- Correspondence to Dr Hjalmar Wadström, Clinical Epidemiology Unit, Department of Medicine Solna, Karolinska Institutet, Stockholm, SE 171-76, Sweden;
- Received July 16, 2015
- Revised November 1, 2015
- Accepted December 14, 2015
- First published January 11, 2016.
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- Data supplement 1 - Online supplement
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