Definitions of outcomes*

Off-label use
Concurrent useUse of inhaler and cigarettes at least several times a week for one month
Non-cessation useUse to reduce smoking or use in situation where cannot smoke for one month
Harmful use
Damage to health (ICD-10)Use caused or made health problem worse
Continued use (ICD-10)Used for ⩾1 month despite harm
Tolerance (DSM-IV and ICD-10)Increasing use of cartridge to obtain similar effect or diminishing effect with repeated use
Withdrawal (DSM-IV and ICD-10)Four withdrawal symptoms rated as moderate or severe or using cartridge to avoid or relieve withdrawal symptoms
Compulsive use (ICD-10)Craving or strong desire to use
Use more than intended (DSM-IV and ICD-10)Probes for loss of control
Unsuccessful efforts to cut down or stop (DSM-IV and ICD-10)⩾2 failed attempts
Use despite harm (DSM-IV and ICD-10)Attribute harm to inhaler and continue use