Aim: To describe differences between reported and non reported data in the out-of-hospital cardiac arrest (OHCA) register in Sweden.
Methods: Prospective and retrospective data of treated OHCA patients in Sweden, 2008-2010 were compared in the Swedish OHCA register. Data were investigated in three Swedish counties with various recording models. Prospective data are those reported by the ambulance crew and retrospective data those missed by the ambulance crew but discovered afterwards by crosschecking with the local ambulance register.
Result: In 2008-2010, the number of prospective reported cases was n=2, 398 and retrospective cases n=3, 198 which indicates a 25% missing rate.
When comparing the two groups, the mean age was higher in patients who were reported retrospectively (69 years versus 67 years; p=0.003). There was no difference between groups with regard to sex, time of day and year of OHCA, witnessed status or initial rhythm.
However, bystander CPR was more frequent among patients in who were reported prospectively (65% versus 60%; p= 0.023) where as survival to 1 month was higher among patients who were reported retrospectively (9,2% versus 11,9%;p=0.035)
Conclusion: Among 3, 198 cases of OHCA in three regions in Sweden 800 (25%) were not reported prospectively by the ambulance crew but retrospectively when discovered as missing cases. Patients who were reported retrospectively differed from prospectively reported cases by being older, less frequently receiving bystander CPR but having a higher survival. Our data suggest that patients who suffer OHCA and are prospectively reported to a quality register may be influenced by selection bias.
2013.