Table 1.

Candidate predictors used in the random forest algorithms

Category	All Candidate Predictors
Questions related to mental health	Psychiatric institution or psychiatric hospital stay; Psychiatric diagnoses in chart reviews; Use of psychotropic medications (e.g., antidepressants, sedative hypnotics, atypical and typical anti-psychotics)
HR-QoL	EQ-5D-3L—standardized instrument - Descriptive system (mobility, self-care, usual activities, pain/discomfort, and anxiety/depression) - Current health state with a visual analog scale – scores range between 0–100
Sociodemographic characteristics	Age; Gender; Race/ethnicity; Immigration status; Living situation; Shared accommodation details; Education; Employment; Monthly income; Source of income
Behavioral characteristics	Injection drug use (ever/P6M); Non-injection drug use (ever/P6M); Needle/equipment sharing behaviors (ever/P6M); Snort (ever/P6M); Sharing behaviors for snorting apparatus (ever/P6M); Marijuana use; Therapy for drug addiction; Alcohol use (ever/P6M); Alcohol abuse; Smoking (ever/P6M); Sexual orientation; number of sexual partners; Sex work; Incarceration (ever/P6M); Tattoos; Body piercing
Clinical characteristics	BMI category; HIV viral load; CD4 count; HCV RNA; HIV disease stage; AIDS defining illness; health services used in the past 6 months (walk-in clinic, emergency room, inpatient, general practitioner, HIV clinic and specialist); Previous interferon-based HCV treatment; current antiretroviral therapy; Hepatitis B diagnosis; sexually transmitted disease diagnosis; end-stage liver disease (cirrhosis, ascites, varices, portal hypertension, encephalopathy, hepatocellular carcinoma); APRI, a measure of liver fibrosis; cardiovascular disease; autoimmune disease; hypertension; thyroid disease; psoriasis; lipodystrophy; hypercholesterolemia

Abbreviations: HR-QoL Health related quality of life, EQ-5D-3L EuroQoL-5Dimension-3Level, P6M in the past 6 months, BMI Body Mass Index, HIV Human Immunodeficiency Virus, CD4 Cluster of differentiation 4 receptor, HCV Hepatitis C virus, RNA Ribonucleic acid, AIDS Acquired Immunodeficiency Syndrome, APRI Aspartate Aminotransferase (AST) to platelet ratio