Interval censoring Analysis of Factors affecting the time of development of pulmonary restrictive disorder in yazd tile workers

Respiratory diseases are one of the most common occupational diseases in Iran. This study aimed to investigate the factors affecting the time of development of pulmonary restrictive patterns in the workers' spirometry in Yazd tile using interval-censored survival analysis. This was a historical cohort study, which was performed on 596 male tile industry workers in Yazd Province. All cases were recruited from those who admitted for annual periodic medical checkup since 2008 to 2013 without restrictive pulmonary disorder and follow up regarding restrictive pulmonary disorder at Occupational Medicine Clinic in Yazd Province. Data analysis was performed by R statistical software (version 3.2.3) using interval-censored survival data. To investigate the effect of variables for univariate and multivariate regression models, complete parameter was used. Akaike's criterion was used to compare the efficiency criterion parametric models. Working unit in the multivariate analysis was an effective factor in the diagnosis of pulmonary restrictivedisorder in the workers (p<0.05). Employment in the crusher unit in comparison with ballmillunit reduced the risk of development of pulmonary restrictive disorder by 15%. Working in the other units reduced the risk of development of pulmonary restrictive disorder by 18% in these workers. Log-logistic model was the best fitted parametric model to the data according to Akaike's criterion