Pediatric spinal cord injury in Sweden; how to identify a cohort of rare events

Abstract

Study design: Register study enhanced and verified by medical records and personal interviews and examinations. Settings: Sweden. Objectives: To define a method of identifying a study population of rare events. To point out the relative importance of every step, an example is given of identifying persons who sustained traumatic spinal cord injury (SCI) in childhood. Methods: Cases were identified in seven steps that all needed to be fulfilled, from definition of selection criteria through combination of several data sources, to the use of several verification methods. Results: Initial screening by registers identified 384 possible cases, which however were found by subsequent analysis to include a large number of incorrect cases. At completion of all analytic steps, 35 living cases could be fully verified and 14 deceased cases could be partially verified. Conclusions: Registers offer a practical initial source for study population identification. The screening of International Classification of Diseases codes defining SCI only included less than 30% of 'true' SCIs. Subsequently, further refinement and quality control is necessary in order to ensure validity. Such further verification is time-consuming, but nevertheless necessary in order to verify a true cohort.

Traumatic spinal cord injury among children and adolescents; a cohort study in western Norway

“…2 Dislocation of other and unspecified parts of neck S13. 4 Sprain and strain of cervical spine S14.0 Concussion and edema of cervical spinal cord S14. 1 Other and unspecified injuries of cervical spinal cord S22.0…”

“…Only a few population-based estimates of paediatric TSCI exist. 3,4 The incidence of spinal cord injuries was 1.9 per million among children aged 0-18 years in Finland in the period 1997-2006. 3 A study from Sweden found an incidence of 4.6 per million children.…”

“…3 A study from Sweden found an incidence of 4.6 per million children. 4 If pre-hospital fatalities were excluded, the incidence was 2.4 per million. 4 We have previously reported the incidence of TSCI in western Norway (an unselected geographically defined cohort) during 50 years.…”

“…4 If pre-hospital fatalities were excluded, the incidence was 2.4 per million. 4 We have previously reported the incidence of TSCI in western Norway (an unselected geographically defined cohort) during 50 years. 5,6 In this study, we assess the temporal trends of the age-adjusted incidence of TSCI, and demographic characteristics among children and adolescences.…”

On the need of validating inpatient registers

“…4 A common problem for many administrative database researchers is whether the diagnosis code in question detects all true cases in these databases, for example. 5 Blomqvist 4 discusses three methodological approaches for assessing the completeness of registration of cases. The first is to compare the data source with several other independent data sources, the second is review of medical records and the third builds on a comparison between total number of cases in different sources.…”