Bigdeli et al. BMC Public Health 2010, 10:406 http://www.biomedcentral.com/1471-2458/10/406 insufficient pre-hospital emergency medical services including rapid services and effective management of RTI victims and their transportation [12] and therefore their improvement and system evaluation is crucial [13,14]. Pre-hospital care is unsatisfactory in many countries, especially in LMICs [7-9], where the majority of trauma deaths occur in the pre-hospital phase. Rapid arrival of the EMS at the crash scene and proper victim transpor- tation by trained personnel may reduce injury severity and reduce the number of preventable deaths. It is important to note that many trauma experts consider that the first 60 minutes after injury occurrence - referred to as the “golden hour"- are the most effective for saving lives [15]. After this period, the risk of death or injury severity rises significantly [15]. This “golden hour” consists of various time intervals, e.g. notification interval, activation interval, response interval, on-scene interval, and transport interval (see Appendix 1). Rapid responses are believed to be one of the most important criteria for the quality of care provided to trauma patients [15]. Measuring these various time intervals can be an important step towards the evalua- tion of the EMS function. However, to our knowledge there is a lack of information about the various pre-hos- pital time intervals of road traffic injuries and the differ- ences between these for city and interurban roads area in Iran. The present study therefore was designed to estimate the average timings of various time intervals of RTI at the pre-hospital phase by EMS to trauma centres in the capital city of West Azarbaijan Province of Iran. Method This is a retrospective cross-sectional study on time intervals of RTIs that were identified in the centre for ambulance dispatch sites from 20 March 2005 to 20 March 2007 in the Urmia city of Iran. The pre-hospital data of all RTIs were reviewed and the average of the different interval times was analyzed. Study area and study population This study was undertaken in Urmia, the capital city of the West Azarbaijan Province of Iran, which is located in the centre of the province. West Azarbaijan province shares a common border with Iraq, Turkey and Russia Azerbaijan. For feasibility reasons Urmia was chosen for the study. The population was about 887 318 in 2006. The rate of fatal RTIs in this province was estimated at 34 per 100 000 in 2005 [16]. Data collection instrument A standard questionnaire designed by the Ministry of Health and Medical Education in Iran, was used in this study. The questionnaire has demographic information on patients or victims including name, sex and age, Page 2 of 7 disease or external cause of injury and information about time of services including time of emergency call, time of ambulance departure to scene, time of arrival at scene, time of patients’ transportation, time of arrival at hospital, time of leaving the hospital and time of return- ing to ambulance depot, location of crash scene (in cities or on interurban roads), as well as distance cov- ered by the ambulance from the departure to return to depot. In this study, time intervals including time of emergency call, time of ambulance departure to scene, time of arrival at scene, time for patients’ transportation and time of arrival at the hospital were used. Figure 1 illustrates these different time intervals. Data source and case selection Trained EMS ambulance personnel record information about patients/or victims of RTIs. Ambulance personnel are responsible for death and injury registration. For each patient there is a questionnaire to be filled out (see also data collection). After data collection by techni- cians, these data will be fed into a central computer located at the ambulance site dispatch centre by a trained technician. Initially, all calls to the ambulance centre were reviewed. In total, there were 22 182 regis- tered calls to the EMS in Urmia that resulted in EMS activity. Among all calls during the study period, 2 210 were related to RTIs. The inclusion criteria were, if they qualified as RTI victims and resulted in a ground ambu- lance dispatch; and received service from them, e.g. they were transported from the scene by one of the region’s EMS. Incident locations were defined as “city” and “interurban roads” if they occurred in the Urmia geo- graphic area, according to the Statistical Centre of Iran definition. The cases lacking in complete information about time intervals were excluded (183 cases). In total, 2027 cases were analyzed in this study. Data treatment Descriptive analysis on various pre-hospital time inter- vals including: activation interval, response interval, on- scene interval, transportation interval and the total pre- hospital intervals were investigated, using mean, median, mode, maximum, minimum and 95% confidence inter- vals. Moreover, bivariate analyses were conducted for time intervals (five categories) and crash location (two categories) using t-tests and Chi2 test, to detect signifi- cant association and differences (P < 0.05) in distribu- tion between categorical and continuous variables, respectively. Moreover, the distribution of time of injury occurrence (four categories for time of injury; seven categories for date of injury; and four categories for sea- son of injury) was considered for city and interurban roads, using Chi2 test. In order to test the difference between weekdays and seasons of injury occurrence in