Evaluating the advice on screening regimes for newly arrived asylum seekers: a register based cohort study

Abstract

Background: There is an ongoing discussion on how antimicrobial resistant microbes should best be handled. During 2015, many European countries received a high number of asylum seekers. In Norway, some doctors chose to screen all asylum seekers for methicillin-resistant Staphylococcus aureus (MRSA), a practice that the Norwegian Institute of Public Health advised against, because it might have delayed the tuberculosis (TB) screening. TB is a prevalent and life threatening disease among newly arrived asylum seekers. This study is done to evaluate the advice to refrain from screening the newly arrived asylum seekers for MRSA. Methods: To evaluate this advice, a retrospective cohort study using data from the Norwegian Surveillance System for Communicable Diseases (MSIS register) was done. The epidemiology of MRSA and TB among the newly arrived asylum seekers in 2014, 2015 and 2016 was described. Tests for association and difference were done with Pearson’s r and t tests. A probabilistic comparative risk assessment model with Markovian properties was then built using these data and values found in the literature as parameters to investigate the consequences of different scenarios. A Monte Carlo simulation with 1000 iterations of the model was performed. Results: The estimated incidence proportion of MRSA in this group is 0.74 % with a 95 % confidence interval of 0.34 % to 1.14 %. Of all the MRSA cases found, 23.2 % were positive for Panton-Valentin leucocidin toxin. The detection rate of TB in the entire period is 0.30 %. 2 cases of TB were MDR-TB, whereof 1 was XDR-TB. There was no association between MRSA and resistant active TB infection, and a clinically irrelevant association between notified MRSA and active TB infection (correlation coefficient of 0.012, p=0.013). The model showed that a MRSA screening program could avoid 9 MRSA infections and 0 MRSA attributable deaths, while a TB screening program could avoid 55 TB infections and 2 TB attributable deaths. Conclusion: The advice to prioritize the TB screening program was correct. There is no indication to screen for MRSA other than to prevent transmission at the TB diagnostic station, which is unnecessary. This will require waiting for the MRSA test result before screening for TB – a screening that can avoid more disease and death. The group of newly arrived asylum seekers have a heterogeneous risk set for these infectious diseases, and screening programs for MRSA and TB should be adjusted correspondingly. The difference in risk sets leave little room for synergy between the two infection control measures.