Background: There have been few reports on relationships between Shift Work (SW) and time to Noise-Induced Hearing Loss (NIHL). This research explores the relation between SW and time to NIHL among male workers. Methods: Between 1990 and 2015, this historical cohort study was conducted. Two different definitions events (Low Frequency Hearing (LFH) and High Frequency Hearing (HFH)) of NIHL An average pure-tone hearing threshold was thresholds at 1, 1.5 and 2 kHz for LFH(un-normal>20) and 4, 6 and 8 kHz for HFH (un-normal>20) for Air (AC) and Bone (BC) conduction, in both ears, respectively. In this study Kaplan–Meier and Multilevel Cox Model in addition R version 3.2.1 and MLWiN software used to analysis data. P-values less than 0.05 are considered to be statistically significant Results: There were 6632 male workers in the research survey (mean age=35(±5)). Among these subjects, 2678 (40%),278 (4%) and 3676 (56%) were Day Workers (DW), Weekly Rotating Shift workers (WRS) and Routinely Rotating Shift workers (RRS), respectively. The result of this study showed more hazard risk of ear problem in LFH (Hazard=1.55 with 95% CI= (1.06-1.39)) and HFH (Hazard=1.08 with 95% CI= (1.04-1.13)) in RRS rather than day workers. In WRS group ear problem has been seen just in LFH (Hazard=1.55 with 95% CI= (1.2-2.0)). Conclusion: The findings of the 15-year historical cohort study generally support a relationship between SW and time to NIHL. Therefore, more actions in the field of noise control, greater use of safety devices as well as increased staff training on the use of safety devices recommended for shift worker.

Abstract:Background and purpose: The survival rate of gastric cancer patients has significantly increased during the last decades because of the advances in this type of cancer treatment. The purpose of the current study was to examine the survival levels of gastric cancer through Weibull regression and its affective causes. Materials and methods: In this research, the records and personal information of 643 patients who were evolved by gastric cancer and referred to Imam Khomeini hospital of Sari (2007Sari ( -2013 were studied in order to determine their levels of survival. During the study, 74 cases of patients were exempted from the study due to their defective data, and the data collected from 569 cases were analyzed to obtain the results. In the current study, the impact of factors affecting Survival time was determined using the Weibull regression model. The analysis of data was performed using Stata statistical Software in 0.05 significance level. Results: The findings of the study showed that patients were estimated to experience 5 years of survival probability equal to 0. 75, 0.68, 0.54, 0.41, 0.3 during the time period November -December, 2013 the 1, 2, 3, 4 with a median survival time equal to 19 months, resulting in a survival mean equal to 24.49 months. Based on the Univariate and Multivariate analyses methods, some variables like: stage and metastasis were determined as the affective factors on the survival probability (p-value <0.05). Conclusion: In this study, it was then concluded that the life span of examined patients is very low in comparison with developed countries, which might be because of late reference or delayed diagnosis and the lack of facilities for treatment. Thus, the factors such as earlier diagnosis of the problem and screen methods could certainly influence and increase the patients' survival rate.