Dear all,
1. On Wednesday 6th April, the RSS Leeds/Bradford local group will be
hosting a series of talks on "design of clinical trials".
The meeting will be held at Leeds University School of Mathematics on
Level 8, Mathematics Active Learning Lab (MALL), starting at 2pm, with
refreshments from 1.30pm in the level 9 foyer of the School of Mathematics.
2. On Thursday 19th May, the RSS Leeds/Bradford local group will be
hosting two talks on "body shapes, body clocks and athletic performance".
The meeting will be held at Leeds Metropolitan University Carnegie
Pavilion, room CPV335, starting at 3pm with refreshments from 2.30pm.
Further details of both events can be found on our webpage:
http://tinyurl.com/rss-lba
==================================================================
Dr. Paul D. Baxter
Secretary/Treasurer, RSS Leeds/Bradford Local Group,
Division of Biostatistics, University of Leeds, Leeds, LS2 9JT, UK.
-------------------------------------------------------------------
Leeds/Bradford: Wednesday 6 April, 2.00pm, University of Leeds.
Design of clinical trials
Clare Relton (University of Sheffield)
Rethinking pragmatic clinical randomised controlled trial design
The implementation and interpretation of both pragmatic and explanatory
randomised controlled trials are associated with significant problems in
the area of recruitment, patient preferences, ethics and treatment
comparisons. This talk will describe a trial design that helps address
these problems - the "cohort multiple randomised controlled trial"
(cmRCT). The cmRCT design has several innovative features: a large
observational cohort of patients is recruited and used as a multiple
trials facility; each randomised controlled trial uses random selection
of some participants (not random allocation of all); and "patient
centred" information and consent is applied. I will discuss where the
cmRCT design is best suited to, as well as address some of the analysis,
implementation, and ethical questions related to the cmRCT design.
Several examples of trials currently using this design will be provided.
Ivana Holloway (University of Leeds)
Design challenges for cluster randomised trials in stroke rehabilitation
Cluster randomised trials (CRT) are practically and statistically the
preferred design choice for stroke rehabilitation trials, when the
intervention is delivered at service level, due to the contamination
risk if patient-level randomisation is employed. Statistical issues
encountered in the design and implementation of CRTs, illustrated by two
UK trials: Training for Caregivers after Stroke (TRACS) and Longer-term
Stroke Care (LoTS-Care) will be addressed.
Patients are admitted to stroke units following their stroke, so
necessarily cannot all be recruited at one time - the ideal design for a
CRT. Hence, the design must minimise the potential for differential
recruitment between randomised arms.
Sample size calculation in CRTs requires estimation of the intracluster
correlation coefficient (ICC) and cluster size. Maximum power is gained
when cluster size is equal across all clusters. We will discuss methods
employed to minimise cluster imbalance and consequent loss of power. We
will also describe the randomisation method, which allows centres to be
randomised in two waves.
The successful implementation of both TRACS and LoTS-Care trials
demonstrates that large multicentre CRTs in stroke rehabilitation are
feasible, but issues regarding service provision for stroke patients
should be addressed in the trial design.
Helen Marshall (University of Leeds)
Statistical issues in the design and analysis of randomised surgical
trials: a practical example of the possible solutions
Surgical randomised controlled trials have unique design and
implementation issues which in turn bring many problems and issues to
the analysis of such data. This presentation will describe the key
problems encountered and the solutions adopted for the design and
analysis of surgical trials performed at the CTRU.
Alex Szubert (University of Leeds)
Timing of randomisation in clinical trials: a review
Although the timing of a randomisation in a clinical trial should be as
close as logistically feasible to the point at which treatments diverge,
the timing of that point may not be clear. For example, in
haematological oncology there are trials of initial chemotherapy
designed to eradicate or reduce disease followed by maintenance
treatment intended to prolong the period where the disease is in
remission. In some trials, patients are randomised between these initial
chemotherapies then, once they have received chemotherapy, or achieved a
sufficiently good response, they are randomised again between
maintenance treatments. In others, they are randomised at the outset to
receive a whole package, for example either (1) control chemotherapy and
control maintenance treatment or (2) experimental chemotherapy and
experimental maintenance treatment. Trials will be compared and contrasted.
Other considerations with regard to the timing of randomisation will be
outlined:
1. After vs. before baseline investigations;
2. Randomised vs. non-randomised phase II trials and;
3. Run-in periods.
The meeting will be held at Leeds University School of Mathematics on
Level 8, Mathematics Active Learning Lab (MALL), starting at 2pm, with
refreshments from 1.30pm in the level 9 foyer of the School of Mathematics.
-----------------------------------------------------------------------
Leeds/Bradford: Thursday 19 May, 3.00pm, Leeds Metropolitan University.
Body shapes and body clocks in athletic performance
Alan Nevill (University of Wolverhampton)
Predicting the optimal body shape for health and physical performance
Human physique consists of three distinct but interrelated
anthropometric components, 1) body size, 2) body composition and 3)
structure or shape (Slaughter and Christ, 1995). Body size refers to the
physical magnitude of the body and its segments (stature, mass, surface
area, etc). Body composition consists of the amount of various
constituents in the body such as fat, muscle, bone, etc. Body structure
or shape describes the distribution of body parts expressed as ratios,
such as the body mass index (BMI= Mass / Height2), the inverse ponderal
index = (Height/Mass0.333) or the head length-to-body length (exclusive
of head) ratio. The later concept of shape was discussed by Mosimann
(1970), who defined the term shape as the ratio of two body dimensions
measured in the same units that would yield a `dimensionless` ratio
variable reflecting body shape. The curial index (simplistically defined
as the leg height below the knee divided by the leg height above the
knee) is a typical example.
The purpose of this talk is to outline a number of methods that can be
used to predict the optimal human body shape for a variety of health and
physical performance measures.
Greg Atkinson (Liverpool John Moores University)
Keeping athletes in time with their body clocks
Chronobiologists investigate time-dependent changes in physiological
variables. Circadian rhythms refer to variations that recur every 24
hours. Many circadian rhythms at rest are endogenously controlled,
persisting when an individual is isolated from environmental
fluctuations. Experimental studies on performance circadian rhythms need
to be carefully designed to control for serial fatigue effects and to
minimise disturbances in sleep. Observations of rhythmicity in
performance variables are also highly influenced by the degree of
repeatability of the measuring equipment.
The majority of the components of sports performance peak in the early
evening, close to the daily maximum in body temperature. Exceptions are
short-term memory, tasks demanding fine motor control, heart rate-based
tests of physical fitness and prolonged submaximal exercise carried out
in hot conditions which all peak in the morning. Athletes are advised to
schedule their heaviest training session in the evening, since higher
work-rates are selected spontaneously at this time of day. Athletes who
train only in the early morning are unlikely to reverse the evening
superiority of self-selected work-rates fully.
The normal circadian rhythms can be desynchronised following a flight
across multiple time-zones or during shift-work. Although athletes show
all the symptoms of "jet lag" (increased fatigue, disturbed sleep and
circadian rhythms), more research work is needed to identify the effects
of transmeridian travel on the actual performances of elite sports
competitors. Shiftwork interferes with participation in competitive
sport, although there may be greater opportunities for shiftworkers to
train in the hours of daylight for individual sports. Possible
interventions to "treat" these disruptions are bright light or exercise
itself. These and other aspects of the human body clock will be covered
in the lecture with particular emphasis on the time-series analyses that
are employed.
The meeting will be held at Leeds Metropolitan University Carnegie
Pavilion, room CPV335, starting at 3pm with refreshments from 2.30pm.
You may leave the list at any time by sending the command
SIGNOFF allstat
to [log in to unmask], leaving the subject line blank.
|