Table 4.
Final multiple linear regression analysis for total amount billed (log2 value)
| Value name | β coefficient | 95% CI | P-value |
|---|---|---|---|
| (Constant) | 20.091 | 19.420 to 20.761 | <0.001* |
| Age | 0.008 | 0.005 to 0.012 | <0.001* |
| Type of insurance | |||
| Not insured | Ref. | N/A | N/A |
| Medial aid | –1.173 | –1.833 to –0.513 | 0.001* |
| NHI | –0.793 | –1.407 to –0.179 | 0.012* |
| Admission year | |||
| 2011-2012 | Ref. | N/A | N/A |
| 2019-2020 | 0.578 | 0.413 to 0.744 | <0.001* |
| 2017-2018 | 0.524 | 0.359 to 0.689 | <0.001* |
| 2015-2016 | 0.292 | 0.124 to 0.459 | 0.001* |
| No. of comorbidities | 0.082 | 0.027 to 0.136 | 0.003* |
| Flynn score | 0.037 | 0.015 to 0.060 | 0.001* |
| Admission C-reactive protein level | 0.02 | 0.013 to 0.026 | <0.001* |
| Admission white blood cell count | 0.019 | 0.007 to 0.031 | 0.002* |
| Admission blood glucose level | 0.001 | 0.000 to 0.002 | 0.038* |
| Admission body temperature >37.5℃ | –0.201 | –0.388 to –0.014 | 0.035* |
| Peak body temperature >37.5℃ | 0.321 | 0.163 to 0.479 | <0.001* |
| Surgery performed after admission | 0.76 | 0.552 to 0.968 | <0.001* |
| Type of surgery | |||
| I&D alone | Ref. | N/A | N/A |
| Other surgery without I&D | –0.42 | –0.828 to –0.013 | 0.043* |
| Length of surgery under GA | 0.005 | 0.003 to 0.007 | <0.001* |
| I&D location | |||
| Operation room | Ref. | N/A | N/A |
| Outpatient clinic after admission | –0.569 | –0.764 to –0.374 | <0.001* |
| ER | –0.465 | –0.703 to –0.227 | <0.001* |
| Tracheostomy performed | 0.595 | 0.218 to 0.972 | 0.002* |
| Time from admission to first surgery | 0.069 | 0.032 to 0.106 | <0.001* |
| Length of ICU stay | 0.031 | 0.018 to 0.043 | <0.001* |
| R value | 0.904 |
(CI: confidence interval, Ref.: reference, N/A: not applicable, NHI: National Health Insurance, I&D: incision and drainage, GA: general anesthesia, ER: emergency room, ICU: intensive care unit)
*P<0.05.
The following variables were eliminated from the multivariable analysis model to adjust for clustering of outcomes: number of infected spaces, medically compromised, diabetes mellitus, incision and drainage, GA performed, additional surgery performed, ICU use.