University of Oulu

Helle N, Niinimäki M, Linnakaari R, et al. National register data are of value in studies on miscarriage—Validation of the healthcare register data in Finland. Acta Obstet Gynecol Scand. 2022;101:1245-1252.doi:10.1111/aogs.14445

National register data are of value in studies on miscarriage : validation of the healthcare register data in Finland

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Author: Helle, Nea1,2; Niinimäki, Maarit3,4,5; Linnakaari, Reetta1;
Organizations: 1Department of Obstetrics and Gynecology, University of Helsinki, and Helsinki University Hospital, Helsinki, Finland
2Department of Obstetrics and Gynecology, HUS Hyvinkää Hospital, Hyvinkää, Finland
3Department of Obstetrics and Gynecology, Oulu University Hospital, Oulu, Finland
4PEDEGO Research Unit, University of Oulu, Oulu, Finland
5Medical Research Center Oulu (MRC Oulu), University of Oulu, Oulu, Finland
6Department of Biostatistics, University of Helsinki, Helsinki, Finland
7Finnish Institute for Health and Welfare (THL), Helsinki, Finland
8Departments of Molecular Medicine and Surgery, and Neurobiology, Karolinska Institute, Stockholm, Sweden
9Academic Primary Health Care Center, Region Stockholm, Stockholm, Sweden
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.9 MB)
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Language: English
Published: John Wiley & Sons, 2022
Publish Date: 2023-05-29


Introduction: Despite the high prevalence of miscarriages, they are not systematically registered and few epidemiological studies have been done. As Finnish health registries are comprehensive and widely used in research, we validated the Finnish register data concerning diagnostics and treatment of miscarriage, and treatment-related adverse events.

Material and methods: We conducted a validation study regarding miscarriage-related codes of diagnoses and surgical procedures in a Finnish National Hospital Discharge Registry (NHDR) by comparing the information from the NHDR with that of the hospital records. We selected a random sample of 4 months during 1998–2016 from three hospitals, comprising 687 women aged 15–49 experiencing a first miscarriage during follow-up. Women with diagnoses unrelated to miscarriage, or proven to be other than miscarriage, were excluded. The final sample consisted of 643 women with confirmed miscarriage, which was used for analyses regarding the diagnosis, treatment and adverse events of miscarriage treatment.

Results: The majority of miscarriages registered in the NHDR were confirmed by the hospital records (positive predictive value [PPV] = 93.6% [95% confidence interval [CI] 91.8%–95.4%]). Different types of miscarriage were also reliably identified; spontaneous abortion with PPV = 85.6% (95% CI 80.9%–89.2%), missed abortion with PPV = 92.7% (95% CI 88.8%–95.3%) and blighted ovum with PPV = 91.1% (95% CI 84.3%–95.1%). The PPV of surgical treatment (62.2% [95% CI 55.7%–68.3%]) was lower than the PPV of non-surgical treatment (93.3% [95% CI 90.5%–95.3%]). The diagnoses regarding adverse events of miscarriage treatment could be reliably identified. The PPV for clinical infections was 76.0% (95% CI 56.6%–88.5%) and for retained products of conception or/and vaginal bleeding 96.8% (95% CI 83.8%–99.4%).

Conclusions: The coverage of the NHDR was good concerning identification of miscarriages, different types of miscarriages and non-surgical treatment. Nevertheless, there is a need for clearly defined procedural codes concerning to medical treatment of miscarriage. The register-based data are reliable and practicable for both clinical evaluation and research concerning miscarriage.

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Series: Acta obstetricia et gynecologica Scandinavica
ISSN: 0001-6349
ISSN-E: 1600-0412
ISSN-L: 0001-6349
Volume: 101
Issue: 11
Pages: 1245 - 1252
DOI: 10.1111/aogs.14445
Type of Publication: A1 Journal article – refereed
Field of Science: 3123 Gynaecology and paediatrics
Funding: Helsinki and Uusimaa Hospital System (EVO grant, O.H.).
Copyright information: © 2022 The Authors. Acta Obstetricia et Gynecologica Scandinavica published by John Wiley & Sons Ltd on behalf of Nordic Federation of Societies of Obstetrics and Gynecology (NFOG). This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.