Outline. Quality of Data Linkage Megan Bohensky August Background Quality in Data Linkage Study Example Reporting Standards.

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1 Outline Background Quality in Data Linkage Study Example Reporting Standards Quality of Data Linkage Megan Bohensky August of 20

2 Benefits of Data Linkage Data Linkage is Popular Data is distributed over various departments, data systems and organisations Patient outcomes are hard to track after leaving hospital Many variables not captured in healthcare databases (e.g. detailed SES info, occupational surveillance data, carcinogen exposure data) PubMed Search of Data Linkage returned results State/National centres have been established in Australia Health data collection is rapidly growing New entities are entering the market 3 of 20 4 of 20

3 Outline Quality in Data Linkage Actual match status Background Quality in Data Linkage Study Example Reporting Standards Link status Matches Non-matches Linked Data True Links (TP) False Matches (FP) Total Links Non-links Missed matches (FN) True Negatives (TN) Total Nonlinks 5 of 20 Total matches Total Nonmatches Total Record pairs

4 Quality in Data Linkage Data Linkage Quality in Data Linkage Name Sex DoB John C Bloggs M Jack Bloggs M Name Sex DoB John C Bloggs M Joan Bloggs M Name Sex DoB John C Bloggs M J Bloggs M The accuracy of data linkage has been shown to vary by: Participants age Gender Ethnicity Native language Regional location Education level 7 of 20 Zingmond D, et al (2004). Linking hospital discharge and death records accuracy and sources of bias. J Clin Epi, 57:

5 Data Linkage Quality in Data Linkage Outline Different linkage operators have produced different results using the same software and data (Hoving et al, 2006) Different linkage software have been shown to produce different results with the same operators and data (Campbell et al, 2008) Background Quality in Data Linkage Study Example Reporting Standards 9 of of 20

6 Study Example Study Example LINKAGE VALIDATION PROJECT Linkage Variables Gold Standard URN Date of Birth Age at admission Gender Hospital Hospital LOS Hospital Admission Date Hospital Discharge Date ICU days Practical Method Age at admission Gender Hospital Hospital LOS Hospital Admission Date Hospital Discharge Date ICU days 11 of of 20

7 Study Example Study Example Gold standard (URN & DoB) Practical Method Results: Characteristics of Unmatched Cases 100.0% 80.0% % difference 2% difference % difference Characteristic Odds of being unmatched (95% CI) Gender (female vs male) 1.23 ( ) Transfer (Yes vs No) 1.44 ( ) % Linked 60.0% 40.0% Overseas-born? (Yes vs No) 1.37 ( ) Elective admission? 0.66 ( ) 20.0% 0.0% 13 of % difference Hospital A Hospital B Hospital C Hospital D Length of Hosp Stay> 20 days 2.32 ( ) 14 of 20

8 Outline Reporting Standards Background Quality in Data Linkage Study Example Reporting Standards REporting of studies Conducted using Observational Routinelycollected Data (RECORD) Extension of the STROBE guidelines (STrengthening the Reporting of OBservational studies in Epidemiology) 22 items in total 15 of of 20

9 Analysis Linkage Process Case Identification Reporting Standards Reporting Standards Item Name Description Assessed for eligibility from data source 1 (n = ) Assessed for eligibility from data source 2 (n = ) RECORD 12.3 Linkage State whether the study included person-level, institutional-level or other data linkage across two or more databases. The methods of linkage and methods of linkage quality evaluation should be provided. Records pairs evaluated* (n = ) Definite matches (n = ) Possible matches (n = ) Non-matches (n = ) Clerical review required (n= ) Excluded prior to (n = ) RECORD 13.1 Participants Describe in detail the selection of the persons included in the study (i.e., study population selection) including filtering based on data quality, data availability and linkage. The selection of included persons can be described in the text and/or by means of the study flow diagram. Total records linked (n = ) Analysed (n = ) Excluded from analysis (n = ) (give reasons) (n = ) (for which variables) Records not linked (n = ) 17 of of 20

10 Final Recommendations Thank You! 1. Increasing the use of routine data linkage will help to improve data quality 2. Systematic, quality assessment of linkage is needed 3. Ensure integrity and completeness of datasets before linkage 4. If potential linkage bias is identified, analyses should account for this 5. Data linkage studies should be reported in a clear and systematic manner 6. Unique identifiers, such as national health identifiers, would improve linkage quality 19 of of 20