Does type and number of used substances affect the severity of illness in patients with substance use disorders?

Background Substance use disorders (SUD) are considered as serious mental illnesses, with variability of age of onset, duration of illness, and type of used substance among patients. The effect of type and number of substances used on the severity of such an illness are worth scientific investigation. In this study, we tried to investigate the probable relationship between type and number of used substances with the degree of severity of substance used disorders in a sample of upper Egyptian patients. To predict risk factors associated with the severity of SUD. Results Opiates (including tramadol) were the most frequently used substances followed by cannabis and then heroin. Patients using poly substances scored significantly higher than the ones using a single substance on AIS (p = 0.001), as well as on the legal, drug, and family and social subscales of ASI (0.012 0.006, 0.002 respectively). Multiple stepwise linear regression analysis demonstrated that the number of used substances was the most prominent factor in determining severity of substance-related disorder. Conclusions Using more than one substance is common in patients with substance use disorders. This is usually associated in more severe form and consequences of illness. So, some substances and combinations are associated with more morbidity than others.