{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,6]],"date-time":"2026-03-06T02:17:41Z","timestamp":1772763461253,"version":"3.50.1"},"reference-count":28,"publisher":"BMJ","issue":"12","content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Open"],"accepted":{"date-parts":[[2019,12,5]]},"published-print":{"date-parts":[[2019,12]]},"abstract":"<jats:sec>\n                    <jats:title>Objectives<\/jats:title>\n                    <jats:p>To assess validity of record linkage using multiple indirect personal identifiers to identify same-patient hospitalisations and definition of episode of care (EC) due to acute coronary syndrome (ACS).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Using national hospital discharge data to identify all admissions due to ACS, we used six different linkage rules using indirect identifiers with increasing level of detail and compared validity against a pseudonymised unique identifier used as gold standard (GS). Contiguous hospitalisations within each matched group of hospitalizations occurring within 28\u2009days of each other were considered one EC. We classified hospitalisations according to time between the first pair of hospitalisations as hospital transfer (HT: \u22641\u2009day), early readmission (ER: 2\u201328 days) or recurrent cases (&gt;28 days).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>There were 146\u2009671 hospitalisations (unlinked), 121\u2009987 ACS 28-day EC (linked GS), with 18\u2009398 HTs (\u22641\u2009day), and 6286 ERs (\u226428 days). Linkage rules using demographic and residence code variables produced linkage rates with highest validity for rule using sex, date of birth and four-digit residence code with sensitivity of 98.4 (95% CI: 98.4 to 98.5); specificity of 97.8 (95% CI: 97.6 to 98.0) and Cohen\u2019s \u03ba of 0.9 to detect ACS-EC, compared with GS linkage rule. Similarly, validity for HT and ER was high and of similar magnitude, with sensitivity ranging between 97.2% and 98.1%, and specificity between 98.8% and 99.9%, respectively.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Our internal linkage validation study using indirect patient identifiers will allow calibration of incidence rates and performance indicators, accounting for the effect of HT and readmissions.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1136\/bmjopen-2019-033486","type":"journal-article","created":{"date-parts":[[2019,12,31]],"date-time":"2019-12-31T05:05:15Z","timestamp":1577768715000},"page":"e033486","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":5,"title":["Internal deterministic record linkage using indirect identifiers for matching of same-patient hospital transfers and early readmissions after acute coronary syndrome in a nationwide hospital discharge database: a retrospective observational validation study"],"prefix":"10.1136","volume":"9","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0824-4598","authenticated-orcid":false,"given":"Afonso","family":"Rocha","sequence":"first","affiliation":[{"name":"Center for Health Technology and Services Research (CINTESIS), University of Porto-Faculty of Medicine, Porto, Portugal"},{"name":"Cardiovascular Rehabilitation Unit, Physical Medicine and Rehabilitation, Centro Hospitalar Universit\u00e1rio Sao Joao EPE, Porto, Portugal"}]},{"given":"Lu\u0131s Filipe","family":"Azevedo","sequence":"additional","affiliation":[{"name":"Department of Health Information and Decision Sciences (CIDES) & Center for Health Technology and Services Research (CINTESIS), University of Porto-Faculty of Medicine, Porto, Portugal"}]},{"given":"J C","family":"Silva Cardoso","sequence":"additional","affiliation":[{"name":"Department of Cardiology, Centro Hospitalar Universit\u00e1rio S\u00e3o Jo\u00e3o, University of Porto-Faculty of Medicine, Porto, Portugal"}]},{"given":"Thomas G","family":"Allison","sequence":"additional","affiliation":[{"name":"Department of Cardiovascular Medicine and Cardiovascular Surgery, Mayo School of Medicine, Rochester, Minnesota, USA"}]},{"given":"Alberto","family":"Freitas","sequence":"additional","affiliation":[{"name":"Department of Health Information and Decision Sciences (CIDES) & Center for Health Technology and Services Research (CINTESIS), University of Porto-Faculty of Medicine, Porto, Portugal"}]}],"member":"239","published-online":{"date-parts":[[2019,12,30]]},"reference":[{"key":"2025121408033780000_9.12.e033486.1","doi-asserted-by":"crossref","DOI":"10.1186\/s12913-016-1489-0","article-title":"Methodological issues on the use of administrative data in healthcare research: the case of heart failure hospitalizations in Lombardy region, 2000 to 2012","volume":"16","author":"Mazzali","year":"2016","journal-title":"BMC Health Serv Res"},{"key":"2025121408033780000_9.12.e033486.2","doi-asserted-by":"crossref","DOI":"10.1136\/bmjopen-2017-019226","article-title":"Exploring the effects of transfers and readmissions on trends in population counts of hospital admissions for coronary heart disease: a Western Australian data linkage study","volume":"7","author":"Lopez","year":"2017","journal-title":"BMJ Open"},{"key":"2025121408033780000_9.12.e033486.3","doi-asserted-by":"crossref","unstructured":"Ib\u00e1nez B , James S , Agewall S , et al . 2017 ESC guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation. 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