Table 2

Characteristics of drug use when subjects in the HC group reported using only 1 drug in a given month and when the same subjects reported using both drugs in the same month In different questionnaires

No. of subjectsEither drug used in the month; mean no. (and SD)Both drugs used in the same month; mean no. (and SD)
Days of useInjections/dDays of useInjections/d
Heroin915.7 (12.9)2.5 (1.5)14.6 (10.2)2.6 (1.8)
Cocaine3616.1 (12.0)10.7 (9.6)16.3 (10.8)11.0 (12.0)