Table 1.

Data sets included in the metaregression

Study	Years	N [ages 18–35]	Measurement time frame			RDS recruitment	Percent residence in Chicago
			Homeless	IDU network	Risk behavior
CIDUS 2 (Thorpe et al., 2000)	1997–1999	695	6 months	NA	6 months	No	0.61
CIDUS 3 (Booth and Strathdee, 2007)	2002–2004	775	6 months	3 months	3 months	No	0.32
NATHCV (Boodram et al., 2011)	2002–2005	110	6 months	NA	6 months	No	NA
NIHU (Broz and Ouellet, 2010)	2004–2006	150	NA	30 days	6 months	No	0.56
SATHCAP (Rothenberg et al., 2009)	2005–2009	453	12 months	6 months	30 days	Yes	0.62
PSYCH (Mackesy-Amiti et al., 2012)	2008–2010	610	6 months	6 months	6 months	Yes (partial)a	0.28
NHBS IDU2 (Centers for Disease Control and Prevention, 2012)	2009	143	12 months	30 days	12 months	Yes	0.74
NHBS IDU3 (Centers for Disease Control and Prevention, 2015)	2012	59	12 months	30 days	12 months	Yes	0.52
SOCNET (Boodram et al., 2015)	2012–2013	163	6 months	6 months	6 months	No	0.80
NHBS IDU4 (Centers for Disease Control and Prevention, 2018)	2015	263	12 months	30 days	12 months	Yes	0.54
MOOD (Mackesy-Amiti and Boodram, 2018)	2016–2017	180	6 months	6 months	6 months	No	0.61

^a.Partial RDS recruitment; 40% of sample was recruited by outreach.

RDS: Respondent driven sampling.

CIDUS: Collaborative Injection Drug Users Study (CDC).

NATHCV: Early natural history of HCV infection among injection drug users (NIDA).

NIHU: Non-injected heroin use, HIV, and transitions to injection (NIDA).

SATHCAP: Sexual Acquisition and Transmission of HIV Cooperative Agreement Project (NIDA).

PSYCH: Psychiatric disorders and HIV risk behaviors among young injection drug users (NIDA).

SOCNET: Social networks of young injection drug users (Chicago DCFAR).

MOOD: Emotion dysregulation and risky behavior among people who inject drugs (NIDA).

NHBS: National HIV Behavioral Surveillance (CDC).