title: [Use of a logistic regression model at two levels in the analysis of medical practice variations: the prophylactic cesarean].
abstract: We show the use of a hierarchical logistic model to study the variations of the prophylactic cesarean section rate between the maternity hospitals of the Rhône-Alpes region. These variations are analyzed according to the women characteristics at first level, and the maternity hospital characteristics at second level. We present the two-level hierarchical logistic model and the method of estimation of the fixed and random parameters. Then, we compare and discuss the results obtained with those of the usual logistic model. The usual logistic model underestimates the standard error of the regression parameters. In our example however, the results obtained with the hierarchical model do not modify the conclusions concerning the effect of the women characteristics. All the women characteristics increase significantly the probability for a woman to have a prophylactic cesarean section. Nevertheless, the hierarchical model reveals the effect of the maternity hospital characteristics and shows that the maternity hospitals which receive many "at risk" women tend to perform fewer prophylactic cesarean sections than the others, in women with the same characteristics. It permits to estimate the residual variance of second level linked to the unobserved characteristics of the maternity hospitals. It permits to show that the effect of the main characteristics of the women (previous cesarean section, dystocia, chronic fetal distress) vary between maternity hospitals.
authors.affiliation: Département d'Information Médicale des Hospices Civils de Lyon, Hôtel Dieu.
authors.forename: M
authors.initials: M
authors.lastname: Rabilloud
authors.forename: R
authors.initials: R
authors.lastname: Ecochard
authors.forename: Y
authors.initials: Y
authors.lastname: Matillon
mesh_terms: D015982:Bias; D002585:Cesarean Section / Q000706:statistics & numerical data*; D005260:Female; D005602:France; D006302:Health Services Research; D006771:Hospitals, Maternity; D006801:Humans; D016015:Logistic Models; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data*; D011247:Pregnancy; D015203:Reproducibility of Results; D012307:Risk Factors