Author's response to reviews Title: Mortality after Primary Shoulder Arthroplasty: An analysis of 4,019 patients from 1976-2008 Authors:

“BMI ≥ 30 was associated with lower risk of 90-day mortality (OR, 0.25; 95% CI:0.08,0.78). In univariate analyses, patients undergoing TSA had significantly lower 90-day mortality of 0.4% (8/2,580) compared to 1% in HHR (20/1,411) (odds ratio, 0.22 (95% CI: 0.10, 0.50); p=0.0003). Conclusions: 90-day mortality following shoulder arthroplasty was low. An underlying diagnosis of tumor, higher comorbidity and higher ASA class were risk factors for higher 90-day mortality, while higher BMI was protective. Pre-operative comorbidity management may impact 90-day mortality following shoulder arthroplasty. A higher unadjusted mortality in patients undergoing TSA versus HHR may indicate the underlying differences in patients undergoing these procedures.” Under diagnosis, the category tumor is missing. The Deyo-Charlson index has to be cleared up with literature/reference. Response: The category tumor was provided in the first table as the third row under diagnosis (n=182 (5%)) and also in table 2. We have added additional explanation regarding Deyo-Charlson index as suggested. “(c) Deyo-Charlson Index, a validated measure of medical comorbidity (11), is a summative weighted scale of 17 comorbidities (including cardiac, pulmonary, renal, hepatic disease, diabetes, cancer, HIV etc.), for example, conditions such as myocardial infarction, dementia, peptic ulcer disease etc. each get a score of “1”; diabetes with endorgan damage, hemiplegia, renal disease, malignancy each get a score of “2”; moderate-severe liver disease a score of “3”; metastatic solid tumor and AIDS/HIV each get score of “6” – this was categorized as 0 or ≥1, since the median for this population was zero” What is the mortality of an matched (age, gender, comorbidity, DeyoCharlson, ASA class) population in comparison to the study group? It were all elective cases except trauma? Were fracture cases operated