RESUMO
BACKGROUND: Prostate specific antigen (PSA) is an important biomarker to monitor patients after treated with radiation therapy (RT). The aim of this study is to evaluate the relationship between the PSA data and prostate cancer recurrence using the joint modeling. METHODS: This historical cohort study was performed on 422 prostate cancer patients. Inclusion criteria included: patients with localized prostate cancer referring to Cancer Institute in Tehran (Iran) from 2007 to 2012, and under radiation therapy. Joint model has two components or sub-models. We showed the results by parameter estimating the longitudinal sub-model and survival sub-model. EM algorithm, Newton-Gauss and Gauss-Hermit law were used for final model parameters. R software version 3.2 was used for statistical analysis. RESULTS: In this study, considering the inclusion and exclusion criteria, out of 422 patients, the data on 314 cases were selected for analysis and the main result of joint model was obtained. PSA directly and significantly was associated with recurrence risk, therefore increasing 2.6 ml/lit PSA (one unit in transformed PSA) increases 39% recurrence risk (95% CI for RR: 1.09-1.77). Also, slope of PSA trend has significant association with prostate cancer recurrence risk (95% CI for RR: 1.05-1.41). CONCLUSION: This study showed a significant relationship between PSA, and its slope with the recurrence risk by joint model, with regard to the pathological, demographic and clinical features in the Iranian population.
RESUMO
BACKGROUND: Stability of the knee joint is achieved by a complex process in which the anterior cruciate ligament (ACL) plays an important role. The rupture of this ligament is quite frequent especially in athletic young subjects. Various methods have been used to reconstruct the ACL. One of the new methods is to use a graft combined from peroneus longus and hamstring. As there is no evidence regarding this method, it was aimed to evaluate the efficiency of this method. METHOD: Two groups of normal and those with ACL injury, in whom their ACLs were reconstructed with the new method, participated in this study. The kinematic and kinetic parameters during walking on level surface were evaluated by a motion analysis system (Qualysis) and a Kistler force plate. The difference between the parameters of operated and non-operated sides and also between patients and normal subjects was evaluated by use of a two sample t test (p-value was 0.05). RESULTS: The results of this study showed that the pattern and magnitude of the loads transmitted by lower extrimity joints differed between normal and ACL reconstructed subjects. The sound side pattern and magnitude of motion were also influenced by ACL insufficiency. CONCLUSIONS: The results of the current study showed that the reconstructed ACL by use of this method did not have enough performance to restore the function of the leg. As the knee joint is unstable following the use of this method, it is recommended to find a new method of ACL reconstruction to improve the function of this ligament after reconstruction.