Table 5.

Comparisons between the Random Sample of 617 Olmsted County Residents Who Met Rochester Epidemiology Project (REP) Criteria for Possible (Symptomatic) Traumatic Brain Injury (TBI) (i.e., Cases) and Their Matched^a Non-TBI Controls for Costs in the 6 Years after Baseline^b Adjusted for Differences between Cases and Controls with Respect to Medical Conditions before Baseline^c

		Adjusted mean costs
Time period	No. of pairs (% entering period)	Cases	Controls	Adjusted mean difference in medical care costsd,e(95% CIf)
Full period: Baseline to 6 years	617 (100%)	$13,018	$10,718	+$2300 (+$2190, +$2428)
1 day to 6 months	616 (99.8%)	$1300	$1771	−$471 (−$497, −$440)
6–12 months	576 (93%)	$993	$978	+$15f (+14, +17)
1–6 years	537 (87%)	$11,645	$8227	+$3418 (+$3236, +$3634)

^aControls were matched to cases for age, sex, calendar year, non-head injury severity at baseline, and length of follow-up.

^bDate of incident TBI for cases and closest REP registration date for controls.

^cAssessed using Resource Utilization Bands (Johns Hopkins Bloomberg School of Public Health, 2002).

^dAnalyzed using recycled predictions (Basu et al., 2006).

^eDollar values were adjusted for inflation and geographical wage differences to express costs for each year in 2007 nationally representative constant dollars.

^fBootstrapped values for 95% confidence intervals (CI).

^gTwo-part modeling was used to account for high percentage with zero costs.