High acquisition rate and internal validity in the Scandinavian Obesity Surgery Registry

The Scandinavian Obesity Surgery Registry (SOReg) is a national quality register that has collected data on bariatric surgery in Sweden since 2007.

Evaluate the acquisition rate and internal validity of entered data in SOReg as well as completeness.

National quality register, Sweden.

The acquisition rate during 2012-2018 was compared with Swedish national databases, while registered data in 89 selected variables (67 mandatory) was compared with medical records of 1860 randomly selected patients from all bariatric centers (n = 39-43) reporting to SOReg. The evaluation was done by 1 independent observer. Completeness of data in the entire registry for the same time period was studied.

The acquisition rate was 97.4%, because 33,716 of 34,628 patients recorded in the National Inpatient Registry were registered in SOReg. Exact agreement of reabstracted data was seen in 99.0% of 100,200 unique entries. All studied variables had an almost perfect agreement with Cohen's kappa ranging from .87-1, that is, >.81 according to Landis and Koch criteria. In addition, .3% (n = 301) missing data entries were discovered, mostly in administrative variables. In the mandatory variables, overall completeness was high; however, declining with time in parallel with reduced follow-up rate, 50% at 5 years.

The high acquisition rate and internal validity implies that SOReg reflects Swedish bariatric surgery on a nationwide basis. Hence, SOReg data can be used to monitor quality of care and in research. The overall completeness could be improved by a higher registration rate during long-term follow-up.