Author

Data Source

Diagnosis/Treatment Codes and Algorithms

Study Cohort

Validation Methodology

Comments

Erzen et al. (1995)

Country: Canada

Source: Physician claims from Manitoba Health

Years: 1983 and 1988

Codes: ICD-9-CM 493

Algorithm: One or more contacts in physician billing claims.

All ages were examined and then grouped as follows: 0-14 years, 15-34 years, 35+ years

There was no validation data source. Specificity, sensitivity and predictive values are not reported.

Morrison et al. (2001)

Country: Scotland , UK

Source: Scottish Morbidity Records

Years: 1981-1997

Codes: ICD-9 493

ICD-10 J45, J46

Algorithm: A patient’s first admission for asthma was labelled as the first admission; all subsequent admissions were labelled as readmissions.

Age of cohort was not specified.

There was no validation data source. Specificity, sensitivity and predictive values are not reported.

Huzel et al. (2002)

Country: Canada

Source: Physician billing claims from Manitoba Health

Years: 1993-1994

Codes: ICD-9 493

Algorithm: One or more contacts in physician billing claims

20 to 44 years of age

Survey data

Max Sens = 70.1%

Max Spec = 99.8%

Max κ = 0.62

“Even if five years of physician contacts were studied, the claims identified only 63.3% of people reporting an asthma attack in the 12 months before the survey, 65.1% of people reporting being on medication, 62.0% of those reporting either an attack or using medication , and 70.1% of those reporting both an attack and using medication.” p.410

Hansell et al. (2003)

Country: England

Source: Mortality data from the Office for National Statistics (ONS; 1991-1995).

Hospital Episode Statistics (HES) from the Dept. of Health (1990/91 to 1993/94) and from the Data Science UK (1994/95). General Practice Research Database (GPRD; 1991-1995)

Codes: ICD-9 493

Algorithms: From HES, emergency hospital admissions with the ICD-9 code as a primary diagnosis were abstracted. From GPRD, patients who consulted in primary care with an inhaler prescription during the current year plus a current or prior diagnosis of asthma in each year from 1991-1995 were identified.

Survey included ages 2 years and above.

Health Survey of England , 1995.

Specificity, sensitivity and predictive values are not reported.

“There was little consistency in patterns for asthma from the different data source.” p. 281

Kozyrskyj et al. (2004)

Country: Canada

Source: Hospital separations, physician billing claims, prescription drug records from Manitoba Health.

Years: 1995-1998

Codes: ICD-9 493

Algorithms: At least one physician claim or hospitalization for asthma-like diagnoses in one year. In the absence of these diagnoses, at least one prescription for an inhaled corticosteroid or cromone, or ketotifen concomitant with an inhaled or oral beta-agonist, or two or more prescription for an inhaled or oral beta-agonist.

Ages 5-15 years

A prescription for an asthma drug was used as the gold standard.

Max Sens = 73.9%

Max Spec = 91.4%

Borzecki et al. (2004)

Country: USA

Source: Out-patient clinic (OPC) file for 1998 and 1999, and patient treatment file (1999), from a National Department of Veterans Affairs electronic database.

Codes: ICD-9 chronic obstructive lung disease/asthma 490.x, 491.x (all except for 491.8), 492.0, 493.x, 496.x

Algorithms: Varied the minimum required number of claims with a given diagnosis from 1 to 2 and varied the number of years of data from 1 to 2.

Outpatients receiving primary care at 10 different sites across the country.

Electronic clinicians’ notes (i.e., medical outpatient charts).

Max. Spec = 92%

Max. Sens = 81%

Max κ = 0.68

Wilchesky et al. (2004)

Country: Canada

Source: Medical claims from Quebec

Year: 1995-1996

Codes: ICD-9-CM 493.0-493.9

Algorithm: One or more medical claims with the relevant ICD-9-CM code

66 years of age and older

Physicians’ charts

Max Sens = 43%

Max Spec = 99%

Macy et al. (2005)

Country: USA

Source: Southern California Kaiser Permante hospital, outpatient, and prescription data

Year: 2001

Codes: ICD-9-CM 493.xx

Drug codes were not specified, but included β-agonists (excluding oral terbutaline), orally inhaled corticosteroids, other inhaled anti-inflammatory drugs, and oral leukotriene modifiers.

Algorithm: Any discharge diagnosis of asthma in the hospitalization database; or two or more asthma-related medication dispensations in the prescription database; or any ED or regular clinic asthma-related claim in the outpatient diagnosis and procedures database.

18-64 years

Medical chart review and questionnaire/ examinations.

Specificity, sensitivity and predictive values are not reported.

Schatz et al. (2005)

Country: USA

Source: Southern California Kaiser-Permanente asthma database (linked hospital discharge database, outpatient diagnosis and procedures database, a membership database, and a prescription database)

Year: 2002-2003

Codes: ICD-9 493.xx

Algorithms: One or more of the following criteria in the prior 12 months: 1) Any hospital discharge diagnosis of asthma in the hospitalization database (ICD code), 2) the dispensing of two or more asthma-related dispensings (excluding oral steroids), including β-agonists, inhaled steroids, other inhaled anti-inflammatory drugs, and oral leukotriene modifiers, 3) an asthma related visit to the ED or regular clinic listed in the diagnosis and procedures database

Ages 5-56

No validation source was used

Specificity, sensitivity and PPV are not calculated.