Fibrosis staging in chronic hepatitis C: analysis of discordance between transient elastography and liver biopsy.

In chronic hepatitis C, transient elastography (TE) accurately identifies cirrhosis, but its ability to assess significant fibrosis (Metavir > or = F2) is variable. Constitutional and liver disease-related factors may influence TE and here we examined the variables associated with differences. Three hundred consecutive hepatitis C virus (HCV)-RNA positive patients had biochemical tests, TE and a biopsy performed on the same day. The Dale model was used to identify the variables associated with discordance between biopsy and elastography results. In 97 patients (34.2%), TE and histological assessment were discordant. Seventy-six of 286 (26.6%) had stage > or =F2 and TE < 7.1 kPa (false negative); 21 of 286 (7.3%) had stage or = 7.1 kPa (false positive). No patient with discordant results had cirrhosis. By Dale model, aspartate aminotransferase (AST) was found to be the unique variable significantly related (P = 0.046) with discordance between biopsy and TE. Discordance rate was 43.4% (82 patients) with AST < 1.5 x UNL vs 25.8% (25 patients) with AST > or = 1.5 x UNL (P = 0.004). False negative rate was 43.4 (82 patients) with AST < 1.5 x UNL vs 17.1% (13 patients) with AST > or = 1.5 x UNL (P < 0.001). Areas under the receiver operating characteristic (AUROC) for F > or = 2, according to AST < 1.5 x UNL vs > or = 1.5 x UNL were 0.738 (95% CI: 0.683-0.812) and 0.854(95% CI: 0.754-0.907). Transient elastography is not adequate on its own to rule out or to rule in significant fibrosis, as it is influenced by major variations in biochemical activity of liver disease. Liver stiffness, at low levels of AST, can underestimate fibrosis.

Uncertainty and the demand for medical care.

This paper provides an analysis of the effects of uncertainty on the demand for medical care using a simplified version of Grossman's human capital model of the demand for health. Two types of uncertainty are analysed: the uncertainty surrounding the incidence of illness and the uncertainty surrounding the effectiveness of medical care. In the first the consumer's basic level of health is assumed to be a random variable; in the second the effectiveness of medical care is assumed to be random. Comparative static results are reported indicating the effects on the demand for medical care of both increases in the means of these distributions and mean-preserving spreads of the distributions.

Uncertainty, inequalities in health and the demand for health.

As it has become increasingly recognized that inequalities in health stem more from inequalities in wealth, rather than from inequalities in access to medical care, economists have begun to suggest that Michael Grossman's model of the demand for health may be a useful analytical framework for investigating the issue. Ironically, the more popular of Grossman's two submodels--the 'pure-investment' model--provides little by way of insights into the relationship between inequalities in wealth and inequalities in health. In common with other pure investment models of human capital formation, Grossman's model predicts that an individual's health investment decisions at each stage in the lifecycle will be independent of his initial wealth. This paper shows that if uncertainty is introduced into the model, this result no longer holds. It also shows that if individuals display decreasing absolute risk aversion, wealthier individuals will invest more in health capital than individuals who start life with relatively small stocks of financial capital.