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Biomedical subjects

I Chalmers

Publications and source records attributed to I Chalmers.

At least 19 recordsLinked to original sources
PubMed2001

Involving consumers in designing, conducting, and interpreting randomised controlled trials: questionnaire survey.

OBJECTIVE: To assess the extent to which consumers are involved in the work of clinical trial coordinating centres in the United Kingdom and the nature of consumers' involvement in randomised trials coordinated by these centres. DESIGN: National surveys using structured questionnaires with some open ended sections. SETTING: 103 clinical trial coordinating centres in the United Kingdom identified through a database assembled in 1997 by the NHS clinical trials adviser. PARTICIPANTS: Named contacts at 62 coordinating centres and investigators in 60 trials that were identified as involving consumers. MAIN OUTCOME MEASURES: Number of coordinating centres and number of trials in which consumers were involved and the nature of consumers' involvement. RESULTS: Of the 62 eligible centres, 23 reported that consumers had already been involved in their work, and most respondents were positive about this involvement. 17 centres planned to involve consumers. 15 centres had no plans to involve consumers, but only four of these considered such involvement irrelevant. Responses from investigators about the 48 individual trials were mostly positive, with respondents commenting that input from consumers had helped refine research questions, improve the quality of patient information, and make the trial more relevant to the needs of patients. CONCLUSIONS: Consumer involvement in the design and conduct of controlled trials seems to be growing and seems to be welcomed by most researchers. Such involvement seems likely to improve the relevance to consumers of the questions addressed and the results obtained in controlled trials.

Humans↗
PubMed2001

Comparing like with like: some historical milestones in the evolution of methods to create unbiased comparison groups in therapeutic experiments.

Histories of clinical trials have recorded and analysed the development of quantification in therapeutic evaluation, the emergence of probabilistic thinking, the application of statistical methods and theory, and the sociology, ethics and politics of clinical trials; but it is surprising that they only rarely identify as a distinct theme the development of efforts to control biases. An exception is Kaptchuk's recent account of the history of blinding and placebos for reducing observer biases. In this complementary paper I introduce and discuss some milestones between 1662 and 1948 in the development of methods to control selection biases when assembling therapeutic comparison groups, to ensure, as far as possible, that 'like is compared with like'. In the paper I note (i) that treatment allocation based on strict alternation abolishes selection bias as effectively as treatment allocation based on strict random allocation; (ii) that use of schedules based on random numbers is more likely to prevent foreknowledge of allocation schedules, and thus the risk of introducing selection bias at the point of recruitment to trials; (iii) that a concern to conceal allocation schedules was the rationale for using schedules based on random numbers in the Medical Research Council trials of vaccination for whooping cough and streptomycin for pulmonary tuberculosis; and (iv) that the introduction of allocation concealment more than half a century ago remains the most recent substantive milestone in the history of efforts to control selection biases in therapeutic experiments.

Epidemiologic Methods↗
PubMed1999

Ultraviolet radiation-blocking characteristics of contact lenses: relevance to eye protection for psoralen-sensitised patients.

Nine brands of contact lens marketed as "UV protective" were tested for ultraviolet (UV) transmission in order to assess potential suitability for psoralen-sensitised patients. UV-transmission characteristics of hydrated lenses was tested with a Bentham monochromator spectro-radiometer system. All lenses showed minimal transmission loss in the visible band. The performance of the nine lenses was uniform for ultraviolet B radiation with negligible transmission, but showed variation in transmission for ultraviolet A radiation. None of the lenses complied with UV-transmission criteria used previously to assess UV-blocking spectacles. Only two lenses had UV-blocking characteristics which came close to the arbitrary criteria used. The performance of ordinary soft and hard lenses was very similar, with negligible blocking of UV radiation. None of the nine contact lenses marketed as "UV protective" excluded sufficient UVA to comply with criteria in current use to assess UV protection in spectacles for psoralen-sensitised patients. However, the improved UV-blocking characteristics of contact lenses identified in this paper compared to previous studies suggests that such a contact lens will soon become available. Meanwhile, contact lens-wearing systemically sensitised PUVA patients should continue to wear approved spectacles for eye protection whilst photosensitised with psoralen.

Contact Lenses↗