Annals of internal medicine
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    This article has been corrected. The original version (PDF) is appended to this article as a Supplement. 
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    This article has been corrected. The original version (PDF) is appended to this article as a Supplement. 
- 
    
    This article has been corrected. The original version (PDF) is appended to this article as a Supplement. 
- 
    
    This article has been corrected. The original version (PDF) is appended to this article as a Supplement.