The Spine Blog

Friday, May 2, 2014

The Usual Suspects: Predictors of Length of Stay and Readmission After Laminectomy

Many papers have looked at predictors of patient reported outcomes and complications following laminectomy for lumbar spinal stenosis, with age, comorbidities, increased body mass index (BMI), smoking, larger magnitude of surgery, and revision surgery all predicting worse outcomes and a higher rate of complications. As payers and policymakers begin to focus more on quality metrics as possible drivers of reimbursement, both length of stay (LOS) and readmission rate have been suggested as proxies for the quality and value of services provided. While these outcomes are not likely the most important from the patient’s perspective, increased LOS and readmission are both significant drivers of cost and are likely here to stay as measures of the quality of care. On this background, Dr. Grauer and his colleagues at Yale performed an analysis of the National Surgical Quality Improvement Program (NSQIP) database to determine independent predictors of both LOS and readmission within 30 days following lumbar laminectomy for spinal stenosis. They queried the database for 2011 and 2012 and included 2358 stenosis patients undergoing laminectomy without fusion in their study. The average LOS was 2.1 days, and the 30 day readmission rate was 3.7% Patients who had a LOS of ten or more days (1% of the population) were not included in the readmission analysis as the database only included 30 days from the date of surgery, and much of this time was taken up by the inpatient admission in this group. Not surprisingly, the strongest predictors of increased LOS and readmission were increasing age, increasing BMI, and American Society of Anesthesiologists (ASA) score of 3 or 4. Patients 80 or older stayed on average an additional day compared to those less than 60, and those with a BMI over 35 had odds of readmission nearly 4 times those with a normal BMI. Additionally, baseline hematocrit less than 36 predicted increased LOS and pre-operative steroid use predicted readmission. Not surprisingly, the most common cause of readmission within 30 days of surgery was surgical site infection.


Now that payers and policymakers have started to focus on proxies for quality of care such as LOS and readmission rate, papers like this play an important role in understanding these phenomena. The strongest predictors of increased LOS and readmission were the usual suspects—age, obesity, and comorbidities. Unfortunately, with the possible exception of obesity, these are generally not modifiable, so they are unlikely targets for interventions to reduce the risk of increased LOS and readmission. However, this paper does provide information to share with patients pre-operatively so that individual patients get a sense of their individualized risk for increased LOS and readmission. These data can also be used in risk adjustment models so that providers and hospitals treating different patient populations can be compared fairly. Further investigations should look at the effect of peri-operative complications (i.e. durotomy, medical complications, etc.) and magnitude of surgery on these otucomes, as they will almost certainly have an effect. This paper also offers an interesting commentary on the type of patients undergoing laminectomy—in this series, 40% were over age 70, 50% were ASA 3 or 4,  and 20% were diabetic. While laminectomy without fusion is considered to be a relatively benign surgical intervention, any intervention in such a population comes with relatively high risks. Patients who have these and other risk factors should be advised of their increased risk of complication during the consent process such that they are truly informed about the possible outcomes.


Please read Dr. Grauer’s article on this topic in the May 1 issue. Does this article change how you view the problems of increased LOS and readmission following laminectomy? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor