comparison of the results of cox proportional hazards model and parametric models in the study of length of stay in a tertiary teaching hospital in tehran, iran

survival analysis is a set of methods used for analysis of the data which exist until the occurrence of an event. this study aimed to compare the results of the use of the semi-parametric cox model with parametric models to determine the factors influencing the length of stay of patients in the inpatient units of women hospital in tehran, iran. in this historical cohort study all 3421 charts of the patients admitted to obstetrics, surgery and oncology units in 2008 were reviewed and the required patient data such as medical insurance coverage types, admission months, days and times, inpatient units, final diagnoses, the number of diagnostic tests, admission types were collected. the patient length of stay in hospital 'leading to recovery' was considered as a survival variable. to compare the semi-parametric cox model and parametric (including exponential, weibull, gompertz, log-normal, log-logistic and gamma) models and find the best model fitted to studied data, akaike's information criterion (aic) and cox-snell residual were used. p