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Table 1 Identification criteria utilized in the published studies. Part A: Studies with low risk of bias (in chronological order)

From: Algorithms to identify COPD in health systems with and without access to ICD coding: a systematic review

Authors, publication year, country Dataset used Study population / COPD population Age limitation ICD codes Hospitalization Ambulatory visit Physician claims (ambulatory) Pharmacotherapy Spirometry Oxygen therapy COPD-related surgical procedure Algorithm Risk of bias
(low or high)
Gershon et al. (2009)
Canada [22]
- Ontario Health Insurance Plan
- Canadian Institute of Health Information discharge abstract Db
SP: 442
COPD-P: 113
X   X X       Years > 35.
At least one ambulatory claim and/or at least one COPD hospitalization
low
(validated algorithm: sensitivity 85%, specificity 78.4%.
Reference standard: expert opinion)
Gershon et al. (2010)
Canada [23]
- Ontario Health Insurance Plan Db
- Canadian Institute for Health Information Db records
- Ontario Registered Persons Db
1996:
SP: 5,548,341 COPD-P: 430,000
2002:
SP: 6,444,492 COPD-P: 603,770
2007:
SP: 7,082,086 COPD-P: 708,743
X X X X X      Years > 35.
At least one COPD physician billing claims and /or at least one COPD hospital discharges (ICD code 491, 492, 496 or J41-J44).
low
(validated algorithm: sensitivity of 85.0% and a specificity of 78.4% - Gershon et al. 2009)
Cooke et al. (2011)
United States [24]
- Two departments of Veterans Affairs inpatient and outpatient Db SP: 9,573
COPD-P: 4,564
X X X X   X X    Years ≥40
1. FEV1/FVC < 0.70
2. FEV1/FVC < lower limits than normal.
low
(Algorithm: sensitivity 72%, specificity 74%.
Reference standard: spirometry)
Gershon et al. (2011)
Canada [25]
- Registered Persons Db
- Canadian Institute of Health Information Discharge Abstract Db
- Ontario Health Insurance Plan Physician claims data
SP: 13,022,536
COPD-P: 579,466
X X X X       Years > 35.
ICD-9491, 492, 496; ICD-10 J41-J44.
One hospitalization or One ambulatory care visit (general definition) / three or more ambulatory care visits in a 2 year period (second, specific COPD definition).
low
(validated algorithm: sensitivity of 85.0% and a specificity of 78.4% - Gershon et al. 2009)
Austin et al. (2012)
Canada [26]
- The Ontario Chronic Obstructive Pulmonary Disease Db
- The Registered Persons Db
- The Canadian Institute for Health Information, Discharge Abstract Db
- The Ontario Health Insurance Plan physician billing Db
- The Ontario Mental Health Reporting System
COPD-P: 216,735 incident
COPD-P: 638,926 prevalent
X X X   X      Years > 35
1. At least one physician billing claims or
2. At least one COPD hospital discharge: ICD-9 codes 491, 492, or 496; ICD-10 codes: J41, J42, J43 or J44.
low
(Algorithm: sensitivity 85.0%, specificity 78.4%.
Reference standard: expert opinion-based on Gershon et al. 2009)
Gershon et al. (2013)
Canada [27]
- Registered Persons Db
- Canadian Institute of Health Information Discharge Abstract
- National Ambulatory Care Reporting System Db
- Ontario Health Insurance Plan Physician Claims Db
- Ontario Home Care Db
- Ontario Drug Benefits Db
SP: 7,246,982
COPD-P: 853,438
X   X X X      Physician-diagnosed COPD:
1. Years > 35 and
2. Having one hospitalization related to the COPD and/or
3. One ambulatory care claim related to the COPD.
low
(Algorithm: sensitivity 85.0%, specificity 78.4%.
Reference standard: expert opinion-based on Gershon et al. 2009)
Gershon et al. (2014)
Canada [28]
- The Registered Persons Db
- The Canadian Institute of Health Information Discharge Abstract Db
- The Ontario Health Insurance Plan Physician Claims Db
SP: 13,000,000
COPD-P: 807,046
X X X   X      Years ≥35.
1. At least one COPD physician billing claims and/or
2. At least one COPD hospital discharge as per the following codes: 491, 492, 496 ICD-9 or J41, J42, J43, J44 ICD-10
low
(Algorithm sensitivity 85%, specificity 78% when compared with clinical evaluation)
Gershon et al. (2015)
Canada [29]
- The Registered Persons Db
- The Canadian Institute of Health Information Discharge Abstract
- The Ontario Health Insurance Plan Physician Claims Db
- Ontario Registrar General Death Db
SP: 7,626,745
COPD-P: 836,139
X X X X X      Years > 35
COPD: ICD-9 and ICD-10
1. At least one COPD physician billing claims and/or
2. At least one COPD hospital discharge.
low
Algorithm: sensitivity 85.0%, specificity 78.4%.
Reference standard: expert opinion (based on Gershon et al. 2009).
Crighton et al. (2015)
Canada [30]
- The Registered Persons Db
- The Canadian Institute of Health Information Discharge Abstract Db
- The Ontario Health Insurance Plan Physician Claims Db
- National Ambulatory Care Reporting System Db
SP: NA
COPD-P: 722,494
X X X X X      Years ≥35.
1. One or more COPD hospitalizations and/or
2. One ambulatory care claim (ICD-9: 491, 492, 496 or ICD-10: J41, J42, J43, J44)
low
Algorithm: sensitivity 85.0%, specificity of 78.4%.
Reference standard: physician clinical evaluation
Doucet et al. (2016)
Canada [31]
- linked health administrative data:
(1) the health insurance registry of the R’egie de l’assurance maladie du Qu’ebec (RAMQ),
(2) fee-for-service data (physician billing),
(3) hospital discharge
(4) drug data for the 65 years and older,
(5) mortality data.
SP: NA
COPD-P: 444,709
X X X   X      1. One or more visits to a physician
2. One hospitalization with a COPD diagnosis
3. Years ≥35
ICD-9 codes 491–492 and 496 or ICD-10-CA J41–44.
low
(validation against clinical reference standard: sensitivity of 85% (95% CI: 77.0 to 91.0%) and a specificity of 78.4% (95%CI: 73.6 to 82.7%)
Romanelli et al. (2016)
Italy [32]
- Hospital discharge register (HDR)
- The cause-specific mortality register (CMR)
- Clinical and spirometric data from clinical (hospital or outpatient) charts at the Institute of Clinical Physiology (ICP) of the National Research Council (NRC)
SP: NA
COPD-P: 2,544
X X X X    X    years ≥40
1. Hospital discharge with a primary or secondary COPD diagnosis (ICD-9: 490, 491, 492, 494, 496) or
2. Received a diagnosis of COPD in hospital or outpatient charts or
3. FEV1/FVC < 0.70 at spirometry or
4. COPD as a cause of death.
low
(validation from clinical and spirometric data)
Gershon et al. (2017)
Canada [33]
- 4 government health administrative databases:
(1) The Registered Persons Database
(2) The Ontario Health Insurance Plan Physician Claims database
(3) The Canadian Institute of Health Information Discharge Abstract database
(4) the National Ambulatory Care Reporting System
Data were linked using unique encoded identifiers
SP: NA
COPD-P: 874,336
X X X X       Years ≥35.
1. One or more COPD ambulatory care visits and/or
2. One or more COPD hospitalizations
COPD ICD-10 codes J41–J44
low
(validation against clinical reference standard was 85.0% sensitivity and 78.4% specificity)
Lee et al. (2017)
Canada [34]
data from the Electronic Medical Record Administrative data Linked Database (EMRALD®) SP: 5,889
COPD-P: 364
X X    X X     years ≥35
several electronic medical record algorithms; the one with best validation results included:
1. Three or more physician billing codes for COPD per year;
2. Documentation in the cumulative patient profile (CPP);
3. Tiotropium prescription; or ipratropium (or its formulations) prescription and
4. A COPD billing code
low
(validation against an abstracted patient chart reference standard: sensitivity of 76.9% (95% CI:72.2–81.2), specificity of 99.7% (99.5–99.8)
McGuire et al. (2017)
Canada [35]
- Ministry of Health of British Columbia administrative databases on provincially funded health services.
PharmaNet data on all medications
- Data on deaths (from death certificates)
SP: 50,021
COPD-P: 594
  X X   X      ICD-9 codes 491, 492, 493.2, 496, or ICD-10 codes J43 or J44 in hospital/outpatient physician visit data.
Primary outcome: first COPD hospitalization
low
(used an algorithm which was validated against a clinical reference standard by Gershon et al. 2009)
Westney et al. (2017)
United States [36]
- Medicaid Analytic eXtract (MAX) file from Centers for Medicare and Medicaid Services SP: NA
COPD-P: 291,978
X X X X       Years 18–64
1. ICD −9 codes 491.0, 491.1, 491.2, 491.8, 492.xx, 493.2, 494.xx, 496.xx and
2. One or more inpatient billed claims from the inpatient file or at least two outpatient billed claims
low
(used a validated algorithm from Gershon et al. 2009)
  1. The next-to-last column on the right gives the identification criteria based on the statements contained in the publication
  2. SP Study population, COPD COPD-P population, Db Database, NA Not available; see also list of abbreviations