients examined, and the possibility of publication bias, there is insufficient evidence to support or refute the efficacy of occupational therapy in Parkinson's disease. There does not appear to be a consensus as to the best practice in occupational therapy when treating people with Parkinson's disease. A survey of therapists is needed to determine what methods of occupational therapy are currently being used by therapists to treat Parkinson's disease, and whether there is a consensus as to 'best-practice'. Large well designed placebo-controlled RCTs are needed to demonstrate occupational therapy's effectiveness in Parkinson's disease. Outcome measures with particular relevance to patients, carers, occupational therapists and physicians should be chosen and the patients monitored for at least six months to determine the duration of benefit. The trials should be reported using CONSORT guidelines.

Maintaining the integrity of the clinical evidence base

Abstract: During the last decade at least 15 antiretroviral drugs have come onto the market bringing longer life and vastly improved quality of life to AIDS patients. Continued progress depends critically on the quality of clinical trials. It is noted that clinical trials form the basis of effective research and development but its reliability is threatened by the following flaws: 1) conflict of interest among investigators; 2) inappropriate involvement of research sponsors in their design and management; and 3) publication bias in dissemination of results. In this perspective several measures to maintain the integrity of the clinical evidence base are proposed. This includes the proposition that university-based investigators and researcher staff should be prohibited from holding stocks stock options or decision-making positions in a company that may be affected by the results of their clinical research. Furthermore it is suggested that a declaration on the rights and obligations of clinical investigators and the proper management of clinical trials evidence base is appropriate.