, respectively. However, analysis of subgroups defined by age, gender, body mass index, and GFR level showed that the biases of the two formulas could be much larger in selected populations. Furthermore, analysis of the SD of the mean difference between estimated and measured GFR showed that both formulas lacked precision; the CG formula was less precise than the MDRD one in most cases. In the whole study population, the SD was 15.1 and 13.5 ml/min per 1.73 m 2 for the CG and MDRD formulas, respectively. Finally, 29.2 and 32.4% of subjects were misclassified when the CG and MDRD formulas were used to categorize subjects according to the Kidney Disease Outcomes Quality Initiative chronic kidney disease classification, respectively.

SUMMARY This study was an epidemiological questionnaire survey of a representative sample of the French population that included 12 778 individuals and in which adapted DSM-IV criteria for the de®nition of insomnia were used. Our goals were not only to assess the prevalence of`insomnia' using these criteria, but also to compare the results obtained with those of prior studies using di erent de®nitions of`insomnia'. The aim of this study was also to identify where areas of agreement and disaggreement existed, as we believe that it is important to emphasize these points because DSM-IV recommendations are supposedly re¯ected in clinical practice. Seventy-three per cent of the individuals surveyed complained of a nocturnal sleep problem, but only 29% reported at least one sleep problem three times per week for a month, and 19% (2428 subjects) had at least one sleep problem three times per week for a month and complained of daytime consequences (DSM-IV criteria). Only 9% had two or more nocturnal sleep problems with daytime consequences and were classi®ed as`severe insomniacs'. Our study indicates that if DSM-IV criteria are used, the diagnosis of insomnia' is lower than in other epidemiological studies. The DSM criteria have an advantage in that they emphasize the daytime consequences of nocturnal sleep disturbances, which seem to be responsible for the most important socio-economic costs of the problem.

Plasma vasopressin levels are almost always increased at the initial phase of septic shock and decrease afterward. Relative vasopressin deficiency is seen in approximately one-third of late septic shock patients.