Table 3. Opioid overdose prevention and naloxone knowledge among study participants over time, by trial arm.

Rx-OOKS	Rx-OOKS score* mean (95% CI)		Difference(95% CI)	Time×interventionP value
	Intervention arm (n=519)	Usual care arm (n=485)
Time 0	19.3 (18.9 to 19.8)	11.4 (11.0 to 11.8)	7.97 (7.41 to 8.54)	<0.001
4 months	14.8 (14.4 to 15.1)	13.2 (12.8 to 13.6)	1.57 (1.04 to 2.10)
8 months	15.5 (15.1 to 15.8)	14.0 (13.6 to 14.3)	1.50 (0.95 to 2.05)

^*Range of the Rx-OOKS scale is 0–25. Higher Rx-OOKS score represents greater knowledge.

Rx-OOKSPrescription Opioid Overdose Knowledge Scale