68 Abstracts

Sample Size Considerations in Chronic Disease Clinical Trials: Number of Patients Versus Follow-up Time M. Bauer , C R e d m o n d , a n d B Bar ton , LJmvcrs~ty ot P;ttsbure, h, lYnnsyh,ama (03) The power and the size ot tests comparing the exponential taflure rates ot two treatments depend on the n u m b e r of observedtaf lures The tollow-up tlme needed to observe the lequlred number of lallures can be shortened by increasing the numbe r ot patients entered on the s tudy Conversely, the num ber ot patients required can be minimized bv Encreasing the duration of follow-up

The NSABP Statistical Unit has developed a computer program [follow tng George and De~,u, ] Chron D~s , 1974] which permits the user to explore mteractivelv the relationships among sample size, tolh)w-up time and power for an}' specmed ,.ah.les ot tt~e failure rates and test size Some of the ethical, practical and statistical issues revolved m balancing sample s~ze versus follow-up time will be discussed Example-, based on data ~lom NSABP Stage 1 and Stage IJ breast cancer clinical trials ',','ill be presented

Comparison of Estimated Patient Accrual and Sample Size from a Ptlot Study and Trial Data Involving Acute Disease N o r m a C. Fox, Ty le r D H a r t w e l l , W K e n n e t h Poole, a n d S u z a n n e M u l h n , Re:catch Triangle Institute, Research Triangle Park, North Carohna (04) Fhe Multlcenter Investigation lor the Limitation ot lntarct Size (MILLS) conducted ,i pilot ,-,tudv during the planning phase of the chnlcal trial to determine the estimated proport ions and n u m b e r of acutely ill patients ot various tvpes These groupings were comphcated ,,ersus uncomphcated patients, 0-."4 hours versus ~ 18 houls trom t.me ot onset to treatment, and myocardial infarction cont~rmed versus not conl~rmed These estimated proportions, and numbers and those trom other patxent groups ot the pilot study are compared to the trial's llrst two year's experience Consequences w~th regard to estimates ot pat,ent accrual anct ,-,an~ph? size tor hypothesis testing are d~scussed

Johnson and Johnson's Live for Life Program Tyle r t t a r t w e l l , Paul Stolley, Phf l ,p [ h s e r c h i a , Joan Dav i e s , a n d John R a s s w e f l e r , Research Triangle Institute, Rc,,earch "l'ru~n,~le Park, North Carohna (05) lh~s paper will describe an ongoing trial to e~aluate Johnson and Johnson's [,lye tot l.tte Program This program Js a health promotion ettort in the workse t tmgdes~gned to encourage employees to to l low htestyles which will result in good health The health habits and htestyle changes that are be,ng studied include reducing smuklng, controlling blood pressure, lowering cholesterol le~,els by diet, tol lowmg a regular exercise program, managing stress, reduc,ng excess weight, and increasing health knowledge

To lnveMigate the elhcao., ot the Live tor Llie Program .i two-year quas~-exper~mental design is being used which in~olves tour Johnson and Johnson plants in New ]ersey which receive the Live tor l,lte Program while live other plants participate as "controls " Data analysis will involve comparisons ot several d~tterent groups on the xarlables ot Mterest including treatment versus control plants tor all employees and volunteers m treatment and control plants Analysis will primarily be tnvo lved w~th comparisons based on changes t rom basehne le~ els

Data Banks and Clinical Trials: From Adversaries to Complementary Tools Se lma C. K u m t z , C y n t h i a ( ; r o s s , a n d Albe r t H e y m a n , ()BFS, NINCDS, NIH. Bethesda, Maryland (06) There currently exists a misconception which attei'f?pts to place randomized contiolled chn~cal trials and data banks as opposing Iorces with the same goals A chnlcal data bank as used in the national pilot Stroke and Traumatic Coma Data Banks ~s a collection ol patient observat ions from multiple hospital centers each containing patients" medical history, description ot the onset ot the d~sease, therapy and outcome recorded throughout the patients chnleal course according to an established set of detlnltlons lhese data are entered, stored and retrieved In a rapid, flexible manner through the use ot a computer system which retains rntormatton on the temporal relationships of data The ,~tudles generated lrom the data banks are ob,,er', atlonal They can either describe disease c¢~ur,.,e or pro', ide association,.., arnc, ng premorbld character-