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

Table 6 Multiple linear regression analysis to detect the predictors affecting Addiction Intensity Scale (AIS) scoring

	Unstandardized coefficients		R	R²	P value
	B	Std. error	R	R²	P value
Constant Age of onset Duration of addiction Education Overall number of substances Current number of substances	13 −0.14 0.02 0.2 1.28 −0.77	2 0.07 0.08 0.08 0.29 0.4	0.580	0.337	0.040* 0.849 0.013* < 0.001* 0.057