Table 1

Definitions used to ascertain Alzheimer’s disease, Parkinson’s disease, motor neuron disease, amyotrophic lateral sclerosis, Alzheimer’s and other dementias, and parkinsonism in this study

Neurodegenerative diseaseDiagnostic codes in DAD and NACRS
(ICD-10-CA)19
Diagnostic codes in OHIP20 Case definition
Disease follow-up period:
1 January 2006 to 31 December 2016
Disease follow-up period:
1 January 1999 to 31 December 2016
Alzheimer’s diseaseG30At least one record with one diagnostic code in any diagnostic field in DAD or NACRS
Parkinson’s diseaseG20
Motor neuron diseaseG12.2
Amyotrophic lateral sclerosisG12.20
‘Alzheimer’s and other dementias’F00, F01, F02, F03, G30290, 331At least one record with one diagnostic code in any diagnostic field in DAD or NACRS or at least two physician encounters with at least one diagnostic code in OHIP within 12 months
ParkinsonismG20, G21.0–0.4, G21.8–9, G22, F02.3332
  • The OHIP code 290 refers to dementia, and code 331 denotes to other cerebral degenerations, which includes Alzheimer’s disease, but Alzheimer’s disease cannot be differentiated from code 331.20

  • DAD, Discharge Abstract Database; NACRS, National Ambulatory Care Reporting System; OHIP, Ontario Health Insurance Plan Claims Database; ICD-10-CA: International Statistical Classification of Diseases and Related Health Problems, Tenth Revision.;