Substance use treatment; Detoxification; Outpatient; Outpatient detoxification; Outpatient methadone/buprenorphine or naltrexone treatment; Methadone used in Treatment; Does not treat alcohol use disorder; Federally-certified Opioid Treatment Program; Methadone maintenance; Methadone maintenance for predetermined time; Methadone; Motivational interviewing; Relapse prevention; Substance use disorder counseling; Private for-profit organization; State Substance use treatment agency; State department of health; Commission on Accreditation of Rehabilitation Facilities (CARF); SAMHSA certification for opioid treatment program (OTP); Drug Enforcement Agency (DEA); Cash or self-payment; Comprehensive substance use assessment; Interim services for clients; Complete medical history/physical exam; Screening for substance use; Drug and alcohol oral fluid testing; Drug or alcohol urine screening; HIV testing; STD testing; TB screening; Testing for Hepatitis B (HBV); Testing for Hepatitis C (HCV); Discharge Planning; Naloxone and overdose education; Outcome follow-up after discharge; Housing services; Assistance with obtaining social services; Opioids detoxification; Medication routinely used during detoxification; HIV or AIDS education, counseling, or support; Hepatitis education, counseling, or support; Health education services other than HIV/AIDS or hepatitis; Substance use disorder education; Smoking/vaping/tobacco cessation counseling; Individual counseling; Smoking permitted without restriction; Adults; Young adults; Female; Male; Opioid use disorder clients only; Vaping permitted without restriction; Case management service; Early intervention for HIV; Integrated primary care services