[Cholelitholysis].

The most common instance of multivariate observations is the case of repeated measures over time. The two most widely used methods for the analysis of K repeated measures for two groups are the K degrees of freedom (d.f.) T2 MANOVA F-test and the within-subjects 1 degree of freedom ANOVA F-test. Both require complete samples from normally distributed populations. In this paper, I describe alternative K and 1 d.f. distribution-free procedures which allow for randomly missing observations. These include a large-sample analysis of means, the Wei and Lachin multivariate Wilcoxon test with estimates of the Mann-Whitney parameter, and a multivariate Hodges-Lehmann location shift estimator based on the multivariate U-statistic of Wei and Johnson. Each of these methods provides a distribution-free K-variate estimate of the magnitude of group differences which can be used as the basis for an overall test of group differences. These tests include the K d.f. omnibus T2-like test, 1 d.f. tests of restricted hypotheses, such as the Wei-Lachin multivariate one-sided test of stochastic ordering, and the test of general association based on a minimum variance generalized least squares (GLS) estimate of the average group difference. I then describe covariate stratified-adjusted GLS estimates and tests of group differences. This approach also provides tests of homogeneity (interaction) for within-subjects and between-subjects effects. I illustrate these analyses with an analysis of repeated cholesterol measurements in two groups of patients, stratified by sex. Such analyses provide an overall distribution-free summary estimate and test of the treatment effect obtained by combining the group differences over both time (repeated measures) and strata.

Chenodeoxycholic Acid↗

PubMed1992

[Results of the treatment with biliary dissolvents].

Cholesterol gallstones can be dissolved by chenodeoxycholic acid or by ursodeoxycholic acid administered orally. This treatment is subject to the following conditions: the gallbladder must be functioning; the gallstones must be radiolucent; the stones must not be too large; the main bile ducts must be patent; the cholelithiasis must be symptomatic but without severe complications. The two biliary acids are equally effective, but ursodeoxycholic acid is preferred to chenodeoxycholic acid because it is devoid of undesirable side-effects. The effectiveness of treatment varies from one published series to the other, but it primarily depends on the size of the gallstones: if they are less than 5 mm wide dissolution can be obtained in 70 to 80% of the cases. After the end of treatment the bile becomes lithogenic again, and a relapse is possible; after 5 years this relapse occurs in about 50% of the patients. The position occupied by biliary acids in the treatment of gallstones is modest, owing to the conditions of their use and to the advantages of surgery, and notably laparoscopic surgery. Biliary acids are usually given to elderly people or to subjects at high risk for anaesthesia or surgery. Attempts have been made to introduce another cholesterol dissolvant, methyl-tert-butyl-ester, directly into the gallbladder by the transcutaneous-transhepatic route. The gallstones were dissolved, but the invasiveness of this technique and the potential toxic effects of this particular drug are such that the indications for this treatment are extremely reduced.

Chenodeoxycholic Acid↗