Contracts between the hospital and the sponsor of the trial are complex and often take considerable time to negotiate.
Recruitment to trials is complex and often protracted; selection bias may compromise generalisability.
Measuring BMD in large, randomized trials is complex, as many sites do not have access to appropriate radiological facilities.
Assessment of the role of the funding source in drug trials is complex because of the variety of levels of involvement reported, ranging from financial support and donation of study medication by a pharmaceutical company, to input of the manufacturer in the trial design, conduct, data analysis and publication of results.
The business of performing clinical trials is complex - and perhaps never more so than when a potent mix of immunosuppressive drugs is supplemented with a far more specific biologic, in the hope of getting better disease control in patients with hard-to-treat autoimmune conditions.
It should be acknowledged that motivation to enrol in trials is complex and may include altruism, desire for improvement of one's own health, out of a sense of obligation to the doctor and the expectation of increasing scientific knowledge (Hussain-Gambles et al, 2004).
While monkey trials are quick and vicious — give the drug, zap the caged animals with virus, wait a bit, and dissect a few — ethical human trials are complex.
However, the statistical issues involved in the design, conduct, analysis and interpretation of equivalence and non-inferiority trials are complex and subtle, and require that all aspects of these trials be given careful consideration.
Also, analyses of cluster randomised trials are complex.
