 |
 |
Dear Tim: I've struggled with these issues in a study in which we looked at levels of evidence provided by the urological literature. My take would be that your study should be categorized as level 4 since you did not prospectively study two (parallel) cohorts over time. Your retrospective component is the weakest link, so to speak. I'd be interested to hear what others have to say. Ph* Philipp Dahm, MD, MHSc, FACS Associate Professor of Urology, Associate Residency Program Director & Director of Clinical Research Department of Urology University of Florida College of Medicine, Health Science Center Box 100247, Room N2-15 Gainesville, FL 32610-0247 Phone: (352) 273-7647 Fax: (352) 392-8846 Email: [log in to unmask] This communication may contain information that is legally exempt from disclosure. If you are not the intended recipient, please note that any dissemination, distribution or copying of this communication is strictly prohibited. Anyone who receives this message in error should notify the sender immediately by telephone, or by return email and delete the message from their computer. -----Original Message----- From: Evidence based health (EBH) [mailto:[log in to unmask]] On Behalf Of Olive Goddard Sent: Tuesday, April 01, 2008 9:26 AM To: [log in to unmask] Subject: Re: FW: Question on level2b or level4 for publication? Dear Colleagues, I have received the following query from Tim Blackburn ([log in to unmask]) If anyone could help him I am sure he would be most grateful. All good wishes, Olive I wondered if I might presume to ask for your advice on how to classify the Oxford level of evidence for my paper. I am submitting a paper on a non-concurrent (before-and-after study) cohort study with 13% loss to follow up. The cohorts are consecutively recruited but the 'before' cohort was retrospective and the 'after' one was prospectively studied in a non-blinded way. Would you classify this as level 2b, or 4 due to lack of identical outcome measurement (i.e. retrospective and prospective) using the Oxford system? The primary outcome measures are hard objective data - pre-op and postop haemoglobin measurements plus numbers of units of blood transfused in the interim (from which a bleeding index is then derived). I am seeking an independent expert in literature reviewing such as yourself who may be familiar with the Oxford CEBM levels of evidence system. I will fully understand if you are too busy to reply to this presumption on your time. Warm regards Tim Blackburn FRCS(OMFS)(Ed) FRCS(Clin Surg in Gen)(Ed) FDSRCS(Eng) MBBS(Hons)(Lon) BDS(Hons)(Lon) Consultant Oral Maxillofacial Head & Neck Reconstructive Surgeon, Manchester Royal Infirmary T: +44 (0)7885 294097 -----Original Message----- From: Evidence based health (EBH) [mailto:[log in to unmask]] On Behalf Of Olive Goddard Sent: Tuesday, April 01, 2008 9:26 AM To: [log in to unmask] Subject: Re: FW: Question on level2b or level4 for publication? Dear Colleagues, I have received the following query from Tim Blackburn ([log in to unmask]) If anyone could help him I am sure he would be most grateful. All good wishes, Olive I wondered if I might presume to ask for your advice on how to classify the Oxford level of evidence for my paper. I am submitting a paper on a non-concurrent (before-and-after study) cohort study with 13% loss to follow up. The cohorts are consecutively recruited but the 'before' cohort was retrospective and the 'after' one was prospectively studied in a non-blinded way. Would you classify this as level 2b, or 4 due to lack of identical outcome measurement (i.e. retrospective and prospective) using the Oxford system? The primary outcome measures are hard objective data - pre-op and postop haemoglobin measurements plus numbers of units of blood transfused in the interim (from which a bleeding index is then derived). I am seeking an independent expert in literature reviewing such as yourself who may be familiar with the Oxford CEBM levels of evidence system. I will fully understand if you are too busy to reply to this presumption on your time. Warm regards Tim Blackburn FRCS(OMFS)(Ed) FRCS(Clin Surg in Gen)(Ed) FDSRCS(Eng) MBBS(Hons)(Lon) BDS(Hons)(Lon) Consultant Oral Maxillofacial Head & Neck Reconstructive Surgeon, Manchester Royal Infirmary T: +44 (0)7885 294097