. Références and D. Cox, Regression models and life tables (with discussion), Journal of the Royal Statistical Society, Series B, vol.34, issue.1, pp.187-220, 1972.

I. Bourdel-marchasson, M. Barateau, and V. Rondeau, A multicentric trial of the effects of oral nutritional supplementation in critically ill older inpatients, Nutrition, 1999.

R. Allman, Pressure Ulcers among the elderly, New England Journal of Medicine, vol.320, pp.850-853, 1989.

T. Finucane, Malnutrition, Tube Feeding and Pressure Sores: Data Are Incomplete, Journal of the American Geriatrics Society, vol.3, issue.suppl, pp.1435-1440, 1996.
DOI : 10.1111/j.1532-5415.1995.tb05822.x

D. Norton, R. Mclaren, and A. Exton-smith, An investigation of geriatric nursing problems in hospitals, pp.193-238, 1975.

F. Kuntzmann, Dependence evaluation in institution (Evaluation de la dépendance en institution) in Israël L, 1984.

L. Wei, D. Lin, and L. Weissfeld, Regression Analysis of Multivariate Incomplete Failure Time Data by Modeling Marginal Distributions, Journal of the American Statistical Association, vol.4, issue.408, pp.1065-1073, 1989.
DOI : 10.1002/sim.4780070115

E. Lee, L. Wei, and D. Amato, Cox-type regression analysis for large numbers of small groups of correlated failure time observations. Survival Analysis : State of the arts, JP Klein, pp.237-247, 1992.

D. Lin, MULCOX: a computer program for the Cox regression analysis of multiple failure time variables, Computer Methods and Programs in Biomedicine, vol.32, issue.2, pp.125-135, 1989.
DOI : 10.1016/0169-2607(90)90092-N

D. Lin, MULCOX2: a general computer program for the Cox regression analysis of multivariate failure time data, Computer Methods and Programs in Biomedicine, vol.40, issue.4, pp.279-293, 1993.
DOI : 10.1016/0169-2607(93)90013-B

D. Commenges and H. Jacqmin-gadda, Generalized Score Test of Homogeneity Based on Correlated Random Effects Models, Journal of the Royal Statistical Society: Series B (Statistical Methodology), vol.59, issue.1, pp.157-171, 1997.
DOI : 10.1111/1467-9868.00061

D. Lin, Cox regression analysis of multivariate failure time data: The marginal approach, Statistics in Medicine, vol.19, issue.21, pp.2233-2247, 1994.
DOI : 10.1002/sim.4780132105

J. Klein, Semiparametric Estimation of Random Effects Using the Cox Model Based on the EM Algorithm, Biometrics, vol.48, issue.3, pp.795-806, 1992.
DOI : 10.2307/2532345

P. Hougaard, Frailty models for survival data, Lifetime Data Analysis, vol.35, issue.3, pp.255-273, 1995.
DOI : 10.1007/BF00985760

K. Liang, S. Self, K. Bandeen-roche, and S. Zeger, Some recent developments for regression analysis of multivariate failure time data, Lifetime Data Analysis, vol.8, issue.4, pp.403-415, 1995.
DOI : 10.1007/BF00985452