TABLE IV.

Unadjusted and adjusted regression models of reinjury risk, by timescale (N=43,114)

Characteristic/Model	Calendar quarters			Quarters with any wages			FTE quarters (hours worked/520)
Unadjusted	HR	95% CI	Pa	HR	95% CI	Pa	HR	95% CI	Pa
Impairment (Ref: No PPD award)			.001			<.001			<.001
WBI <10%	0.95	0.91–0.99		1.05	1.01–1.09		1.05	1.01–1.10
WBI ≥10%	0.90	0.84–0.96		1.29	1.21–1.38		1.37	1.28–1.47
Adjusted	HR	95% CI	Pa	HR	95% CI	Pa	HR	95% CI	Pa
Impairment (Ref: No PPD award)			.947			<.001			<.001
WBI <10%	1.00	0.95–1.05		1.06	1.01–1.11		1.08	1.03–1.13
WBI ≥10%	1.00	0.92–1.06		1.26	1.18–1.36		1.34	1.25–1.44
Body part (Ref: Spine/neck)			.423			.005			.004
Upper extremity	0.99	0.94–1.03		0.94	0.90–0.98		0.94	0.89–0.98
Lower extremity	0.97	0.92–1.02		0.92	0.87–0.97		0.92	0.87–0.96
Other/multiple	0.96	0.91–1.01		0.95	0.90–1.00		0.95	0.90–1.00
Functional Comorbidity Index	0.93	0.88–0.99	.017	0.97	0.92–1.03	.364	0.98	0.92–1.04	.405
Female (Ref: Male)	0.85	0.82–0.89	<.001	0.84	0.81–0.88	<.001	0.91	0.87–0.94	<.001
Age (Ref: 18–24)			<.001			<.001			.004
25–34	0.93	0.88–0.97		1.02	0.97–1.06		1.01	0.97–1.06
35–44	0.95	0.91–1.01		1.09	1.03–1.15		1.09	1.04–1.16
45–54	0.88	0.83–0.93		1.04	0.98–1.10		1.04	0.98–1.11
55–64	0.74	0.68–0.80		0.95	0.88–1.02		1.00	0.93–1.08
≥65	0.45	0.38–0.54		0.70	0.59–0.83		0.87	0.73–1.04
Preferred language (Ref: English)			<.001			<.001			<.001
Spanish	1.14	1.08–1.20		1.19	1.12–1.25		1.11	1.05–1.17
Other	0.81	0.73–0.91		0.80	0.71–0.90		0.74	0.66–0.83
Urban-rural residence county (Ref: Large central metropolitan)			.025			<.001			<.001
Large fringe metropolitan	1.06	1.01–1.11		1.09	1.04–1.14		1.10	1.05–1.15
Medium metropolitan	1.05	1.00–1.11		1.07	1.01–1.12		1.08	1.03–1.14
Small metropolitan	1.01	0.95–1.07		1.00	0.94–1.06		1.02	0.96–1.08
Micropolitan	0.99	0.92–1.06		0.98	0.92–1.05		0.99	0.92–1.06
Noncore	0.93	0.82–1.05		1.00	0.89–1.14		1.04	0.92–1.19
Pre-injury wages ($10,000 increments)	1.05	1.03–1.08	<.001	0.82	0.80–0.85	<.001	0.69	0.67–0.72	<.001
Large employer (Ref: Small employer)	1.22	1.17–1.26	<.001	1.16	1.12–1.21	<.001	1.13	1.09–1.17	<.001
Industry sector (Ref: Information, Finance, Real Estate, Professional)			<.001			<.001			<.001
Agriculture, Forestry, Fishing, Hunting	1.18	1.06–1.31		1.21	1.09–1.35		1.20	1.08–1.34
Construction, Utilities, Mining	1.08	0.98–1.19		1.14	1.04–1.26		1.22	1.11–1.34
Manufacturing	1.34	1.22–1.47		1.33	1.21–1.46		1.28	1.17–1.41
Retail/Wholesale Trade	1.13	1.04–1.23		1.11	1.02–1.21		1.09	1.00–1.19
Transportation, Warehousing	1.24	1.12–1.38		1.30	1.18–1.44		1.28	1.15–1.42
Administrative, Support, Other Services	1.15	1.06–1.25		1.20	1.11–1.30		1.22	1.12–1.32
Education, Health Care, Social Services	1.27	1.17–1.38		1.25	1.15–1.36		1.24	1.14–1.35
Arts, Entertainment, Hospitality	1.13	1.03–1.24		1.13	1.03–1.24		1.17	1.06–1.28
Hazard group	1.03	1.02–1.04		1.04	1.03–1.05		1.04	1.03–1.05

Note: In addition to covariates shown, models were fully stratified by year of initial injury (baseline hazard unique to each year).

Abbreviations: CI, confidence interval; FTE, full-time equivalent; HR, hazard ratio; PPD, permanent partial disability; Ref, reference category; WBI, whole body impairment.

^aP value on referent line reflects joint test for set of categories within variable