Variables of interest are described using mean and standard deviation when normality is present, and with median and interquartile range otherwise. The rate of OSHA reports was calculated as the number of reports per 100 Full-time Equivalent (FTE). An FTE was defined as 2000 hours of work per year.
Multivariable mixed effects logistic models were constructed for hypothesis testing. The fixed effects were specified as hours of work in the previous 7 days, categorical quartile of familiarity of crew on the shift, binary recovery less than 11 hours, continuous number of shifts in the month, and the percentage of work hours occurring between the hours of 10pm and 6am. A random agency effect was implemented to account for the clustering of EMS workers within agencies and a random worker effect to account for the correlation between repeated measures within worker. The analysis was performed using Stata version 12.1 MP, College Station, TX: StataCorp LP.
The primary outcome was the presence/absence of an OSHA reportable occupational injury or illness. A sensitivity analysis was performed to assess changes in the observed associations after excluding reports classified as illness, to explore the possibility that reports of illness may not share the same relationship between exposure and outcome.
Multivariable mixed effects logistic models were constructed for hypothesis testing. The fixed effects were specified as hours of work in the previous 7 days, categorical quartile of familiarity of crew on the shift, binary recovery less than 11 hours, continuous number of shifts in the month, and the percentage of work hours occurring between the hours of 10pm and 6am. A random agency effect was implemented to account for the clustering of EMS workers within agencies and a random worker effect to account for the correlation between repeated measures within worker. The analysis was performed using Stata version 12.1 MP, College Station, TX: StataCorp LP.
The primary outcome was the presence/absence of an OSHA reportable occupational injury or illness. A sensitivity analysis was performed to assess changes in the observed associations after excluding reports classified as illness, to explore the possibility that reports of illness may not share the same relationship between exposure and outcome.