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Open Access Correspondence

External review and validation of the Swedish national inpatient register

Jonas F Ludvigsson12*, Eva Andersson3, Anders Ekbom2, Maria Feychting4, Jeong-Lim Kim3, Christina Reuterwall56, Mona Heurgren7 and Petra Otterblad Olausson7

Author Affiliations

1 Department of Paediatrics, Örebro University Hospital, Sweden

2 Clinical Epidemiology Unit, Department of Medicine, Karolinska University Hospital, Karolinska Institutet, Sweden

3 Section of Occupational and Environmental Medicine, University of Gothenburg, Sweden

4 Institute of Environmental Medicine, Karolinska Institutet, Sweden

5 Research Unit, Jämtland County, Sweden

6 Department of Public Health and Clinical Medicine, Umeå University, Sweden

7 Department of Statistics and Analyses, National Board of Health and Welfare, Stockholm, Sweden

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BMC Public Health 2011, 11:450  doi:10.1186/1471-2458-11-450

Published: 9 June 2011

Abstract

Background

The Swedish National Inpatient Register (IPR), also called the Hospital Discharge Register, is a principal source of data for numerous research projects. The IPR is part of the National Patient Register. The Swedish IPR was launched in 1964 (psychiatric diagnoses from 1973) but complete coverage did not begin until 1987. Currently, more than 99% of all somatic (including surgery) and psychiatric hospital discharges are registered in the IPR. A previous validation of the IPR by the National Board of Health and Welfare showed that 85-95% of all diagnoses in the IPR are valid. The current paper describes the history, structure, coverage and quality of the Swedish IPR.

Methods and results

In January 2010, we searched the medical databases, Medline and HighWire, using the search algorithm "validat* (inpatient or hospital discharge) Sweden". We also contacted 218 members of the Swedish Society of Epidemiology and an additional 201 medical researchers to identify papers that had validated the IPR. In total, 132 papers were reviewed. The positive predictive value (PPV) was found to differ between diagnoses in the IPR, but is generally 85-95%.

Conclusions

In conclusion, the validity of the Swedish IPR is high for many but not all diagnoses. The long follow-up makes the register particularly suitable for large-scale population-based research, but for certain research areas the use of other health registers, such as the Swedish Cancer Register, may be more suitable.

Keywords:
Classification of diseases; disease; epidemiology; morbidity; register