Table 1.

Case definitions of selected chronic diseases using Ontario health administrative data

Chronic disease	Case definition	Validation
Hypertension	Either one hospital admission with a hypertension diagnosis,a or an Ontario Health Insurance Program (OHIP) claim with a hypertension diagnosis followed within two years by either an OHIP claim or a hospital admission for hypertension	Sensitivity = 72% Specificity = 95%
Myocardial infarction	One hospital admission with myocardial infarction as a most responsible diagnosis,b excluding patients transferred from another acute care hospital or discharged with a total length of stay less than three days	Sensitivity = 89% Specificity = 93%
Congestive heart failure	Aged >40 years, and either one hospital admission with a congestive heart failure diagnosis,c or one OHIP claim/emergency department record with a congestive heart failure diagnosis followed within one year by a second record from either source or one hospital admission	Sensitivity = 85% Specificity = 97%
Diabetes mellitus	Either one hospital admission with diabetes mellitus diagnosis,d or an OHIP claim followed within two years by either an OHIP claim or a hospital admission with diabetes mellitus diagnosis	Sensitivity = 86% Specificity = 97%
Dementia	Aged >20 years, and either one hospital admission with a diagnosis of dementia,e or at least three OHIP claims for dementia within two years, or at least one prescription for drugs relating to dementia	Sensitivity = 75% Specificity = 99%
Parkinsonism	Aged >20 years, and either at least two OHIP claims for Parkinsonism within one year, f or at least one prescription for Parkinsonism and one OHIP claim within six months either before or after the drug prescription	Sensitivity = 78% Specificity = 100%
Multiple sclerosis	Aged >20 years, and either one hospital admission with a Multiple sclerosis diagnosis,g or five or more OHIP claims within two years	Sensitivity = 84% Specificity = 100%

^aHypertension: ICD-9 401-405; ICD-10 code I10-I13 or I15.

^bMyocardial infarction: ICD-9 code 410; ICD-10 code I21.

^cCongestive heart failure: ICD-9 code 428; ICD-10 code I50.

^dDiabetes: ICD-9 code 250; ICD-10 code E10-E14.

^eDementia: ICD-9 code 046.1, 290.0-290.4, 294, 331.0, 331.1, 331.5; ICD-10 code G30, F00-F03.

^fParkinsonism: ICD-9 code 332.0-332.1; ICD-10 code G20, G21.0-G21.4, G21.8-G21.9, G22, F02.3.

^gMultiple sclerosis: ICD-9 code 340; ICD-10 code: G35.