Table 2 and Graphs 1, 2, and 3 illustrate descriptive statistics. Our cohort averaged 74.61 years (SD = 6.47) and included 188 patients between 60 and 69 years of age, 309 between 70 and 79, and 179 between 80 and 89.
Seventy-nine medical complications were recorded: 24 urinary tract infections, 18 lobar pneumonias, 10 deep vein thrombosis (2 of which were further complicated by pulmonary embolism), 12 cerebrovascular accidents (8 transient ischemic attacks, 4 ischemic strokes, one of which resulted in death), and 15 cardiological complications (8 atrial fibrillations requiring pharmacological treatment, 7 myocardial infarctions including 5 treated with coronary angioplasty and stent placement and 1 fatality).
Fifty-two early surgical complications were also encountered that presented the following distributions: 16 CSF leaks (seven of which required surgical revision), 11 wound dehiscences (nine necessitating reoperation); 13 postsurgical hematomas (all subsequently incised and drained), 12 radicular post decompressive deficits (6 of which did not report any further neurological recovery).
Total late surgical complications were 63 (12 spondylodiscitis, 21 device mobilizations/screw fractures, and 30 adjacent segment diseases). Table 3 summarizes complications’ distribution with their respective percentages.
The different distributions and means of the hypothetical risk factors are analyzed and illustrated in Table 2. More specifically, there were 104 patients in ASA class 1 (15.41%), 250 ASA class 2 (37.04%), 221 with ASA 3 (32.74%), and 100 in a constant threat of life (ASA 4, 14.81%).
Sixty elderlies were under anticoagulant therapy, while 165 under antiaggregant. BMI averaged 26.06 (SD = 2.74). One hundred seventy-six individuals suffered from osteoporosis, while 103 had diabetes mellitus (60 of which were insulin-independent and 43 insulin-dependent).
Statistical analysis demonstrated that the percentage of individuals with ASA 4 and the percentage of patients taking anticoagulant therapy was significantly lower between individuals in their sixties and seventies with respect to those in their eighties (8%, 14.3%, and 23%, respectively for ASA 4 (Χ2 (2) = 39.357, P < 0.001) and 16.7%, 41.7%, and 41.7%, respectively for use of anticoagulants (Χ2 (2) = 8.911, P = 0.012)) which probably accounts for the higher absolute number of medical complications found in the latter group (Χ2 (2) = 9.041, P = 0.003).
A high BMI raises considerably chances of suffering from medical complications, irrespective of age groups (B = 0.366, Wald = 37.701, P < 0.001).
Taking antiaggregant therapy did not increase the risk of developing medical complications in this type of surgery. It may have only a weak correlation with overall early surgical complications (B = 0.910, Wald = 5.895, P = 0.015), especially for what concerns wound dehiscence (B = 1.754, Wald = 4.684, P = 0.030). Similarly, osteoporosis was the only weak significant risk factor that correlated with late surgical complications (B = 0.712, Wald = 3.874, P = 0.049).
Importantly, when controls for the other variables were added to the regression, age was never a significant predictor for any of the above listed complications except cerebrovascular diseases (Table 3 and Table 4) which on the contrary were significant at P = 0.005 (B = 1.745, Wald = 7.715).
Conversely, other risk factors such as ASA (B = 0.888, Wald = 15.019, P < 0.001), ID diabetes (B = 1.734, Wald = 13.896, P < 0.001), and anticoagulant use (B = 1.696, Wald = 16.556, P < 0.001) positively correlated with medical complication rates. Interestingly, NID diabetes had a negative correlation with the latter (B = − 1.051, Wald = 4.090, P = 0.043).
Considered all together, early surgical complications were not different between the three age groups. Post-surgical CSF leaks, hematomas, and neurological deficits were not determined by any other risk factors.
Finally, in our study, ASA and BMI were the two risk factors that positively correlated with the highest number of complications; more specifically, both were associated with UTI, pneumonia, cerebrovascular accidents, and spondylodiscitis, while ASA was with TVP alone and BMI with device mobilization alone as well.