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Biomedical subjects

Tom Jefferson

Publications and source records attributed to Tom Jefferson.

36 records · Page 2Linked to original sources
PubMed2003

Unintended events following immunization with MMR: a systematic review.

Public debate over the safety of the trivalent measles, mumps and rubella (MMR) vaccine and the drop in vaccination rates in several countries persists despite its almost universal use and accepted effectiveness. We carried out a systematic review to assess the evidence of unintended effects (beneficial or harmful) associated with MMR and the applicability of systematic reviewing methods to the field of safety evaluation. Eligible studies were comparative prospective or retrospective on healthy individuals up to 15 years of age, carried out or published by 2003. We identified 120 articles satisfying our inclusion criteria and included 22. MMR is associated with a lower incidence of upper respiratory tract infections, a higher incidence of irritability, similar incidence of other adverse effects compared to placebo and is likely to be associated with benign thrombocytopenic purpura (TP), parotitis, joint and limb complaints and aseptic meningitis (mumps Urabe strain-containing MMR). Exposure to MMR is unlikely to be associated with Crohn's disease, ulcerative colitis, autism or aseptic meningitis (mumps Jeryl-Lynn strain-containing MMR). The design and reporting of safety outcomes in MMR vaccine studies, both pre- and post-marketing, are largely inadequate. The evidence of adverse events following immunization with MMR cannot be separated from its role in preventing the target diseases.

Bias↗
PubMed2003

Systematic review of the effects of pertussis vaccines in children.

OBJECTIVE: To assess the efficacy and safety of whole-cell and acellular pertussis vaccines administered to children singly or within diphtheria, tetanus and pertussis (DTP) vaccines. DATA SOURCES: We searched the Cochrane Library, MEDLINE, EMBASE, Biological Abstracts and Science Citation Index to December 2001. Specialised websites and bibliographies of retrieved articles and reviews were assessed. Vaccine manufacturers and investigators were contacted for additional data. REVIEW METHODS: We included randomised and cohort studies comparing efficacy and/or safety of pertussis vaccines with placebo, DT, no intervention or each other. RESULTS: We included 52 studies (49 randomised controlled trials (RCTs), 3 cohort studies). All tested whole-cell and acellular vaccines were significantly more effective than placebo against pertussis. Absolute efficacy of whole-cell DTP varied from 37 to 92%. One- and two-component acellular vaccines had lower absolute efficacy (67-70%), than vaccines with >/=3 components (80-84%). Whole-cell vaccines were associated with significantly higher incidences of swelling and induration (odds ratio (OR) 11.67, 95% confidence interval (CI) 8.83-15.44), fever (OR for fever >39 degrees C 3.36, 95% CI 2.06-5.49) and crying for >2h (OR 4.72, 95% CI 2.94-7.59) than placebo or DT. Differences in incidence of hypotonic hyporesponsive episodes (HHE) and convulsions were not statistically significant. Acellular pertussis vaccines did not cause a higher incidence of local signs, fever, convulsions, HHE or prolonged crying than placebo or DT. CONCLUSION: All tested pertussis vaccines were efficacious. Whole-cell vaccines show variable efficacy, making interpretation of direct comparisons unreliable. Acellular vaccines with >/=3 antigenic components showed higher efficacy than one- and two-component vaccines. The adverse event profile of acellular vaccines was similar to that of placebo and considerably better than that of whole-cell vaccines.

Child↗
PubMed2002

The Brighton Collaboration: addressing the need for standardized case definitions of adverse events following immunization (AEFI).

UNLABELLED: To further scientific progress of immunization safety, comparability of data from clinical trials and surveillance systems is essential. Comparability requires the availability of standardized case definitions for adverse events following immunization (AEFI) and guidelines for case determination, recording and data presentation. METHOD: International collaborative working groups, consisting of professional volunteers from developed and developing countries, conduct systematic literature reviews to develop 50-100 AEFI definitions. Case definitions are finalized after a comment period by a reference group consisting of organizations concerned with immunization safety, and will be disseminated via the world-wide-web and other means for free world-wide use. RESULTS: Literature reviews yielded substantial diversity in data collection and presentation. We have developed standardized case definitions together with guidelines for use in clinical trials and surveillance systems. CONCLUSIONS: Diversity in safety methods leads to considerable loss of scientific information. We have built the necessary international network of currently about 300 participants from patient care, public health, scientific, pharmaceutical, regulatory and professional organizations to develop and assess standardized AEFI case definitions and guidelines. Evaluation studies, global implementation, ongoing definition development and a continuously growing network will be essential for the success of the collaboration.

Adverse Drug Reaction Reporting Systems↗
PubMed2002

Effects of editorial peer review: a systematic review.

CONTEXT: Editorial peer review is widely used to select submissions to journals for publication and is presumed to improve their usefulness. Sufficient research on peer review has been published to consider a synthesis of its effects. METHODS: To examine the evidence of the effects of editorial peer-review processes in biomedical journals, we conducted electronic and full-text searches of private and public databases to June 2000 and corresponded with the World Association of Medical Editors, European Association of Science Editors, Council of Science Editors, and researchers in the field to locate comparative studies assessing the effects of any stage of the peer-review process that made some attempt to control for confounding. Nineteen of 135 identified studies fulfilled our criteria. Because of the diversity of study questions, methods, and outcomes, we did not pool results. RESULTS: Nine studies considered the effects of concealing reviewer/author identity. Four studies suggested that concealing reviewer or author identity affected review quality (mostly positively); however, methodological limitations make their findings ambiguous, and other studies' results were either negative or inconclusive. One study suggested that a statistical checklist can improve report quality, but another failed to find an effect of publishing another checklist. One study found no evidence that training referees improves performance and another showed increased interrater reliability; both used open designs, making interpretation difficult. Two studies of how journals communicate with reviewers did not demonstrate any effect on review quality. One study failed to show reviewer bias, but the findings may not be generalizable. One nonrandomized study compared the quality of articles published in peer-reviewed vs other journals. Two studies showed that editorial processes make articles more readable and improve the quality of reporting, but the findings may have limited generalizability to other journals. CONCLUSIONS: Editorial peer review, although widely used, is largely untested and its effects are uncertain.

Peer Review, Research↗
PubMed2002

Measuring the quality of editorial peer review.

CONTEXT: The quality of a process can only be tested against its agreed objectives. Editorial peer-review is widely used, yet there appears to be little agreement about how to measure its effects or processes. METHODS: To identify outcome measures used to assess editorial peer review as performed by biomedical journals, we analyzed studies identified from 2 systematic reviews that measured the effects of editorial peer review on the quality of the output (ie, published articles) or of the process itself (eg, reviewers' comments). RESULTS: Ten studies used a variety of instruments to assess the quality of articles that had undergone peer review. Only 1, nonrandomized study compared the quality of articles published in peer-reviewed and non-peer-reviewed journals. The others measured the effects of variations in the peer-review process or used a before-and-after design to measure the effects of standard peer review on accepted articles. Eighteen studies measured the quality of reviewers' reports under different conditions such as blinding or after training. One study compared the time and cost of different review processes. CONCLUSIONS: Until we have properly defined the objectives of peer-review, it will remain almost impossible to assess or improve its effectiveness. The research needed to understand the broader effects of peer review poses many methodologic problems and would require the cooperation of many parts of the scientific community.

Evaluation Studies as Topic↗
PubMed2002

Quality of systematic reviews of economic evaluations in health care.

CONTEXT: Reviews performed almost a decade ago showed considerable gaps in the quality of reporting and methods applied to economic evaluations of health care interventions. Measures taken by the research community to address the issue included the promulgation of guidelines and the publicizing of good practice in economic evaluation. METHODS: To assess the quality of methods of systematic reviews, economic evaluations in health care, and reporting methods, we conducted full-text searches of private and public databases for the period 1990 through March 2001 and corresponded with researchers active in the field. A total of 102 reports were identified, but only 39 were included. Quality of systematic reviews was assessed by a 6-item checklist. RESULTS: Quality of review methods was reasonable, but more attention needs to be paid to search methods and standardization of evaluation instruments. The reviews found consistent evidence of serious methodological flaws in a significant number of economic evaluations. Lack of clear descriptions of methods, lack of explanation and justification for the framework and approach used, and low-quality estimates of effectiveness for the interventions evaluated were the most frequent flaws. Modest improvements in quality of conducting and reporting economic evaluations appear to have taken place in the last decade. CONCLUSIONS: Proper allocation of resources on the basis of economic evaluations remains uncertain. Editorial teams and regulatory bodies should perform quality assurance based on a single widely accepted and validated standard instrument.

Cost-Benefit Analysis↗
PubMed2002

Hepatitis B vaccination: risk-benefit profile and the role of systematic reviews in the assessment of causality of adverse events following immunisation.

Since the early 1990s, several cases of demyelinating diseases were reported in France in association with the vaccination against hepatitis B. A large scientific, regulatory, and public debate took place to reassure the growing concern of the population. The objective of this paper is to examine the decision process undertaken both in France and in Italy; to outline the main findings of the studies conducted before and after the French decision to suspend the vaccination campaign among adolescents; and to describe the contribution of systematic review and causality criteria in the evaluation of the risk-benefit profile of vaccines. Even on the basis of the early findings, which appeared to be compatible with a low increase in the risk associated with the vaccination, it was apparent that the risk-benefit profile was unchanged for newborns, and was essentially unchanged for adolescents and for high-risk adults. The availability of subsequent negative association studies provided further reassurance. It is essential to rely on well-conducted systematic reviews to produce valid and reliable estimates of the risk-benefit profile.

France↗
PubMed2002

Advances in the Diagnosis and Management of Influenza.

Vaccines are the mainstay of influenza prevention. In the treatment of a likely or certain case of influenza, ion channel inhibitors (amantadine and rimantadine) and neuraminidase inhibitors (oseltamivir and zanamivir) can be effective in reducing the duration of illness in adults. In the absence of a likely or certain influenza diagnosis, ion channel inhibitors or neuramindase inhibitors have lower effectiveness, and symptom relief becomes the rationale for treatment of influenza-like illness. Because both influenza and influenza-like illness are self-limiting, safety of interventions is paramount, especially in children. Echinacea extracts, steam, chicken soup, ipatropium bromide, and oxymetazoline in adults are the interventions that appear to have the best empirical evidence.

Journal Article↗
PubMed2002

1st International Symposium on the Evaluation of Safety of Human Vaccines. 22-23 May 2002, Istituto Superiore di Sanitá, Rome, Italy.

The first international meeting to focus exclusively on vaccine safety, brought together vaccine surveillance specialists, trialists, pharmaceutical companies, regulators, researchers and academics to examine and discuss methodological problems in the assessment of the safety of human vaccines. The 1st International Symposium on the Evaluation of Safety of Human Vaccines took place in Rome, Italy on 22 - 23 May 2002. The Istituto Superiore di Sanitá (ISS), Rome, Italy, sponsored the symposium. The symposium was opened by D Greco (Head of Epidemiology and Biostatistics, ISS and a well-known vaccine trialist) who spoke of the need for the gathering and sharing of information regarding adverse effects of vaccines, as single studies "are not enough" and "have their limitations". Vaccines have come along way since their first use, however, as there is public concern over real or perceived adverse events, collaboration is of great importance as uncertainty about the effectiveness and safety may affect coverage of immunisation programmes.

Congresses as Topic↗