Adult spinal deformity surgery patients may have “significantly lower” chance of complication when treated at teaching hospitals

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PatientA study published in the Journal of Neurology: Spine has found that “patients who undergo adult spinal deformity surgery at a teaching hospital may have significantly decreased odds of developing a postoperative complication”, in comparison with patients treated at nonteaching hospitals in the USA. The results come from a retrospective study of a prospectively collected database—the US Nationwide Inpatient Sample—which provides inpatient data from about eight million admissions per year.

The research team—led by Rafael De la Garza-Ramos (Baltimore, USA)—noticed that results from teaching and nonteaching hospitals for certain spinal conditions seemed to vary, with only “limited data on the impact of teaching status on inpatient outcomes” available for adult spinal deformity. “Although teaching hospitals claim better quality of care than nonteaching hospitals,” the authors state, “there have been conflicting data when examining outcomes specifically in degenerative spinal disease cases.”

Hypothesising that outcome results would vary between teaching and nonteaching hospitals for adult spinal deformity cases, the authors investigated the records of 7,603 patients who had undergone elective surgical treatment for adult spinal deformity between 2002 and 2012.

As well as collecting demographic information (age, gender, etc.), the team identified complex cases—demarcated by fusion of more segments, and/or cases involving osteotomy—as well as revision cases, according to International Classification of Diseases, Ninth Revision coding. The researchers considered a centre to be a teaching hospital “if it has an American Medical Association-approved residency programme, is a member of the Council of Teaching Hospitals, or as a ratio of interns and residents to beds of one to four or higher.”

The total number of patients treated at a teaching hospital was 4,650 (61.2%), with 2,953 (63.2%) treated at nonteaching hospitals. The mean age of patients at nonteaching hospitals (62 years) was significantly higher than at teaching hospitals (59 years, p<0.0001). Primary payer data, as well as rates of comorbidities was significantly different between centre type, with nonteaching hospitals treating more Medicare patients (53.7% versus 45.6%, teaching hospitals) and more patients with diabetes (12% versus 9.5%) and chronic lung disease (18.2% versus 15.6%). Treatment for more patients in the teaching hospital group was primarily funded by private insurance companies (46.2%) in comparison to those at nonteaching hospitals.

The proportion of patients undergoing complex treatment and revision procedures were also significantly different between the groups, with teaching hospitals performing complex surgeries 27.3% of the time (21.7%, nonteaching hospitals) and revision surgeries 5.2% of the time (3.9%, nonteaching hospitals).

Data were evaluated for inpatient morbidity, which was defined as the development of one or more complications, as well as inpatient mortality and length of stay. A large number of complications were examined—including acute respiratory failure, acute kidney injury and pneumonia—with a subcategory of procedure-related complications defined. This sub-category included such complications as wound complication, iatrogenic stroke and neurological complication.

Researchers found significant differences in crude length of stay between the groups, with an average of seven days at teaching hospitals in comparison with 5.2 in nonteaching hospitals. The overall crude complication rates were 47.9% (40.8% procedure-related) in teaching hospitals, and 49.8% (42.8%) in nonteaching. Mortality rates were 0.4% in both groups of patients.

Once a multivariable logistic regression analysis was performed, researchers observed that “having adult spinal deformity surgery at a teaching hospital was associated with significantly lower odds of developing a postoperative complication” (odds ratio 0.89, 95% confidence interval 0.82–0.98; p=0.03). “Importantly,” they comment, “this analysis controlled for operative parameters such as number of fused segments, osteotomy, and revision procedures, as well as patient characteristics.” Variables most associated with complication were coagulopathy (odds ratio 4.3, 95% confidence interval 3.5–5.3; p<0.001), revision procedure (odds ratio 3.4, 95% confidence interval, 2.6–4.4; p<0.001) and complex procedure (odds ratio 2.1, confidence interval 1.9–2.4; p<0.001).

To further investigate the complication risk associated with complex procedures, researchers performed a further multivariable analysis, which “revealed that teaching hospitals had a significantly reduced risk of complication development (odds ratio 0.58, 95% confidence interval 0.47–0.72; p<0.001) compared with nonteaching hospitals.”

The authors speculated that the higher complexity of adult spinal deformity surgery in comparison to procedures used to treat degenerative spinal disorders could be a reason for the discrepancy in complication rates observed for these procedures at teaching hospitals. “Commensurate with our findings, other studies have found better outcomes in teaching hospitals for more complex procedures such as lung cancer resection, abdominal hysterectomy” and others.

Authors reported a number of limits to the study—including the retrospective nature of the study, the lack of information regarding Cobb angles, etc., and the risk of hospital “upcoding bias”, for example. Further research, the authors suggest, is needed “before definitive conclusions can be established.”

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