| dc.description.abstract | ÖSSZEFOGLALÁS
A szerzők bemutatják a túléléselemzés alkalmazási területeit, alapvető fogalmait,
módszereit és az eredmények értelmezését. A gyakorlati alkalmazást esettanulmányokkal illusztrálják. Első példájuk egy közegészségügyi alkalmazás, amelyben
az övsömör és a demencia kapcsolatát vizsgálják. Ezt követően a hazai tejelőtehén-állományok paratuberkulózis- (PTBC) szeropozitivitása és a selejtezés
valószínűsége közötti összefüggést tárják fel. Az elemzés szerint a PTBC-pozitív
tehenek átlagosan 160,5 nappal korábban kerülnek selejtezésre, és kétszer akkora
eséllyel esnek ki a termelésből.
SUMMARY
Background: In human studies survival analysis is already an established method.
Veterinary medicine should follow the trend and take advantage of the time-to-event data from digital individual records.
Objectives: In this study the basic concepts, methods and the application areas
of survival analysis, as well as the interpretation of its results, are presented. The
use of survival analysis techniques is illustrated by a public health case study and
an investigation of the relationship between the serological infection status of
paratuberculosis (PTBC) and the probability of culling dairy cows.
Materials and Methods: In the human application, the association between
herpes zoster and dementia was investigated using a Cox model and data from
the entire Danish population. In the veterinary example, the survival functions
for the PTBC-positive and negative strata were estimated using the Kaplan-Meier
method. The risk of culling animals one year after the date of serological PTBC
testing was calculated. The tobit model used in a previous study [1] to estimate
the difference of mean survival time between the ELISA positive and negative
groups was presented and a new marginal tobit model was fitted to the data. The
hazard ratio of the two groups was estimated using a Cox model.
Results and Discussion: In the human epidemiological study, a positive association between herpes zoster and subsequent dementia was found only in
patients with central nervous system involvement. In the veterinary application,
PTBC-seropositive cows are culled 160.5 days earlier and are twice as likely to be
out of production than negative animals. These results are consistent with previous research findings and highlight the need for PTBC screening and control. | en_US |
