Table 9.

SCE rate ratios by clusters and demographics.

	Rate ratio	95% LCL	95% UCL	p-Value
Cluster 1 vs. 4	1.25	0.90	1.73	0.187
Cluster 2 vs. 4	1.62	1.01	2.59	0.044*
Cluster 3 vs. 4	0.91	0.70	1.18	0.465
Cluster 1 vs. 3	1.38	0.99	1.90	0.054
Cluster 2 vs. 3	1.79	1.12	2.84	0.014*
Cluster 1 vs. 2	0.77	0.47	1.27	0.309
Years of commercial vehicle driving	0.98	0.97	0.99	0.010*
Age	1.00	0.99	1.01	0.644
Gender (M vs. F)	1.98	1.21	3.26	0.007*
BMI	1.03	1.01	1.04	0.005*

^*Indicates the p-value < 0.05.