Eva Pamias, MD1, Hermes Garcia, MD1, and Gisela Murray, MD1
1Section of Neurosurgery, Medical Sciences Campus, University of Puerto Rico, San Juan, Puerto Rico
“The Impact of Provider Volume on the Outcomes After Surgery for Lumbar Spinal Stenosis,” by Dasenbrock et al. Neurosurgery. (June 2012).
1. Significance/context and importance of the study:
The hospital and surgeon’s volume and its impact in the outcome of surgery has been subject of study for many years in the neurosurgical field. This investigation give surgeons and patients an evidence base perspective regarding the importance of the volume-outcome association for lumbar spinal stenosis surgery, making this study a very important tool for patients and referring colleagues in order to decrease the risk of complications for this type of surgery.
2. Originality of the work
There have been previous articles that address the volume-outcome subject for different types of neurological surgeries. However, this study is very original in terms of using a nationwide inpatient sample data in order to evaluate spinal stenosis; an area with very limited previous publications regarding the relation of volume-outcome.
3 and 4. Appropriateness of the study design or experimental approach/ Adequacy of experimental techniques:
This study use of a retrospective data that was collected form an agency that use the nationwide data to keep adequate quality control on healthcare. This data, together with the use of a multivariate logistic regression analysis and the continuous provider volume evaluation, makes the study design trustable regarding the data collection and experimental techniques.
5. Soundness of conclusions and interpretation;
The interpretation of data can be very challenging in a study using data from different institutions. The inclusion criteria for this study, including in-hospital mortality, complications, length of stay and discharge disposition, was taken into consideration for the presentation and interpretation of the data. The demographics, surgeon volume and hospital volume was interpreted properly and later presented in the conclusion in a very convincing way.
6. Relevance of discussion:
The authors presented the discussion in a very objective way. Not only including the strengths of the study, but also pointing the limitations, including collecting the data from the NIS, and how this fact leave a question regarding the data of the other hospitals not included in the investigation. The relevance of this, relay in the fact that future investigation is needed for this subject.
7. Clarity of writing, organization of paper
The organization was simple and concise, most notably in the discussion where the authors commented on each relevant point findings and results of their study. After the first paragraph summarized their study findings, each subsequent paragraph further discussed details of such finding and their interpretation was stated at the end of each paragraph. Also of note, the Results section was clearly organized with headings to focus the reader on whether analysis was on Hospital Volume, Surgeon Volume, or subgroup analysis of fusion and decompression, thus reviewing the paper is quick and sections are found easily. This helps the reader analyze their interpretations for further commentary and clearly understand the points the authors want to emphasize. For last, the clarity in writing of this paper is such that as a resident, one can approach a not completely academic theme of provider volume and costs with familiarity.
8. Economy of words
As stated in a prior section, one of the strengths of this article is the clarity in the text, which is mostly a result of the economy of words. No extensive narrative or excessive complex wording is used. The article is approachable and the relevant points are clearly expressed.
9. Relevance, accuracy and completeness of bibliography
The authors state one of the initial publications regarding volume-outcome association (Luft et al 1979)(1), and provide several other publications (2-55) regarding provider volume-association on outcome mostly relevant to other medical or surgical practices. This points to how such analysis can be applied in general to different specialties, including cardiothoracic, colorectal & neurosurgery. Review of those articles helps the authors choose and utilize an adequate database to perform their study from a general, not necessarily neurosurgical perspective. Further interpretations of their results, from a more focused neurosurgical point of view, is supported by articles (54-72). Articles chosen as review for this study were found relevant and accurate for the purpose of the study, however further articles regarding the relevance of the relationships of volume with readmission rates and with long-term outcomes (stated in the first paragraph of page 1352) would have strengthened this statement.
10. Number and quality of figures, tables and illustrations
The data in this study was presented in relevant tables, for example Table 2 and 3, regarding the association of surgeon volume on their chosen outcome measures. Due to the multitude of outcome measures and quartiles, presenting this kind of data without confusing the reader is challenging. Despite the initially overwhelming data in the tables, the authors were able to explain what is relevant in each in the narrative, thus making the tables more accessible. The figure was helpful to visualize the trends and % regarding each outcome, however, marking which of those percentages was statistically significant would have strengthened the figure.
11. Future/Next Step
The authors clearly and thoroughly state the several limitations to this study to highlight several topics to further analyze in future studies. As always, a prospective approach is suggested, so as to obtain data regarding more specific outcome measures towards spinal stenosis, that will add knowledge regarding the impact of surgeon and hospital volume on improvement of pre-operative pain and neurological function. As stated by the authors, despite the utility of the NIS database, those outcomes are not obtainable from it, arguing on the necessity of clearly stating those outcome measures used in a neurosurgical setting, such as the Visual Analog Scale and the Oswestry Disability Index.