Volume 23, Number 5—May 2017
Research
Invasive Nontuberculous Mycobacterial Infections among Cardiothoracic Surgical Patients Exposed to Heater–Cooler Devices1
Table 4
Results from logistic regression models to evaluate exposure length variables in investigation of invasive extrapulmonary NTM infections among patients who underwent cardiothoracic surgery, York, Pennsylvania, USA, 2015*
Regression models | Odds ratio (95% CI) | p value |
---|---|---|
Univariable models† | ||
Patient characteristics | ||
Age, per 1-y increase | 1.0 (1.0–1.1) | 0.4 |
Male sex | 3.0 (0.7–16.8) | 0.2 |
White race | 1.8 (0.2–244.3) | 0.7 |
Chronic lung disease: yes | 2.9 (0.7–11.4) | 0.1 |
Diabetes: yes | 0.3 (0.03–1.5) | 0.2 |
Immunocompromised: yes |
1.5 (0.3–6.0) |
0.6 |
Length of surgical exposure | ||
Surgical time with HCD, h | ||
0 | Referent | |
>0 to <4 | 1.8 (0.2–15.4) | 0.6 |
≥4 to <5 | 2.6 (0.2–23.6) | 0.4 |
≥5 | 15.6 (3.2–103.9) | 0.002 |
Time on bypass, h | ||
0 | Referent | |
>0 to <2 | 1.7 (0.2–12.2) | 0.6 |
≥2 |
19.0 (3.7–133.0) |
0.001 |
Final logistic model‡ | ||
Model 1.1, only surgical time with HCD retained in the final model: Surgical time with HCD >5 h | 13.2 (3.2–62.9) | 0.0008 |
Model 1.2, includes surgical time with HCD and immunocompromised status | ||
Surgical time with HCD >5h | 13.6 (3.3–68.8) | 0.001 |
Immunocompromised: yes | 2.2 (0.4–12.2) | 0.4 |
Model 2.1, only time on bypass retained in the final model: Time on bypass >2 h | 16.5 (3.8–84.0) | 0.0004 |
Model 2.2, includes time on bypass and immunocompromised status | ||
Time on bypass >2h | 16.6 (3.8–88.4) | 0.0006 |
Immunocompromised: yes | 2.1 (0.3–12.0) | 0.4 |
*HCD, heater–cooler device; NTM, nontuberculous mycobacteria.
†Regression models for factors considered in the multivariable model; each regression model used Firth’s penalized maximum likelihood method.
‡Each final regression model used Firth’s penalized maximum likelihood method; other variables (sex, age, immunocompromised status, chronic lung disease) were removed because of nonsignificance.
1Preliminary results from this study were presented at the Epidemic Intelligence Service conference, May 2–5, 2016, Atlanta, Georgia, USA; and the American Society for Microbiology Microbe conference, June 16–20, 2016, Boston, Massachusetts, USA.