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Marra CA, Esdaile JM, Guh D, Kopec JA, Brazier JE, Koehler BE, Chalmers A, Anis AH.Marra CA, et al. Among authors: guh d.Med Care. 2004 Nov;42(11):1125-31. doi: 10.1097/00005650-200411000-00012.Med Care. 2004.PMID: 15586840