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The Spine Blog

Sunday, April 14, 2019

Risk factors for readmission following lumbar surgery

Risk factors for readmission after spine surgery have been studied extensively, generally using large administrative databases. Smaller investigations looking at the experience at a single institution have also been published but have generally included fewer patients and have been relatively underpowered. While administrative databases include large numbers of patients, they generally lack the clinical details germane to spine surgery necessary to draw meaningful conclusions. The Quality and Outcomes Database (QOD) was created to capture large numbers of spine surgery patients along with the important details relevant to spine surgery such as patient reported outcomes, underlying diagnosis, and surgical technique. This database captures spine surgery patients from 86 institutions in the United States through chart review and patient questionnaires. The current study used data from over 33,000 lumbar surgery patients in order to evaluate risk factors for 90-day readmissions. Patients with deformity, infection, trauma, and tumor were excluded. The authors classified the readmissions as medical (i.e. DVT, PE, cardiac disease, renal disease, non-surgical site infection, etc.) or surgical (i.e. surgical site infection, wound dehiscence, CSF leak, disk reherniation, hardware failure, new neurologic deficit, hematoma or pain) and developed multivariate regression models evaluating risk factors for the two types of readmissions. The overall 90-day readmission rate was 6.15%, with 2.5% being readmitted for medical complications and 3.6% for surgical complications. The risk factors for both medical and surgical readmission were higher ASA grade, increased number of levels treated, higher baseline ODI score, and anterior approach. Increased age, male gender, heart disease, unemployment, fusion, and not smoking were risk factors specific for medical readmission. Specific surgical readmission risk factors included increased BMI, female gender, depression, and African American race. With the possible exception of non-smokers being at higher risk for medical readmission, these risk factors are consistent with the prior literature on the topic.

The authors have done a nice job using a relatively novel dataset to explore risk factors for readmission following lumbar surgery. They identified the usual suspects for readmission—increasing age, medical and psychosocial comorbidities, and surgical invasiveness. The one anomaly is that smokers were at somewhat lower risk for medical readmission, though this has been shown in prior studies. The causal chain behind this association is not clear, though active smokers may be generally younger and more robust than non-smokers. Additionally, smokers are strongly motivated to stay out of the hospital where smoking is not permitted, and they have shorter hospital length of stay following surgery. While this study does not provide any new information, it supports what has been shown in the literature and this consistency helps to validate the QOD database. The real question is whether this information can be used to identify patients at high risk for readmission and intervene in some way to lower their readmission rate. Very little has been published on this, though it seems that diverting increased resources (i.e. nurse phone calls, visiting nurses, more frequent follow-up with primary care providers, etc.) to high-risk patients could save resources in the long-run. While some complications and readmissions are unavoidable, many readmissions could likely be avoided with increased intensity of post-operative care. Currently, decisions about which patients to target for more post-operative surveillance are based on provider perception and patient demand. Models like those in the current study might be used to select patients for such an intervention in a more accurate, objective fashion. Hopefully future studies will evaluate such programs to determine if they are effective.

Please read the article by Dr. Sivaganesan and colleagues in the April 15 issue. Does identifying these risk factors change how you will target patients for increased post-operative surveillance? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor