Characteristics of the matched cohort of patients who underwent total knee arthroplasty*
| Characteristic | No. (%) of patients† | p value‡ | |
|---|---|---|---|
| Spinal anesthesia n = 2790 | General anesthesia n = 2790 | ||
| Sex | > 0.99 | ||
| Male | 1009 (36.2) | 1009 (36.2) | |
| Female | 1781 (63.8) | 1,781 (63.8) | |
| Age, yr, mean ± SD | 66.2 ± 9.3 | 66.2 ± 9.5 | 0.84 |
| BMI, mean ± SD | 33.4 ± 6.4 | 33.3 ± 6.6 | 0.78 |
| ASA score | 0.98 | ||
| 1 or 2 | 1845 (66.1) | 1847 (66.2) | |
| 3 or 4 | 945 (33.9) | 943 (33.8) | |
| Medical comorbidities§ | |||
| Cancer | 361 (12.9) | 362 (13) | > 0.99 |
| Cardiac illness | 771 (27.6) | 779 (27.9) | 0.83 |
| Chronic hepatic conditions | 47 (1.7) | 47 (1.7) | > 0.99 |
| Chronic pulmonary conditions | 284 (10.2) | 291 (10.4) | 0.79 |
| Chronic renal conditions | 89 (3.2) | 91 (3.3) | 0.94 |
| Dementia | 30 (1.1) | 32 (1.1) | 0.90 |
| Diabetes with complications | 595 (21.3) | 605 (21.7) | > 0.99 |
| Previous stroke | 48 (1.7) | 48 (1.7) | > 0.99 |
| Obesity | 783 (28.1) | 783 (28.1) | > 0.99 |
| Moderate or severe mental health disorders | 131 (4.7) | 131 (4.7) | > 0.99 |
ASA = American Society of Anesthesiologists, BMI = body mass index, SD = standard deviation.
↵* 22 357 records of patients with spinal anesthesia were extracted and matched with 2790 records of patients with general anesthesia on age, sex, BMI, ASA Score and baseline comorbidities using the propensity score matching technique.
↵† Unless indicated otherwise.
↵‡ Propensity scores were used to control for selection bias between the spinal and general anesthesia groups, and propensity-adjusted p values (from χ2 test for categorical variables and by Student t test for continuous variables) for preoperative patient characteristics are reported. The model successfully reduced selection bias by eliminating significant differences in preoperative variables (the adjusted p value was > 0.05 for all).
↵§ Chronic pulmonary conditions include congenital disorder of the respiratory system, chronic obstructive pulmonary disease, pulmonary hypertension, respiratory failure, cystic fibrosis, tuberculosis and other chronic lung disease.
Moderate or severe mental health disorders include delusional disorder (including schizophrenia), bipolar or manic mood disorder, eating disorder, intellectual disorder or delay, and mental disorder resulting from brain injury or other illness.