TABLE 2—

Regression Analysis Comparing Patient-Level Medical Costs Across Levels of Severity: Sample of Patients, United States, January 1, 2007–December 31, 2010

	Unadjusted Analysis, CR (95% CI)		Adjusted Analysis, CR (95% CI)
Sample	Moderate TBI	Severe TBI	Moderate TBI	Severe TBI
Primary analysis,a mo
0–3	6.44 (5.79, 7.17)	14.55 (13.05, 16.23)	4.91 (4.53, 5.32)	11.07 (10.19, 12.03)
4–6	1.79 (1.42, 2.26)	4.06 (3.21, 5.14)	1.80 (1.53, 2.11)	3.84 (3.26, 4.52)
7–9	1.31 (1.07, 1.61)	2.79 (2.27, 3.43)	1.30 (1.10, 1.54)	2.37 (1.99, 2.82)
10–12	1.40 (1.13, 1.73)	2.10 (1.69, 2.61)	1.33 (1.12, 1.60)	1.84 (1.54, 2.21)
Subgroup analysis,b mo
0–12	3.84 (3.31, 4.44)	8.55 (7.38, 9.91)	3.53 (3.27, 3.82)	7.70 (7.10, 8.33)
13–24	1.29 (1.08, 1.54)	2.04 (1.70, 2.43)	1.22 (1.05, 1.42)	1.95 (1.67, 2.27)

Note. CI = confidence interval; CR = cost ratio; TBI = traumatic brain injury. CRs compare the costs to the reference group (mild TBI) in each category. Adjusted regression analysis included the following covariates: age, gender, region, rurality, polytrauma, severe extremity injury, comorbidity diagnosis in the preceding 6 months, and total medical costs in the 6 months before index TBI. Separate models were conducted for each follow-up interval.

^aExclusion criteria included the following: at least 12 months of enrollment, geographic region, and nonnegative costs at each time interval (n = 319 103).

^bExclusion criteria include those listed in footnote a; however, enrollment was restricted to those with at least 24 months of enrollment (n = 157 073).