Table 1

International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes used in this study

DescriptionICD-9-CM codes
Poisoning-related diagnoses
 Unintentional alcohol poisoningE860
 Unintentional drug poisoningE850–E858
  Illicit opioids (including opium and heroin)E850.0 (965.00, 965.01)*
  Prescription opioids (including methadone, and other opiates and related narcotics)E850.1–E850.2 (965.02, 965.09)*
  Non-opioid analgesicsE850.3–E850.9 (965.1–965.9)*
  Sedatives/hypnotics (including barbiturates)E851–E852, 967*
  Tranquilisers (including benzodiazepines)E853 (969.1–969.5)*
  AntidepressantsE854.0, 969.0*
  Other psychotropic agentsE854.1–E854.8 (969.6–969.9)*
  Drugs acting on central and autonomic nervous systemE855 (966, 968, 971)*
  Other drugs (antibiotics, other anti-infectives and all other drugs†)E856–E858 (960–964, 972–979)*
Substance use disorder-related diagnoses
 Alcohol dependence syndrome303.0–303.9
 Drug dependence304.0–304.9
 Tobacco use disorder305.1
Mood and anxiety disorder-related diagnoses
 Bipolar disorders296.0–296.1, 296.4–296.9
 Depressive disorders293.83, 296.2, 296.3, 300.4, 311
 Anxiety disorder293.84, 300.0–300.3, 300.5, 300.89, 300.9, 308, 309.81, 313 (minus 313.23, 313.81, 313.89, 313.9)
  • *When external-cause-of-injury codes (E-codes) for poisoning by the specific type of drug were not available, these additional diagnosis codes were used to identify the drug type.

  • †‘All other drugs’ include hormones and synthetic substitutes; primarily systemic agents; agents affecting blood constituents, cardiovascular system, gastrointestinal system, smooth and skeletal muscles and respiratory system, skin and mucous membrane, and ophthalmological, otorhinolaryngological and dental drugs; water, mineral and uric acid metabolism drugs; and other specified/unspecified drugs.

  • Source: Commission on Professional and Hospital Activities.39 The International Classification of Diseases, Ninth Revision, Clinical Modification. Ann Arbor, Michigan, 1978.