TABLE 3.

12-Month Direct Health Care Cost Differences by Anti-CCP Category^a

Type of Encounter	Label	Beta Estimate	SE	P Value	Estimated Mean in Anti-CCP-Positive Patients, $	Estimated Mean in Anti-CCP-Negative Patients, $	Estimated Mean Differences in Anti-CCP-Positive and Anti-CPP-Negative Patientsb, $
Office visit	Unadjusted	0.05	0.04	0.176
	PS weighted	0.06	0.04	0.138	338	326	12
Rheumatologist visit	Unadjusted	0.26	0.07	0.0001
	PS weighted	0.29	0.07	< 0.0001	298	222	76c
Laboratory testing	Unadjusted	0.22	0.04	< 0.0001
	PS weighted	0.23	0.04	< 0.0001	398	215	183c
Prescription	Unadjusted	0.43	0.07	< 0.0001
	PS weighted	0.46	0.08	< 0.0001	6,671	4,172	2,499c
ED	Unadjusted	-0.11	0.21	0.607
	PS weighted	0.06	0.23	0.809	1	-3	3
Hospitalization	Unadjusted	-0.20	0.28	0.467
	PS weighted	-0.26	0.31	0.406	52	654	-602
Total	Unadjusted	0.24	0.08	0.003
	PS weighted	0.25	0.08	0.001	7,465	5,302	2,163c

Note: These results are from the generalized linear models using difference-in-difference unadjusted and propensity score methods. Variables used in the propensity score models and regression models were age, gender, race/ethnicity, and Elixhauser Comorbidity Index score.

^a Cost differences are shown in 2015 U.S. dollars.

^b Estimated mean changes were calculated using recycled prediction methods after the generalized linear models using gamma distribution, log link.

^c Statistically significant findings (P < 0.05).

CCP = cyclic citrullinated peptide; ED = emergency department; PS = propensity score; SE = standard error.