Characteristics of infants receiving prompt first diphtheria-tetanus-pertussis immunisation in an infant cohort.

The Centers for Disease Control in the United States have stated that studies to determine factors associated with failure to receive the first recommended dose of diphtheria-tetanus-pertussis are required. We examined an infant cohort to identify family and infant characteristics predictive of prompt first immunisation, to document changes in prompt first immunisation rates over time and to identify reasons for immunisation delay. The study sample consisted of one-fifth of live births in Tasmania at risk of sudden infant death syndrome. From 1 January 1988 to 31 December 1994, families of 8011 infants (83 per cent of eligible infants) participated in a telephone interview when the infants were a median postnatal age of 11 weeks and 3 days. Prompt immunisation was defined as the report by parents of diphtheria-tetanus-pertussis vaccination before a postnatal age of 10 weeks. The proportion of cohort infants promptly immunised increased (P < 0.0001) over time from 1988 to 1994. Prompt immunisation was associated with various characteristics of the infant and family. The proportion of infants promptly immunised decreased as birth order increased and as the interpregnancy interval between the index child and his or her immediately elder sibling decreased. After exclusion of infants not promptly immunised because of illness, birth order and interbirth interval remained significant predictors of prompt immunisation, suggesting that these factors are acting to increase immunisation delay through pathways unrelated to their potential effect on infant illness rates.

Modelling prevalence of a condition: chronic graft-versus-host disease after bone marrow transplantation.

A variety of estimators have been proposed for modelling how the proportion of patients with a transient condition varies over time. In this paper we compare these estimators qualitatively and quantitatively and introduce a new estimator based on a generalized additive model (GAM). The assumptions on which the various estimators are based are discussed. Using simulations we compare their performances and investigate their robustness to departures from the assumptions. The GAM estimator is the only one which can incorporate covariate information. Even when estimating a single prevalence function without any covariate information the GAM estimator is seen to be preferable as long as the censoring mechanism is random censoring. The GAM prevalence estimator is applied to data on chronic graft-versus-host disease following bone marrow transplantation.

The micro- or home computer as a teaching aid in postgraduate medical study.

The home computer 'magic' portrayed by the advertising media, supposed to bring computer science to the fingertips of every man, woman and child, is assessed by a practical medical lecturer. Reviewable data banks from which data can be retrieved almost instantaneously, the elimination of filing cabinets and stockpiles of notes, and the efficient storage of clinical patient data together with the relatively low cost and ease of operation make the computer one of the most exciting additions to modern teaching aids.