Table 3.

Crude and adjusted relative risk estimates assessing the association between past 3-month drug use status and completing study protocol

	Completing protocol a
	Crude Estimates		Adjusted Estimate
	RR (95% CI)	p-value	ARR (95% CI)	p-value
Drug use
Non-drug users (Reference)	1.00		1.00
Other drug users b	1.26 (1.05 – 1.51)	0.012	1.24 (1.03 – 1.49)	0.023
Stimulant drug users b	1.08 (0.89 – 1.31)	0.453	1.04 (0.85 – 1.27)	0.736
Stimulant drug users vs. other drug users c	0.85 (0.74 – 0.99)	0.040	0.84 (0.72 – 0.98)	0.024
Age d	0.99 (0.99 – 1.00)	0.361	0.99 (0.98 – 1.00)	0.233
Race
White (Reference)	1.00		1.00
Black	0.80 (0.63 – 0.99)	0.044	0.79 (0.62 – 0.99)	0.045
Hispanic	1.01 (0.85 – 1.21)	0.901	0.99 (0.83 – 1.18)	0.892
Employment
Not working full time (Reference)	1.00		1.00
Working full time	0.97 (0.85 – 1.11)	0.705	0.94 (0.80 – 1.11)	0.485
Income
< $20,000 (Reference)	1.00		1.00
$20,000 - $59,999	0.99 (0.84 – 1.15)	0.853	0.97 (0.82 – 1.15)	0.745
≥ $60,000	0.96 (0.80 – 1.15)	0.646	0.99 (0.80 – 1.23)	0.919

Abbreviations: RR, risk ratio; CI, confidence interval; ARR, adjusted risk ratio.

^aIndividuals who did not complete the study protocol served as the reference group for the model outcome.

^bReference category for categorical variable comparison is ‘Non-drug users’.

^cReference category was changed from ‘Non-drug users’ to ‘Other drug users” in order to obtain RR and ARR estimates when comparing ‘Stimulant drug users’ to ‘Other drug users’.

^dAge modeled as a continuous variable in all crude and adjusted relative risk regression models.