Major Surgical Complications in Spine Surgery: Is Age a Significant Risk Factor?

Methods: All adult patients undergoing spine surgery at our center over a four-year period were included in this study, for a total of 1937 patients (605 age 18 - 39; 1001 age 40-64, 331 age 65 and over). One independent observer abstracted baseline medical histories and comorbidities as well as post-operative complications. Major risk factors explored included history of cardiac disease, cancer, smoking, diabetes, substance abuse, obesity, respiratory problems, previous infections and hypercholesterolemia. Details of surgical procedure, including type of surgery, duration of surgery and blood loss were also captured. Major complications were defined as death, CVA, embolism, pneumonia and deep wound infections.Patients ranged in age from 18 years to 91 (average age 48 years) and 41% were males. Thirty percent of the population was deformity patients, 49% degenerative patients and the remaining 21% had various other spine problems. Thirty-five percent of the patients underwent a combined anterior posterior procedure, 13% anterior alone and 34% posterior alone.Statistical analysis included descriptive summary, bivariate correlation to assess individual risk factors (univariate analysis) and multivariate regression.

Results: The overall major complication rate was 2.1% (40 patients). There were no intra- or post-operative deaths. Major complications included 7 CVA (0.4%), 2 embolism (0.1%), 3 deep wound infections (0.2%) and 28 pneumonia (1.4).Comorbidities increased with age (percent of patients with any major comorbidity: 45.8% age 18 - 39; 62.4% age 40 - 64; 82.2% age 65 and older; p<0 .05). Incidence of any major complications increased with age (1.7% 18 - 39; 1.5% 40 64 and 3.7% 65 over; p<0.05); similarly the incidence pneumonia also (p< 0.05). The complication were for patients either history respiratory problems or previous infections. When effect these two comorbidities taken into account, was NOT a significant risk factor (multivariate regression, p>0.05).

Discussion: Although this study included a large population of nearly 2000 patients, the overall low incidence of major complications limits the analysis available. Conclusions related to risk factors for death, CVA, embolism and deep wound infections are limited.Simple analysis of major risk factors indicates that major complications increase with increased age. Confounding this finding is the increase of underlying comorbidities with increased age as well. The comorbidities were found to be stronger indicators of risk of complication than age itself. Thus patients with similar baseline comorbidities are compared, age is not a significant risk factor.

Conclusions: The overall complication rate in this population is low. Although the number of complications was higher in the elderly, comorbidities are the more important factor to be considered in making surgical decisions and assessing risks. In patients with similar comorbidity profile, age is not a significant risk factor.